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.338 RUM AR platform

DIESEL758

Sergeant
Full Member
Minuteman
Oct 3, 2010
172
2
50
texas, san antonio
Does anybody make barrels in a .338 RUM for an AR platform???? I don't want to buy a already built AR I just need a barrel. Also what bolt to use??
 
Does anybody make barrels in a .338 RUM for an AR platform???? I don't want to buy a already built AR I just need a barrel. Also what bolt to use??

Nope...not gonna happen with ANY production, mainstream large-frame AR (Armalite or DPMS-pattern, etc.)...not even CLOSE! The mag-length for most all large-frame AR platforms is around 2.81" MAX!

Hell, the case-length alone on the .338RUM is 2.76" and most common loads will get your COAL out to ~3.6" or so.

The more common .338 class cartridge for the large-frame ARs is the .338 Federal which is essentially a .308 case opened up to accommodate the .338 size bullets with a max COAL of 2.8" or less. Its a great round for hunting on short to medium ranges with good ballistics to match that capability, including some larger NA game animals, but it sucks as a long-range performer due to the limited case capacity, etc.

Some companies are working on .338LM and other class cartridges with semi-autos, but none of them will be "plug-n-play" compatible with the current ARs on the market for the above reason.
 
They've made 300 Short action ultra mag AR's, Their no longer in production and tuff to find. You could wildcat a saum to 338 I guess? Nemo Arms makes a sweet 300 win mag that is nice but far from affordable. That's as close as you'll ever get to a 338 rum in an AR.
 
The only company that's making an AR style firearm like that, that I'm aware of which coincidentally in this instance is not a whole lot, is NEMO with their "Omen" rifle. It's chambered in 300wm, and the prices I've seen hover around $5,500-$6,000
 
I guess I should of figured that since I really could not find anything. What about this .338 federal?? Is it a good round?? I just recently built a 6.5 GRENDEL that was a tac driver. I want to move up to the bigger AR platform and try something new. I have a .308 AR so I would like to stay away from that. I am building this gun not interested in buying one built. Main use will be shooting targets out to 1000yrds and anything in between. Also used for hog and white tail hunting but like I said main use will be targets.
 
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I guess I should of figured that since I really could not find anything. What about this .338 federal?? Is it a good round?? I just recently built a 6.5 GRENDEL that was a tac driver. I want to move up to the bigger AR platform and try something new. I have a .303 AR so I would like to stay away from that. I am building this gun not interested in buying one built. Main use will be shooting targets out to 1000yrds and anything in between. Also used for hog and white tail hunting but like I said main use will be targets.

The .338 Federal is generally NOT suitable for long range in my experiences. It'll work great on hogs and whitetails, as well as other larger game like elk, etc., and particularly as a brush gun, but its max effective range is only around 4-500yds for medium sized game animals. As I previously stated, the 338 Federal was never designed/manufactured (or even reloaded) to be a long-range cartridge. It shines with bullets between 180-210grs for game where you can get MVs of between ~2850 to ~2600 respectively, but forget trying to run the heavier 250gr and 300gr SMKs and other suitable longer range pills from it because you are prettywell stuck with getting only low MVs at best.

If you want a "target" upper that'll still be capable of decimating your local whitetail and hog population from a large-frame AR, I'd look to the 6.5 CM (multiple sources for barrels...same bolt as the .308), or get with a company like Accuracy Systems for a complete upper configured in .300WSM, .300SAUM, or an even more unusual chambering for the large-frame ARs like the .284Win...all VASTLY better options for long-range performance out of the large-frame ARs in comparison to the Federal. The 6.5CM is arguably the best choice (or even the 6CM) because the others will have mag-issues, require other non-standard parts, etc.
 
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Does the 6.5 creedmoor use the .308 platform ?? Ammo seems to be priced good as compared to other big calibers. Where is a good place to get a barrel ?? Will this round be basically like my 6.5 GRENDEL which out shined my .308 in every aspect even though on the smaller ar15 platform?? Sorry for all the questions it took me over a year to build my GRENDEL I just want to get all the right parts. Is the 6.5 CM ammo easy to find say at academy or bass pro shops or even gander mountain??
 
Yes...the Creedmoor (whether 6.5 or 6mm) both use the large-frame AR as a base platform, as well as the same general operating system components, including bolt, mags, etc.

