Topic: 308 ORC extraction issues (Read 2986 times)

olyinaz · « **on:** April 09, 2011, 12:25:29 PM »

Just one guy's report: I got a Bushmaster 308 ORC for Christmas and it's not run correctly since I got it. Extremely frustrating. It jams up, usually due to a failure to extract properly which leads to a failure to eject. If I load one round the one round would often wind up just sitting there on top of the mag. This video illustrates the issue VERY well:

http://www.youtube.com/watch?v=dgsY89csA4E&feature=youtube_gdata_player

I sent the rifle off to Bushmaster and they didn't do squat. "Polished the feed ramps" and function tested it. Got it back and it had the EXACT same issue. Gee thanks. At least it only took two months for this useless process that cost me money to run its course.... I have no idea what ammo they use to function test at Bushmaster, but I took the rifle directly to the range with six different brands of .308 WIN and 7.62 NATO ammo and the only brand that would run was Bear Silver (zinc plated steel case).

What's interesting is the rifle has always fired Russian steel cased .308 just fine. Extracts and tosses them like a champ. I suspect that the stiffer rims and perhaps slightly lower pressure (I've always found new Russian made commercial ammo - not Russian mil-surp - to be mild by comparison to other types and in my view it explains the "sooty" complaint that you often hear about this ammo).

Everything else was a complete disaster out of three different mag types - Bushmaster steel, C Products steel, and Magpul polymer.

I discovered that this malfunction is EXTREMELY common with DPMS LR-308s (search the internet and you'll be swamped with the issue). I tried all of the standard suggestions one at a time looking for the golden BB - new mags, polished any sharp points on the extractor, polished the chamber (such as you can with a chromed chamber), ran it wet, tried to get a few hundred rounds through the gun. Nothing did a dang thing to help.

So I could send it back to Bushmaster at MY cost - shipping a gun is not cheap - or I could throw in the towel and start buying parts to try and fix it. I even went so far as to seriously consider just buying a new JP Enhanced bolt assembly and a new chrome plated bolt carrier. Long story short I ordered the Armalite extractor spring kit (3 piece kit) and a new DPMS extractor. It now runs with all brands of ammo but with some not well. What is clear is that the gun is over gassed (and I have seen this complaint from other 308 ORC owners). The rims of ejected cases have a very pronounced indentation from the extractor and the rims are indeed bent back by the extractor. Not to the point that I'm worried that they'll rip right off, but I would not reload this brass it's so deformed. It's greater or lesser depending upon the brand and loading. As before, Bear Silver runs like a champ and the cases look completely undamaged. I found one brand of brass that runs well also.

So here I sit. I've got a rifle that runs, but not what I call "runs well", and I'd not trust it for hunting where I'd want an assured follow up shot. I assume that what has happened is that I've got a rifle that, due to "tolerance stacking" would not run as built. I think it's still not going to run well unless I put an adjustable gas block on it. I only paid $800 for my 308 ORC but in my opinion that does not excuse anything. That's a lot of money for some folks and I am one of those folks.

I will never buy another DPMS product. The more I've read up the more I've become convinced that they are "cheap" ARs in general. It's too bad that Bushmaster has been purchased by and will likely be ruined by DPMS's parent company, and I suspect that's already underway with this LR-308 product as marketed buy Bushmaster.

I'm always interested in comments and suggestions, but that's my story and given my experience I'm sticking to my opinions.

Best,
Oly
Tucson, AZ

edgecrusher · « **Reply #1 on:** April 09, 2011, 04:49:01 PM »

Sorry to hear about that oly, my friend had the same issues and basically rebuilt hos with better parts. The good news is you came to the right place, everyone here will do more to help than dpms, welcome to the forum.

imschur · « **Reply #2 on:** April 09, 2011, 06:16:15 PM »

Hi Oly,

Im reading and writing on the fly so forgive me if I miss a detail you wrote or seem short. The boss is hollering for me

Anyhow , a few things, first off the ammo you mention your using, even the stuff that works I believe is specifically mentioned on the DPMS site as not working reliably in a DPMS 308 and the Bushy is a DPMS after all. Have you tried a few boxes of name brand ammo? Even the PRVI Partisan works reliably and is pretty accurate.

