I have a 7.5 in. SIG 516 Pistol, with brace. The Buffer is marked "H2". Does this mean it is a heavy buffer?

I am replacing the 7.5 in. barreled upper receiver with a 14.5 in. barreled upper receiver. Can I use the same old buffer and spring in the new configuration?

H&K-Guy

quote:

Originally posted by H&K-Guy:
I have a 7.5 in. SIG 516 Pistol, with brace. The Buffer is marked "H2". Does this mean it is a heavy buffer?

I am replacing the 7.5 in. barreled upper receiver with a 14.5 in. barreled upper receiver. Can I use the same old buffer and spring in the new configuration?

H&K-Guy

It’s the middle of the heavy buffer range. They are labeled H(or H1), H2, and H3. You may be able to use it with the 14.5 barrel, but it would depend on how the longer barrel’s gas system is set up.

there are standard buffers, heavy (h) buffers, and heavier buffers (h2), and even the H3 (heaviest). I like h2 buffers.

The length and type of the gas system can also matter. with the longer upper, If you have any issues of reliability, try an H, or standard, and see what you like better. it'll change felt recoil - the heavier H2 will make a 14.5" shoot "softer" than a standard buffer in the same system. an H2 with a mid-length gas system, so long as it's reliable, would be fantastic IMO.

Others who've probably had more time, experimentation, and experience with building kits may have more suggestins

quote:

Originally posted by Dwill104:

quote:

Originally posted by H&K-Guy:
I have a 7.5 in. SIG 516 Pistol, with brace. The Buffer is marked "H2". Does this mean it is a heavy buffer?

I am replacing the 7.5 in. barreled upper receiver with a 14.5 in. barreled upper receiver. Can I use the same old buffer and spring in the new configuration?

H&K-Guy

It’s the middle of the heavy buffer range. They are labeled H(or H1), H2, and H3. You may be able to use it with the 14.5 barrel, but it would depend on how the longer barrel’s gas system is set up.

The SIG 516's old 7.5 in. and new 14.5 in. systems run SIG's piston operating systems. Both have the gas piston adjusted to standard, whatever that means. However, the new 14.5 in. barreled upper has the piston about 3 in. longer in the front than the 7.5 in.

Hope that helps.

H&K-Guy

Buffers are one of the tunable aspects of an AR. You can't say with certainty exactly what the optimum should be. Run it and see. If you have issues change it.

lazy ejection is the first tell tale if the buffer is getting too heavy. I would go as heavy as you could while still having brisk ejection.

Heavier buffers are just extra mass in your operating system. ARs are dumb, gas-feeding pigs out of the box and buffers are a cheap and easy stop-gap when dealing with over-gassing issues. Equal gas moving more weight equals a slower recoil pulse.

However if you have an adjustable gas system like the one in a 516 I suggest trying to adjust that first. Personally I like to start with the most restricted gas setting and the lightest buffer possible. If your gun works in that setting and locks back on the last round, congrats, you're done. If it doesn't lock back, try upping the gas and playing with the buffer weight until you have a gun that reliably locks back on the last round and minimizes recoil impulse.

quote:

Originally posted by caneau:
Heavier buffers are just extra mass in your operating system. ARs are dumb, gas-feeding pigs out of the box and buffers are a cheap and easy stop-gap when dealing with over-gassing issues. Equal gas moving more weight equals a slower recoil pulse.

However if you have an adjustable gas system like the one in a 516 I suggest trying to adjust that first. Personally I like to start with the most restricted gas setting and the lightest buffer possible. If your gun works in that setting and locks back on the last round, congrats, you're done. If it doesn't lock back, try upping the gas and playing with the buffer weight until you have a gun that reliably locks back on the last round and minimizes recoil impulse.

Yeah. Adjustable gas block flips what isaid. Didn’t know they he 516 was adjustable. Thought it was 2 settings.

quote:

Originally posted by hrcjon:
Buffers are one of the tunable aspects of an AR. You can't say with certainty exactly what the optimum should be. Run it and see. If you have issues change it.

This ^^^^^

I considered my rifle's parameters and went with an "H" for my 14-1/2" bbl. It works, but the brass is banging off the brass deflector pretty hard and ejection seems a mite too "brisk." So I'm going to try a Spike's ST-T2 Tungsten Heavy.

In fact: Just minutes ago ordered, for the 2nd time, 20 ea. of a variety of .223 and 5.56 ammo, to go along with what I stock, to repeat the function test with the new buffer. (And a couple boxes of FGGM, 69 and 77 gr, to see how tight I can get it to group at 100 yards, which has been awaiting the optic I finally got for it.)

quote:

Originally posted by smithnsig:

quote:

Originally posted by caneau:
Heavier buffers are just extra mass in your operating system. ARs are dumb, gas-feeding pigs out of the box and buffers are a cheap and easy stop-gap when dealing with over-gassing issues. Equal gas moving more weight equals a slower recoil pulse.

However if you have an adjustable gas system like the one in a 516 I suggest trying to adjust that first. Personally I like to start with the most restricted gas setting and the lightest buffer possible. If your gun works in that setting and locks back on the last round, congrats, you're done. If it doesn't lock back, try upping the gas and playing with the buffer weight until you have a gun that reliably locks back on the last round and minimizes recoil impulse.

Yeah. Adjustable gas block flips what isaid. Didn’t know they he 516 was adjustable. Thought it was 2 settings.

Apparently they have 3 positions and you can upgrade to a 4 position one. But yes, the less adjustable the gas block the more the buffer plays a role in turning the gun for minimal recoil.

Case in point -- I have an 18" mid-length that has a Superlative piston. That is an incredibly adjustable system and I was able to dial down the gas to "just enough" with an empty buffer. Works great once dialed in but it took about 20-30 rounds to get it right. And it's not something I'd recommend on a defensive gun -- it's a bit too fickle and proprietary.

My 14.5 middy was easier though -- drop in an H2 and call it good. But it also has a regular FSB so I have a lot less gas adjustment. Is it as tuned as the 18" Heck no, but it's reliable and simple.

Bottom line -- keep it simple (buffer) for a defensive gun unless you really trust your gas block. For a race/tuned gun then adjusting the gas is key (no pun intended) to getting the best performance.

I just want to give a shout out to all of you guys for your responses. I've learned a great deal.

I think I am going to adjust the buffer before I do the gas piston setting. Yes, I know the gas setting is easily adjusted, but I may want to suppress it in the future, so I want as much latitude in adjustment as I can.

I wish I could just drop on a 16 in. barrel, and a standard buffer, with the piston set to standard. That would make things easier, as we would be dealing with known metrics. Unfortunately, I purchased this gun as a pistol. I'm not sure about the laws, but I don't believe I can ever change it into a rifle by adding a full size upper. If I did that, I believe I could never legally change it back to a pistol again. So I'm a little out of my depth with this mix of settings and hardware.

Given your responses, I'm going to try standard ammo, standard gas settings, and the H2 buffer first. I have a number of different kinds of ammo to test, so I should know soon whether this will work or not. If the extraction and last hold open features work, then I'll be done with it. If not, I will try an H buffer, and go from there.

Thank you guys for your continued support. I'll keep you informed as to my progress.

H&K-Guy