AR Buffer discoveries

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I’m now running H2s in my mid length 5.56 ARs and an H3 in my 5.56 pistol. I can’t speak to the pistol just yet as I received the buffer just a few days ago, but the others feel better running 4.3 oz over their previous 3.0s

Rather than wait and hope I can find Spike’s buffers on sale I’ve taken to simply buying complete systems from Kaw Valley Precision; that is carbine extension, carbine spring, end plate, castle nut, and H2 or H3 buffer (they sell specific packages) for $60. Saves me the trouble of hunting down individual parts and they’ve been gtg so far.

Edited to add: I actually purchase these from right to bear rather than directly from KVP. 3.0, 4.3, and 5.4 oz kits all run the same price there, $59.95


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I have used both an adjustable gas block (agb) and a configurable buffer kit to tune an AR-15. The problem with threads like this is that they are absolutely confusing for people who haven't dealt with this before and are trying to figure out what to do or what is involved. If it was as easy as, "H2 worked for me!" - then that is all that would need to be sold. Unfortunately, it is not always that simple. There are so many AR gas system configurations and barrel lengths. A person is tuning their AR either by reducing the gas flow via an agb or increasing the buffer weight.

I like the adjustable gas block. It goes to the source and reduces the volume of gas used to cycle the rifle. It can adjust from no gas to full gas. There are drawbacks too. First, is cost. By the time you buy the agb, gas tube, roll pin (if needed), you have typically spent over $100. That is without eventual rebuild kits (depending on what kind you get.) Remember that the burnt powder carbon rich gas has to go somewhere, which is typically through the threads of your agb adjustment screw. Secondly, you have to put everything together and tune it. Remove muzzle device, probably the handguard, pull of the current gas block and gas tube, assemble the gas tube on the agb, place the assembly on the barrel, and make sure the new block is aligned with the gas port.

You're done, right? Not yet, because now you have to adjust it and tune it at the range for the ammo you want to use. Most of the time a person sets it with a little slop for colder weather or some margin with lower powered ammo. However, if you have it set for a certain ammo and decide to try something a lot lower or higher powered, now you are back to adjusting it again. Hopefully, you will remember which way to adjust for more gas or less. If not, you may end up practicing your pogo-ing skills - haha.

The buffer weight solution is simpler in some ways. If you guess right at what you need and buy a H1/H2/H3 buffer, it is as simple as pulling the takedown pin, depressing the buffer retaining pin, and replacing the buffer. Of course it does not affect the excess gas going through the port, but it is a quick solution for usually $50 or less and you didn't have to take the upper apart.

Maybe in today's day and age there is some sort of calculator that takes variables such as: ammo, port size, gas system, bcg weight, and buffer weight into consideration so that you can be right the first time. (Remember that the military chooses their buffer requirements based on knowns - their specifications for ammo, gas system, barrel length, gas port size, etc.)

If you guess wrong, and only have the one buffer with you (ie - the one in the gun), you will not have a fun range day. With this method, it is better (IMHO) to buy the kit and have at least two buffer weights made up already. Changing weights in a buffer is driving out one pin, using a padded clamp or vice to pry off the buffer bumper, and replacing between 1 and 3 of the steel weights with tungsten weights. Push the bumper back on, drive the pin back in, and you are ready to put it back in the gun. If you have a few guns that need tuning, just buy the tungsten weights and the solution could be as low as $30 per gun.

I won't go too far into this, but if you are the guy with one lower and several uppers of various calibers, then it's about how much money you want to spend. AGB's for "all your uppers" will cost a lot, but will be very simple, since the gas setting is set per the upper. OTOH, with no agb's and adjusting via the buffer weight, you are always having to remember which buffer you need for which upper (or just bringing them all, JIC).

Short story is that I have used both and both ways work to tune an AR.
 
Or...if you’re assembling your own ARs, and it might be assumed if you’re shopping for buffers since complete ARs come with a buffer, you might try a pin gage so you know gas port size (if manufacturer doesn’t list it) or even checking say a firearms forum for knowledge gained on the barrel you have and what buffer/spring combo worked for others.

It’s not as if a buffer is hyper tuned to work within a tiny window as opposed to a wide spectrum of ammo, and that ammo is a controlled variable by the end user. Again, plenty has been written on the subject so getting buffer selection right the first time shouldn’t be an issue.

Think you’ll be shooting a wide range of ammo with different uppers? Buy another lower or, if funds won’t allow, then buy an H3 Kit the first time and throw a $10 standard carbine buffer in the cart. Then you can mix and match between 3 light and 3 heavy weights giving you from 3.0 to 5.4 oz.
 
I have 4 complete rifles. One in 9mm, two in 7.62x39, one in 5.56. Next range trip made I will carry a 4 oz. buffer to try just for the halibut.
The one 7.62 rifle that I have fired quite a bit already has the 3.oz buffer and works fine. Just for laffs's I'm a gonna try the 4 oz buffer as an experiment.
My new scope for the 4th rifle is hung up in shipping from CDNN. There is still too much snow in Michigan to freeze myself at the range anyway.
Speaking of abbreviations,
 
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I've only had one seriously over-gassed rifle, an AR10 style. Wasn't really an issue until I started shooting suppressed, after ripping a couple of rims I needed to do something. This was my solution:

https://www.righttobear.com/RCA-Adjustable-Gas-Key-p/1ad-gky.htm

Less expensive than many heavy buffers and as long as you can properly stake a gas key, its pretty easy to setup.
 
Don't forget about the springs, I use sprinco springs in my AR's, they work great and last a long time. You should measure your buffer spring to make sure it is in military spec at minimum, although this may not be relevant for a 7.62x39 rifle.
 
An E-mail to/from the Bear Creek people settled it for me. The AR-7.62 complete upper I just got from them is designed to mate with my PSA Carbine lower kit with it's 3 oz buffer. They say no adjustment is necessary.
The only question remaining in my mind is: "Is two cases of ammo enough when you have two AR_7.62's????"
Pondering this logistics problem with my short wallet remains to be settled. Hey maybe I can put it on my credit card?
 
^^^ See, it was easy after all. Ask the guys who built it. Sometimes the internet experts...well...

Here's a thought re: bolt/carrier bounce. Have someone shoot it while you watch. You will see for yourself whether or not you need to mess with it. I would say no. Over time you will likely break a bolt or two before other stuff wears out.

M
 
^^^ See, it was easy after all. Ask the guys who built it. Sometimes the internet experts...well...

Here's a thought re: bolt/carrier bounce. Have someone shoot it while you watch. You will see for yourself whether or not you need to mess with it.

I’ll trust a number of those “internet Experts” over Moore Machine any day of the week and 5 times on Sunday. To your second point, well, you better have some great eyes.

Realize the brakes in your daily driver can stop a Freightliner but they aren’t the sensible choice. Will work is not the equivalent of best choice.
 
Bolt will likely break first anyway, depending on what you are shooting. Have a spare.

That is all I would be concerned about. If OP's upper breaks notify Mr. Moore.



M
 
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