I am relatively new to the AR platform & am learning as I go.  I am doing a build and have acquired a CAA SRS Stock It says it requires an A2 Buffer tube.  I have found this one here:  https://www.midwayusa.com/product/489724/dpms-receiver-extension-buffer-tube-ar-15-a1-a2-stock  which I plan to use.  I am finding variances in springs available.  Most say "Carbine" length & this ones says that it will work with either, which confuses me:  https://www.midwayusa.com/product/693755/tubb-speedlock-systems-flat-wire-buffer-spring-ar-15-rifle-chrome-silicon  I am sort of under an impression of the more expensive, the better, especially when I see a spring like this one, costing significantly less:  https://www.midwayusa.com/product/959340/ar-stoner-buffer-spring-ar-15-rifle-stainless-steel

Can anyone point me in the right direction of what I really need, especially if I am totally pointed in the wrong direction?

Sorry for all the links, hopefully it isn't too confusing.  Appreciate any input.

Welcome to the forum!  The CAA SRS stock was designed to convert A2/A4 stock into a "sniper" stock.  So if you don't already have an A2/A4 rifle lower, you will need the A1/A2/A4 buffer tube that you found on Midway's website.  As for springs, I've used both the Tubb's and the good old-fashion USGI springs and there's really no difference in performance.  But don't ask the guys who shoots competition  There's an argument for chrome-silicon to be better at holding tension for a longer "life-span", but to me it's not worth 3 times the price.  Although you didn't mention, you will also need a rifle (A1/A2/A4) buffer in order for the stock assembly to be complete.  Rifle Buffer  I hope this was helpful and keep us posted with the progress of your build.

Thanks for pointing out that there is an actual "rifle" buffer.   will probably have some more questions and will keep you posted.  Thanks again.

http://damageindustries.co/index.php?route=product/product&product_id=391&search=spring

http://damageindustries.co/index.php?route=product/product&product_id=389&search=buffer

I think the big nono with buffers is:
A rifle buffer is longer to fit the longer rifle tube.
A carbine buffer is shorter to fit the shorter carbine tube.

Do not use a carbine buffer in a rifle tube.
The back of the gas key will ram into the lower before the bumper on the back of the buffer hits the end of the tube.

Good to know...do they make different weighted rifle buffers, like the carbine ones?  Is that something I may want to be concerned about?  The plan is to be a suppressed 300 blackout SBR.

Not sure, but would assume so.
Carbine buffer seems to be more popular so prob more availability and options.

I think I would get the heaviest rifle buffer you can find and see what is in there.
After that, shoot it to see how it does, then start swapping stuff around and see what it does.
Should be easy to find brass/steel/alum/nylon spacers somewhere like Lowes to change the weight around.

Cheap/easy, good chance to learn more about how the damn things work, and prob even be able to make it shoot nicer.

No.



H3 buffer, not shown in pic, is 5.3 oz



http://www.brownells.com/rifle-parts/bolt-parts/caliber-conversion-kits/9mm-fixed-stock-buffer-tube-spacer-sku739000019-44739-51603.aspx

http://www.brownells.com/rifle-parts/stock-forend-parts/buffer-tube-parts/buffer-tube-hardware/ar-15-m16-buffer-spacer-prod44889.aspx

There are spacers available to allow the use of carbine springs and buffers in a rifle length receiver extension (buffer tube).

As pointed out in a previous post, a carbine buffer in a rifle length extension will beat the hell out of your lower, unless a spacer is used.



The springs available from Damage Industries have a great reputation and the price is hard to beat.

I forgot about the low mass rifle buffer from JP...

https://www.jprifles.com/buy.php?item=JPLMB

...I saw the price and said, " Forget about that."

https://www.kakindustry.com/ar-15-parts/lower-parts/buffer-tubes-and-parts/ar15-buffer-system

KAK has a kit to configure a carbine buffer as needed. Kind of pricey but it may actually be cheaper than buying several heavy carbine buffers to find the sweet spot.

Just finished a build with colt lower 6920 and a SHilen 20 inch 223 Wylde barrel with Wilson adj gas block, new buffer tube Assy, would not lock back even with the gas wide open..reinstalled the block..its perfectly aligned..holes are good...no "rifle" spec spring or buffer would work...put in the carbine spring with JP Lo Mass rifle buffer..eats and spits as fast as I can pull the trigger with 100% lock back. So like others mentioned Some experimenting may be necessary to obtain optimum performance.

If you had a rifle buffer in a carbine tube of course it wouldn't lock back. The buffer is too long.

Now this has actually brought up a question I have.  Are all 9mm buffers like that?   That looks like the one I have, but I didn't realize there were any weights inside of it.  Or maybe it means the reciprocal weight is the rear part of the buffer, since it's in 2 pieces.  I didn't know about the rubber pieces inside.  I thought people worried about bolt bounce with 9mm because they didn't have recirprocal weight.   Hmmmmm........