SBR /Pistol Short Stroking

Moderators: e292644, blueeyedwolf

Post Reply
nhgunnut2
II
Posts: 7
Joined: Fri Jul 13, 2018 11:40 am
Country: US
Location: NH

So I have bought the 12 inch upper from Atlantic and built "Pistol" first range, running mostly Winchester white box. 2 or 3 rounds out of every mag would short stroke. (eject but not pick up the next round.) Thelower was running the SBPD brace with the buffer and spring that came with the Brace. Since the trip to the range I have installed a Wolf reduce power Buffer Spring which I hope resolves this . Anyone else running a similar set up run into Short Stroking?
You do not have the required permissions to view the files attached to this post.
User avatar
e292644
Site Admin
Posts: 453
Joined: Thu Apr 20, 2017 5:47 pm
Country: USA
Location: AZ
Contact:

Seems to me it's under-gassed. You may need to open it a little bit.
See reference HERE
Qwerty
II
Posts: 40
Joined: Thu Jun 01, 2017 6:26 am

Shoot some more. Brush the chamber thoroughly. Probably a couple hundred rounds may free it up a bit. Don't open the gas port right away, you can't undo that.
Jiro
II
Posts: 29
Joined: Sat Oct 07, 2017 4:27 pm

Qwerty wrote: Mon Jul 23, 2018 12:36 pm Shoot some more. Brush the chamber thoroughly. Probably a couple hundred rounds may free it up a bit. Don't open the gas port right away, you can't undo that.
The pistol I did has an 11.5 inch barrel. This was at least a year before the 12 and 12.5 inch uppers were available. I have a 12 inch version and only around 200 of those came in. The rest are 12.5.
It was in fact made from a 16 inch upper with the heavier barrel profile. The GP on those are much to small to cycle the shorter barreled action. It was necessary to open it up and as a matter of fact it is because of this gun and conversations with Steve from wolf that the 12 and 12.5 inch uppers came about. They settled on the GP on those at being at 0.095. Several hundred FP brass rounds must be used to get those to seat and function 100%. I used IMI 855.
Tula ammo has proven to be the most unreliable even after break in.
nhgunnut2
II
Posts: 7
Joined: Fri Jul 13, 2018 11:40 am
Country: US
Location: NH

Thanks for the feed back guys ,in looking at some of the brass , I am seeing some scratching so along with the breaking in , I am going to hone the chamber ( I usually this with my ARs any way)
nhgunnut2
II
Posts: 7
Joined: Fri Jul 13, 2018 11:40 am
Country: US
Location: NH

First, thank you guys for feed back. I made 3 changes and the result is that it is now running Wolf 223 55 grain Winchester whitebox M193 and Aguila 55 grain 223 reliably .
The changes were swapping in a Wolf Reduced power buffer spring and Lightly honing the chamber (Always lots of Lube) . These 2 changes resulted in eliminating short stroking. Lastly I swapped the Muzzle device (You Purists please forgive me) to a A2 Birdcage so that I can Run My Gemtech Halo it. I am falling in love with this ugly little Mut of a gun.
crafts.jpg
You do not have the required permissions to view the files attached to this post.
Qwerty
II
Posts: 40
Joined: Thu Jun 01, 2017 6:26 am

That looks badass!

JP
Iamscotticus
L
Posts: 87
Joined: Thu Nov 16, 2017 9:00 pm

maybe with that can you can use the stronger spring.
pls share what hone you used.
useful info for the benefit of others.
thanks.
nhgunnut2
II
Posts: 7
Joined: Fri Jul 13, 2018 11:40 am
Country: US
Location: NH

Well , as it happens a buddy had "borrowed" my Flex hone , so I went full "Jethro" went over to to Runnings grabbed a 45, caliber brush , then stopped at Autozone and grabbed a tube of fine Valve Lapping compound. attached the brush to a length of cleaning rod put the rod in the chuck of a cordless drill. Put a little bit of lapping compound on the brush, push it into the chamber and run the drill lightly
.
Post Reply