20 Practical AR Problem HELP!

[Joey_Denis]

Hello All,

So I have an issue with a new build. I bought a Mcgowen Barrel and just got it in. Cleaned the barrel, and got the gun together, loaded up a bunch of test loads, and took it out to shoot. Every shot fires, but the cases are not ejecting. The bolt comes back about a third of the way, then closes and it is EXTREMELY difficult to open with the charging handle. The case seems to be sticking in the chamber, however, there are no visible signs on the brass. So I did some trouble shooting. Thought it may be a gas problem replaced gas block and tube, no change. Ran a different BCG, no change. Ran the original BCG in a different up (in case it was an extractor issue) shot fine with both a .223 and a .300AAC. Took it back out today, just to fiddle with it a bit more, and now the cases are sticking enough the extractor is pulling off and the case is not even coming out and has to be pushed out with a rod. I bought and built this thing for a gopher hunt the I am leaving for next weekend. I have called and emailed mcgowen several times, with no response, which from what I have ready in reviews, is sadly typical. I posted a few pictures, the one where you can see the brass is day one, this is as far as it would go back, then push forward. The second is today, when it was stuck enough it couldn't pull the case without letting go.

Any advise or ideas that you guys may have would be helpful. I am up for trouble shooting everything to bring this with me!

 

[Ggmac]

The brass seems to have marks , ring , but that's from enlarging the photo . Is your gas tube aligned , bore scope it to be sure . Get a pic of the brass and primer pocket .
Something changed to make it worse , possible gas tube alignment , some blocks aren't ment to be seated against the barrel shoulder , it all depends on barrel machining and gas block . Borescopes are the best way to see it .

 

[Joey_Denis]

The brass seems to have marks , ring , but that's from enlarging the photo . Is your gas tube aligned , bore scope it to be sure . Get a pic of the brass and primer pocket .
Something changed to make it worse , possible gas tube alignment , some blocks aren't ment to be seated against the barrel shoulder , it all depends on barrel machining and gas block . Borescopes are the best way to see it .

I have attached a few pictures of the brass, I am confident the alignment is correct. I didn't scope it, but I measured with calipers the distance to center of the hole from the shoulder and from the edge of gas block and aligned it with the top. One of the blocks wanted to be seated on the shoulder, one wanted to be just off. And the spent gas ring on top of the barrel is perfectly round around the hole, I don't think I'm unbalanced. I will definitely take it somewhere to have it scoped if needed, but I have built about a dozen AR's and never had a problem, and even tried it with different gas blocks. Again, I'm not an expert, let me know if you feel this could definitely be the issue.

On the brass there are two vertical scratches on every case. Not sure what that could be, I was thinking contact with the feed ramp? I'm at a loss, I have never had this issue with another build. Again, any advice I will take as useful and explore it. Please let me know your thoughts when you see the brass. It may be helpful to not, this was made off once fired .223 Remington Brass.

As an addition, Mcgowen's gunsmith just emailed me this:


"Received your message about your at not ejecting. You may need to open the gas port slightly. Meaning that you don't want to open up more than .005"at a time. We set at a nominal dimension, but that being said, yours may need some opening up. It is easier to open the port to tune it than to try to make it smaller and that would tend to force you to use and adjustable gas block. The port should be at .082", you can use a drill but before you drill put a dowel down the bore to protect against going through the bore to the other side of the bore. Any burr that is left inside will be shot out within a few shots."

Am I crazy? I just bought a custom barrel and they are telling me to take a drill to it???

Thanks!!!

 

[Ggmac]

It looks to have rings in the chamber that are showing as the marks on the brass . 2/3 from bottom are the necks tight in chamber , and did the primers fall out or did you deprive already .
It's not unusual for you to open up the port , as they said it's easier to open than go the other route . They have no control over end user variables .

 

[Joey_Denis]

It looks to have rings in the chamber that are showing as the marks on the brass . 2/3 from bottom are the necks tight in chamber , and did the primers fall out or did you deprive already .
It's not unusual for you to open up the port , as they said it's easier to open than go the other route . They have no control over end user variables .

Are the rings in the chamber a machining issue with the manufacturer? My necks are sized to .228, the loaded rounds are right at .232, I have asked them for the actual dimensions of the chamber. I deprimed a couple of cases without sizing at all to show some primer pockets and ones with primers. Are rings in a chamber and needing to open a gas port common things to run into on custom barrels? I have done a bunch of builds but always bought commercially produced barrels.

