BRN-10 buffer problem

[Flintlock Tom]

A couple months ago Brownells had a sale on the parts for their retro AR-10 (the "BRN-10"), which would allow me to build one for 1/3 to 1/2 the cost of the assembled rifle.
Brownells BRN-10
So, I'm building the rifle and find that the rifle buffer bottoms out in the buffer tube and doesn't allow the BCG to travel far enough back to engage the bolt catch. I tried putting a carbine buffer in and hand cycling and found that, now, it does travel far enough back to engage the bolt catch.
Would there be any issues in using a heavy carbine buffer in an AR-10 rifle? Is there a shorter AR-10 buffer?
Any other ideas?

Thanks!

[Pofoo]

Brownells should know and exchange any part that doesn't work.

[ar15barrels]

A couple months ago Brownells had a sale on the parts for their retro AR-10 (the "BRN-10"), which would allow me to build one for 1/3 to 1/2 the cost of the assembled rifle.
Brownells BRN-10
So, I'm building the rifle and find that the rifle buffer bottoms out in the buffer tube and doesn't allow the BCG to travel far enough back to engage the bolt catch. I tried putting a carbine buffer in and hand cycling and found that, now, it does travel far enough back to engage the bolt catch.
Would there be any issues in using a heavy carbine buffer in an AR-10 rifle? Is there a shorter AR-10 buffer?
Any other ideas?

Thanks!

Do NOT use a carbine buffer in a rifle buffer tube without a proper spacer to take up all the slack.
The buffer MUST stop the excessive travel of the carrier or the key will impact the charging handle and damage the reciever and charging handle.

You are PROBABLY running an AR-15 rifle buffer which is LONGER than a 308 rifle buffer.
Make sure you are running a 308 rifle buffer and a 308 rifle spring.
They are different than an AR-15.

[Flintlock Tom]

Thank you, I hadn't considered "over travel".

[xsefan]

Measure your buffer and spring. Maybe they sent you at15 not .308 parts

[ar15barrels]

Thank you, I hadn't considered "over travel".

You need 3/16" to 1/4" of over-travel between the point the bolt catch will engage the FRONT of the bolt and the buffer will strike the inside of the buffer tube.
More travel than that and you start breaking bolt catches or charging handle catches or receivers.
Less travel than that and you get failures of the bolt catch to engage on an empty magazine.