AR15 9mm build, What weight Buffer?

[brstevns]

Putting together a 9mm upper, 16 inch barrel just flash hider. Blowback bolt type. What type or weight buffer would you use?

[Ickisrulz]

I use a buffer made for a 9mm AR. I don't know exactly how heavy it is. Before that I used an H-2 with about 6 quarters added. I understand you want to use as much weight as possible, but not too much as to prevent cycling.

[Moleman-]

I use 7.5 ounce to 8 ounce extended type buffers turned from SS.

[Gtek]

I have put a few together and total mass of buffer (H3)/bolt group between 18-21 ounces has been flawless with and without can. Also do not forget to make spacer to place in behind spring in rear of lower extension if landing on 556 lower and not using 9mm specific lengthened buffer. Go grab your normal 556 AR and lock BCG open clear, hold bolt latch in with left thumb and pull charging handle to rear. Bumping between two points you should see about .700" in movement. Make spacer to duplicate found dimension in travel with 9 upper installed to prevent beating your bolt catch out of an AR lower if used with mag adapter. Putting 556 upper back on just remove spacer. Made mine from 1" Delrin and reduced OD to .995" and they fall out to remove. I have Stern Defense mag well adapters, bolts, barrels and have been very pleased so far.

[brstevns]

I use 7.5 ounce to 8 ounce extended type buffers turned from SS.

Would the quarter trick still be useful with this type of buffer?
Gtek thanks for answering this question.

[Gtek]

If using stock length AR buffer yes spacer (quarters, delrin, closet dowel, etc.), extended purpose (lengthened nose) built 9mm and or pistol caliber does not need. But no matter what combo I would recommend check of distance between bolt stop to seated in rear extension with charging handle pull.