Thinking about getting one for my Colt 6720. It would be something for close range deer hunting. Is there a best,and what do I need to know about them?

Get a Wilson barrel when they have their next sale. Out of three, all have shot MOA or better.

There are other good barrels - White Oak, Daniels Defense, etc that will perform as well, I just have more Wilsons.

Remington green/white boxed ammo is usually pretty cheap, pretty dirty, and hasn’t grouped for me.
S&B Ammo doesn’t group well for me, YMMV.

Hornady has been my constant performer OTC in 110-120 grain.

I usually run an 18 barrel mid-length, and have one rifle length.

Haven’t connected with the deer,yet. They were on the wrong side of the fence, so can’t comment the knockdown.

RE what they do to deer, I've a 6/6.8. It kills fine. Can't tell any difference between it and a 223, so the full on 6.8 will do just fine.

Beyond that no comment.

If it was I my first and last contact would be Ben Tripplet at bison Arms. They use bat extension match barrels and stand behind their stuff very well.
The fulcrum barrels are as good as anything out.

I have 3 of them
1st one I bought from Iron works tactical
Two.More I built

All have ARP Barrels
All shoot less than an inch at a Hundred Yards with Hornady 120 SST Factory loads.

Kills Deer just fine,little recoil.

Last ammo I bought was from PSA, xm68gd. 90 grain bonded Bullet At about 2800 FPS out of a 16 inch barrel !!
Bought for 7.99 a box of 20,If you end up getting one get on the notify list from PSA.Once they notify you act immediately as they go FAST

I realized I don't need three 6.8 rifles so I have listed the one I bought from Iron Works Tactical in the classifieds.

I have only one with a wilson combat barrel, its OK but mine has not been spectacular., 1-2 inch groups with everything I have shot in it. I used a stag bolt, a bravo company KMR handguard and a upper receiver AH64 guy sold me. I hunt with the gun regularly, its main attribute is that it make a bigger exit hole than a 223 and bigger blood trail.

My daughter used one for a few years, 20” ARP barrel. Shoots at least MOA and some loads better. We hunted with handloaded Barnes 95gr TTSX bullets and the factory federal XM68GD a 90 gr Speer gold dot bullet. Both loads have worked outstanding on Texas deer and hogs. Go check out the 6.8 forum, you’ll get tons of info and pics.

another good place to deal with for 6.8 barrels is AR15 performance. There is a TON of info at 68forums.com

When he's open, taking orders & has stock..........which doesn't seem to be very often.

MM

Predator masters have the 6.8 covered.

kwg

Are you buying a complete upper or assembling yourself?
If building your own, there have already been some great suggestions regarding barrel brands. I have used ARP for my own 6.8s in the past with satisfactory results.

I would focus more on what options you want and go from there. What is your target weight, barrel length preference, etc. Almost every brand of AR made today is capable of shooting 2MOA or less. Most are capable of 1MOA or better. You state your needs are for close range deer. What we consider close range varies, but even a rifle that only shoots 2MOA is fine for deer out to 300 yards, which is within the window the 6.8 performs best at.

Check with Harrison at ARP. The knowledge you get from him in addition to the barrel will be excellent.

Go with a ARP (AR Performance) barrel. Great barrels, great price and as mentioned above mine shoot sub MOA with factory Hornady 120gr SST loads. The SST performs well on deer.

ARP 16”, Scout profile (5R). Factory 120gr Hornady SST. Can’t recall if it was 267 yards or 276 yards. Either way it was a bang! Flop!







Factory Hornady 120gr SST (200 yards).



Factory SSA 110gr Accubond (200 yards).

Nice rifle Smack 😁

Blackstone Arms in Texas builds custom uppers that are a better grade than PSA or Stag. He squares the receivers and beds the barrels, test fires every upper. Very experienced with the 6.8. He uses ARP barrels and Viking rails.

You may be exaggerating a little, closes at 5pm eastern time. The barrels sell out quick. It is a small shop and a limited amount of product is added to the site every day to keep from having long shipping delays.

