To recap..........

I showed up at the Tucson 1000 yd range with a varmint rifle in 6mm Rem. 14x Leupold scope, HS Precision stock, trued 700 long action, Pac-Nor #5, 27" long with a 1x8 twist and in a three-groove rifling configuration. I shot off my Hoppes front rest and Protektor rear bag on 8 Jan. I became hooked.......

Since the barreled action was showing promise, and I needed to limit my budget since we are building a new house, I thought about how I might ease into this in a cost effective manner. I have now learned that like all other shooting pursuits I have engaged in, there is no cost effective way to "ease in" to this.

The plan was front rest, stock, scope, and a load with 115 grain MKs. I figured that would get me through the year. Well, I did all that and pushed my original budget a bit, but it was all working. Then last night, after mounting the scope, I started in with the new bullets. I started by checking seating depth. I started with some 107 MKs to see how much the throat had moved. I figured there would be some erosion, and I wanted to see how much.

Would you believe .300"? That is not a typo. The throat had eroded a full 3/10ths of an inch in the barrel's 200 round life. I assume most of that happened at the match, when I was shooting 10-shot groups in heavy rifle.

I was stunned. The barrel now has as much freebore as if I had bought a 240 Wby. I realize the 6mm Rem is a tad high case capacity for a 6mm, and I know Pac-Nor barrels are soft, but come on, .300" in 200 rounds?

Fortunately, Jerry (the local 1000 yd rifle machinist who is moving in a month) hasn't packed his lathe up yet, Bruno's is only a 2.5 hour drive, and Bruno's had a Krieger 6.5mm, 1x8.5 LV barrel blank in stock--along with some 6.5x284 brass and most of the other stuff I need.

If I had checked this rifle's throat right after the match, I wouldn't have even ordered the scope and stock. I would have bought another Tucson shooter's 308 Patriot light gun (on a 700), and then bought a much lower end scope. Such is hindsight.............

Oh well, I guess I'll be better off with a new Krieger barrel in 6.5x284 and the Nightforce scope, right? (Just say yes, I don't even want to consider the alternative.)

All this bring up some thoughts on throat erosion.

Three times now I have fired strings and gotten barrels hot, and each time the throat has eroded excessively.

The first was several years ago, a factory Rem SS Sendero in 7mm Rem Mag. I started shooting 5-shot groups. I'd shoot five in a row, then let the barrel cool. In 400 rounds the throat moved about .040". I heard that is not uncommon for that chambering. I got rid of the rifle and got another SS Sendero, this one in 300 Win. After 825+ rounds, the throat had moved maybe .010". I started shooting three-shot groups and didn't shoot the barrel when it was more than lukewarm.

A couple years ago I was messing around with a 338-06. It too was a Pac-Nor barrel. The 338-06 isn't know for throat erosrion, but when I kept it hot for a few rounds it too erodoed noticably (like .010 in 80 rounds), whereas when I kept it cool, the throat didn't move. On this barrel, I was careful and stopped the experiment after noticing the throat movement, and kept form hurting the barrel.

I guess my issue is whenever I shoot barrels when they are hot, I seem to erode the throat excessively.

Several years ago I started using Rem Bore Cleaner, which like JB Bore Paste, is a non-embedding abrasive cleaner. I have very good luck using it with several rifles. I remember reading a test in Precision Shooting a while back how that RBC was so fine that all it did was polish the 600 grit lapping marks, and as such the author said it would not harm a bore.

Now I am wondering if I should be routinely using RBC or JB Bore paste.

Thoughts?

Blaine

Just copied this from the Krieger Website..............

"Abrasive cleaners work very well. They do not damage the bore, they clean all types of fouling (copper powder, lead, plastic), and they have the added advantage of polishing the throat both in "break in" and later on when the throat begins to roughen again from the rounds fired. One national champion we know polishes the throats on his rifles every several hundred rounds or so with diamond paste to extend their accuracy life. "

How much pressure are you operating at with the 6mm?

