20 Practical - Help!

[Joey_Denis]

Hello All!

I am having some trouble. I built an AR15 in 20 Practical and I continue to get stuck cases and the bolt won't cycle. I have sent the barrel back to Mcgowen to have them take a look, and they say everything is as it is supposed to be. However they do not do any sort of actual testing with it with loaded rounds or even empty cases. I am wondering if my case sizing is off. Just dropping and empty case into the chamber and light pressure is enough to get it jammed. Based on my measurements, I should be ok, but I was wondering if anyone could help me out. I am looking to get a piece or two of sized or once fired brass from one of your rifles that I could try in the chamber to see if it gets stuck. I'm more than happy to pay for whatever it costs! Thanks for any assistance!

 

[Coyotefurharvester]

If you use the bolt release to pickup a round from a magazine, does it go into battery and then extract properly without firing? With no markings on the brass.

 

[Joey_Denis]

With the bolt release it will pick up the round and go into battery, but once its in, its stuck. When it comes out, there are no significant markings on the brass to indicate where it could be binding. If you drop a case into the barrel (when its off the rifle) and tap the back of the round with your finger, it will get stuck enough you cannot pull it out with your fingers, you would have to use pliers or a cleaning rod. I'm going to try to get some pictures of the brass to share.

 

[LA50SHOOTER]

With the bolt release it will pick up the round and go into battery, but once its in, its stuck. When it comes out, there are no significant markings on the brass to indicate where it could be binding. If you drop a case into the barrel (when its off the rifle) and tap the back of the round with your finger, it will get stuck enough you cannot pull it out with your fingers, you would have to use pliers or a cleaning rod. I'm going to try to get some pictures of the brass to share.

Joey, - You've kind of answered your own question regarding this matter, it appears based on your statements that the brass has not been sized enough to accommodate reliable operation. What does a fired case measure compared to a sized case ? at approx. 0.200 & 0.400 ahead of the rim ?

 

[hogpatrol]

What brand of brass? It sound like Lapua. Is it new brass or something fired in another AR?

 

[Joey_Denis]

What brand of brass? It sound like Lapua. Is it new brass or something fired in another AR?

I've tried both Hornady and Remington once fired out of another of my rifles. Maybe i should start with fresh brass? I am going to take some measurements tonight as requested in an earlier post and will post them here.

 

[Terry]

Are you using a small base sizing die?

 

[Doug30racer]

i had the same trouble in a bolt gun when i started, the brass were a hair long at the shoulders, once i bumped them back a bit more they all feed fine. loaded or empty case didnt matter, they would stick, and when fired they were worse. make then a bit shorter and you will be ok

 

[Dusty Stevens]

Paint it with a magic marker and start slipping it in a little bit til it sticks then see where. You can have the chamber honed a bit to match your die IF you full length sized this brass. Sounds like your other chambers and your die is on the big size and the new one is on the small end of size

 

[Jdne5b]

Using 5.56 brass fired in AR-15s for my 20 Practical AR-15 I was getting stuck cases as well.

I had to go to a small(er) base die than my Redding .223 die. I use a Hornady .223 die as it sizes the base more than the Redding

 

[jepp2]

I am looking to get a piece or two of sized or once fired brass from one of your rifles that I could try in the chamber to see if it gets stuck.

I would be happy to send you what you need. Just PM me. FWIW, I load for 4 20P's, and use every kind of 5.56 brass, and have never taken my small base die out of the box. No saying some folks don't need them, I just never have.

Recognize there is a whole lot more I don't know about your problem than I do know. But it sounds like you aren't setting the shoulder back sufficiently. But an easy way to check is:
- size your case what you think is the correct amount of shoulder set back
- detach the upper from the lower
- slide the BCG back to open the action
- take the sized brass and slide it into the chamber with your fingers
- slide the BCG forward with your fingers
- using only finger pressure (and it shouldn't take that much) the bolt should close and rotate into the fully locked up position

If you can't close the bolt with your finger pressure, you have a brass sizing problem.

 

[Joey_Denis]

Thanks for all of the good feedback. I will try tinkering with the sizing and see if that makes a difference! Thanks again to all!

 

[Justin B]

I had the same problem with LC brass was stressfull but like you I got help on the forum here bumped my shoulder back and presto no more problems

 

[nmkid]

C'mon man! What finally happened?

 

[Forum Boss]

A lot of the once fired bulk 5.56x45 brass comes from military and has been fired through machine guns. It may need to be aggressively sized with small base die. Hornady brass may not hold up well to repeat loadings.