Every time I visit his site he is sold out

I don't know about their recent offerings, but I can also vouch for them. I have an easy half dozen + great deer rifles, but that Bison 6.8 upper on my Rock River lower comes out of the safe each fall, and's been gittin' 'er done for 6-7 years. Great accuracy, easy to carry, All aluminum and stainless so easy care until the end of the season. Bison.

How about 6.5 Grendel? Debating between the two for a deer/hog hunting setup. Seems more follks are building the 6.8, but the Grendel is a little cheaper to shoot. Looking for a lightweight upper that wont cost a grand.

You saying a Grendel is cheap to build and shoot than a 6.8 spa? I"d never have thought I"d see that day.

OTOH a lot of whats up, is what do you have and what do you want? I have a 6.8 necked to 6. So I'd go Grendel anyway but it was always going to be a higher dollar build and ammo.

Rost,
It seems there a quite a few low cost options in Grendel factory ammo compared with the SPC. With quality parts, it seems both uppers will be about the same to build, if I don’t build it myself. Both seem to preform about the same inside 300 yds, and from what I’ve been reading, past that the Grendel seems to outperform the SPC.

The reason I asked is that I’m trying to get my wife to come hunting with me (mostly Eastern deer for her to start with). She’s a lefty, has an AR, and is comfortable shooting that. She’s small and recoil sensitve, so I was thinking of picking her up a lefty youth 243 bolt gun to start with, but also was considering the Grendel or SPC for her since she’s familiar with, and comfortable with her AR. If she takes to it, hunting mulies and pronghorns is in her future, so I thought she wouldn’t have to move to another rifle for that. With the pics I’ve seen, the SBC/Grendel can get that done too, which wasn’t on my fadar before but is now. Thanks for the information, it’s much appreciated.

Craig

if you can't kill a deer with a good bullet and 223, the issue isn't with the 223 choice... FWIW. I"ve taken them out to almost 600 with the 223 and never lost or wounded a single one.... barnes is a great start bullet wise... partitions are not out of the formula either. The 63 Sierra semi point is one of the few reliable Sierra bullets I still trust

I’ve killed a lot of stuff with a 223. The 6.8 and others are just better suited to it, if it’s deer and hogs. Odd angles and getting an exit, is where some cartridge/bullet combos might have issues. Angles, distance, time, and movement all need to line up more perfectly than others, for some stuff. Stand hunting vs still hunting or even drives, hogs moving at night, areas impossible to track....those beg for more, IMO. I’ll probably still kill some deer/hogs with my 223s this year. It’ll probably all happen from stands under controlled scenarios and I’ll carry something with more bullet at other times. JMO

I've been shooting some of that Wolf "military classic" 6.5 Grendel load, and have been pleasantly surprised with it's accuracy and performance from my 12.5" barrel. For $5-$6 per box of 20, it's pretty cheap to shoot IMO.

I was a fan of the 6.8 until I stopped listening to the 6.8 fanboys and tried a Grendel too. Don't think I'll go back. Unfortunately the 6.8 SPC has a lot of fanboy hype around it, so it can be hard to find good accurate info. (The Grendel probably does too, for that matter, but I've pretty much ignored it and done my own thing, as I went against conventional Grendel wisdom with the short 12.5" barrel and it's worked out great.)

I'll just leave this here. Just finished.

Colt LE6920 built into 6.8 SPC II.



AR15Performance 16" 6.8 SPC II 3R T-Scout barrel
AR15Performance NIB 7.62 bolt
Midwest Industries 12" G3 lightweight M-Lok handguard
YHM 9383 low profile mid-length gas block
Geissele SSA-E trigger
Zeiss Conquest V4 4-16x44 duplex scope
Seekins 30mm rings
Silencerco Hybrid suppressor
Silencerco ASR flash hider/mount
ASC steel magazine

I have built a lot of both calibers over the last 12 years or so.
I see a lot of overlap. However being someone that has made probably about 80-100 of them, and loading and used ammo for both calibers I think I can safely say that the 6.8 is a bit better carbine shell and the 6.5 is a better rifle shell. When I say "a bit" that's what I mean. Both fan clubs will say their religious object is "by far the best" and both are just worshiping a thing instead of clinging to naked truth.