Secondly you can do the heavy duty extractor upgrades on these just like an AR-15, Check this stuff out

98Z5V · « **Reply #3 on:** April 10, 2011, 01:01:10 AM »

Oly, I'm just south of you, in Sierra Vista. I'l install an adjustable gas block for you. Pick one up and let me know when you want to do it. Cool places to shoot down here, too.

survivalshop · « **Reply #4 on:** April 10, 2011, 03:30:40 AM »

Good video , I can see by it , that the extractor is pulling off the case before the case is fully released from the chamber .
The reason the steel case fodder works is because of the stronger material (steel ) for the case . The extractor is not pulling past the soft brass .

Chamber is too rough & if you polished it ,it wasn't enough. DPMS chambers are notorious for this .

The over gassing is a possability & that could be handled a couple of ways , as was said , a adj. gas block or you can use a Superior shooting systems flat spring ( spring will hold case in chamber longer)and or go to one of Slashes heavy buffers.
If you say the Wolf is low powered ammo & it works , one would think an over gassed rifle would not care what ammo was in there .

imschur · « **Reply #5 on:** April 10, 2011, 03:58:53 PM »

From DPMS

Ammunition Warning After extensive testing, we have found that only ammunition manufactured to SAAMI (Sporting Arms and Ammunition Manufacturers Institute) specifications is reliable in DPMS rifles. DPMS recommends the use of high quality, domestically produced ammunition for best results and highest accuracy. For plinking and practice, we recommend only domestic, commercially manufactured ammunition. Please note: the use of hand-loaded ammunition voids the factory warranty. The use of all ammunition listed below also voids the warranty.
We have incurred feeding problems with the following:

- Israeli ammunition
- Korean ammunition
- Chilean ammunition
- Portugese ammunition
- PMP
- South African produced surplus
- Lacquer Coated Ammunition or Steel-cased, lacquer coated ammunition
- Wolf
- Norinco
- Silver Bear
- Any steel-cased (coated or non-coated) ammunition
We have reviewed several reports, from several manufacturers’, regarding problems using this ammunition. The problem appears to be the bullet contour and the overall length of the cartridge, which is contacting the rifling before firing. This is creating a gas port pressure and chamber pressure higher than recommended, therefore causing feeding and extraction problems due to the increased bolt carrier velocity. In addition, there is accelerated fatigue on internal parts. There are also indications that brass may be out of spec, which could create an unsafe condition.
We have used this ammunition in the past for testing purposes and found the brass is extremely soft and can “flow” into microscopic pores and grooves in the chamber creating “sticky” extraction. This has been reported in many types of rifles, but is more prevalent in semi-automatic weapons.
The problem with this ammunition is that the lacquer coating on the case. As the barrel heats up, the lacquer turns to a soft, varnish substance and upon cool down, becomes very solid and difficult to remove. This effectively creates an undersized chamber and creates understandable problems.

Your rifle is an investment and it only makes sense to choose quality ammunition for a quality rifle!

survivalshop · « **Reply #6 on:** April 10, 2011, 08:13:13 PM »

Ya , right or some times with a mass produced rifle we get a sub quality one once in a while , that won't feed any ammo .

They have to cover there a$$ is why that's out ,we all know that.

A tight chamber is good for accuracy & most DPMS will shoot nice groups ,but every thing is a give & take kinda thing .

Tight chamber /tight group ,but ammo specific.

A Milspec 7.62 chamber should feed any decent quality NATO/308 ammo.

I'm all for the using & buying domestic made ammo.

