BCG/Buffer Physics

**Inix** · 10-14-15, 19:17

I was wondering if someone could shed some light on the practical physics of the AR action, primarily dealing with the bolt carrier group and buffer weights.

Functionally, if two setups had the exact same weight, however one had a light weight carrier while the other setup had a standard carrier but a lighter buffer, would these two operate differently? Or when considering the action weights would you sum them and look at them as the same?

Thanks

**mcnabb100** · 10-14-15, 21:15

I don't think there would be any difference.

**Clint** · 10-14-15, 21:23

IF there were no movable weights in the buffer, it would make no difference where the mass was distributed.

**Inix** · 10-14-15, 21:27

Interesting, makes you wonder why people buy light weight carriers at all if they can just take it out of the buffer. Thanks for the replies!

**lysander** · 10-14-15, 21:47

Originally Posted by Inix

I was wondering if someone could shed some light on the practical physics of the AR action, primarily dealing with the bolt carrier group and buffer weights.

Functionally, if two setups had the exact same weight, however one had a light weight carrier while the other setup had a standard carrier but a lighter buffer, would these two operate differently? Or when considering the action weights would you sum them and look at them as the same?

Thanks

The reciprocating mass is what matters as to bolt velocity. Whether the weight is in the carrier or in the buffer makes no difference.

Moving, or free floating weights in the buffer prevent bolt bounce on both end of the stroke. On the forward stroke, it doesn't make much difference unless you are shooting full auto. On the rearward stroke free weights in the buffer stop the carrier/bolt from rebounding off the back of the receiver extension and tend to slow the cyclic rate.

**Inix** · 10-15-15, 14:51

I am not familiar with the JP silent capture system, but are its weights free to move somewhat, or is it completely secured.

In a traditional system then, would it make it more reliable to have a light carrier with extra heavy buffer to further reduce bolt bounce, yet keep the same overall action weight?

**tom12.7** · 10-16-15, 06:48

There are some studies that show an increase in buffered mass without an increase in total mass has made improvements in A5 systems.

**lysander** · 10-16-15, 07:44

Originally Posted by Inix

I am not familiar with the JP silent capture system, but are its weights free to move somewhat, or is it completely secured.

In a traditional system then, would it make it more reliable to have a light carrier with extra heavy buffer to further reduce bolt bounce, yet keep the same overall action weight?

Unless you are a lucky owner of a fully automatic AR, bolt bounce is a non-issue.