I tried searching but couldn't find any info. putting together A mid length AR and would like to know the right buffer and spring to use. I have a spare 7" tube with a 3oz buffer. The buffer has loose weights in it if that helps. 16" barrel.

That’ll probably work fine.

An H or H2 may be better.

I have a standard buffer and spring in mine and never had any issues.

Hmmmm should I change it

a properly gas, 16 mid will run fine on a standard carbine buffer.  I have played with mine by swapping weights inside between steel and tungsten.  The simple three steel worked great and didn't batter the stroke.

I use a standard carbine buffer in my Midlength gun (Spikes Tactical branded FN CHF barrel), no issues to report soft shooting gun and accurate

The primary purpose of a buffer is to prevent bolt bounce during full auto fire.  People use them for the secondary purpose of slowing the action.  If your gun is working with a CAR buffer, it'll probably work with an H1.  If you go to H2 or H3 maybe it won't work anymore.  Maybe it will depend on the temperature...

The buffer has three jobs:

•Absorb the energy of the bolt carrier group as it compresses the spring inside the tube.

•Push the bolt carrier group back into the upper receiver, chambering another round.

•Reduce and control felt recoil for the shooter.

^ It also provides mass to create momentum to compress the spring. Gas only pushes the carrier about 1/4”. Momentum gets it to the rear from there.

More mass also creates a longer dwell time at full compression.  That gives the magazine more time to it’s job too.

I use H for middies, and H2 for carbine gas (regardless of bbl length; 16" mid, 14.5" mid, 16" carbine, 11.5" carbine).
Recoil impulses are very similar. No reliability issues with factory ammo.

FWIW, the buffer does do several things.  It adds mass to the bolt carrier group, and adds an element of adjustability, with the 3 weights inside of either steel or tungsten (heavier).   A standard carbine buffer has 3 steel; an H1 has 2 steel and 1 tungsten; an H2 has 1 steel and 2 tungsten;  H3 has 3 tungsten.  The spring is what absorbs the energy of the rearward motion of the bolt carrier and buffer, and returns them forward into battery. The "loose" weights in the buffer give a "dead blow" effect going into battery to reduce the possibility of the bolt "bouncing" back out of battery.   This is helpful in full auto guns; probably not absolutely necessary in semi-auto guns.  Adding weight to the buffer slightly delays the bolt unlocking, slows the velocity of the BCG, and therefore delays ejection slightly.  Unless the gas port is a bit large and the gun is "overgassed" (and most are, at least slightly)  a carbine buffer should work fine.  If the gun is functioning 100% and  you're getting ejected empties 5-8' away and somewhere between 2 and 3 o'clock, I wouldn't mess with it.   If all the brass is banging off the deflector and landing at 1 o'clock, you may want to add some weight.  An H1 or H2 also may soften the felt recoil a little, and move the ejection more toward 4 o'clock, but you risk losing some reliability if the gun gets dirty or perhaps in cold weather.

It'll depend on the gas port size.

Generally I like Sprinco Blue or White springs and an H or H2 buffer.

I think what I called an "H1" is simply an "H"

For my DD M4V7 I used whatever carbine spring DD has in it and threw and H2 buffer in there. Virtually zero recoil.

Standard buffer, don't get a heavy buffer for midlength.

My Factory Colt with mid length gas CR6960 came with a H buffer.

Read this and stick with std GI milspec components, the fancy shit does nothing for you and only gives grief.


https://www.arbuildjunkie.com/ar-15-buffers-and-buffer-springs-basics/#:~:text=rifle%20receiver%20extensions.-,AR%2D15%20Buffers%20and%20Buffer%20Springs%20%E2%80%93%20What%20Does%20the%20Buffer,it%20more%20enjoyable%20to%20shoot.

Carbine rifle - carbine buffer
Mid-length rifle - carbine buffer

Both run flawlessly.

That should work fine, but I would consider the A5 system. It smooths out the recoil a decent amount and helps a lot on shorter barrels too.

It's really going to depend on your gun. I'd probably throw a standard spring in there with an H buffer and call it a day. I have 3 midlengths. A larue (known for huge gas ports) 14.5 that has a springco blue with an H2, a 16" bcm that has proven perfectly reliable with an H2, but is currently running a springco white with an H and a triarc 14.5 with a brt gas tube that will only lock back with a std buffer & spring. They're all 100% reliable, but it doesn't mean that if I mixed and matched the pieces that would still hold true. Without knowing more info on your gun, I stick by standard spring and H buffer.