Heavy buffers, hydraulic recoil buffers, Tubb cws and velocity

[DevilDog]

I've been shooting highpower rifle off-and-on for 10+ years. Last year I tried out the Tubb carrier weight system on my Bushmaster DCM service rifle. This rifle shoots great (still has the original Bushmaster DCM barrel), but the brass it ejects got dirty in a hurry - which is often an indicator on a gas gun that the action is opening while the gas system is still "blowing stuff around". It wasn't that I really cared about whether my brass was clean or not, but it seemed like a symptom to a real problem.

So on the suggestion by a fellow highpower competitor I tried the Tubb cws to hopefully slow down the action some. Basically, the Tubb carrier weight system is just weight - it inserts into the back of the bolt carrier, adding a fair amount of mass to the carrier, which then requires more force to work the action. I think the intent was that the orginal Stoner design was meant for lighter bullets and highpower competitiors tend to shoot 68-80 (and sometimes 90) grain bullets and the cws would compensate for the additional bullet weight. At least that is how I understand the theory.

When I used the cws, the brass came out cleaner, the recoil did change, maybe even dampened a bit (hard to tell a recoil change with a 14 lb 20" AR), and surprisingly, all my zeroes dropped about 1.5 moa across the course, making me wonder if that was due to just the change in recoil or did I actually gain some velocity?

Theoretically, the Tubb cws is doing something similar to heavy and hydraulic buffers. I hope to get a chance to do some velocity comparisons with/without the Tubb cws soon, but I am curious, anyone out there compared velocities with/without either heavy buffers or hydraulic recoil buffers?

[twl]

The added mass to the moving parts in the AR action will tend to slightly delay the bolt unlocking.
It is not likely that this alone would cause a velocity increase that would be of any note, although some very small amount may be possible.

There was a discussion on another board awhile back about some wild claims of a person getting 150fps increase with the Enidine hydraulic buffer in a LW piston gun. No other LW users could duplicate this. This theory of big increases was debunked by the Enidine distributor, which measured around 3fps - 5fps increase in his tests with the buffer. Other users reported similar results.

Users of our MGI RRB buffer(7 oz.) do not report any significant velocity changes after installing the buffer.

It is likely that your POI change has to do with some other effect of using this weight in your gun.

[Heavy Metal]

Could simply be the weights are changing the harmonics or changing the force of lock-up.

Gas guns always group differently when they slef-cycle thant when you manually chamber the first round. Changing the force of the lock-up could have had a similar effect.