D.R.D. Posted September 27, 2013 Report Share Posted September 27, 2013 I'm building my first .308AR. It's use will be for longer-range precision work. My choices are influenced by Crusader Weaponry's builds and By LaRue's PredatOBR It's pretty straight-forward. My question and concerns are in Bold/Italics Thanks in advance for any help that will have me get it right the first time and avoid expensive mistakes! Here are my current specs (so far, I only have the Receiver) Receiver Set: SI Defense Barrel: 20" Black Hole Weaponry heavy barrel (.936) with rifle length gas system Muzzle device: R&D MRAD removable (so I can shoot f-class, with a can, of with a brake) Anyone have experience with these or with Badger Ordinace's FTE / FTE Micro? Gas block: BTE or JP low-profile Adjustable (Will these fit under the Troy Battlerail? If not, what lighter full-length rail will work?) Handguard: 13" Troy TRX-Battlerail Buffer tube: DPMS rifle length stamdard Buffer & Spring: DPMS standard A1/2 rifle buffer & spring (with permanent Slip-Stream Treatment by Crusader Weaponry) Any reason why I should choose another Buffer? (Like a low mass, heavy buffer, etc.) I'm looking for reliability & smooth precision shooting. Bolt Carrier Assembly w/ Bolt: Si-Defense Phosphate (with permanent Slip-Stream Treatment by Crusader Weaponry) Any reason why I should choose another BCG? (Like a low mass) I'm looking for reliability & smooth precision shooting. Stock: Magpul PRS Grip: Large-Frame Ergo or BCM Gunfighter Mod 1 or 0 Trigger: Geissele SSA-E (Any better suggestions?) Charging handle: PRI Gas Buster (with permanent Slip-Stream Treatment by Crusader Weaponry) Lower / Upper parts kits: ADCO / DPMS (Any concerns here?) Bipod & optics mounts: ADCO Scout Bipod: Harris or Atlas (suggestions?) Cheers, DRD Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 27, 2013 Report Share Posted September 27, 2013 (edited) I went with an Atlas bipod over the Harris. Super strong and rigid, but it does take a little more time to deploy/fold. I feel that Harris isn't interested in keeping their product up-to-date (i.e. no direct rail mount option, only swivel mount) and they are simply milking the most out of an old(or ancient) design. SSA-E is a good choice especially for the money. Personally, I don't feel comfortable/safe with any less trigger force than the SSA-E. You'll want to go with a heavy buffer. I have a custom 12-oz buffer (See: ) in mine to help with recoil control as well as improve the cyclic action. If you're looking at building for long range shooting I strongly recommend a 20-MOA optic mount. You can get a full one-piece mount with the 20 MOA forward cant or a 20MOA riser with regular scope rings. -S P.S. Welcome to the forum!! Edited September 28, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 28, 2013 Author Report Share Posted September 28, 2013 shibiwan, Thanks for the welcome and all the advice! I've got a few follow up questions based on what you wrote: 1. Does the Atlas have a swivel or cant feature? 2. When you recommend heavy buffers, do you mean this: http://heavybuffers.com/ar10rifle.html I've heard so many people talk about "low-mass" or various sizes to fit different stocks. My concern, as I had written is reliability and controlability. I'd also heard that a heavy buffer is used more in a carbine length gas system, and will slam the action more than necessary in a rifle length, only contributing to more recoil and wear on the rifle. I'm quite confused here. What am I not understanding? 3. This is the optic I'm considering: http://swfa.com/SWFA-SS-3-15x42-Tactical-Rifle-Scope-P62238.aspx Will I need a 20MOA base for this? If so, why? Do you have any recommendations? (best quality for the lowest price preferred) Thanks again! DRD Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 28, 2013 Report Share Posted September 28, 2013 (edited) shibiwan, Thanks for the welcome and all the advice! I've got a few follow up questions based on what you wrote: 1. Does the Atlas have a swivel or cant feature? 