If both rounds are used in identical rifles with identical barrel lengths and loaded to identical pressure using bullets of similar weight and construction (how they hold together or don't) you will see the truth of the matter.

I own a chronograph, and I make the barrels from blanks myself, and I have used various rifling types and twists in both, so what I say next is fact, not wishful thinking.

I have killed 33 head of game and a few farm animals with a 6.8 SPC and I have killed 7 head of game with 6.5 Gs and seen about 25 others killed, all with guns I have made.

The 6.8 gives a slight amount more velocity in barrels of 16" and less then the 6.5 does, assuming bullet weights of within 5 grains of each other. That advantage is gone at about 80 yards and in the very best cases, about 100 yards.

The larger diameter of the 6.8 bullets makes for a larger wound channel, and that effect can be seen as an average when antelope and deer killed at up to about 150 yards. At around 150 yards to 250 yards I can see no difference in the lethal effect of good HUNTING bullets from either one. It's basically a wash. This from killing, or seeing killed almost 60 deer and antelope with both cartridges.

I have made 6.8s with barrels from 14.5 to 26 inches long and I can without any reservations that barrels of longer then 20 inches are a waist on the 6.8. You gain so little for every inch past 20" that it's not worth anything. In fact shooting the same ammo in one gun with a 26" and my own 20" rifles the difference of velocity was 23 FPS. The 26" was faster, but only 23 FPS. I can almost spit that fast and throw a rock at about that speed. It's irrelevant.

The 6.5 however shows gains up to 24Inches that are worth looking at.
The 6.5 "out flies" the 6.8 at distance, and from the range of 250 out, the 6.5 G starts to leave the 6.8 behind. Is slight but noticeable, until you get to about 400-450 yards in it's lethal effects, but the 6.8 is about to the end of it's usefulness at about 450 and the 6.5 will keep beings a good killer out to about 550 or even 600.

Contrary to the writings of the "Church of the 6.5 G", neither one is a good choice for killing game past that range. Remember that physics still apply, even if your love for the shape of the brass powder bottle is involved.

The 6.5 G is notast good as it can be when fired from short barrels.
Most of the published date from the "Church of the 6.5 G" is data from longer barrels. Not all, but much is. The Grendel shines in 20 to 24" barrels, being super accurate and reaching out better than any other intermediate rifle cartridge available today. It is as I said above, a better rifle round.

Most 6.8SPC data is shot from 16" barrels and is more realistic. The 6.8 fired from a 16 inch barrel can and often does out run the 6.5G from the same length barrel, and the kills are far more dramatic then you might expect. In the 33 deer and antelope I have killed with my 6.8s all but 2 have been "bang-flops" and the 2 that were not were very short blood trails. About 5 yards.

About 1/2 the deer and antelope kills with the 6.5 G have run short distances. The longest run I have seen so far being about 60 yards. Dead is dead, so I can't say the 6.8 was "better" at killing game, but at ranges of 150 yards and closer, it has shown itself to be a few seconds faster in a majority of cases. Both are effective and very good shells and until a see blood trails of 150 to 300 yards from the G. I am not going to say anything bad about it's performance. The difference in speed of the kill is usually in favor of the 6.8 at these ranges, but perhaps not enough to concern yourself with.

Another thing that the 6.8 has had over the 6.5 is the better selection of hunting bullets but the same can be said in reverse about the 6.5 when it comes to target bullets. This statement is not as true today as it was 12 years ago however, because there are several companies looking at the market and improving the selection of good 6.5 bullets today. By now it also may be a wash. (note: the 125 gr 6.5MM Nosler Partition is outstanding in the Grendel)

So if I were to give blanket advice about getting one over the other it comes down to one question:

If you buy either a 6.8 or a 6.5, is that going to be your only rifle for hunting?