I use both and they wont hurt your barrel, especially if you have a good bore guide. You probably dont have to use them that often. I use butches bore shine. 2 wet patches, soak the brush and five in and out soak the brush again 5 in and out, let it set about 10 minutes and then patch it out. one patch damp with kroil and one dry patch. firtst two shoots into the backstop and your ready to go. If you start to see copper then hit it every so often with the Rem or JB. But a little copper wash is not necessarily a bad thing. Re: heavy class: its real easy to shoot several sighters- and then several during the 2 or 3 minute time when they mark the targets, and then when you fire your ten for record your barrel is really smoking! I try to keep my sighters to a minimum and take fairly aggresive clicks to get on the clay bird or gong right away and stop. Then shoot the minium shots during the marked sighter period, but always fire one just seconds before the end of marked shots end. See where this hits, hold on or off accordingly when the record targets come up and start firing immediatly before conditions change. If you get all sighted in nice and the have a wait till the record targets come up conditions might change and you will be lost, maybe even off target! Been there! If your last shot at a marked target was off the X just hold off for it and get those shots off downrange with your best guess for hold off. I am no means real good at this and work wont let me shoot as much as I like but this has worked for me and have won most relays (not matches) I have been in.
I wonder if your barrel is really shot? Look into it with a bore scope. Shoot the hell out of it till it quits. I have seen barrels where the first 2 inches looked like charcoal but they still kicked butt.

Lefty

Blaine, I have burned out a few barrels in my lifetime and I have drastically changed the way I reload for a match rifle. I have found that by loading down to 10 to 15% below max pressure I increase barrel life dramatically. I don't shoot 1000 yards but I know you have to stay supersonic, so maybe look for a load that will get you there without as much pressure.

I think a heavier barrel will also help you, something like a HV #7 gives a lot more area for heatsink.

As an example, I use a 22-250 for 300 yard prone where we fire 2 strings of 20 rounds 20 minutes each. I have put close to 600 rounds through this barrel and the throat has barely moved and shows almost no fire cracking under the bore scope. I only run it at about 3350fps with 52 grainers and it just hums along without getting excessively hot. This barrel is a HV #7 shilen. I also use ball powder which is supposed to have lower flame point than extruded though not by much.

I don't know that much about it but isn't that the main point of fluting, to give more surface area too cool off?

Blaine,
The obvious answer is to choose a large bore with a smaller case capacity. I think that a short 300 Magnum might do the job.
It all depends on your budget. I know shooters who rebarrel every year. I can't afford to do that so I don't shoot 1000 yds. When you shoot a three gun 1000 yd match you are really talking about well heeled shooters. 30 caliber is pretty popular because if you go any bigger the recoil becomes a problem and any smaller than that and bore erosion becomes a problem. There is always a tradeoff. A 308 Winchester is very accurate at long range, talk to some Palma shooters.
Great White North

Portagas, yes you are correct, fluting is supposed to help cooling. I have never used a fluted tube so I really have nothing for comparison and don't know if it really works as described compared to an unfluted tube. I pretty much stick with what I know, and a big fat barrel with mild powder charges and pressure makes for lots of shooting.

Shane,

The 6mm Rem is a standard 65,000 PSI chambering, like most are. My load was generating 3060 fps from a 27" barrel, which is about right. There were not any high pressure signs of any kind.

Lefty,

Your method is exactly how the other guys have coached me to shoot. The 6mm barrel may be reusable if I cut 1/2" off the shank and rechamber, but I am leery about spending money on something that may not work.

TBS,

I try to keep loads under the max as well. High pressure signs just started to show up at 3200 fps with this load, and I thought backing it off to 3060 was a significant reduction. With the 6.5, I certainly will not push it....

GWN,

The 6.5 / 284 has a better case capacity to bore ratio, though when I start from scratch I will probably build a 300 WSM.

I like the the .300 wsm and shoot it in the light class and it has a brake..the only disadvantage is if I am going to shoot it in the heavy class to I would have to remove the brake. Not that it hurts you or anything w/o the brake but it moves around a bit and you have to spend a bit more time getting back on target dicking around with the rest. with a lighter recoiling rifle it will track the bags well and let you shoot a little quicker. What would be ideal is something that recoils like a 6BR but bucks wind like a .300 with 220 gr. matchkings!
When you find it let me know!

Lefty

Lefty,

The biggest thing I noticed at my first match was how much even a 11 lb 6mm moved around on the bags. What a pain! My 6.5x284 will come it at just under 17 lbs. It has a proper stock and I now have a proper rest. That should make a huge difference.

