PSA 20in upper, question [Archive] - Glock Talk

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Cole125
12-13-2011, 11:22
Quick question here, I am thinking about getting a PSA 20in flattop upper which has rifle gas system. I have a completed lower with a carbine buttstock, action spring and buffer tube. Will the PSA upper work on this lower?

Thanks. Also can anyone comment on the 20in PSA uppers? I am looking to build a SPR and looking for a decent 18-20in upper for under $600.

Cole125
12-13-2011, 13:23
In other words do you need a rifle length buffer tube and action spring to run a upper with a rifle length gas system?

WoodenPlank
12-13-2011, 13:43
In other words do you need a rifle length buffer tube and action spring to run a upper with a rifle length gas system?

Nope. I have run an 18" rifle gas upper on a carbine buffer tube, buffer, and spring no problem. Might have to play with your buffer choice a bit, but otherwise it will run fine.

Cole125
12-13-2011, 15:51
Okay thanks thats what I wanted to hear. I am still a little confused about the reason for two lengths of buffer tubes and springs. On a rifle length gas system does the BCG get hit with more or less gas than with a carbine length system?

faawrenchbndr
12-13-2011, 16:31
The buffer set-up is a bit confusing at first.
Think of it this way, the buffer must fir the stock, not the upper.
There are A1 & A2 rifle stocks and carbibe stocks. The A2 uses a rifle
length tube along with a small spacer at the end of the tube. Then there
is the carbine buffer tubes. There are four position & six position tubes.
There are also a few different buffer weights for the "carbine" buffers.

WoodenPlank
12-13-2011, 18:06
Okay thanks thats what I wanted to hear. I am still a little confused about the reason for two lengths of buffer tubes and springs. On a rifle length gas system does the BCG get hit with more or less gas than with a carbine length system?

The longer the gas system, the softer the felt recoil due to lower pressures in the gas system.

ddbtoth
12-14-2011, 17:49
Also the heavier buffer is there to slow down the sharper recoil pulse due to the gas port being closer to the chamber. The heavier the buffer, the "softer" recoil pulse. But if you go to heavy it will short stroke or not eject and chamber the next round.

Cole125
12-14-2011, 18:21
So are you saying a 20in rifle length upper will be less reliable with a standard carbine buffer and spring?

I know I will have to try it for myself to know for sure, but I would like to know in advance so I can order a rifle stock, spring and buffer if needed.

ddbtoth
12-14-2011, 18:44
So are you saying a 20in rifle length upper will be less reliable with a standard carbine buffer and spring?

I know I will have to try it for myself to know for sure, but I would like to know in advance so I can order a rifle stock, spring and buffer if needed.

I would try it out-there are lots of variables, including ammo, that could affect the cycling of the weapon. The gas pulse (higher because the vent hole is closer to the chamber in a carbine vs. a 20") , the strength of the spring, the weight of the buffer. For instance, Wolf ammo is considered weak, and may not cycle the weapon with a heavy buffer and carbine spring. If you have a bought a bunch of it and it gives you problems, try a lighter buffer and see if that increases reliability. Cheap ammo for practice that works is better than expensive ammo that you can't really afford to shot a lot.

Cole125
12-14-2011, 19:02
Thanks for the helpful input. The 20in upper would be a long range rife and I would shoot the expensive match grade stuff in it anyways. I suppose I could just buy it and if I am having short stroke issues I could purchase a different buffer or a complete rifle receiver extension.

WoodenPlank
12-14-2011, 19:27
Cole, unless you are using an extremely heavy buffer, I doubt you will have any issues. The rifle buffer weighs almost as much as a carbine H3 buffer, but the carbine has a shorter spring. If you do have any issues, try a different weight buffer.

samuse
12-15-2011, 22:30
I haven't seen any SPR barrel on PSA's site.

The A2 barrel is not an SPR barrel and won't be even close to a SPR.

crazymoose
12-18-2011, 11:16
The Canadians use the 20" barrel with carbine stock as their service rifle. They use the standard carbine spring with an H2 buffer.