As for barrels, many companies offer ready-to-install 6.5CM tubes...not so much on the 6mm. The 6.5CM barrels can be sourced from very high quality outfits like Fulton Armory (they regularly stock Krieger SS, 8-twist, 20" and longer CM barrels) for ~$600 as well as JP Enterprises (they sell a hell of a 22" tube that comes complete with a JP enhanced bolt, properly matched/headspaced to the individual barrel) for around the same price range. Here's a link to Fulton, as well as JP:

Fulton Armory - FAR-308 Barrels

JP - Barrels

As for sourcing ammo...I can't help you with either of those two retailers you mentioned, but generally speaking, the Creedmoor ammo is available online at many major ammo retailers, and at places like your "big box" outdoors shops like Cabelas, etc., but you'll fare quite a bit better reloading for it! Not quite mainstream enough yet that it'll pass the Two Dot test if that's what you are worried about. ;)
 
Thank you!! I will check those places for the barrels. As for the the ammo I did find some good prices online so it looks like I will order some from there. Also I came across a DPMS barrel chambered in the 6.5 creedmoor on midway USA is that a good barrel??
 
I have not used one of the DPMS 6.5CM tubes personally so I can't speak from experience, but people seem to report MOA or better with them when shooting match ammo from what I have read from various sources. YMMV.
 
I thought I would never see the day.....I was thinking that the only magnum calibers that would be offered up in a precision rifle would be in a Barrett type weapon platform. Guess you learn something everyday...
 
Ok I found a 24" barrel from DPMS at midway USA. Or a JPenterprise 22" barrel with matched bolt. What bolt carrier do I need to purchase for these two barrels??? Will a armalite ar-10 bolt carrier work??? I will be using the new SI matched upper and lower.
 
Ok I found a 24" barrel from DPMS at midway USA. Or a JPenterprise 22" barrel with matched bolt. What bolt carrier do I need to purchase for these two barrels??? Will a armalite ar-10 bolt carrier work??? I will be using the new SI matched upper and lower.

SI Defense's stuff is DPMS LR-308 pattern, as is the JP barrel/bolt and, obviously, the DPMS barrel. Do NOT mix and match parts between different large-frame AR platforms (i.e. - No Armalite carriers with DPMS bolts or Armalite barrels with DPMS bolts, etc.). Thus, you need a DPMS-pattern LR-308 carrier to go with a DPMS-pattern bolt and DPMS-pattern barrel. Otherwise, you can run into problems in a hurry. If it were mine, and you don't already have a BCG/bolt, then I would get the JP setup with the matched bolt and get a quality carrier to run with it. No sense trying to reinvent the wheel looking all over the place for parts when you know that the JP barrel/bolt will be right straight out of the box. JP also sells DPMS-pattern .308 carriers (low mass...in a couple different finishes) designed to run with their low mass operating system if you are sparing no expense on this build and you are interested in those components. Just an FYI.
 
SI Defense's stuff is DPMS LR-308 pattern, as is the JP barrel/bolt and, obviously, the DPMS barrel. Do NOT mix and match parts between different large-frame AR platforms (i.e. - No Armalite carriers with DPMS bolts or Armalite barrels with DPMS bolts, etc.). Thus, you need a DPMS-pattern LR-308 carrier to go with a DPMS-pattern bolt and DPMS-pattern barrel. Otherwise, you can run into problems in a hurry. If it were mine, and you don't already have a BCG/bolt, then I would get the JP setup with the matched bolt and get a quality carrier to run with it. No sense trying to reinvent the wheel looking all over the place for parts when you know that the JP barrel/bolt will be right straight out of the box. JP also sells DPMS-pattern .308 carriers (low mass...in a couple different finishes) designed to run with their low mass operating system if you are sparing no expense on this build and you are interested in those components. Just an FYI.

Thank you, coming from the ar-15 platform to AR-10 is a little different. I also noticed the DPMS barrel says it does not have M4 feed ramps. Is this normal?? The SI defense upper just says it has feed ramps. Will this be a problem??
 
I would NOT, repeat NOT, run a non-M4 barrel with an M4-cut upper receiver. This pic pertains to an AR-15, but the theory is the same with regard to the large-frame ARs as well:

3144gvt.jpg


As you will see, an M4-cut upper receiver mated to a standard, rifle barrel/extension can cause bullets to jam up when feeding because of the overhang from the non-ramped barrel extension over top of the receiver cuts. If it does feed given the extra mass/force of the larger .308 carrier, it can cause damage to your bullets as the round chambers. Now, there is nothing to keep you from making the M4 cuts into the barrel extension yourself if you have the tools to do it, or having a competent smith do it for you. ADCO does that particular service for ~$15 + S&H both ways if you are interested.
 
Ok, does the SI or DPMS uppers have the M4 cut outs or are they rifle cut?? I can not find any info

I'm at work and don't have access to my pics (not even sure I have any of the inside of the upper), but the last one I assembled for a friend definitely had the feed ramp cuts in the upper receiver to the best of my recollection. I'll look tonight when I get off work and let you know for sure if I can find a pic.

If you want to confirm in the meantime, drop a dime on the SI folks. They are very helpful, courteous bunch in my past dealings with them.
 
Thanks ORD, I will try and get ahold of somebody over there. If it does have the ramps then I can just have my barrel extension cut. I guess really no big deal. The SI upper and lower will be here in about 3 weeks and the barrel not till 11-04-13