If the answer is yes I will recommend the 6.5 over the 6.8, because it is nearly as good at close range,(1-150 yards) just as good at mid ranges (175 to 250) and better at the longest range is should be used for hunting deer (300 to 550 or maybe even 600)

If the answer is no, I'd ask what the other rifle is.

If it's a 243, 25-06, 6.5 CM or Swede, 270, 280, 30-06, 300 mag, 7MM Mag and so on,---- I'd have to say you already own a better long range right then either one of the contestants, so long range is not as much a factor. If you have no need for a 300 yd + Semi-Auto rifles that you don't already have beat, the 6.8 is a bit better for hunting in heavy weeds, timber and brush because it kills a bit faster, and the 16 inch carbine is handier than the 20 or 24" rifle.

And the very most important factor to making the decision is the last one.
Simply.....which do you like better?

You will shoot the one you like more than one you don't like, and shooting it a lot will allow you to learn it's trajectory and drifts a LOT better then reading about them in book sand on the web.

Always remember that it's 98% the man and 2% what he's using, so getting what you like may be more important than all other facts I have listed above.

Me....I sold my Grendel because I have a 25-06, 6.5X54, few 270s a few 30-06s a few 308s and a 300 mag, a 9.3X62 a 9.3X74R and a 375H&H---all of which out kill either one of these 2 cartridges, at every range over 300 yards. Some of these rifles are shorter and a bit lighter then my Grendel was.
But I kept the 6.8 because it's shorter and handier then the G was, and it drops deer and antelope "NOW" at the ranges I use it for. It's probably the fastest handling brush gun I own, even faster then my 6.5 Mannlicher or my 30-30 lever action. So for my own use I like the 6.8 better, even though for many others I would recommend the 6.5 first.

An honest answer to the question "what's this rifle for" is the best way to answer your own question.

Great writeup, szihn. And pretty much describes exactly why I went with the 6.8.. in addition to after talking to and not being able to get straight answers from just about every 6.5 Grendel barrel vendor out there. Not so with Harrison at AR15Performance. My requirements were 300 yd and under gun with excellent accuracy and bang-flop termnal performance from a 16" barrel at those ranges from the get go.

And, as you mentioned, also have at my disposal .223/5.56, 6.5 CM, .264 WinMag, .270, .30-06, .45-70.

Out of all the barrels you have made Have any of them been 10.5 inch pistol barrels ?
If so what kind of Velocities were you getting with xm68gd ?
Are the barrels you have made 3R or 5R ?
Which bullets do you prefer for Big whitetail deer?

bcraig.
No I never made any pistols in either caliber. I have made carbines in both with 14.5" barrels bu that's as short as I have gone. In doing 14.5" I have to permanently attach the muzzle breaks of flash hiders to make them legal so the overall length will be at 16" according to ATF

I had to look up xm68gd. I had no idea what you were talking about. But I find it's a factory round offered by federal.
Again, no info for you. I loaded all my own ammo. When I first started working with the 6.8SPC I was making brass from 30 Remington and also 30-30 by cutting off the rims and deepening the extraction groove.

Barrels: Now I can answer some questions.
For my 6.5 Gs I have used ER Shaw blanks in 1-8 twist and Green Mountain barrels, also with 1-8 twist, as well as one Pacnor 1-8" twist.

In the 6.8 bore size I have used a bunch.
I have used take-off Ruger M77 270 Winchester barrel with a 1-10 twist.
A Browning FN mauser take-off barrel with a 1-12" twist.
A Weatherby rifle barrel with a shot out throat, was a 270 Magnum. 1-12" twist
A Remington M700 take off with a 1-10" twist.
About 30 Green Mountain blanks with 1-11 twist.
About 10 ER Shaw barrels that were made on a special run with 1-9.5" twist
5 Pacnor blanks with 5 groove 1-10 twist.
About 6-7 with Shilen barrels I got from Brownells 1-10"
4 that I made with Adams and Bennet blanks I got from Midway. 1-10"

