Buffer Spacer for AR15 9mm Blowback Rifle - Aluminum
The reason why it's better to have less bolt travel on a 9mm upper is that the 9mm cartridge length isn't near the full length of a .223/5.56 cartridge so it doesn't need the same amount of travel. All of this extra travel is just wasted energy and thus creates excess wear and tear on your expensive 9mm AR-15. This spacer takes up the extra space that isn't needed in a 9mm AR and shortens the distance the bolt travels to the amount that it actually needs to travel.
Bolt catches break on 9mm ARs due to the bolt having a running head-start on the bolt catch after the last round is fired. This puts excess pressure onto the bolt catch when it pops up and can cause them to break time and time again. Our spacer solves this issue by shortening the distance that the bolt travels thus not letting it get a running head-start on the bolt catch again.
Because there is less distance that the bolt has to travel, you are going to be able to have faster follow up shots due to a shorter reset. Also, due to there being more spring pressure there will be less gas getting shot up into your face and more of it shooting out the muzzle which is an obvious plus.