Blaine

Lefty the round you may be looking for is the 6XC. It is ment to drive the 115 gr tubbs bullets to 3100 and change with great barrel life. BC of said bullets is in the mid 580's and the smith that is building mine says 2500 rounds. Although F class is more forgiving on the accuracy requirements and rapid strings. The round has been doing well against the 6.5's locally and they are what is supposed to beat the big winney ballistically.

Will know for sure in about 45 more days. Should be blasting by then.

I actually have thought about it.....but the last thing I need now is to start with another rifle, dies, barrels, bullets load development etc. divorce is very expensive. I do think the cartridge will be a winner though. Love to hear about yours as soon as you get it going.

Lefty

Sounds really good. Would be nice if you could get to the World Open at Williamsport pa. this summer. Pretty good shoot. Last year a 6.5X.284 took it all both light and heavy. If you do compete in Williamsport your rifle will have to weigh in under 16 1/2 lbs..Pain in the butt, but Williamsport started it all and they go by their rules. Let us know how your rifle does when you get it.

Lefty

" I know Pac-Nor barrels are soft, "

I'm surprised that quote went unchallenged. I can't say one way or the other but I hope your wrong.

I posted asking about it being the heat treatment being softer, or the actual type of metal. Also about using 4 ought steel wool around a brush as a cleaner. That was in between the first and second post. Don't know what happened, or why it aint there.

Nobody really stepped up and explained or really bit on it. Confused like the rest.

I didn't intend this to be an inditement against Pac-Nor, but here is my experience with them. I have had 5 Pac-Nor barrels, and three were outstanding. With that said:

More than one rifle builder has told me Pac-Nor barrels are soft, and that is based on their experience machining them. I have also noticed how easy it is to scratch one up when hunting, and then am amazed at how well the scrathes will polish out with steel wool. All this leads me to believe they are a bit soft.

Pac-Nor seemed to have struggled a while back with quality, and I know many hunters, shooters, and a couple rifle builders that quit using them. Please don't ask me to name names, because the builders especially want to remain anonymous. I bought this 6mm barrel around the time of the uncertain QC.

Maybe Pac-Nor got a bad lot of steel, like what happened to me last month when I was 170 miles from home and an aftermarket (to the lift kit) suspension component broke, completely settling my truck's suspension on the right side. This was due to improperly heat treated steel, so I know personally "bad steel" can happen to anyone.

Of the two 3-groove Pac-Nors I have, the 6mm shot well with one particular seating depth. Move it .005 either direction and it didn't like it. The 30 cal Pac-Nor three-groover I have is a bit more fussy, and I haven't found what it likes. After 750ish round when chambered in 30-06, I could not find a load with a hunting bullet that would not ocassionally open three-shot groups up to 1.125". Many feel that is acceptable for a #4 contour barrel in a hunting rifle, and if it hadn't been a fully accurized rifle built on a 700 in good stock, it would have been. I had it rechamberd to 300 Win, and so far it seems to be shooting a bit better, but I have not sorted it out yet. Needless to say I am almost completely soured on Pac-Nor three-groove barrels.

It is possible that a 1/2" could be cut off the 3" shank of the 6mm barrel and it could be rechambered. However, I am not enthused about putting more money into something that may not last. Been there done that too many times, like with those suspension components that failed. That was the second set of I had problems with.........

Realize I am not anti Pac-Nor. My favorite rifle still wears a Pac-Nor, and I still have high hopes for my 30 cal Pac-Nor. I had a 338 RUM and a 300 Win, both with Pac-Nors, that were extremely accurate, and when shooting them like the hunting rifles they were (never when hot), the throats showed very little erosion.

Blaine

Blaine,

Thanks for the very informative thread. Your attention to detail always amazes me, even though it shouldn't, given your profession.

Anyhow, what are your thoughts towards Lothar Walther barrels, as Celt seems to prefer.

