So I'm about to embark on my first build. I bought my lower (anderson arms, only one available at the time) a few months back at my local gun store. the guy working told the guy beside me, buying the same lower, that it was the commercial version of the lower. Something about the buttstock threads being different? From the research and reading i've done on this sight there is no commercial or milspec lowers, they're all essentially "the same" measurement wise. the only difference is the buttstock/buffer tube assembly need to be both commercial or both milspec. so my questions are:
1. is my lower a commercial or milspec or neither or does it matter?
2. are there any special considerations i need to take with using this lower?

from the research i've done on this sight i've decided to go with the ST-T2 Heavy Buffer (by Spikes Tactical), which is milspec, therefore i should get a milspec buffer tube assembly and stock, right? and i should have no problems?

also, is the stag arms LPK a good choice or would you recommend another LPK? i've seen people use so many different ones on this site that I'm not really sure whats best.

thanks in advance!

You are correct.  The tubes/stocks will be be mil/com spec'd.

Unless your lower is actually used buy the military, it's not truly mil-spec. Your lower is made to mil-spec standards which is all that matters. Unless it's out of spec.

The ST-T2 is not mil-spec. It's just a quality buffer that isn't used by the military as far as I know. What you need to know is that there are 2 different carbine buffer tubes(RE). Mil-spec and commercial. You need to use a mil-spec tube with a mil-spec stock. Same with commercial. I'm sure someone will post the pic of the differences.

Stag makes a very good LPK and BCG.

Understand that mil-spec is simply specifications made by the military. It doesn't necessarily mean it's the best. I like better then mil-spec.

so the buffer doesnt have to be mil spec even if the buffer tube and stock are milspec?

i saw the comparison picture posted here that was from magpul's site, if that's what you're referring to.

Milspec buffer tube dimension vs "commercial" buffer tube dimension is strictly the OUTSIDE diameter of the tube, threads and interior dimensions are all the same.  Threads on a milspec diameter tube typically look a little different toward the back, this is one of the easier ways to identify a milspec diameter tube.


It's irrelevant whether you get a buffer tube that is milspec or commercial outside diameter, or an "entry" tube for that matter.

I don't recommend the ST-T2 or any other non-buffering shot filled spring guide.  I strongly suggest using an actual buffering buffer, say an H2 if you're looking for one of that weight.

I've had good results with Stag LPKs but haven't bought any in a few years.  Their BCGs are good also.  Stag is the OEM for many of the parts sold at higher prices by a variety of online vendors, so might as well get it from them for less.

do you mind explaining the difference? i'm looking on BCM and see if i buy the buffer kit i can choose the standard buffer or H, H2, H3. but I thought the ST-T2 replaces the standard buffer and is supposedly better in reducing felt recoil.

Buffers slow and smooth the transitions in the BCG movement... smooth out the opening sequence, hold the BCG at the rear of it's travel slightly and prevent it from rebounding from the back of the buffer tube, and then provide a longer duration "push" on BCG closing to control bolt bounce, which is the rebounding of the BC away from the barrel extension.  They do this by having a series of weights separated by rubber washers, so that there is a staged sequence of weights... the first weight compressing a rubber washer, then when full compression is reached the next weight starts compressing the next washer, etc.  Standard design carbine buffers have a sequence of three weights and washers, rifle buffers have 6 or 7.  By contrast the ST-T2 has a single mass of pellets and no washers.  A mass of pellets behaves (regardless of marketing) much more like a single weight than the sequence of staged weights in a standard design buffer... as such, it provides little buffering action.  There's high speed video out there if you want to compare the buffering vs standard buffers, bolt bounce is pretty easy to see in high speed video.

If you want to reduce rifle movement (what most people call recoil is really the buffer/BCG stack hitting the back of the buffer tube), the most important factor is that you want to get a reasonable gas system setup so that your cyclic rate is under control.

If you want a "gamer" rifle for competition or whatever you can also use an adjustable gas system and lightweight moving parts and tune the operating system down to a minimal amount of energy... this approach is NOT recommended for any defensive use firearm as you're radically narrowing the reliability envelope by doing that.

gamma, are you saying the ST-T2 will have bolt bounce ?

i only ask because i have never heard of this. i slapped a full auto ar together about a month ago form spare parts and the only spare buffer i had was either a stardard carbine buffer or an ST-T2 so i threw the ST-T2 in it and it rand fine. no bolt bounce, ran fine in semi and full.

i would think the tungsten powder would make it act like a dead blow and be smoother.

Everything has bolt bounce, it's just a matter of how much.

IIRC from the video the T2 looked similar to a standard CAR buffer, while H and H2 types has progressively less.  I looked on 'tube but couldn't seem to find it... maybe it's gone.  It's been 4 or 5 years ago I think.



The point of a dead blow is to deliver a controlled impact... the point of a buffer is to reduce and smooth an impact.

i'll be honest i dont even know where i got the T2 i just figured it was spikes version of a H2.

H2= 2 tungsten so i figured T2= 2 tungsten. wasnt till you posted about it that i bothered to see what it was. i will say it ran fine. i only put one mag through it in full auto just to test it all out. 3rd burst 3rd burst and then dumoed the mag but she ran smooth and seemed GTG.

it sucks i cant find any places that allow rifle cal full auto. the place i got to shoot it let me run one mag through it since we were there till after closing and no other customers were around. the range guys wanted to see if it would work (i wasnt sure it would either) as i this was first full auto conversion i had done. posted pics of it in this section.

found a vid you speak of bolt bounce

very intersting stuff. the 9mm got flung around hard. i wish they would have done the H2 and H3 buffers as well.

next time i get to shoot it , i will bring one of my H's out of one of my other rifles in case it doesnt want to cycle.

i know form talking with someone else who just did their first conversion a couple months ago, theors would run fine in semi but not in full. he had a standard carbine buffer. he swapped in an H and it ran fine.

also mine is an 11.5 upper (spare parts scrounging) and so that should have a slightly less powerful gas pulse so that could also be why mine ran fine.

edit: just watched the hydraulic vs standard vid and the hydraulic was worse, i didnt expect that.

Stag Arms LPK is a good choice. Ordered it directly from Stag, fast shipping, decent price, and all the parts were there. I chose them over DPMS but if I would have had the budget I would bought the Colt LPK. No regrets, so far though.