And there may be a few others that I can't remember as I write this.
What I have found is that the twist rate is being marketed like the Emperors New Cloths. Many on those the worship in that "church" try to convince others that some special twist or rifling geometry is 'the best' and "extra special" It's BS. What matters most is the quality of the bore and the care in making the barrels and chambers concentric.
This group was fired by me about 15 years ago with my 20" AR in 6.8. I saved it because it's a personal "trophy" for me. I have shot many groups of about this size with several ARs I have made, but this I shot with IRON Sights. I can't see well anymore, and even when I had 20/10 vision I could not do this on demand. As I said, it's the best I ever did. But what is interesting about this is that it was shot with a $85 barrel with a 1-9.5 twist, which I turned myself and lapped for about 20 minutes. Standard style rifling 4 grooves.
I was zeroing it with a set of irons and I had a 10 round mag. My friend bob Ellis was on the spotting scope. Shots 1-5 were low and right and bob would say "come up and left" several times and the rounds walked over on the paper until round #6 touched the corner of the square. (you see that last sighter on the target) Bob said "Come up one click and left one click and shoot me a group" I fired the last 4 rounds as carefully as I could.

Here it is.
6.8 at 100 by Steve Zihn, on Flickr

I was and I am very pleased with the accuracy, but the barrel and the rifling were not "special"

Bullets.
I have used Speer 90 grain TNTs, Remington 100 grain Core-Lokts, Remington 115 grain FMJ, 110 grain Sierra Flat base, Barnes 110 grain X bullets (old ones not made anymore) Hornady 110 grain HPs, Nosler 110 grain and 100 grain Accubonds, Hornady 130 grian flat base and Winchester 130 grain power Points.

Here is what I can tell you:
the 90 gr Speer is made as a varmint bullet for the 270 Winchester and they do not recommend using it for big game. I should have listened. Even at 2980 FPS MV instead of the 3650 to 3700 you can get from the 270 Win, these bullet come apart and penetrate extremely poorly. OK, my fault. Speer says they blow up and you know want.......they do! I am my Friend Clay killed 3 antelope with them and gave up on them for anything larger than a coyote. Yeah we kills the antelope, but by hitting them just right. After gutting therm I would condemn the use of these for any big game. Wound cavities of only about 5" deep. The most accurate bullet I have shot so far however.

Remington 100 grain. Excellent terminal effects and good but not great accuracy About 1.25 MOA is standard, but these bullets penetrate VERY well and make BIG holes. 1-1/4 MOA is fine because the round is "done" at about 450 to 500 yards and at those ranges you still have accuracy good enough to hit something 1/4 the size of a small deer's chest. When you could buy them, they were cheap and for hunting I have to give them very high marks. Sadly I think Remington has screwed up (Again) in deciding not to sell them any more.
Here is a pic of a wound made by one of them. That's my fist in the pic.
6.8 wound channel by Steve Zihn, on Flickr

Remington 115 Grain FMJ. Not legal to hunt with so I killed goats and sheep to test it. Exactly what you'd expect. Slender wounds for about 4" and then the bullet tumbles and makes erratic and pretty large wounds. All bullets exited. Plenty of "kill" but the bullet paths can turn off at times, sometimes as much as 30 degrees. Not very accurate and from my 2 guns the best I could get was about 3 MOA.

Sierra 110 Grain. Super accurate and penetrates about 1 foot deep and sometimes up to about 14" before the jackets come loose. Sheds it's jacket 100% of the time, so this would be a good deer bullet but not good for anything much bigger and not what I would choose for raking shots from rearward angles My guns shoot them under 1/2 MOA. Our Whitetails are not large like the ones that come out of the north-east or Canada, so in most cases you can get full penetrating effects on deer up to about 200 pounds.

Barnes 110 grain. Also super accurate with 5/8 to 1/2 inch being common. Too expensive to practice with however. All my kills with these were close and the effect were perfect, but I don't know at what range they will fail to open up. Maybe someone else could answer that question. One kill was on a 250 pound Mule deer hit at the point of the shoulder and the bullet exited in front of the other hip about 8". This would be one I would recommend if you can afford to buy them and shoot them in practice.

