D.R.D.

Can you use the same bolt carrier group in two different uppers? For instance, if i have a heavy 20" barrel and a BCG properly mated and headspaced, can I then switch that upper out for another with an 18" standard profile barrel, and use the same BCG? Is the BCG mated to the barrel or the barrel mated to the BCG? Thanks! DRD

imschur, I hear you, but actually I'm in the middle of several builds, and this is one I can wait for. I'd rather get the 'right' barrel and wait. Cerakoting would only be for the outside, which is great. I've used that before. I'm more concerned about the bore's exposure to corrosive elements (mostly salt), that's why I'm looking into the nitride/melonite "treatment" of the Chrome-Moly metal. (That treatment on Stainless steel will actually make the next layer down from the surface less corrosion resistance, hence why I'm not asking about SS) Why skip the CMMG? Their barrel (while overpriced) seems to have more of the features I'm looking for already fabricated than others do. It's this one: http://www.cmmginc.com/product_p/38df40b.htm DRD

I'm looking into a chrome-moly 308AR barrel for another upper build. I'd like it to have nitride/melonite coating for increased corrosion resistance (salt water/sea air). I know some can be made that way, or finished later. This needs to be precision barrel, so standard to heavy contour, 18 - 20", preferably 5R and/or polygonal rifling. These are some brands I've found. I don't know if they build to all these specs. Anyone have experience with any? Any others that I haven't listed? Compass Lake Krieger? (criterion only makes CM in lightweight profiles) McGowen PacNor Rock Creek CMMG POF (Don't know if they sell barrels only - are these piston only, or can one use a barrel for DI?) Thanks, DRD

I found this forum when searching for info about a ARs chambered in .308 on google

Thanks - great input all. To answer some questions: -This will be for anwhere from 100 to 1000+ yards, So, heavier: 168 / 175 / 178 gr. -Mainly prone or supported shooting. I don't envision shooting off-hand with it much. I may make another upper for that. -Why not a complete rifle? $$$ on hand. I'm budgeting by purchasing pieces of the best quality for the lowest price, then assembling once I've got everything. -No plans on having this done this year. I'm currently collecting parts for 6 different rifle builds right now (My lightweight AR15 is in the lead ;-) Will this 15" match the height of the DPMS upper? http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_ID=1209 Has anyone mated an SI-Defense Lower with that DPMS assembled upper? Do they fit without any play? Is that something a gunsmith could easily address? Thanks again, DRD

All of you have been very helpful and generous with your knowledge and info. I'm clear that the Barrel and trigger are the two places not to skimp when building a longer-range precision machine. Now that I've got a better idea what direction I need to head in, I'm curious about the true performance comparison of a few parts. To start, I've got a SI-Defense lower. Go to go as I understand it. Maybe not a Mega, but I have yet to understand the difference. So, to complete the receiver parts, do I get an SI Defense upper to match (even though it won't be a true 'matched set')? or do I go with the cheaper assembled DPMS upper? Bottom line: will it truly have any affect on performance, accuracy or durability? A) Si Defense Upper $325 or B ) DPMS Assembled upper $190 The same question goes for the BCG. Does getting a SI Defense BCG make a difference in a SI Defense Upper? Or is it all about having a gunsmith mate the BCG to the barrel? Again will any combination really make a difference in performance or reliability? C) Si Defense $305 or D) Anderson Machine $205 As for Triggers, I'm gonna go Geissele. Either SSA-E, SD-E, or Hi-Speed DMR. I need to get my hands on them to feel which one I like best. Lastly, is the barrel. There are just so many choices, and every manufacturer seems to have a reason why theirs is best. Do I go budget (yet quality), or save forever for a big name, or...how do I figure out what will be the "best bang for the buck" barrel? E) Bison Armory 20" SPR SS / SI-Defense SASS / Nemo Arms $225 / 237 / 277 or F) BHW / Rainier / FA / Criterion / Krieger / Bartlien $325 and up, up, up... Thanks as always for your help and insights...the research part is fun too! Not as fun as shooting, but still entertaining ;-) DRD

Best of luck and an easy recovery

By The "b word", do you mean Black Hole, Bull Barrel or Bartlien? It seems Rainer doesn't stock the heavier profiled barrels, though.

