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cdbwinchester

cdbwinchester

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458 socom

I have acquired a Rock River Arms .458 (upper and lower) that is virtually brand new (shipped November 2013 from Rock River). I am not the original owner and I have had issues with the rifle since my first rounds through it. Did the usual internet searches and fixes suggested (magazine alterations etc) and had a gunsmith take a look at it. I discovered today why I have had problems - the lugs around the feed ramp are being peened by the bolt lugs.
What would have caused this. Would a new barrel suffer the same result if I don't get to the root of the problem or is it a manufacturing defect in the barrel?
All and any advice very much appreciated!
 
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That's odd, it looks like the bolt head is rotated into the 'locked' position when it hits the barrel extension. Normally this would be impossible as the cam pin rides in the channel that the charging handle rides in.

Look in your receiver, is there are excessive wear in the charging-handle channel? Is the cam pin worn down at all? When you rack the charging handle slowly (no mag in) does it smoothly go into battery? or does it feel like it's hanging up?

I suppose it could be faulty heat treatment and the steel is so soft that the copper jacket is peening it, but I can't see the steel being that soft.



To me it looks like an issue with the bolt head not in the right orientation after it strips the round off the magazine, i would look for scars/marks inside the upper first.
 
Ok, so it's a little difficult for me to tell by the pictures but I will tell you what I think I see.

I believe (and I may be wrong) that those marks on the barrel extension are not from the bolt lugs hitting going into battery.

Because they have ground down the bottom of the barrel extension to create a larger feed ramp for the larger round, I believe that area of the lugs has been thinned/weakened.

So I think those marks are actually indents from the recoil of the bolt against the extension from the inside (when the bolt is in battery/locked).

Can you describe, specifically, what issues you are having with the gun?
 
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So whats the actual problem ?

Are you having failure to chamber a round ? This is not uncommon since its easy to resize Socom case improperly due to the goofy shape .

This is often caused by lack of lube INSIDE the case neck . I use Redding dry neck lube . As the press is raised you can feel the expanded ball dragging as it goes back out of the case neck . This can pull the neck "up" moving the shoulder

Burn rate of powder is a bit fussy on the 458 socom so easy to have short stroke ( doesn't pick up another round / doesn't lock back on empty mag ) . Is that the problem ?

Bolt Extension Dents

The indentations are not from the bolt unless you have thing serious wrong with your cam pin , which I can't imagine that could actually happen to have the bolt put indentations into the extension like that .

The bolt head is aligned with the barrel extension long before bolt is in batter and then rotates after its entered

Indentations are not from the round . I have over 1000rds through my RRA 458 Socom ( ouch ! ) and the only thing that that happens to the massive feed ramp is the top of center lug of the extension will wear down a bit since its what gets hit by the projectile when chambering . Projectile doesn't come anywhere near where those dents are

I doubt RRA will give you a barrel since I don't think there is anything wrong with your barrel.

Question : how did you get the barrel off . The older CAR Socoms had their one piece forend that had Loctite Red ( permanent ) on ! You could easily damage the upper trying to get it off

IMO the dents are not from the bolt head / rounds being chambered . No idea how they got there but not sure with problem that would cause
 
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Apologies for not replying to all of your comments, suggestions and questions sooner.
I passed along many of the comments etc by you all to the gun shop where I had the 458. I ended up speaking to Rock River and was told they potentially would need to see it but the first stop for both the upper and lower would be to Questar. From the beginning I was informed by both RRA and Questar that it could be the ammo (low pressure) that was causing the jamming, misfeeds, and thus the issues around the lugs. I sent along 20 rounds of the ammo to Questar of which they tested in the rifle and it came in at 150fps less than the recommended 1800fps. The only ammo brand that RRA uses and recommends is SBR.
 
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Are you set up for reloading? You could reload to the velocity spec they want. I thought that most people in Canada with 458's were already reloading for that already anyway because of the lack of 458 ammo in Canada.
 
Yes I am pretty much set for reloading 458 but RRA will not warranty anything that has used handloads - pretty much standard with manufacturers.
 
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It would probably be cheaper to do the paperwork to send it back to RRA than import anything less than several cases of factory ammo. Check with site sponsor IRUNGUNS. They may be able to help with either the ammo or export/import of your rifle. Or get your rifle back from Questar and load some hot handloaders and see what happens. Good luck with it.
 
So I was thinking of getting the Rock rivers AR in 458.... Are there others out that may have one and make there own ammo who can comment on its function. Thanks
 
Kingjenky said:
So I was thinking of getting the Rock rivers AR in 458.... Are there others out that may have one and make there own ammo who can comment on its function. Thanks
Click to expand...

Have never fired factory ammo in mine. I find mine very forgiving in terms of projectiles ( round nose to Hornady flex tip bullets from 250Gr to 500gr ...ouch... ) and load

I have also fired reduced subsonic loads that cycled fine

The RRA 458 only working with one particular factory ammo is nonsense . Lots of various load data online for guys with the RRA 458

You should check if the gas block is misaligned if you think its not getting enough gas . The RRA gas block on mine had set screws but barrel was not dimpled so it can rotate

Also you should try to pull back on charging handle fully and have it chamber rounds . Run a bunch through gun . If it is still hanging up its not a gas issue / short stroke
 
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