2. When you recommend heavy buffers, do you mean this: http://heavybuffers.com/ar10rifle.html I've heard so many people talk about "low-mass" or various sizes to fit different stocks. My concern, as I had written is reliability and controlability. I'd also heard that a heavy buffer is used more in a carbine length gas system, and will slam the action more than necessary in a rifle length, only contributing to more recoil and wear on the rifle. I'm quite confused here. What am I not understanding? 3. This is the optic I'm considering: http://swfa.com/SWFA-SS-3-15x42-Tactical-Rifle-Scope-P62238.aspx Will I need a 20MOA base for this? If so, why? Do you have any recommendations? (best quality for the lowest price preferred) Thanks again! DRD Yes the atlas has both swivel and cant as standard (cant is only 15 degrees vs 25 on the Harris). The swivel and cant "tension" can be adjusted to how tight or loose you want it. It also requires some breaking in so it will loosen up as you use it and you can tighten back down with the main knob. Heavybuffers.com makes some nice ones... I'm streamlining mine, and maybe offering it up for sale eventually. Light buffers increase the cyclic rate while heavier ones slow it down. Competition shooters (e.g. 3 gun) tend to prefer the lighter ones for super quick follow up shots at the expense of harsher recoil. For long distance shooting, the preference is towards the heavier ones, and this is especially so for the 308AR patterned rifles. The 308AR tends to be "overgassed" due to the higher capacity cartridge. The rifle length gas tube reduces this to some extent, however, a combination of heavy buffer plus an adjustable gas block will help keep things under control and working smoother. SWFA has pretty decent scopes - that is a nice scope and for a little more you can get a first focal plane scope if you're (like me) trained to use the mil reticle for range estimation. Using a 20MOA mount/riser will give you a lot more useable range for any scope. I'm using a Vortex Viper PST 6-24X50 FFP (MRAD reticle) scope. It's a pretty good value at a $950 and the performance approaches scopes that cost 3x the price (Nightforce, Leupold MK4, Zeiss). The 4-16X50 version of the Viper PST scope runs around $900 and also comes with a first focal plane reticle. For the price difference you're getting a first focal plane scope with an illuminated reticle - that's a good value IMO, and their warranty is excellent too! [EDIT] oops, I just realized that the SWFA you posted is an FFP scope too... -S Edited September 28, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
BLKSHEEP Posted September 28, 2013 Report Share Posted September 28, 2013 (edited) Welcome D.R.D. That's some good advice from Shibiwan^^. I'll add that the scope you're looking at has 36 mrads /2 =18 of adjustment, that should get you into the 1000 yard +- range without a 20+ MOA scope mount. Edited September 28, 2013 by BLKSHEEP Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 28, 2013 Report Share Posted September 28, 2013 (edited) I'm using this 20MOA riser: http://www.amazon.com/Weaver-Flat-Riser-Rail-20MOA/dp/B004NRVLVS/ref=sr_1_1?ie=UTF8&qid=1380336859&sr=8-1&keywords=20moa+weaver+riser ...plus a medium Warne 30mm ring set http://www.amazon.com/Warne-Scope-Mounts-Medium-Permanent/dp/B000PX0KQG/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1380337016&sr=1-1&keywords=warne+30mm+rings I still have a little more than 1/4" more room between the top of my rifle rail and the scope so I could have installed using the low rings (1/8" lower than the medium) and gotten away with it -- that would have been optimal since it puts the scope as low as it would go. IMO this gives me tunability - I can get the scope height I want without getting stuck with a one-piece with a pre-set scope height. The other advantage is if I ever upgrade the scope to another with a 34mm, 35mm, or whatever scope tube size, all I have to swap out is the rings and still get the 20MOA elevation in the riser/base. It's my way to be cheap in the long run than if I got a one-piece cantilevered scope mount with 20MOA elevation (check out the AADMOUNT) and then have to get another entire mount later when I upgrade scopes.... Here are some pics - it should give you a good idea about the direction you're going since I have a lot of the parts on your wishlist. :) Edited September 28, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 28, 2013 Report Share Posted September 28, 2013 Buffer & Spring: DPMS standard A1/2 rifle buffer & spring You can't run AR15 rifle buffer parts in a 308AR rifle. It just won't work. You need to source 308-specific parts in this area. Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 28, 2013 Report Share Posted September 28, 2013 (edited) You can't run AR15 rifle buffer parts in a 308AR rifle. It just won't work. You need to source 308-specific parts in this area. Good catch! If you use the standard "A2" Rifle extension tube, the cheapest "factory" option is this buffer: http://www.midwayusa.com/product/913498/dpms-buffer-lr-308-rifle -S Edited September 28, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 28, 2013 Author Report Share Posted September 28, 2013 Wow, thanks for all the replies and info, all! Just to be clear, will this SWFA scope http://swfa.com/SWFA...ope-P62238.aspx work with this ADCO mount http://www.americandefensemanufacturing.com/view/product/25/ ? I understand your points of 20MOA and saving money. However, I thought that if I can, I'd start with this. Then, if I decided to upgrade, I'd get a different./ larger mag. scope with it's own dedicated mount and switch them out easily without losing zero since the ADCO is a quick detach design. How did you get your dope on the stock like that? What is it printed on? Very cool. Also, what kind of barrel is that? (length, contour, weight) You mentioned over-gassed rifles. What does that mean exactly? I'm still trying to understand more about the relationships between the gas-system length, Adjustable gas-blocks, BCG weight, and Buffer mechanisms. I get the general idea, but really want to try and "buy once" and get it right the first time. I'd rather shell out a little more for the best combo/quality on the main operational pieces than fill a box of parts I no longer use (like I have for handguns - LOL!) So what do you think about this combination: 20" barrel http://www.blackholeweaponry.com/catalog/product_info.php?cPath=48&products_id=100&osCsid=ae7feedabb2512f1ba1b04043d3769e2 Heavy buffer http://heavybuffers.com/ar10rifle.html SI Defense BCG http://si-defense.mybigcommerce.com/308-phosphate-bolt-carrier-group/ Gas block (one of these) http://bte-usa.com/parts/AR15-gas-blocks.htm or http://www.jprifles.com/1.4.6_gs.php to fit under this: http://troyind.com/%20/anew-products/troy-battlerail-trx-308-13-8 Also, any feelings about the pros and cons of standard vs bull-barrel contours for precision work? My understanding is that while heavier, the bbl will last longer, vibrate slightly less, and heat up slower, which sounds like a good idea for a semi-auto that moves more than a bolt and can fire in quicker succession. In a polygonal contour, a 20" should gain velocities of a barrel slightly longer, and be easier to clean. My goals here again are reliability, accuracy at a distance, and potential exposure to harsh environments. Thanks again for all your help - this forum is an amazing resource! DRD Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 28, 2013 Report Share Posted September 28, 2013 (edited) The scope and mount will work - just make sure you get the 30mm one. I'm not too familiar with those barrels. Perhaps someone with experience will chime in. I'd say go with Fulton Armory since they have a great record for precision barrels. Heavybuffer.com buffers are great. Make sure you get the right length (i.e. DPMS length - not the Armalite length). Gas Block - go for a low-profile gas block if you want it to fit under the Troy Battlerail (There are 2 versions of the battlerail - hi-profile and lo-profile. You'll probably need the hi-profile to match the SI upper receiver but you should measure your upper receiver before ordering the Troy.) I'm not partial to any adjustable gas block but I'd insist on steel and not