 

[Ggmac]

I can't see how bad the rings are , if you can feel them they are BAD , yes it's a machining issue . There seems to be two rings on the brass , one 1/3 up and the other about 2/3 up .
I would make up a dummy round , no powder , no primer . Sized case and seated bullet , see if it chambers with just thumb pressure , not using the bolt ! And see if it comes out with just tilting the muzzle up . No bolt carrier .

 

[Ggmac]

If any sticking use magic marker on dummy round and again chamber WITH THUMB ! NO BOLT OR BOLT CARRIER , we're looking for interference issues and marks on the brass .

 

[Joey_Denis]

Will try this right now.

 

[Joey_Denis]

Tried this. It is tight. I have the barrel off, pushed it in, just a little thumb pressure, and even tapping it on a block of wood would not release the round. I had to push it out with a cleaning rod. I took a .223 barrel I shot about 100 rounds through today too and have not cleaned yet. Round fell right out. Machining issues?

 

[GrocMax]

Are you using new brass or fired brass? Sounds like fired brass plus small base reamer.
PTG made 223 based reamers are often small base 'match spec'. Discovered this on my 20 Prac reamer, grrrrrr. A standard die WILL NOT size the body down far enough to fit the chamber cut with these 'match spec' reamers! I have to either start out with new brass, or use a small body die to even chamber reliably on a bolt gun. Measure your sized brass at the base, measure your fired brass at the base. if you have a small body die run a round up it and get the base to .374"ish and see how it works, or try one with brand new brass that is .373"-.374" at the base.

Luckily for me 20 prac loaded rounds fit in the Redding 223 small body die.

 

[jepp2]

My necks are sized to .228, the loaded rounds are right at .232, I have asked them for the actual dimensions of the chamber.

Just trying to help sort through things. For my 20P R-P brass loaded is never .232". My throats are .233" and per your numbers you are running 0.004" neck tension. Seems like a lot. With R-P brass my loaded neck OD's run around .228"

I would take new 223 brass and neck it down for the 20P, to eliminate the sizing die. I would be more inclined to think your brass is oversize, rather than the chamber is undersize.

 

[Joey_Denis]

Are you using new brass or fired brass? Sounds like fired brass plus small base reamer.
PTG made 223 based reamers are often small base 'match spec'. Discovered this on my 20 Prac reamer, grrrrrr. A standard die WILL NOT size the body down far enough to fit the chamber cut with these 'match spec' reamers! I have to either start out with new brass, or use a small body die to even chamber reliably on a bolt gun. Measure your sized brass at the base, measure your fired brass at the base. if you have a small body die run a round up it and get the base to .374"ish and see how it works, or try one with brand new brass that is .373"-.374" at the base.

Luckily for me 20 prac loaded rounds fit in the Redding 223 small body die.

I'm loading from once fired brass from my .223, I checked the fired brass shot today and the unfired sized brass, both are right at .374

 

[Joey_Denis]

Just trying to help sort through things. For my 20P R-P brass loaded is never .232". My throats are .233" and per your numbers you are running 0.004" neck tension. Seems like a lot. With R-P brass my loaded neck OD's run around .228"

I would take new 223 brass and neck it down for the 20P, to eliminate the sizing die. I would be more inclined to think your brass is oversize, rather than the chamber is undersize.

What size busing are you using for your final step? I am doing a .233 then a .228, then after seating I get a bit of expansion.

 

[jepp2]

What size busing are you using for your final step?

If I am using bushings, it all depends on the brass neck thickness. Normally .226. But I changed my forming process and now use a 20-223 die for the final step. I did this to reduce case neck runout.

I just measured the gas port on a WOA 20P barrel that I got yesterday. It was 0.085". It is identical to the one I am using currently.

 

[GrocMax]

I'm loading from once fired brass from my .223, I checked the fired brass shot today and the unfired sized brass, both are right at .374

Do you have any brand new brass you can try? PTG loves to throw a monkey wrench into things with the small body stuff, its not much, but enough to cause unforeseen problems with brass fired in a 'normal' sized chamber and sized with a normal die.

 

[DaveTooley]

Over and over again using brass fired in another chamber can and will cause problems. Start with new brass formed correctly. That means no bushing die for forming.

 

[EWaugh]

You may want to check your loaded rounds to make sure they will fit in a case gage.

 

[L.Sherm]

+1 what Dave said, also if your loaded rounds are .232 chances are you are gonna have some neck clearacne issues I would contact mcgowen and request a print. 2 biggest things people should ask is freebore and neck dia. When ordering a AR barrel or pre-fit