3 Groove are picky. That is the word I hae heard about anybodys 3 groover.

Blaine, I still find your way of measuring throat erosion in question. You simply need to get a BORE SCOPE and stop farting around with Stoney Point OAL guages as THE way of measuring throat erosion. They work great for some things, but you can't tie throat erosion to bullet jump. They aren't the same. Case in point, the "lead" or "throat" angle of a barrel changes very quickly and dramatically in the first 200 rounds of being shot. Pac-Nor barrels have VERY steep, sharp leads that wear VERY quickly, but it isn't "throat erosion". This gives many individuals the idea that the throat is wearing prematurely, which isn't the case, even though I have found Pac-Nor barrels to wear rather quickly. The throat needs to be looked at under a microscope or bore scope to REALLY determine throat wear, which looks like a dried up lake bed. With your method of shooting a barrel cool, I, as well as many others aren't getting ANYWHERE near the throat 'erosion' you are and we shoot our rifles hot and with a LOT more rounds down range before the barrels puke. Get a bore scope!

Just because the throat "seems" to be advancing, doesn't mean the barrel is anywhere NEAR being shot out. I have personally owned and seen barrels with NO riflings, lead, or throat for 1-2 inches pound out 3/4" groups with boring regularity. One in particular, a .22-250 went 4,500 rounds and it wasn't taken care of when in a hot prairie dog town. When it quit shooting, it quit abrubtly. Many AR-15 or M-14 shooters go 6,000 + rounds and notice NO deterioration in accuracy, even though the throat may have advanced over half an inch. All I am saying is, there is a LOT more to the equation here than you know. You are detailing a small piece of what is really going on here. Just trying to clear some things up for shooters that might be wondering about throat erosion. Flinch

Brian,

I have a LW barrel on my 338 Win, and it seems very sound. I haven't had significant throat movement in over 580 rounds. I think with the Stoney Point, the seating depth has increased .006 to .008" over that time, and most of that was probably just the sharp edges of the rifling smoothing up a bit. Now I still haven't found a load that I am happy with, but if I were to accept 2600-2650 fps, this barrel will shoot 225 grain Partitions into 1/2" 3-shot groups. I have still not found the majic woth 225 grainers at 2800 fps, but it must be there somewhere..........

Celt has done a bunch of testing with LW barrels. Based on his own research and experience, he says it is not uncommon for a factory barreled 300 RUM to not shoot well after 600 rounds. The last I talked to him about it, he said a LW barreled 300 RUM was still shooting well after 1200. Both John Ricks and Celt have told me LW barrels are made of a harder steel than many.

The biggest thing I wish I had done different on my 338 was buy my own reamer, one made to John's specs--I really like how John has his reamers ground.

Blaine

Flinch,

Good points. I don't really disagree with you (much), but the context is important. Let me try to be more accurate (pun intended) <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Maybe you'd feel better if I called this an "erosion of rifling" or just a "change in seating depth". Maybe the term "throat erosion" is better left to a description of the throat's actual condition (IE, rough and full of minute cracks) as opposed to how I am using it, which is a description of the rifling wearing away near near the throat area causing a corresponding increase in bullet seating depth. If that is your point, then it is well taken, but don't let that go to your head too much <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />. Of course, then the title of this thread gets kind of long: IE, "1000 yd BR, Huge Change in Seating Depth Due to Excessive Wearing of the Rifling Immediately in Front of the Throat and Thus Ruining the Barrel for 1000 yd BR Competiton in it's Present State".

Now, if I borescope this barrel I would not expect to find the cracked and rough throat area one often finds after a couple thousand rounds. And like I posted already in this thread:



However, in a 1000 yd BR rifle, which is the context of this thread, you just cannot use a barrel that increases bullet seating depth .300" per match. And I can promise you the rounding of the rifling's edges does not account for anywhere near .300". I have seen .010" even .020" right off the bat, and I have always expected that was the rounding or smoothing of the front edges of the rifling you mentioned. However, bullet seating depth increases usually slow dramatically after that. Other shooters have related similar experiences in this area. But .300" just a rounding of the rifling? Maybe in a 155mm Howitzer........

The level of precision in these rifles often requires bullets either touching the lands or very close, and that is no longer possible with the 6mm barrel in the shape that it is in. 1/2" 5-shot groups at 100 yds with extreme velocity spreads of 50+ fps does not cut it here. The first thing the guys I was shooting with said was "good shooting". The second was, "you need to get you load sorted out. Are your bullets touching the lands?" More than one guy asked me that.

