Hi, I am building a M110 clone and is using a Nefarious arms M110 barrel, I am having issues with case stuck in chamber and the case head been ripped off, I see there is a lot of people on here saying they have the same issue but I also have a issue where the case gets marred up really bad by the chamber, just want to see what could cause the marring the red primer is igman which is not a good round I know, it would some times eject and sometimes stuck in the chamber, I also tried Hornady, Hornady ejected fine but also had marring on brass
- Thread starter Guan999
- Start date
Pics show a lot of marks on the brass just below the shoulder indicate the chamber was poorly finished.
That is also what I was thinking, is this something that can be polished by a gunsmith or I need to go back to the barrel manufacturer?
get a detailed picture of the whole chamber
It might just be a little rough that will eventually smooth out, or it might just need a little polishing/honing by the mfr. Yeah. I know some people who just wrapped steel wool or green scotchbrite around a 45 ACP brush with some oil and "buffed it out, but I would contact the vendor. No sense in paying a smith to do what should have been done in the first place.
Check head space. If it’s fine polish the chamber.
Normally I would say send it to them for repair but reading reviews it may be years to get it fixed
Normally I would say send it to them for repair but reading reviews it may be years to get it fixed
I would have thought he checked head space as the post said he was building but yes he should ....good call
I had/have the same issue with a cheaper .308 barrel chambered in .308. It only does it with 7.62x51 ammo though; similar, but not the same specs.
That barrel seems to eat all .308 ammo without issue, so I suspect it’s mostly a matter of tolerance stacking in the throat and chamber.
That barrel seems to eat all .308 ammo without issue, so I suspect it’s mostly a matter of tolerance stacking in the throat and chamber.
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Your chamber is rough but not the issue you have. The gun is WAY out of time. The bolts is ripping the rim off as the case is still under pressure as it is trying to extract. Get a adjustable gas block and screw it all the way in so no gas gets to the bolt. Then start by turning it out a 1/2 turn at a time till you get extraction. Then a 1/4 turn after that should be good.
Likely overgassed as said above (super common in 308 ARs), but you'll want to fix that rough chamber first. There are a couple ways to do that; easiest is a ball hone for the 308 chamber that a gunsmith should have, but you can buy yourself for $40-$50. Keep it wet with a solvent or light oil; laquer thinner, mineral spirits, even WD40 all work fine, and spin it in a cordless drill while moving slightly in and out along the chamber. If it leaves a cross-hatch pattern you did it right. I like to come back with extra fine #0000 steel wool wrapped tightly around a brush for a tight fit in the chamber, again wet with WD40 or similar, to burnish the honed finish. That'll leave a smooth chamber finish that extracts easily and does not mark brass.
Once that's done, definitely tune the gas system. Keep in mind that commercial 308 is generally hotter than mil 7.62, but if you tune it to just work reliably with 7.62 it should be able to put up with being a little overgassed for most 308 loads. Some like Hornady Superformance do better with the gas tuned just for those loads though.
Once that's done, definitely tune the gas system. Keep in mind that commercial 308 is generally hotter than mil 7.62, but if you tune it to just work reliably with 7.62 it should be able to put up with being a little overgassed for most 308 loads. Some like Hornady Superformance do better with the gas tuned just for those loads though.
Thanks to everybody who gave me solutions, I have not tried polishing the chamber yet but I took a bore scope to the chamber and took some pictures. Here is what they look like. What could have caused this issue? Manufacturer’s problem? I did have the gun cerakoted. Will polishing the chamber fix these issues?
Attachments
that does not look safe to fire
nothing in those pics is the problem you re having. All i see is scratches with carbon in them.
Pull out the BCG and drop a round into the chamber by hand. Does it drop in freely or stick? I'm wondering if the chamber was cut undersize.
Other possibility, as already mentioned, is the timing. It's trying to unlock the bolt too quickly during the firing cycle. I couldn't find specs on Nefarious' website, so just guessing your barrel is 20" with rifle length gas? What buffer? Standard weight BCG? Adjustable gas block?
If the chamber checks out, I'd start by turning down the gas and going up on BCG or buffer weight to slow the cycle down. I had to use a SA gas block, H3 buffer, and an increased-strength spring on my AR-10 build to get it to stop pulling case rims.
Other possibility, as already mentioned, is the timing. It's trying to unlock the bolt too quickly during the firing cycle. I couldn't find specs on Nefarious' website, so just guessing your barrel is 20" with rifle length gas? What buffer? Standard weight BCG? Adjustable gas block?
If the chamber checks out, I'd start by turning down the gas and going up on BCG or buffer weight to slow the cycle down. I had to use a SA gas block, H3 buffer, and an increased-strength spring on my AR-10 build to get it to stop pulling case rims.
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The very first pic shows the cause of the issue, but it's not the darker longitudinal scratches you're probably looking at, it's the circumferential rings in the chamber (most visible near the upper left of that pic) that were caused by a rough chambering job and not honed out. You can see evidence of this on the brass in the pics in your original post as well, that's why I said it's a rough chamber; I've dealt with this exact issue before and it's clear that's a problem here. Based on the appearance of your brass, you will need to address both this and the overgassing issue to make the rifle reliable.
IME this is usually caused by a manufacturer trying to save costs by cutting down on production times (pushing the reamer too fast/hard) and using reamers past the point where they should be resharpened. Not at all uncommon with lower cost barrels.
You need to hone the chamber or have someone do it for you. This is the correct tool, and I offered some tips on using it in my previous post in this thread. (Get the 400 grit 308 or 7.62x51 if the link doesn't take you straight to it.)
www.amazon.com/gp/product/B00DB8D5U0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
ALSO - looking back at your first pics of the brass, they're showing similar longitudinal scratches to the chamber; were you shooting this in really sandy conditions by any chance? Or was the ammo sandy/dirty? Honing will fix it, but whatever happened there it did damage the chamber.
There's nothing unsafe to shoot in those pics though. No idea what that one guy thinks he saw but you don't need to worry about that.
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If the case is stuck - he will tear the rim up attempting to mortar the case out of the chamber. So it may not be a timing issue.
My SFAR only had issues like this with Igman also.
Any other ammo and it was fine.
How many rounds of steel case ammo would it take to polish that chamber?
My SFAR only had issues like this with Igman also.
Any other ammo and it was fine.
How many rounds of steel case ammo would it take to polish that chamber?
It won't. That chamber was rough to start with and appears to have been damaged with sand or something (maybe corrosion?). It needs to be honed smooth again, and no sense trying other workarounds when the answer is so simple and easy to do, and relatively cheap too.