Hornady 110 grain HPs. My friend Cas got some of them from Hornady before they were even released to the public and we used them in our 6.8s for almost everything in that years season. Again, super accurate with most groups being about 5/8". BAD game bullet! If they open up at all they blow up completely. The other times they pencil through. I killed the biggest white tail of my life with this bullet with a neck shot that broke it's vertebrae, but the hole even through the bones was small enough to fit my finger tightly. Cas shot a deer about 2 seconds later and I saw the bullet hit on the high shoulder through my scope. I saw the blossom of hair and the hit was placed perfectly but that deer got into the trees and we looked for it for about 2 hours. No blood and just some hair to follow for about 30 yards. I and Cas killed 4 antelope and 9 deer that season and some of the bullets blew to pieces, but others made wounds like an arrow with a field point. For anything but paper, don't use these. My last deer was in a field next to a stand of corn about 10 acres large. I made a heart shot and the deer made it about 65 years to the corn and we tracked a very small blood trail for about 40 minutes before Cas found it dead. Wound was about 1/2 around.

Nosler Accubonds in 110 and 100 both.
Other then costing a lot, these cannot be criticized at all. Almost as accurate as the 90 grain Speer with all groups being just a ragged hole. Everything shot with either one of these died as if struck by a 30-06, and the few deer and antelope that didn't fal at the shot had blood trails measured in feet not yards. Every bullet so far has left an exit. This would be my top pic of the ones I lest here. It might have been the 110 grain Remington, but Remington made that impossible for you. The Accubonds are match accurate, and in that way they "beat' the Core-Lokts, but in the real world they both go clear through, they both give good expansion and they both work out to ranges of 350 to 400 yards. I pushed the Remington for a few years because you could buy them by the multiples of thousands for not much money and shooting a LOT of them in practice which makes the man a better shot.

A 1.5" gun in the hands of a 1.5" man shoots 1.5" groups.

A . 1/4 MOA rifle in the hands of a 6" man shoots 6 inch groups, and that is why the less accurate Remington was my favored bullet for a long time, even though there were others that shot better over a bench rest. I don't carry a rest when I hunt, but shooting 5000 to 7000 a year made me a VERY good marksman with my ARs.
Anyway, the Accubonds are outstanding.

130 grain Hornady Spire point and WW 130 grain Power Points. Both loaded to about 2300 FPS. Kill just like they were fired from a 270 Winchester. Band-Flops are common. So are exits. Not all that flat shooting, (about like a standard load from a 303 British) but in areas where you can't see 300 yards, it didn't matter at all.
No bad points to say about either.

The Hornadys shot about .8 in my guns and the Winchesters shot about .6. For hunting on the river bottom either of these might be my choice. Through and through wounds with very short blood trails, or none when they hit the ground as you are still hearing the shot. I don't know what more you could want.

I have several friends that also use 6.8s and they have used a few other bullets, but these above are the ones I can tell you about from personal experience

RE buy and shoot in practice, it doesn't take much practice to verify zero's adn wind drift really... a box of barnes a year should suffice, you can practice shooting with lots of others IMHO.

AND you can often find a cheaper bullet that mimics the more expensive to shoot more, especially at mid or short ranges IE 300 and less that these rounds are best at IMHO.

The 6.8 is apx 100fps faster with 120-123gr bullets out of the same length barrel using Hornady factory ammo per the Hornady website. For whatever reason the Grendel data was shot with a 24" barrel and the 6.8 was shot with a 16" barrel. Add 100fps to get the 6.8 to 20" velocity and subtract 100 from the grendel to get to 20" velocity.
The 6.8 can be loaded to 58000psi and handle it, the Grendel cases can not handle that much pressure. The Grendel cases are thin and start to bulge at the bottom where the case is unsupported. Handloaded the 6.8 can gain another 100fps over factory ammo.
Pretty simple really, the 6.8 has more usable hunting bullets that expand at the possible velocity. The Grendel has more usable target type bullets. Past 400yds the velocity from both are dropping and the bullets may not expand on game properly. I would bet most game in this country is shot under 150yds.

target bullets, MANY work fine on game too... FWIW

In my personal experience, out of short 12.5" barrels the two cartridges produce pretty much equal velocity with similar bullet weights. The Grendel just retains it farther. I'm not sure about the results in long barrels, neither cartridge appeals to me much in a 20+" tube.