aluminum. You should be looking at something like this: http://www.midwayusa.com/product/1070292756/wilson-combat-low-profile-adjustable-gas-block-with-gas-tube-ar-15-standard-barrel-0937-inside-diameter-steel-matte Being over-gassed means that too much gas is returning through the gas tube back to the bolt carrier group. Too much gas to the bolt carrier will "ram" the bolt carrier back faster and more violently. In addition you will notice more carbon fouling in the upper receiver and bolt carrier group. Since the BCG is flying backwards faster, it usually ends up ramming into the end of the travel (i.e. the buffer reaches the end of the tube) and literally bounces back forward. In extreme situations, this will give it insufficient time to eject the spent cartridge and properly load the next round, and ending up jamming both the empty cartridge and new round into the breech at the same time, or a stovepipe situation. Slowing down the bolt carrier by reducing the gas return and a heavier buffer gives the BCG time to eject the spent round properly. My rifle is a CMMG MK3 (bought as a complete rifle) with the CMMG 18" medium countour SS barrel. Rest of the rifle was customized as I went along. It can shoot/has shot sub MOA groups and usually outperforms my rusty marksmanship skills. The label on the stock is a printed label off the industrial labeler I have at our manufacturing shop. It didn't want to stick anywhere else (teflon coated) except on the PRS stock. I have it labelled with the bullet drop info for the Federal GM 175SMK ammo which use for long range targets. I prefer threaded barrels... standard stuff. I'm ex-military and almost everything I get is based on what I'm familiar with. As long as the barrel is crowned properly, the difference is minimal. The threaded barrel will allow all sorts of muzzle devices, including suppressors. Going from 16" to 20" is about a 100-120 FPS increase, I really wanted a 20" but ended up with the 18" because the ballistics between the 18" and 20" are only marginally different (about 50 FPS) and was a tad lighter carry. My rifle & handgun are my SHTF defense weapons, so I do lean towards the more tactical options. -S Edited September 28, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
BLKSHEEP Posted September 28, 2013 Report Share Posted September 28, 2013 (edited) I'm using this one with a 50mm obj. scope, so yes it will work http://www.americandefensemanufacturing.com/view/product/298/ it may be a little higher then needed for the 42mm you're looking at but if you ever go to 50mm you will not need to buy a taller mount. Look here> https://www.primaryarms.com/American-Defense-ADRECON-30MM-p/ad-recon-30.htm Edited September 28, 2013 by BLKSHEEP Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 28, 2013 Author Report Share Posted September 28, 2013 Blacksheep: This is the one I was thinking about: https://www.primaryarms.com/American-Defense-AD-SCOUT-30MM-p/ad-scout-30.htm Same thing with only one QD lever, no? Anyone know the weight on the 14" & 15" models, and the interior clearance height for the gas block on this: http://www.jdmachinetech.com/product/308RL/308CHG.html shibiwan: That gas block is perfect! Thank you! I saw these two are similar. Any pros or cons for either: http://www.precisionreflex.com/Detail.aspx?PROD=186679&TERM=gas%20block http://shopwilsoncombat.com/Adjustable-Lo-Profile-Gas-Block-937-Rifle-Length-Straight-Gas-Tube/productinfo/TR-AGBL-R/ The PRI doesn't have the height - it only says that it might not fit under some handguards. I think the Troy Battlerail is 1.61" of space inside. Thanks for the explanation - very clear. The Fulton barrels look nice...and pricey. Any other input on Bull vs. standard profiles (other than weight...I don't plan on clearing rooms with this rifle. I have other platforms home defense) From what I;ve read performance drops off more significantly after 20", but my question is less than 7" enough dwell time to ensure consistent functioning if you went below 20" with a rifle-length gas-system? DRD Quote Link to comment Share on other sites More sharing options...