Don't shoot reloads , awh man , I wouldn't shoot .

olyinaz · « **Reply #7 on:** April 12, 2011, 12:16:46 AM »

Thanks for the reply guys! I'm on the road but will post a bit more when I get back in.

Much appreciated.

Oly

caporider · « **Reply #8 on:** April 12, 2011, 05:19:39 AM »

Have you tried an o-ring and extra power extractor spring?

My ORC is overgassed, so yours may be even more so. This will cause extraction problems because the BCG is cycling before the brass casing has had time to contract off the chamber walls after firing. I'm going to try a Slash-type heavy buffer and a Tubbs flat wire action spring to see what happens. You could also try an Armalite extended collapsible stock receiver extension vs the standard commercial spec AR15 extension on the ORC.

I haven't spec'd the chamber on my ORC, but if it is not 7.62 NATO you could always take a finish reamer and correct the chamber. The chrome you remove won't be worth writing home about, and it will improve reliability with surplus ammo.

olyinaz · « **Reply #9 on:** April 12, 2011, 11:39:16 PM »

Thanks again for the replies guys. Yes, I have installed the three-piece Armalite AR-10 extractor spring set in my gun and that was what got it to running at all. It's mostly good now, but as I said I don't like the looks of the brass (the extractor is trying to rip the rim right off the back of the casing) so I know that the rifle is over gassed.

I also agree about what was causing the problem with the first extractor and standard spring - exactly as you guys surmise. The over gassing is causing the the bolt carrier to start to the rear too early (case still swelled up and stuck to the chamber walls) and the original extractor and spring were not up to holding on. Now they're holding on...and dang near tearing the case apart!

I ordered an extra strength AR-10 carbine length buffer spring and I'm going to try that next. The adjustable gas block is probably a must also.

Best,
Oly

olyinaz · « **Reply #10 on:** April 12, 2011, 11:47:51 PM »

Quote

DPMS recommends the use of high quality, domestically produced ammunition for best results and highest accuracy.

Which is funny because that's exactly the kind of ammo that would not work. At least six different kinds of first quality domestic 308 and 7.62 NATO. Bear Silver, on the other hand, ran like a champ in my gun.

As far as I'm concerned that whole shpeel from DPMS was simple lawyering up - mostly BS except the part about using quality ammo. Not much to argue with there, but I'm using quality ammo I assure you guys. I didn't buy an AR-10 to feed it Soviet mil-surp! :-)

Best,
Oly

olyinaz · « **Reply #11 on:** April 12, 2011, 11:53:52 PM »

Quote from: 98Z5V on April 10, 2011, 01:01:10 AM

Oly, I'm just south of you, in Sierra Vista. I'l install an adjustable gas block for you. Pick one up and let me know when you want to do it. Cool places to shoot down here, too.

Thank you sir! I really appreciate the offer. Would you happen to have the tools to do a free float hand guard installation as well?

If not I'll probably have them both done here in Tucson at the same time - kill two birds with one stone.

Best,
Oly

(Oh and yes, GREAT places to shoot down there for sure!)

imschur · « **Reply #12 on:** April 13, 2011, 04:38:40 AM »

Just making sure. You would be surprised how many emails I get from guys shooting ammo found under the Titanic or from Chernobyl and they are surprised when they have issues

DPMS chambers can be tight and or rough. lacquered steel cased ammo can compound those issues.

I think there's a thread here someplace on polishing the chamber. The exctractor mod mentioned a few times is a worthwhile endeavor regardless.

Quote from: olyinaz on April 12, 2011, 11:47:51 PM

Which is funny because that's exactly the kind of ammo that would not work. At least six different kinds of first quality domestic 308 and 7.62 NATO. Bear Silver, on the other hand, ran like a champ in my gun.

As far as I'm concerned that whole shpeel from DPMS was simple lawyering up - mostly BS except the part about using quality ammo. Not much to argue with there, but I'm using quality ammo I assure you guys. I didn't buy an AR-10 to feed it Soviet mil-surp! :-)

Best,
Oly