What you say about the cases handling pressure is a theory that didn't hold up for me in practice. It's something the 6.8 fanboys like to repeat a lot, but my personal experience is that most of the Grendel brass can be pushed just as hard or harder than 6.8 brass. The failure modes for both, that I found, was loosening primer pockets before anything else. The smaller diameter 6.8 case should be able to handle more pressure in theory, but I ran into soft brass from both Nosler and Hornady that made reality very different from theory.

I don't know what you're talking about with the "unsupported" comment; there's something wrong with your barrel if it's unsupported in front of the case web; that sounds like more 6.8 fanboy talk IMO. I've not seen bulging of any sort in mine with either cartridge. Have you actually experience this personally?

Actually not fanboy talk but experience. Ever look at the breech close? Notice the chamfer? That would be unsupported along with the .010" between the breech and front of bolt.

Almost anyone can find threads and photos, google bulged Grendel cases or Grendel belted magnum. It's been known for over 10 years...reason the max pressure is 52000psi same as the 220 Russian that Lapua developed the case for and then modified into the Grendel.

And...here's the chamfer, even if it is a rough one.

A loss of support around the front edge of the case web has nothing at all to do with the cartridge, be it 6.8SPC, 6.5G, 223, 458 SOCOM and anything else.
The AR chamber should have a radius around it to keep from catching the brass with a sharp edge, but many makers are using an angled chamfer because it's faster to do with automated machines. They should not! A radius is the way it should be done.

I have had to break the corners on 45 degree chamfers on about 10 Factory built ARs in the last few years. A 45 degree edge is better than a 90 degree, but still not as good as a radius. If you are getting a "belt' it's unrelated to the cartridge, but because the barrel chamber was chamfered too deeply.

Such a thing can happen even on bolt actions if someone is not paying attention to how the finish their chamber. I have set the barrel back on 3 such bolt actions to clean up the mistake in my years of gunsmithing. 2 were on Hobby-made Mausers and one was even a factory Ruger 77 rifle in 308.

Every brand of barrel made must be chamfered wrong then. None of these are my cases or my barrel with the rough chamfer, just one off the internet that showed a clear shot of the chamfer.
There is a thread going right now on the 6mm AR15 cartridges for long range talking about the same thing. As for mine the first was a CSS from Arne the originator of the 6.5 in a PPC case in 2005. Next was an AA, then a Mike Rock 6.5 and 6mm.
All AR15 barrels have a chamfer be it radiused or straight cut and every chamfer is an unsupported area. The photo is a 6.8 and Grendel side by side sectioned. Maybe that will show you why Grendel cases flow into the unsupported part of the chamber and the 6.8 does not. You should be able to see the 6.8 case is much thicker and further from the base. If you can't figure it out from the photo then try this. Section a Grendel case like the one shown. Grendel bolts have a ,136" recess so .136+ .010 for the distance between the bolt face and breech + the depth of the chamfer in your barrel. Measure that far up from the base of that sectioned case. Puts you in the thin wall doesn't it. Now do you think a thin brass wall .022" thick can handle 55-58000 psi when there is no steel chamber wall to back it up? I'll bet not.
Attached file shows more Grendel belted magnums shot this week by someone on the 6mm long range page.

So I have posted several photos of the Grendel belted magnum. If all cartridges do it show me some of a 5.56, surely there are 5.56 belted magnums or 308 belted magnums with all of those being shot.

Grendel blowout

That is WAY too much chamfer. That's a barrel problem, not a case problem, and it's neither necessary or correct for an AR. I have no doubt that some companies do that (notice the link for that pic seems to indicate it might be an Olympic Arms?) but that doesn't hold true for good quality barrels. There's always been some real cheap junk on the AR market (Oly, Model 1 Sales, Bear Creek, etc) but I think most know not to judge a particular cartridge based on junk parts.

