Ignorant about buffers

[cowboybart]

I have a new 16" AA upper and will be putting it on a BushMaster lower. I traded into 2 "Clinton era" collapsables that didn't collapse. I made them collapse albeit with a thumbscrew and not the spring and pin.
What springs and buffers do I need??
How do I tell if they are mil-spec or commercial?
I want to shoot 139gr but based on what I have read here maybe 120/130gr will be more likely.
If possible I would like to play with some sub sonic loads - will I need a different weight buffer/spring for those loads??

[LRRPF52]

I made them collapse albeit with a thumbscrew and not the spring and pin.
What springs and buffers do I need??

How do I tell if they are mil-spec or commercial?

If possible I would like to play with some sub sonic loads - will I need a different weight buffer/spring for those loads??

http://www.65grendel.com/forum/showthread.php?2271-Anyone-come-up-with-a-action-Cycling-Subsonic-Load-yet

[cowboybart]

Looks like if I want to make it a "quick" collapse I need parts 3,4,5 & 6. I'm guessing the length of the tube is specific to MagPul's stock. Mine shows 10.5" long. The O.D shows 1.165" and I.D. shows .995". I'm gonna guess that I have the commercial version, as my tube does not have a step down in diameter, like the almost .040" in the mil version.

[LRRPF52]

If your extension tube (part # 8 in the graph) is a Clinton AWB post-ban, you need a new extension tube as well. If your OD is 1.165", you do have a commercial dia. tube.

I would just get a Milspec tube from Colt or VLTOR.

[cowboybart]

Why will I need a new extension tube??
Should I just abort this stock and get another one?

[Keep The Change]

The Mil-Spec tubes are usually better made as they have to follow the specs and be made of better aluminum. I believe 7075, where as the commercial tubes don't really have to be made with 7075 and the quality is hit or miss with some of the lesser companies.

The comm tubes are larging in OD because the threads are cut into the larger OK. Where the threads are "pressed" into the tube and the threads actually extruded and come out larger in OD than the base tube. If looking at a tube that is the quick way to tell if its mil-spec, plus the mil-spec has a flat end.

The ID is the same so buffers and springs don't matter. I think LRRPF52 was recommending getting a mil spec tube because it is better quality.

I assume your stock is commercial? Does it fit on your current tube?

You could technically still use a commercial stock on a mil-spec tube. The stock will have just a bit of slop in it. The length of the tube should be fine for whatever collapsable stock you use. Magpul and the like work with the standard length tube/receiver extension.

I don't guess we actually answered you buffer question though.

[VASCAR2]

I have a 16" J&T upper with CAR handguard and six position commercial buffer tube/stock. I started out using the Factory Double Star Carbine Spring and buffer. I never had any functioning issues but most cases were ejected to 1 or 2 O'Clock. After reading on this site I bought a Colt H-2 buffer which has softened the recoil and moved the ejection pattern to 2 or 3 O'Clock. The change seems to help my brass as the spent cases are cleaner and not as dinged up. With a mid length hand guard you may have less gas and not benefit from the H-2 buffer. My 20" 6.5 Grendel upper works fine with the carbine spring and buffer in my six position stock.

[LRRPF52]

Just be advised that Milspec dimensions does NOT equal Milspec quality. There are a lot of shops cutting corners when it comes to basically every component of the AR15 system, from detents and springs, to barrels and bolts. The foreign-made or cheaply-made extension tubes are often 2-part, with the end cap welded onto the tube body, then tumble-brushed and anodized to appear to be one-piece.

This is why I like Colt, VLTOR, BCM, DD, Spike's, and AA tubes. A Milspec tube is drop-forged from heated aluminum blanks, then finish-machined and anodized as one piece.

[Keep The Change]

Good point LRRPF52. Stick with quality brands. I have a BCM going on my Grendel build. I did pick up a cheaper tube (can't remember the name) but it came from Cheaper than Dirt (before I boycotted them). It had good fit and finish and installed fine. However, this was a build that I didn't want to spend a ton of money on.

[Rambozo]

Don't get a cheap tube. After experiencing a Vltor Milspec tube, I won't go back.

[Keep The Change]

I wonder if BCM's tubes are made by Vltor? Vltor makes their BCM charging handles....which are AWESOME!!

I have a couple of Vltor products and they are great. Vltor upper is being used for my Grendel build.

[ejkoechling]

When do you figure for an H1,H2,H3, size buffers? How do you know which one to get when getting you parts? I have an H on my 16" 5.56. Do I need a heavier buffer for a 20" AA upper? How do you figure this ? gotta link? I've looked here and found this, but this is more on the tube, Thanks

[explorecaves]

http://www.gundigest.com/guns/rifle-reviews-articles/gunsmithing-the-ar-3-tips-for-buffers-recoil-springs

The weights for the different buffers are listed here: http://www.heavybuffers.com/reference.html and http://www.biggerhammer.net/ar15/buffers/

More weight = slower cycling of the BCG. Too heavy and you can prevent bolt lock back and/or failure to feed from the magazine as the mag spring moves too slow to lift the next round. Too light and the same thing can happen. You want the happy medium. I could be wrong, but I believe most go with an H2 buffer on the grendel...

[GMinor]

I added weight to my Rifle buffer. I added 352 gains of weight to keep the bolt locked just a hair longer. If it ends up being too much, Ill take out the 352, and switch it out for a 175 grain weight.

[montana]

Buy quality, you will save money and prevent headaches later on. Speaking from lots of experience.