New build extraction / feeding / damaged casings issue

S

STEELCITYSLICKER

Regular
Rating - 100%
31   0   0
Location
Halton Region
I recently pieced together my first rifle length gas system AR.

Stag lower, stag upper, TNA BCG, CNA barrel (20").

Took the rifle out for it's first test drive and immediately noticed a couple of things:

- Casings (when they managed to eject) were consistently deformed
View attachment 256568
View attachment 256574

- If after chambering a round, you gently ease back on the charging handle and eject it without firing, the round is stuck and you have to mortar the rifle to get it to drop free as it won't just fall out of the chamber. The ejected round when inspected, looks like it has been chewed up pretty good.
View attachment 256570
View attachment 256575

- Here are a couple of money shots taken today. Im happy to provide more if they help anyone to assist me in diagnosing the issue.
View attachment 256571
View attachment 256572

I'm shelving the rifle until I get this figured out as the damaged casings are worrisome. FWIW, I was using both Atlanta Arms Select ammunition and Hornady Super Performance Varmint.
 
I had the same problem if not worse with a Stag10 build I put together...Could only get off 3 shots at most before the unit would jam doing a lot of damage to the affected brass...Also like you say I could not eject an unfired round without pounding on the charging handle and butt stock...Even without a round in the chamber the BCG was difficult to pull out of battery.

Changed out the Stag BCG with a Brownells unit and no more problems...Zero...Thing is now a failure free tack driving machine.

I notice Arms East has had no Stag 10 BCG's listed for quite some time now.

I have a unproven theory on what the problem is but have not looked into it yet...I think the gas rings on the Stag units are either NFG or a bit oversized.
 
Here's my $0.02. First, the ejected cases have minor case mouth dings which is normal and shouldn't be of any concern. Secondly, if you have to mortar the unfired rounds, it means you have a very tight chamber or the bullet is engaging the lands in a major way (not likely going by the picture of the unfired round). Also, in the case of reloads, the cases could not be resized fully. If these were factory rounds, I would suggest a tight chamber. The scratches and dings on the unfired rounds are most likely the result of mortaring. That's what mine often look like when mortaring unfired rounds.
 
I have only built 2 other AR's and with both of those, the case mouth dings flattenedthe case, but this looks different to me....the cases are not flat like I have experienced - instead they are pressed in.

That said, I have limited experience and if you are saying it is normal, I am happy with that.

If I chamber a round, should I not be able to pull back the hanging handle with minimal force and eject the unfired round? Charging handle is incredibly hard to pull back and when I can pull the charging handle out of battery without mortgaging the rifle, the unfired round is stuck and stuck good.

I appreciate the input!

Last gun, I purchased the stripped upper from CTCS and the stripped lower from Arms East. The BCG was bought through TNA. I'm going to switch out the BCG with another and see if that helps at all.
 
I largely agree with Rifledude. Dings in the case mouths making them out-of-round is something that occurs with many firearms designs and is of no consequence. Rounds stuck in the chamber are the result of a tight chamber or short leade, or out of spec ammunition.

The gouges along the case body may be caused by magazine feed lips or a sharp corner on the bottom of the bolt carrier, but are most commonly caused by sharp feed ramps. It is possible that these gouges are what is making your ammuntion out of spec so that it sticks.

You need to put two rounds in your magazine, and mark the top of the first with a Sharpie. Then load and fire the first round, pull the mag and see if the second round is damaged. Then retrieve the first fired case and see where the damage occured relative to the marks.
 
Factory rounds or reloads ?

One of many possible issues you might have a tight chamber

or the feed ramps might be so sharp that they are shaving off brass that when it gets in to the chamber makes rounds jam
 
RifleDude said:
Here's my $0.02. First, the ejected cases have minor case mouth dings which is normal and shouldn't be of any concern. Secondly, if you have to mortar the unfired rounds, it means you have a very tight chamber or the bullet is engaging the lands in a major way (not likely going by the picture of the unfired round). Also, in the case of reloads, the cases could not be resized fully. If these were factory rounds, I would suggest a tight chamber. The scratches and dings on the unfired rounds are most likely the result of mortaring. That's what mine often look like when mortaring unfired rounds.
Click to expand...

The stuck rounds in my rifle were the fault of a tight bolt fit in the bolt carrier not wanting to rotate out of battery...When an unfired round or fired brass were inserted all the way into the chamber by hand they slide right in and out no problem (loose)...But when loaded with the bolt I would have a hell of a time getting them out because of the very tight bolt to bolt carrier fitment ...When firing the rifle the spent case would not clear the receiver and the fresh round would jam into it.

As an example my LMT MWS bolt is very smooth when going in and out of battery loaded or not as the bolt to bolt carrier movement is smooth and easy...As is my Stag10 now that I replaced the BCG with a smooth running BCG...As I said before I'm sure in my case it's the tight fitting gas rings casing the trouble in the Stag BCG.
 
Try this. Grab a chamber brush, put some solvent on it and push it in/out of your chamber a bunch of times. Clean with patches/oil after. Might loosen it up, allowing them to extract.
 
You must log in or register to reply here.
Back
Top Bottom