D.R.D.

Nice . what do those barrels set you back? Back to the original questions....will gas length systems or buffer size/weight affect accuracy?

Found this: "Fluting a rifle barrel makes such a small difference in cooling that it is difficult to measure. The heat transfer coefficient of an object determines how fast it cools. For a rifle barrel you can use the formula for heat transfer coefficient of pipe wall. hwall = 2k/diln(do/di) where k is the thermal coefficient of the material, di is the inside diameter of the barrel, and do is the outside diameter of the barrel. If you double the outside diameter of the barrel you will have 8 times the surface area on the outside, but no change on the inside. This formula tells us that doubling the outside diameter of the barrel gives you a heat transfer coefficient only 1.3 times greater. Therefore an 800% increase in surface area gives a 30% increase in cooling. Fluting only slightly increases the surface area of the barrel. As for stiffness, fluting does make the barrel more rigid than a barrel with the same minor diameter but less rigid than a barrel with the same diameter as the major diameter. A fluted barrel will be very slightly more rigid that a barrel of the same mass. Fluting is a way to reduce the weight of the barrel while having the barrel slightly more rigid than simply reducing the diameter by turning the barrel down. Realistically, fluting is more for looks than anything else." http://www.snipercountry.com/articles/realbenefitsbarrelfluting.asp

I think you are correct. Its just that with fluting, the theory is, that it increases surface area to a thicker barrel that would have taken longer to cool down with out fluting. Or so ive heard. So...whats the deal with this holy carbon barrel of the gods?

What is this carbon fiber barrel you have?

I've read much about how stiffer, heavier barrels decrease vibration, and can help accuracy. I've heard that a longer barrel will usually increase velocity, helping with shots at longer distances. We know it takes longer for a thicker barrel to heat up, and it can dissipate heat quicker due to more surface area. Longer gas systems shoot softer, as do heavier buffers, decreasing overall movement of the weapon, possibly contributing to accuracy and precision. Well, I've got build I'm working on, and it looks like it will come out to about 11 or 12 lbs., give or take. It's purpose is for longer range work. That said. I'm not adverse to making it a lighter platform for other types of shooting as well. Will changes in the weight of the rifle negatively in the following areas affect the accuracy, if all else is equal (shooting at 1K with the same 175 SMK loads)? Replacing the bull-barrel with a standard contour Shortening the barrel to 18" Going from rifle to mid length gas system Changing the PRS rifle-length stock to a collapsible stock (like the Battlelink UBS) Going from rifle length heavy buffer to a carbine heavy buffer - to fit the collapsible stock) Here are the original build specs: · 20” Black Hole Weaponry Black Steel Bull Barrel, Threaded with Polygonal Rifling 1:11 Twist · Troy TRX Battlerail 12 / 13.8” or CMMG Mk3 15" · R&D MRAD Removable Muzzle Brake · Geissele SSA-E / SD-E / Hi-Speed DMR Trigger · Magpul 10 round P-Mag · Large-Frame Ergo Grip or Umbrella Grip 23 · Magpul PRS Stock · SI-Defense Billet Receivers · PRI Gas-Buster Charging Handle · Wilson Combat Adjustable Low-Profile Gas Block (.936”) · CMMG Lower Parts Kit · DPMS Upper Parts (forward assist, port cover & spring) · DPMS A1/A2 Buffer Tube · Heavy Buffer & Spring · SI Defense Phosphate BCG · Basic Slipstream Treatment by Crusader Weaponry (BCG, Buffer, Spring & CH) · Harris HBMR 6-9" swivel-notch or Atlas Bipod · ADM QD Bipod Mount · ADM Scout One-Piece QD or Burris AR-PEPR Optic Mount SWFA Super Sniper 3-15x42 FFP MilDot Reticle, Butler Caps & Sun Shade

What's the difference? Weight, durability, build quality, fit and finish, materials? Would you trust the Burris if push came to shove?

Does anyone know if SI-Defense .308 stripped uppers allow for a forward assist?

Anyone have experience with this scope mount? http://www.manventureoutpost.com/products/Burris-410342-AR%252dPEPR-QD-Scope-Mount-30mm-w%7B47%7DPic.html?google=1 I'd like to know if it will hold zero and be solid atop a .308, and how it compares to the ADM Scouts mentioned above Thanks!

