What buffer weight, spring to use for my .300?
 

Hi guys - got my other parts for my build, but was wondering about buffer weight/size and spring options for my .300 project.

Using a CTR Magpul stock, billet lower, 16" and 10" uppers, almost exclusively subsonic ammo (though will occasionally go hyper) - mostly I'll be loading 220 SMK ammo at around 1000 fps.

So, what buffer (carbine or rifle), weight, and spring should I get for this application?

Thanks!

I'm running a standard weight carbine buffer and spring. Tried a lighter buffer, I think it was letting the bolt/carrier cycle too fast and was outrunning the mag, wasn't picking up the top round and loading.

YMMV.

buffer weight
 

All five of the uppers that I have built all run standard rifle weight buffers and standard recoil springs. Three of the five uppers have the gas port located in the pistol length position and two have the gas port in the carbine length position.

320pf

Are you using carbine/collapsible stocks or regular rifle stocks on these?

buffer weight
 

All of my lowers are standard rifle length stocks. I do not use an adjustable gas block on any of my uppers. I can shoot either super sonic or sub-sonic loads without having to deal with an adjustable gas block.

On the uppers that I have built with the gas port(s) in the pistol length position, I have found that a port diameter of about 0.08 to 0.083" works best. I typically have the barrel built with a 0.072" port and open the port diameter until the rifle runs without any problems.

One other bit of advice. AR's like to run well lubricated. I run my rifles pretty wet.

I hope this helps

320pf

One thing about the A2 stock and standard buffer / spring is the price. Cheap. And it works just fine.

I put my money into the optics, barrel, and trigger. I might shop for a nicer pistol grip.

A well lubricated carrier group gets dirty quickly. But a simple wipe down takes just seconds. I would say I run mine damp. Mobil 1 is my oil of choice. I use the lightest weight that is on the shelf. It puts a nice color on a parked barrel too.

Ctr stock means you'll be using carbine buffer and spring.
Stock carbine buffer is 3.9 oz.
I don't think I'd go any lighter on the buffer but the spring is another matter. Too light a buffer and you can run into momentum problems and it won't fully cycle.
If you're going to be running Subsonic ammo I would get a reduced power buffer spring.


Nick

Reduced power buffer spring - gotcha.

Any idea what type/brand? Does Wollf make one?

I use them myself
.
http://www.gunsprings.com/RifleShotg...t_RsNF.html#AR

I run a 5 position collapsible stock, standard carbine spring, and a hydraulic buffer. I do have a 3 position gas block. No problems what so ever. As far as lubrication, I have some spray graphite that works great. I have it on all my AR's. No mess No collection of gunk No liquid No problem cleaning.