If I were to recut this chamber and keep using this barrel in 1000 yd BR, why should I expect the bullet seating depth to NOT increase the next match like it did the last?

Now, the last 10 shots out of this barrel did go into 12" at 1000 yds, and who knows, that may still translate into 1/2" or better 3-shot groups at 100 yds. If I were using this as a hunting rifle--which was the original intent--I may still be shooting it. So in the sense of it's usefulness as a hunting rifle, the barrel is not really "ruined." However, a 12" 10-shot group in 1000 yd BR is below average.

I agree, we have all shot rifles with so many rounds through them not only could you not get the bullet close to the lands, there's wasn't much left at the muzzle either. And yes, many of these rifles shoot well for their given application. Chances are these weren't 1000 yd BR guns. A common sentiment for 1000 yd rifles is something "wow, that barrel has lasted in excess of 1500 or 2000 rounds and is STILL shooting well. Amazing".

Anyway. I'll think about using the term "throat erosion" a bit differently. Then again, I may stick with it just to keep spinning you up..... <img src="/ubbthreads/images/graemlins/tongue.gif" alt="" />

Blaine,

if you'd like to get rid of that worn out barrel, I'd be glad to pay the shipping if you'd like to send it to me... <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />

Blaine,

Talk to one of your jet engine mechs, and see if he'll run a boroscope down your barrel. Given the nature of the Air Force, they may even have the type that you view on a small TV and perhaps you can even record it on a VCR. The CG hanger were I used to work has that set up, I bet your guys have something better.

Oh great, thanks Flinch........now where am I suppose to get my deals on "shot out" barrels? Leave Blaine alone so I can pick up his scrapes. <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

I hunted last weekend with a big game guide from Australia that also does cull hunts in the outback where they shoot thousands of rounds a day and his comments mirrored yours. If anyone is hard on equipment it would be him, it took him 45,000 rounds to finally wear out a Remington 700 extractor on a .308..................and they said it couldn't be done.

Beat me to the punch. I could go shipping + 25 <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> dang junk barrel. Bet it'd be hell on crows with 55g B Tips.

Spike, how did that barrel look after 45,000 rounds? Was the "throat" advancing on it? You can have his shot out barrels. I think they have been cleaned to death, rather than shot to death <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Blaine, I just attended a BR match as a spectator. I talk to a LOT of the shooters about barrel life etc. EVERYONE of the competitors get 1,000-1,500 rounds out of their barrels before they are no longer competative. That doesn't mean shot out, that means they don't hold 5 shot groups lower than in the 2's. But your throats are severly advanced and shot out at 200-400 rounds. You are doing something wrong buddy. Perhaps cleaning them wrong or too much. Something is amiss here. Flinch

Flinch, what kind of barrel were each of the competitors using?

Flinch,


"Something is amiss here." That is what I am trying to sort out. Most of the 1000 yd guys seem to get at least 1500 rounds before the accuracy goes away. Most have very little throat lengenthing.

I am a bit suspicious of using Rem Bore Cleaner, but Krieger themselves says abrasives are okay. However, I plan on using RBC much less. Most of the guys here only use it when the barrel becomes excessively fouled.

I am also becoming paranoid about using a tight patch, though it seems a stretch to think a tight patch could wear out rifling at the throat........

Not to many guys use Pac-Nors, and many seem to feel Lilja's are also a bit soft. Kriger, Broughton, and Hart are commonly used and all seem to have good life.

No one shoots a 6mm Rem, the thought is it has too much case capacity for it's bore size. Alos, maybe I was pushing it too hard........

Also, the barrel contours ar heavier, and my 6mm barrel become hot after each of the three 5-shot strings in light gun, and very hot after each of the three 10-shot strings.

The 6.5x284 Krieger barrel I have now doesn't get anywhere near as hot after a 5-shot string as the 6mm barrel, and after the first 48 rounds, the throat has only advanced .005" (ish), which is what I expect is the rounding of the rifling.

You know, I thought I had all this sorted out several years ago when the Sendero in 300 Win I had went 825+ rounds with only about .010" of throat movement. Also, I had almost convinced myself that the 7 mag's .040" would have been okay if I had just not shot five-shot strings with it.

I'll have a borescope to use NLT Sat 12 Feb, and I'll post what I see.