Awesome, thanks!

To those also subject to this silliness: Are the bullet buttons for a .308 the same as an AR-15? If not, would someone please provide a link for the .308 version. Thanks, DRD

Thanks all

Where to get the following: http://store.magpul.com/product/MAG290/PMAG http://store.magpul.com/product/MAG002/13 Can one order them directly from magpul? Are they available now? Elsewhere? At better prices? Thanks, DRD

Both would be great to know!

Any sources for DPMS-pattern fully Phosphate (no chrome at all, nor nickel boron) .308 / 7.62x51 Bolt Carrier Groups other than SI-Defense? DRD

I see this DPMS forged upper is available at a good price http://www.midwayusa.com/product/784553/dpms-upper-receiver-assembled-lr-308-a3-flat-top-matte 1. Any experience with this upper for a .308 battle-rifle / general purpose .308 build? 2. I know it may be very hard to get one right now, but does DPMS make a forged lower? 3. Do any companies make forged .308 lowers, or only billet? 4. If they only make billet, why? Thanks, DRD

Thanks for the links

Thanks as always. I had a feeling...SSA-E it shall be. DRD

I'm sure some iteration of this question has graced this board more than once, but here goes. Feel free to link another thread if it was well answered. I;m putting together a precision 308AR platform for medium to long range shooting. I'd like the best trigger available. Everything I've read and heard has pointed me to Geissele. But which one? I;ve seen this on their site: http://geissele.com/pdfs/ApplicationGuide.pdf However, some of the triggers on their site are not on this list like the G2S - which is supposed to be similar to the SSA-E but cheaper. I'm always open to saving money if quality isn't sacrificed. I don;t have experience with the flat triggers, so I don't have a preference between curved of flat (yet). I just want to be able to logically eliminate a few they won't work and narrow down the choices. Requirements: Clear, clean, and crisp break Reliability, reliability, reliability No unnecessarily long uptake travel Weight of pull designed for .308 175 SMK shot out a 20" Polygonal Bull Barrel to 1k yards Which one is the ticket? Thanks, DRD

ditto

Do you have any experience with or opinions about .308 receivers from: Sun Devil ( 6061 billet ) JD Machine Tech (7075 billet) DPMS (6061 forged)

Yeah, er, ...Ill stick with the SI-Defense, LOL! Especially since I've got the SI lower already, n'all. Why are the Megas so expensive?

Blacksheep - awesome links! Shibiwan - I don't see where it says .308 anywhere there - are you sure? What about this one: http://www.cmmginc.com/product_p/55da291.htm So here is my edited thinking based on more research and all your input: · 20” Black Hole Weaponry Black Steel Bull Barrel, Threaded with Polygonal Rifling 1:11 Twist · Troy TRX Battlerail 13.8” or CMMG Mk3 15" or M.I. SS Key Mod 15" · R&D MRAD Removable Muzzle Brake · Geissele SSA-E Trigger · Magpul P-Mag · Large-Frame Ergo Grip or Umbrella Grip 23 · Magpul PRS Stock · SI-Defense Billet Receivers · PRI Gas-Buster Charging Handle · Wilson Combat Adjustable Low-Profile Gas Block (.936”) · CMMG Lower Parts Kit · DPMS Upper Parts Kit · DPMS Buffer Tube · Heavy Buffer & Spring · SI Defense Phosphate BCG · Basic Slipstream Treatment by Crusader Weaponry (BCG, Buffer, Spring & CH) · Harris Bipod · ADM QD Bipod Mount · ADM Scout One-Piece QD Optic Mount SWFA Super Sniper 3-15x42 FFP MilDot Reticle, Butler Caps & Sun Shade Am I missing anything?

Thanks yet again for saving me a potential headache. I already emailed them & cmmg to see if it is 308 compatible. How about twist rate for 175 out to 1k? Will 1:11 be much different than 1:10 in a 20" with same load...all other factors being equal?

Wow, that strike industries looks great. Good price for such a lightweight handrail. I might consider that instead of the Troy. Another question...are lower parts kits interchangeable between AR15 and 308AR? Thanks again for helping me navigate the 308 world, DRD

Will it still work well with the SWFA scope without the 20MOA?