So I read Black Rifle II and it seems the main reason the SPR has a fixed A1 buttstock is that surplus M16A1 lower recievers were used. Setting that aside, what type buttstock would you choose for an SPR build?
For my wannabe 20" SPR/varmint rifles I chose to go with a Defender lower and SOPMOD.The adjustable LOP with a foward mounted magnified optic on a ADM Recon mount is nice.This keeps the CH clear of obstruction also.With the medium contour barrel the weapon balances at the Delta even with the SOPMOD,which is ideal for me.Plus with the stock collapsed the weapon is a couple inches shorter and aids in moving about.And lastly the selection of stocks is much more than being stuck with the fixed A2.
Those are my reasons other than just prefering the collapsible stock.
A rifle length buffer system is more consistent & reliable than a carbine’s, and gets the most out of your rifle.
…So a little bird tells me.
I’m putting a UBR on mine. I’m a tiny short guy and full length stocks don’t jive well with me. The UBR will balance things out well compared to other stocks though.
A2 for the longer tube for the same reason MisterWilson stated.
2nd choice would be the UBR.
with the introduction of the PRS and UBRs, i really don’t see any use for A1/A2 stocks anymore, unless you just like them or don’t want to take out a second mortgage to stock your weapon.
the only advantage to the A2 is perfectly consistent cheekweld… which is actually a huge advantage, with a precision rifle- but the UBR and PRS both do that, and are adjustable to you and your shit.
i think there’s really two different ways to stock an “SPR” style weapon- is the weapon really a carbine that you want to be able to reach out with? or is it a distance gun that you want to be able to use close up if needed? if it’s the former, a SOPMOD/Emod/UBR will fill the roll really well. if it’s the latter, i’d go with either UBR or PRS and wouldnt even consider anything else. my SPR has a SOPMOD, but it’ll be getting a UBR… 'soon as my second mortgage goes through (kidding). 
just my two coppers.
I went with an A2 on mine.
A2 here as well.
For my on going build I went with a A1 length Cav arms stock.
If using fixed I would opt for the A1, adjustable I’d probably look at the UBR or Emod.
I just got my UBR which will eventually be my stock of choice on my 6.8 SPR build. I think the UBR offers the best of both worlds (adjustable but stable and a consistent cheek weld) but Wilson has a good point about the rifle length receiver extension, buffer, and spring.
traditionally, the A1 stock assemblies do, in general, run better than carbine length assemblies- but nowadays, with as consistent o’ quality materials available and the available information with regard to proper timing, its very easy to stock a weapon with a carbine setup just as reliably as any A1/A2. the fixed stock will always be slightly smoother recoil- but there again, the PRS stock uses the A1 setup, and is adjustable… so if you just really gotta scratch that itch, as Mr. Wilson likes to say, the PRS is still a better option IMHO.
I disagree. If it was as easy as you say, the military would have put a collapsible stock system on every A2 in inventory.
And it’s not the consistency of the materials, but of the action of the rifle. As I understand it, the carbine buffer system has a wide spread in carrier velocities relative to the rifle, which affects other things. (like accuracy)
That’s not to say that you can’t have a carbine system that won’t be accurate and reliable, but that if you want to get the most out of it…
I used a A1 length, but then again I live in NYS so what do I know. I am also experimenting with a Sully Stock on a test rifle. May be the best of both worlds.
the military does whatever they do for their own reasons- you gotta take their weapon philosophies with a truckload of salt. the biggest difference between an individual build and military rifles is simply the fact that they’re dealing with weapon decisions on the scale of hundreds of thousands, whereas the private builder is dealing with the weapon in his hands. since, traditionally, and up until only just recently, A1s did run better than carbines, the military, naturally, would chose to purchase 30,000 weapons with A1s- knowing it a proven platform. change is very slow with the military, and they have a record of ignoring advancements for a long time- decades, even.
i admit it can take some tweeking to get a carbine assembly to run well with a rifle barrel/gas setup- but once you find the sweet spot, if you even need to go looking for it (and with a quality spring and properly weighted buffer, you probably won’t), you’ll have a completely reliable setup. there’s examples all around- here, not least of all. what little problems may exist do seem to be pretty much isolated to 20" barrels with rifle gas or 18" barrels with mid gas… at least those are the only two setups for SPRs that i’ve noticed a pattern of problems with. both are fixed by simply increasing buffer weight- H, H2, H3. noveske and vltor did good with their “intermediate” gas on an 18" barrel, which, by all appearances, runs perfectly with carbine stocks. i run a C buff in my sample of 1, runs great. Rifle length 18s also seem to run perfectly fine with carbine assemblies.
but, once again, we nix the debate just by using a PRS.
I am not aware of any problems with the C7 functioning.
i was gonna use them as an example, but i thought i remembered reading that they’d actually had some problems getting that weapon in service… i could certainly be wrong. if so, then yes- more evidence that carbine stocks are good to go. i don’t know how many they have, but it appears to be working for 'em now.
I bought a UBR for this build, but I was surprised how heavy it is. I also have a CavArms C1 buttstock in my parts box, and I’m really considering using it instead; the replies in this thread have me leaning that way now.
The biggest reason I see for using a tele would be the variable LOP for use in different shooting positions.
I also run the CAR buffer with standard spring with .223 Rem pressure ammo.Mostly Black Hills and handloads.
The H buffer and standard spring work very well with 5.56 NATO.The H2 works as well but seems a little sluggish when the rifle gets dirty and hot and Ive had a couple short stroking issues as a result.So I stay with the CAR or H buffer and the weapon is 100% reliable.
Now I did initially have some chambering and ejection issues which was related to the Crane o-ring that came installed in the LMT BCG’s.Once it was removed all was well and the cases land in a nice little pile at about 3:30.
I have a little over 2,500 rounds on my rifle and the nephew just reach 1,000 on the one he uses.No issues to report that were not ammo or mag related.
As far as accuracy and the recoil impulse of the carbine buffer system etc…Ive seen no issues.Rifles do what they need to out to and slightly beyond 400 yards.Anything beyond that is limited by the caliber itself.
Overall the C7 type configuration has become one of my all time favorite setups,and see alot of use as a result.
Yeap,that was my primary reason.Also allows for heavy clothing,gear and different size shooter adjustment.
Plus less weight,bulk and my driving factor cost.Not to mention the fact that Im able to swap stocks around with what I have on hand(including spares) if needed.
So there can be a problem with putting a collapsible stock on a rifle length gas system?
My son and I took a 300 round day class this summer and I let him use my good gun (BCM) and I went with a frankengun built with a Bushmaster 20" barrel, Grant’s M16 BCG, and an old CAR stock with a CAR buffer. Maybe I was lucky but it ran like a champ with zero issues. I really liked the setup, it is a little front heavy but shoots really soft.
If it is going to be used for benchrest/target/prone shooting then I would go with a full size stock. Just a warning about the PRS, they are nice but heavy.
My early 90’s varminter had an A2 stock and the prairie dogs with gaping holes didn’t know the difference:
