Home Forums Hunting & Shooting AR and Tactical Rifles 6.8 SPC upper recomendation

OP most will recommend an 1/11 twist as well with three or four groves. I believe Bison offers a 1/7 as well for subsonics. My personal favorite is a 1/9 or 1/10 twist for the loading of the 130 grn Bergers. The ten twist is ok but at 850 to 900 I found the 130 hit the transonic line and take a crap(destabilize). If you never want to shoot bullets heaver that the Hornadys 120sst the 1/11 or 1/10 is by far the most versatile twist. Hope my rambling helped.

I don't shoot 85 grain etips nor would I want to. I have shot 95 grain bonded with no trouble

Exactly! The exit pressure is lower and are the decibels.

So your vast experience with the 20" has never lead you from the top to bottom of the bullet offerings. Sounds like your talking about something that you have no extensive experience with other than the one time you shoot that one gun/load.
Sight your one gun again in 20".

You can't wait to race you yap in over your head. I will say it slow anything over 18" is a waist of time. If you don't like the muzzle blast get a hider that shoves the blast that's so over powering away from you.

NEVER GET A 308 they have recoil and muzzle blast.

First thing you brought up 85 grain etips not me, I simply stated that I liked 20" barrels and did not find them to be a PITA. Simple statement, I do not like 16" barrels at all and I can tollorate 18. I don't care for etips, so they are a non issue to me and I could care less about how they operate for you. I have some 85 grain Barnes TSX that I have had no problem with.

Would you be assuming the OP will only shoot the bullets you like. I have had many,say ten + 20" guns at my disposal at any given time over the last ten years. The 20" can work fine if the stars align but they have been the most difficult to get bullets from 70 to 180 to cycle in. That's where 18" recommendations come from. It crack me up how quickly you pick a fight on a subject you have no experience or very limited experience at best,to some how try and sound like you know your chit (you don't by the way).

OP get a good quality 18" (I suggest you call Ben at Bison) Fulcrum barrels rock and enjoy your bad azz rifle. Ps ask Ben what he recommends. Tell him Fred from the old SSA said hi.

Wouldn't be a bad idea to build an upper yourself. You can get premium parts and build it for cheaper than buying it. Vltor upper, noveske barrel, BCM charging handle and bcg with the handguard of your choosing. That's what I would recommend.

Mom not assuming anything, I simply stated my preference for barrel length, , your just being s dick as usual. You didn't bring anything into play until after I stated my barrel length preference..

I'm not your mom. Lol.

True to form

Hugs and kisses. From the dick

I tried the BO and sold it, and the 6.8 is still here. I am fixin to sell my 308 Ruger because it weights 11 pounds and this gun is 7.5 pounds. In the TSX type bullets the 85TSX seems like a harder bullet but it kills them fine, goes through shoulders no problemo. I switched to the 95grain TTSX this year but have no experience with it on deer yet. I do believe the harder bullets should be used on shoulders if possible, but the 120SST's shoot to the same POA so I will keep a box of them with me as well. If you get a 20 and put a 2 inch flash hider on it, going to be a pretty long gun. I use these muzzle protectors (flash hiders) to keep the crown good. Go stainless steel or nitrided barrels, my SS Wilson Combat is OK. For years I thought the 6.8 was a joke, but it is really a good cartridge, 250 savage class. You cannot find 1000 rounds of practice ammo for it, on the other hand a 10 shot deer rifle that weights 7.5 pounds with the scope is hard to find, and yes I have shot more than once at pigs, coyotes, and stuff. I would do the 6.8, build it yourself, and reload for the cartridge, you will not regret it.

The 6.8 is one of the guns I am going to keep, along with the OEM Colt and one of the DD guns... I have been thinning the herd so to speak buying a few pistols.

Fred,

I know you like Bison and they were good to you but my experience was terrible. The were very helpful until i ordered and they charged my card. Then they missed their deadline by 4 weeks and wouldn't answer their phones or return messages via email or their site. I had to shame them on the 6.8 forums to get a response. I finally canceled and went Precision Reflex. Just throwing it out there for the OP to consider.

My first 6.8 is a 16 stag upper mostly because I intend to use a suppressor on it and didn't want to have the added length on a 20 inch barrel.

If the suppressor wasn't in the picture I would have gone with an 18 or 20 inch barrel. 3 of my 5.56 AR's are 20 inch and I prefer them over the shorter barrels.

I get the noise abatement strategy with the 20 inch barrel, how much velocity is lost I believe depends a lot on the powder and bullet weight. Anyone have any idea what you lose from 20-16 with 90 to 115 grain bullets with H322? I am shooting benchmark in my 16.5 inch Wilson Combat SS barrel and the accuracy results are very good.

You will gain 20-25fps/inch regardless of the bullet weight. If you use an 85 gr bullet and 1680, 4198 or RE7 powder you will need to open the gas port to around .098". Many book loads only produce 45-48,000psi while factory Hornady produces very close to 54,000psi. If the barrel is ported to run Hornady full pressure ammo it will short stroke with light hand loads. If you run full pressure loads there will not be a problem.

OP here...

I only reload for certain rounds so I may not do it for the 6.8 (if I buy one)...

I assume the base velocity values are from 16 inch barrels and your figures add to it.


Also:
so off the shelf ammo and no ports - any issues there on a 20 inch barrel & function?

A gas operated firearm works off of pressure and pressure curve, I have had no issues with my 6.8 Yankee Hill upper with a 20" barrel with any factory load used in it.

Yes, 20s are usually 80-100fps faster than a 16".
Some ammo like Remington fmj(cheap) and Federal eagle do not produce 54,000psi. If the barrel is ported closely to run with Hornady they may short stroke with light loads but you can have the barrel ported to run with any ammo you want or ported a little large and then run an adjustable gas block. A #40 wire sized bit is .098" a 39 is .0995" that range should run all decent ammo with a standard carbine spring and buffer. If using an H2 or A5 setup you may need a larger port.
The port in the barrel controls everything. It really isn't a big deal to open the port to tune the gas to work with the load you plan to use.
Many don't really think about the whole process. They go to the range with cheap underpowered ammo to start and then get pissed when it doesn't cycle. They open the port to run with junk ammo then it is over-gassed when good ammo is used and it isn't accurate because the carrier starts moving while the bullet is in the bore. Tune the rifle to run with the ammo you plan to use.