BLKSHEEP Posted September 29, 2013 Report Share Posted September 29, 2013 ^^^ Yes same thing but without the 20 MOA & minus 1 QD lever/cam. Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 29, 2013 Author Report Share Posted September 29, 2013 Will it still work well with the SWFA scope without the 20MOA? Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 29, 2013 Report Share Posted September 29, 2013 (edited) Will it still work well with the SWFA scope without the 20MOA? Yes it will. What we're just saying that adding 20MOA of elevation will allow you a little more adjustability if your intent is to go long range. The eventual weight is going to be around 12 lbs when you get it built up. It's not going to vary by much (probably +/- 1lbs) if you're going with the parts you're looking at. Most round float tubes like the one you linked have a 2" (actually 1.98"/50mm) outer diameter and around 1.75" inner diameter. If you're going with a round type float tube, most low-pro gas blocks will clear. I'd lean to the wilson combat one. The PRI one should be fine too. I found the round ones to be easier on my hand than to buy accessories for a quad rail just to make it comfortable to hold. I'm just cheap. LOL The latest "fashion accessory" on the forends are the Keymod style quad rail tubes. Examples of the newer keymod ones are: CMMG Revo, Midwest Industries, Novoske, Strike Industries..... and a lot more... The keymod system is supposed to be a new standard so stuff can interchange between brands but I don't see much more advantage over a the standard picatinny/MIL1913 customizable rail system. Whatever you do, make sure the handguard is made specifically for a .308 since the barrel nut threads are different. Edited September 29, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 29, 2013 Author Report Share Posted September 29, 2013 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 Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 29, 2013 Report Share Posted September 29, 2013 (edited) 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 I'm going to remind you to double check on the Strike handguard - the one I posted does not mention 308 compatibility so do your research before you decide which to get. Personally I'm not even so sure on the quality of that brand.......... Here's the actual product details... start researching! http://strikeindustries.com/shop/index.php/rifle-enhancements/ar15-platform/mega-fins-ak-modular-key-mod-handguard-rail.html Lower parts kits are interchangeable except the bolt catch. Your best bet is probably get a 308 specific LPK from DPMS or CMMG.... like this: http://www.midwayusa.com/product/894635/dpms-lower-receiver-parts-kit-lr-308 Happy to help! -S Edited September 29, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 29, 2013 Author Report Share Posted September 29, 2013 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? Quote Link to comment Share on other sites More sharing options...
BLKSHEEP Posted September 29, 2013 Report Share Posted September 29, 2013 Here's some info. that might help, or make your head hurt :)) http://www.bergerbullets.com/litz/TwistRuleAlt.php http://www.riflebarrels.com/articles/bullets_ballastics/bullet_imbalance_twist.htm Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 29, 2013 Report Share Posted September 29, 2013 Here's some info. that might help, or make your head hurt :)) http://www.bergerbullets.com/litz/TwistRuleAlt.php http://www.riflebarrels.com/articles/bullets_ballastics/bullet_imbalance_twist.htm Ouch... my head hurts! :)) D.R.D - this one from CMMG is for a 308 http://www.cmmginc.com/product_p/38da22d.htm Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 29, 2013 Author Report Share Posted September 29, 2013 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? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 29, 2013 Report Share Posted September 29, 2013 Lower parts kits are interchangeable except the bolt catch. And the mag realease, and the takedown pin, and the pivot pin... Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 29, 2013 Report Share Posted September 29, 2013 (edited) And the mag realease, and the takedown pin, and the pivot pin... You're totally right I'm such a derp. :D D.R.D. - The CMMG MK3 is a 308 (that's what I got) so the one I showed you will fit. The one you linked up is for a 5.56 Edited September 29, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 29, 2013 Report Share Posted September 29, 2013 Nah, you're good, man. There's just a bunch of stuff to keep together on these things. Three different patterns, parts, etc... Quote Link to comment Share on other sites More sharing options...
shibiwan Posted September 29, 2013 Report Share Posted September 29, 2013 (edited) >:D D.R.D. - here's a really nice option instead of your SI upper/lower: http://megaarms.com/maten/receiver-sets/billet-upper-lower-sets/mkm-keymod-upper-ambi-lower-set/ heh >:D (There...just ruined your buget.... muahahaha) Edited September 29, 2013 by shibiwan Quote Link to comment Share on other sites More sharing options...
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