I use an H3 buffer in a couple different guns. I really only have one though, as they're typically quite expensive. About $50 seems normal.

My LGS has some 9mm buffers made by LBE. Length is the same. Overall weight is the same. It has a reciprocating deadblow weight inside. It is about $20.

Differences are: The outside diameter is larger. It maintains the "shoulder" dimension of a normal buffer for the entire buffer body. The material is different. I think it's steel where a normal one is aluminum. This last difference is a guess...

I think the mass of the actual reciprocating weight inside is not as much as a proper H3 buffer. I have not taken them apart to weigh the guts separate from the body. It seems logical though, as the tungsten is what drives the price up.

I have been using the "9mm" buffer in place of a H3 for a little while, and it doesn't manifest any adverse effects.

Worth looking into, for someone wanting to mess with a heavy buffer, but not wanting to spend the coin on a proper H3. From what I read in my research, it seems there's a wide array of 9mm buffer styles, so this compatibility won't be the case with all of them. I only know it to be the case with this particular LBE buffer.

Overall weight of a 9mm buffer should not be the same as an H3. They are generally quite a bit heavier.

A 9mm buffer is closer to an H4 if not MUCH heavier if you don't want bolt bounce and blown out extractors.

So far the best 9mm buffers have been the 9.8 KAK K-spec and Kynshot 9mm hydraulic with an A5 tube with 2.5oz additional weight.

Now I just use a Maxim RDB and it just works.

This particular 9mm buffer, made by LBE, is the same overall weight as an H3 made by the same company. I used a scale.

As a more affordable alternative to a proper H3, in a 5.56 rifle, it's worth considering.

I guess a buffer is hard to screw up, unless I guess they make the plug out of crap.

The only LBE product I've bought was a buffer tube, and my stocks all fit poorly (were loose and rattled). I didn't think you could make a buffer tube too small and still have the buffer fit inside, but I was wrong. No more LBE for me.