In fact, the finish on that chamfer doesn't match the rest of the visible barrel, maybe some doofus tried to cut it himself, and now it's basically scrap metal.

I don't doubt what you describe is a problem some people have encountered with poorly made barrels, but mine sure don't do it. My barrels also aren't chamfered that far; I cut them with the same chamfer as a 5.56, same for the 6.8 based cartridges. I use a wide selection of Grendel brass, some factory Grendel and some fireformed 7.62x39, and have never run into that issue, even though I've turned pressure up to the point of loosening primer pockets.

Are you saying that there are a lot of manufacturers making Grendel barrel with bad chamfers since 5.56s, 6.8s and 308s never have that bulge?

How about this chamfer would it make an unsupported area ? Nope none of these are mine either. Not the CSS, Not the AA, not the Compass Lake Mike Rocks. https://www.youtube.com/watch?v=Ru-ZiaEQNMs

what about these?-







Did you look at the photo of the 2 sectioned cases? Can you explain the difference? What is the max operating pressure of a 220 Russian? 6.5 Grendel?

I'll make it easy on you. I knew of this problem over 12 years ago and talked to Arne about it first after shooting the first 6.5CSS I had and then talked to Bill Alexander about it after the first 24" aa barrel.
Lapua modified their 220 Russian case to make the 6.5 grendel case. The 220 Russian has a max operating pressure of 51,000psi. That is why the Grendel has a max operating pressure of 52,000psi. That is why they said do not try to push the pressure on the Grendel, thin brass and bolt strength.

The chamfers in those barrels above look normal. Are you saying you don't see the difference?

This is what I posted and your response to it. There is an unsupported area between the bolt face and where the chamber walls reach .442" The photos show what the brass does when you push the pressure in a Grendel case. It flows into that unsupported area. As for which is faster out of a 12" barrel that is easily proven also.
From Hornady website - Grendel first-

Test Barrel (24")-2580fps
Muzzle
100 Yards
200 Yards
300 Yards
400 Yards
500 Yards
Velocity
(FPS)
Energy
(ft/lb)
Trajectory
(inches)
2580
1818
-2.4

6.8 info -note the 16" barrel test length-2460fps

Test Barrel (16")
Muzzle
100 Yards
200 Yards
300 Yards
400 Yards
500 Yards
Velocity
(FPS)
Energy
(ft/lb)
Trajectory
(inches)
2460
1612
-2.4


Agree with you about the fanboy remark but it seems it is you that is mistaken about the facts.

Sure I can but you are the one that said a unsupported area did not exist and Grendel brass did not flow into it. Wrong on both counts you were.

Are you saying you can't see the difference between those 2 sectioned cases and why the Grendel brass flows into the unsupported area?

The boogered chamfer photo is a 5.45x39 and came from this thread- http://www.m4carbine.net/archive/index.php/t-18015-p-5.html
It did not cause any of the belted Grendel magnum case I posted photos of so you can stop using that as an excuse.

Thank you for your information

Are you goofy? You're the one who posted it. Maybe try posting something from your own experience, as I have, instead of random stuff you've found online. Some of the stuff you're saying sounds exactly like all the other 6.8 fanboys who've never actually owned a Grendel but somehow know all about it... This kind of thing is exactly what I was referring to with my comments above about the 6.8 fan club.

I posted a photo of a chamfer because you said there is no unsupported part of a chamber. You are wrong and you know you are wrong, every chamber has an unsupported area at that chamfer. The Grendel has .012" more unsupported area in the thin wall since the bolt has a .136" recess. The bolt recess pulls the case .012" further out of the chamber. I told you I had seen it 12 years ago in a CSS, an AA and 2 different Rock barrels. No I don't carry around pieces of junk brass from 12 years ago or even the ones from last year. I talked to Arne and Bill A both about it years ago, they knew then. You can think Grendel cases don't bulge all you want to, I don't really care what you think. Grendel cases will not handle the pressures that the 6.8 case can, or the 5.56 or the 308. Grendel cases will bulge and the photos above prove it.