[Ringo]

Ok, I did a search for DMR-C and found no results. I fount that odd.

Can someone please tell me which is "better" or what the appreciable differences are in these chambers? I have been juggling the idea of a Bison Armory upper (because I like E.R. Shaw barrels) and on from AR Performance. The only difference I've noticed are the chamber styles. Anyone shed some light?

-R.

 

[ron169]

Theres more different than the chamber. If you are referring to an Xtreme barrel, the twist is 1:11.25 where as the Bison is 1:11. The bison barrel is SS and the Xtreme is Chrome lined. As for an answer to your question, the DMR is more of a match grade chamber.

 

[constructor]

The Bison has four grooves and the XT has 5R rifling too.

 

[ArtFWTx]

Ok, I did a search for DMR-C and found no results. I fount that odd. Ron's correct. There are a few differences between these two barrels and chambers. Both are nicely spec'd barrels though.

Can someone please tell me which is "better" or what the appreciable differences are in these chambers?

DMR is the proprietary match 6.8 chamber designed and offered by AR15Performance. It's also used by Titan Armory. It is a high performance design and works well with all 6.8 amunition power levels including hotter handloads. The DMR-C is the version of the DMR chamber with tolerances built in for chrome lining.. hence the C.

The SPC II chamber is the improved version of the original SAAMI chamber with an additional .05 leade for a total leade of .10 which reduces pressures and allows the use of higher performance ammuntion. This is the chamber most of the industry has moved to in replacement of the restrictive SAAMI chamber.

I have been juggling the idea of a Bison Armory upper (because I like E.R. Shaw barrels) and on from AR Performance. The only difference I've noticed are the chamber styles. Anyone shed some light?

As Ron indicated, there are some differences. The XT is more of a custom production barrel designed specifically to maximize 6.8 performance with some additional features:

AR15Performance: "
The 6.8 XT is an affordable upper half with all the right stuff. We used the same match style throat as in the DMR chamber but, with a combat reliable chamber size, a 16" Nitro-Carburized 11.25" twist barrel with modified 5R rifling and other upgrades not found on most production rifles. The lightweight contour is .700" under the guard and .600" from the GB to the muzzle. This basic model has mil spec. plastic handguards with heat shields."

Bison Armory: " 416 Stainless Steel
SPR (18") and Light SPR (16") profile
Ops Inc model 12 suppressor collar shelf
SAAMI Spec-II Chamber
4-groove, 1-11" twist
M4 feedramp barrel extension
Mid length gas system"

The ARPerformance barrels like the XT and RECON are pretty much hard use custom barrels, and Bison barrels are very good production stainless steel barrels. It depends on your use.

Hope that helps.

 

[ArtFWTx]

I try to help with a long cut and paste explanation, and the man himself Constructor answers with a few words. Sometimes it doesn't pay to volunteer.

 

[constructor]

I try to help with a long cut and paste explanation, and the man himself Constructor answers with a few words. Sometimes it doesn't pay to volunteer.

You do know one reason my answers are short is because most of the time I answer while the lathe is making a pass and I have to catch it before it crashes. The other is I don't type LOL

 

[Strawdawg]

To answer your question with reference to the chamber
http://www.68forums.com/forums/showthread.php?t=451

The C stands for the chromelined version

Search often does not pick up short queries

 

[eaglemike]

Is the info in post #4 above really correct?? I'm not seeing where an additional .005" leade is really going to make a significant difference. Is there a decimal misplaced there?
all the best,
Mike

 

[joshuades]

You do know one reason my answers are short is because most of the time I answer while the lathe is making a pass and I have to catch it before it crashes. The other is I don't type LOL

SOunds like a way to end the day. Ever beat up a chuck?

 

[RoAus]

To answer your question with reference to the chamber
http://www.68forums.com/forums/showthread.php?t=451

The C stands for the chromelined version

Search often does not pick up short queries

WHAT! And to think all this time I thought the "C" stood for Constructor!

 

[Clint]

The C is for COMBAT

It has a slightly relaxed body which makes extraction more reliable,

the extra lead length is .050" for a total of .100"

DMR-C

The 6.8 XT is an affordable upper half with all the right stuff. We used the same match style throat as in the DMR chamber but, with a combat reliable chamber size, a 16" Nitro-Carburized 11.25" twist barrel with modified 5R rifling and other upgrades not found on most production rifles.

H, are you having the next batch of barrels FNC? That was quick. When will those hit?

 

[constructor]

The C is for COMBAT

It has a slightly relaxed body which makes extraction more reliable,

the extra lead length is .050" for a total of .100"

DMR-C

H, are you having the next batch of barrels FNC? That was quick. When will those hit?

The chrome guys are backed up because they are doing snowmobile cylinders, I can't wait 2 months like the first time. I have 3- M4 5.56 barrels that are NC'd and shot Adams LWRC so I was impressed with the toughness of the treatment, then I started researching and learned more about the whole process.
I believe they will be just as accurate as the chrome-lined barrels and last as long inside while having a better corrosion resistance outside. On top of that I don't have to sand blast and parkerize so that saves me a day a week, so even though the initial cost is more it will save me time. I am already doing 16hr days and the only thing we are actually manufacturing now is bolts and the custom stainless barrels.
Hope to have them here in 2-3 weeks, most of that is shipping time.
We will have to call everyone with an order and ask if it is acceptable to give them a NC'd barrel instead of chrome.

 

[Ringo]

Guys-

Thanks for all these responses. I forget that there ARE forums out here in the wasteland of the net where people are helpful rather than condescending - so its much appreciated. My use for a 6.8 will be hunting (whitetail and hogs), fun shooting, and home defense - in that order. I was under the impression that the DMR is a step down from the spc2. Thanks for correcting that. For the purposes of hunting - should I consider heavily one or the other?

(as i hold the phone in my hand to order from AR Performance, lol).

-R.

 

[ron169]

If you handload, I would go with the DMR, can load hotter, therefore more velocity, therefore longer range to hunt. Plus the DMR is pretty damn accurate.

 

[Ringo]

Roger - I'll be putting in an order with ARP on monday. Much appreciated, guys.

-R.

Does AR Performance offer 18" Barrels? Anyone know?

 

[Test_User]

If you are comparing barrels they are apples and oranges IMO. One is CL /Nitrided and the other is SS. One uses standard 4 groove the other modified 5R. One is 11 and the other is 11.25 in twist . Comparing the chambers the DMR-C as well as the straight DMR will be more accurate than the SPCII. That was one of the reasons for its design in the first place. The XT barrels will last 2x longer and hold up better to high rate of fire belwo freezing temps as they are 4150CMV and CL or nitrided (=lower maintenance). Bison cost less than the XT barrels. As far as which one is ultimately more accurate there are way to many variables to say for sure. Take a look at some of the posts by users and check targets that are posted will be of some help but then again how well was the load tuned for that barrel etc.. Many many variables.... Some people prefer SS and others prefer CM with CL.