Home Forums Hunting & Shooting AR and Tactical Rifles AR buffer question

Sorry if this is a dumb question. I’ve owned and shot plenty of AR15’s but never messed around assembling or building them.

My question is I just bought a used Aero Precision .223 wild and I now noticed the bolt doesn’t come back far enough for the bolt catch to hold it. It has an older Magpul PRS stock on it. I removed the buffer and spring and swapped it with another rifle and it worked. The buffer that is in the PRS stock is 6” long roughly while the one I swapped is closer to 3”.

This is taking place when I manually pull the charging handle back and attempt to lock the bolt rearward. Not while firing. I haven’t fired it yet.

When I pull the charging handle it feels as if the buffer is bottoming out in the tube.

My question do I have wrong buffer in my PRS stock? Do I need to swap to a shorter one? If so what weight?

The PRS stock is meant for a rifle length receiver extension, but Magpul says it can also mount on many carbine extension tubes.

So, first, determine what length extension tube you are working with.

The long buffer sounds like a rifle buffer, meant for a rifle-length extension tube. If that buffer is used in a carbine extension tube, it would cause problems, likely as you describe.

The shorter buffers are meant for the carbine extension tubes.

Also be aware the springs are specific to rifle or carbine extension tubes.


https://magpul.com/prs-gen3-precision-adjustable-stock.html?mp_global_color=118

So if I have a carbine extension tube I should just run a carbine buffer then correct?

Correct
I have two rifles with PRS stocks, both in rifle configuration. I wasn’t aware a PRS stock would work with a carbine tube, but if you have a carbine tube you need to run a carbine buffer.

Yes. Depending on how the gun is running, you will probably be fine with a standard carbine buffer. If you feel it hitting hard in the back of the extension tube, you may want to try H1, H2, or H3.

I've been using H3 in all my carbines lately, it's a smooth ride. In arctic conditions I may need a lighter buffer, but I don't plan on going to the arctic any time soon.

You were lucky. You'd think the seller would have let you know, or corrected it prior to sale.

Rifle buffer in carbine extension won't work, but no harm. Carbine buffer in rifle extension (without a spacer) allows the carrier key to trash the lower receiver ring.