Lightening the BCG

[MikeRush]

The central mass and roll pin in my CMMG bolt is 3.45 oz. I am going to pull it, and start with a 5.4 oz buffer and work my way down. 

[Flatland Shooter]

11 hours ago, MikeRush said:

The central mass and roll pin in my CMMG bolt is 3.45 oz. I am going to pull it, and start with a 5.4 oz buffer and work my way down. 

Will you also experiment with different power factors on the way down?

[MikeRush]

On 11/20/2016 at 8:28 AM, Flatland Shooter said:

Will you also experiment with different power factors on the way down?

I am targeting 130-135 pf with 125s, so I am looking for the lightest reciprocating mass/spring combo to support that safely and reliably. I have been close to 150 pf with my Prod loads, so dropping the powder charge is beneficial.

If I pull that weight and go to a carbine buffer that would be about a 25% reduction in reciprocating mass. 

[MikeRush]

Just as an update- after the first stage of yesterdays match I removed the central mass from my CMMG bolt using  loads that were slightly above minor PF. The difference was night and day! Recoil was slightly more harsh, but I felt like the bolt was finally moving and I can drive the gun and split the way I want to.

The question for me now is if it is better to remove the weight from the bolt, or the buffer. Initially I was thinking it would be best to keep as much mass in the buffer as possible (a la JP) but swapping buffers is faster and easier. It would be nice to be able to choose heavy for factory ammo or light for USPSA ammo. 

[Aircooled6racer]

Hello: I would do some splits and see if the lighten bolt carrier or a light buffer to see which one is faster. Changing out the buffer spring will come into play as well. Once I get all my parts I plan on doing the same thing. I will try different bullet weights also from 115's-165 grain. Powder will be Tite Group since I have lots of it on hand. Keep us posted on your findings. Thanks, Eric

[Shadowrider]

On 11/27/2016 at 9:50 AM, MikeRush said:

Just as an update- after the first stage of yesterdays match I removed the central mass from my CMMG bolt using  loads that were slightly above minor PF. The difference was night and day! Recoil was slightly more harsh, but I felt like the bolt was finally moving and I can drive the gun and split the way I want to.

The question for me now is if it is better to remove the weight from the bolt, or the buffer. Initially I was thinking it would be best to keep as much mass in the buffer as possible (a la JP) but swapping buffers is faster and easier. It would be nice to be able to choose heavy for factory ammo or light for USPSA ammo. 

KAK sells a "buffer kit".  It's a body, bumper and 3 sets of weights.  It comes with 3 each of, aluminum, steel and tungsten.  Not terribly expensive either.

[Aircooled6racer]

Hello: Anyone doing some more testing on their buffer or BCG? I am thinking of removing the weight on my Matrix BCG to make it about the same weight as a JP BCG. I have played around with a couple of buffers from 7.5-4.3oz in weight. 308 spring and 223 carbine springs. So far with 124's at 131PF the best I have done so far is stock BCG 15.5ozs, 308 spring and 7.5oz buffer. It gives me the fastest splits and tightest groups at my test yardage of 7 yards. I will try some more 147's this week. The 115's are out for me. Thanks, Eric

[troupe]

The challenge is out to all of the engineer/shooters out there to design and build a Benelli style lock-up for the PCC.  Makes sense to me.

[bmiller]

43 minutes ago, troupe said:

The challenge is out to all of the engineer/shooters out there to design and build a Benelli style lock-up for the PCC.  Makes sense to me.

Yes sir, that would be interesting.  

[bmiller]

http://www.thefirearmblog.com/blog/2016/12/19/ar-15-buffers-explained-small-arms-solutions-llc/

Video is long, but interesting.

9 mm info starts at 23 minutes.

Edited December 19, 2016 by bmiller

[Aircooled6racer]

Hello: I just removed the steel insert on my Matrix BCG and made an aluminum slug to go in there. It is 1.850" long x 5/8" diameter. The 1/4" cross hole is at 1" from the end. It brings the total weight down to 13.0867ozs from 15.5911ozs. I'll test it this week with some different buffer setups. Thanks, Eric

[bwikel]

Eric if you removed it for weight why did you replace it at all?

[Aircooled6racer]

Hello: I removed the original steel weight but I made the aluminum one so I can get it close to a JP BCG weight. If I remove the aluminum one and the split pin, that will give me another option to try as well. So I can try different buffers and spring setups. I have a load I really like right now. Thanks, Eric