Good to hear, Wash. I'm still eying BHW's 20" bull barrel to take out to a grand (I heard BHW makes Rainier match polygonals). Still concerned about weather proofing it. Cause if there is something tested that i can do to protect the bore, I would possibly consider a FA, Krieger, Bartlien, etc. Its the cleaning, price, and reported performance of BHW that has me leaning that way...but I'm open to other options. Thanks, DRD

This one? http://www.brownells.com/rifle-parts/barrel-parts/rifle-barrels/ar-15-m16-308ar-nitride-barrels-prod54801.aspx I've heard mixed reviews on their guns, and they are not the cheapest. Who makes their barrels? I found this: http://www.ar15.com/forums/t_3_121/591261_308_AR_barrels_from_NEMO.html Are there any performance, longevity or durability advantages to polygonal vs. this SI or Nemo barrel? I ask since I will often be staying & shooting near/in salt-water -air conditions. I heard Polygonal is easier to clean. I absolutely must have accuracy, but I can't have the thing rust out on me. What kind of treatments or coatings help with this and don't affect performance (inside on the bore)? I assume military DMs / SEAL snipers would need a similar treatment if operating in adverse/wet/salty conditions, no?

Really?! Is it more of a heavy/bull profile or a standard contour? I figured since I'm considering the SI Defense BCG, I would be nice to match it to the barrel. It says it is phosphate finished. Is that different from melonite? (Not that it really matters...I'm planning on having the whole thing Cerakoted anyway)

Anyone heard anything or have any experience with these? http://www.midwayusa.com/product/814978/si-defense-barrel-lr-308-308-winchester-20-m110-sass-contour-1-in-10-twist-matte How might they compare with a Black Hole Weaponry barrel? DRD

LOL!

Doing it 'wrong', maybe?

Nope. So, then what is it about lets say, an AK compared to and AR that is less accurate in the same caliber if not the piston/DI difference? Is it the Barrel rigidity? Rifling? Twist?

That MI Keymod looks great...and so light! What do you think the 15" will weigh? Any insights into the probable interior dimensions? Sams as the SS Gen II maybe?

Will the BCM only be for AR15 platform?

With the added length of movement with the Piston system, doesn't that affect accuracy at longer ranges?

Yes, you did. Thank you. I wouldn't have known about that one if it weren't for you. It's likely the one I'll go with.

LOL - got it. Thanks. Too bad Syrac doesn't make one for bull barrels (.936") DRD

I'm trying to narrow it down and choose from these: Wilson http://shopwilsoncombat.com/Adjustable-Lo-Profile-Gas-Block-937-Mid-Length-Straight-Gas-Tube/productinfo/TR-AGBL-M/ PRI http://www.precisionreflex.com/Detail.aspx?PROD=186815&CAT=4274 To fit under this: MI (15") http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_ID=1209 with this barrel: BHW http://www.blackholeweaponry.com/catalog/product_info.php?cPath=48&products_id=100&osCsid=d6b1fcf3e612a4f68ff7bfe030ce5efd Any suggestions or obvious issues? Thanks

anyone know anything about this BCG? http://www.andersonrifles.net/index.php/shop-parts/upper-parts/bolts-and-carriers/308-win-bolt-carrier-group.html

Thanks survivalshop, ...too bad you dont have a qd system on your scope to switch over to your 16", and give that side by side experiment a go!

Anyone actually make one of these go bang yet? Especially in an SI Defense receiver? Looks like a great deal as long as performs... Btw, anybody running an SI Defense BCG?

Robocop, Ouch. Enjoy! 98zv5, How does the Tubb CWS differ from just running a heavier buffer?