Is anyone using a standard carbine buffer or an H buffer in their 9mm AR, and if so, how well has it been shooting?
Also, how much extra weight does a tungston bolt insert add to the bolt over the standard steel insert?
I'm working on a project and need some feed back before I progress.

From an A2 stock user, the minumum I would go with the 9mm is the 3.8oz  "H" buffer, but the "9mm" buffer would dupilcate that of the std rifle buffer.  I personally have my rifle buffer weighted to 7.0oz, as I use a suppressor, and the delay in cycle helps reduce the amount of trash I get out the eject port.

Only in full-auto doe weight really make the world of difference, as weight is used to slow the cyclic firing rate.

Remember ---  CAR style buffers in the CAR tube, and  rifle buffer in a rifle tube.. do not swap, you'll break something.

Good information, thanks.

I test fired my project prototype and it ran great.  Now I need to do some refining so I have an other question.
How long is the Bushmaster carbon 15 buffer tube?

From what I have read the new tubes fall somewhere between the AR pistol tubes Model 1 sales used to make and I think Gunsmoke still does, and a carbine length tube.

Could someone please measure theirs.  I need to know overall length and how much sticks out the back when mounted.

Also, does anyone else make buffer tubes shorter then a carbine tube?

Thanks in advance for the info.