I wanted to keep the buffer discussion ongoing, but if you will, focused for the gamer like me that is trying to reduce the amount of movement shown in the scope.. for lack of another term I''ll call scope shake... I don't really care about recoil per se, just how much the rifle moves around...the goal for me is to have a 25yd offhand scope shake of half an 8" target bull or "A" zone of a USPSA metric target.... I'm currently using a load that out of my g34 is 133pf load... my current set up is a 16" with 3 port comp with porpoise holes, a NFA modular bolt, and a 6.2oz rifle buffer with rifle spring in an A1 stock...currently I'm at the outside limit requirement with about a 6" shake at 25yd.... I would appreciate any responses ... thank you Les L-747

I got my rifle buffer machined down and will be experimenting with different weights this week

I have some different springs to try also

Also have a Tubb 308 flat wire spring on order per JoshV06 recommendation

If I find anything interesting I'll report back

So what weight buffer and spring combo would you start with?  I'm  also in the middle of a 16" barrel build and am going to try 5.5oz buffer with the  KVP Extra Power recoil spring

There are a lot of things you can fiddle around with to try and change the feel to something that works better for you than just the buffer.
1. solid/multi-piece/hydraulic buffer
2. action spring
3. ramped or non-ramped bolt
4. milspec trigger group, reduced power springs, aftermarket trigger
5. weight of overall gun and balance (neutral or forward/rearward)
6. how you hold the gun when shooting it (vfg or afg)

Most of my 9 AR's are set up with collapsible stocks, 7.5-16" barrels, milspec triggers with reduced power springs and 5.5 oz. buffers with non-ramped bolts or 7.5oz. buffers with ramped bolts.  I only use standard action springs.  They are all semi and non-suppressed.  I run standard A1/A2 flash hiders on most.  I run ammo at about the same pf as yours.  I run my stocks fully collapsed or 1 notch out and a vfg close to the magwell so I can keep the gun tight to my body when shooting.  Others I shoot with swear by an afg further out on the rail and say it provides better control.  I've never really tried to quantify the amount of sight movement I get, but when I shoot it regularly and run it in matches, I tend to be pretty quick and accurate with it.

The biggest problem with 9mm AR is that they are blowback and they will never really be "smooth".  If you want smoother recoil and less movement, get rid of it and buy a roller locked MP5 or something similar - pretty much anything non-blowback.

what is the logic behind the (5.5 oz. buffers with non-ramped bolts or 7.5oz. buffers with ramped bolts)?

list for the DIY types... for rifle buffers containing

7 1/2 lead shot   ... 6oz
1/2" brass rod     ... 6.2 oz
full dia. brass rod... 7oz... thank you SBR 7_11
poured lead .......     9oz

I haven't heard this before

I would guess it would have to do with a ramped bolt maybe weighing slightly less? Or maybe the ramped bolt has less resistance when resetting the hammer?

Either way I don't think there's any hard an fast rule.

Oops

This is where I think the tubb spring really stands out

It has 20% more force holding the bolt closed but doesn't have any additional compressed force compared to a standard carbine springs.

To have the same bolt closed force most high power spring would have roughly 50% more compressed force

Sorry I'm a total 9mm AR newb. Do you mean you use this one? : http://www.davidtubb.com/tubb-springs/bufferspring-sr-ar10

Is there an easier way to get the Tubbs flat wire spring into the receiver extension? I'm guessing a small flat tool to hold down the buffer stop?

Greetings,

Today, I finally got a chance to try an experiment with my 9mm AR (DDLES GSF lower). When I built it, I used the Slash 9Q ( xtra heavy) buffer and the higher power Wolf spring he suggested with it. A round guess would be 4000-6000 rounds since I got it going and with some minor exceptions at first it has been virtually 100% reliable with every ammo type I've tried (probably a dozen and a half at least). Prior to the actual build, I'd read about using the Endine "hydraulic" buffer specifically for 9mm. I'd been wanting to give that a try pretty much for the same reason as the OP in this thread. There is a lot of weight being sent back on recoil and subsequent scope movement. I was also interested to see if the felt recoil would be any different.

SO, I ran 2 mags of 10 rounds each S&B 115g. I wasn't sure at all what would happen, so the first mag was very slow fire. Actually, no issues whatsoever! The second mag, I semi-rapid fired (about 2 rounds/second), with the same positive results. Due to the gnats being just about unbearable and it looking like rain, I stopped at that point. I really can't say if I felt any difference in recoil, but the EoTech 'seemed' to be more stable on the rapid fire mag (I have a 3-9x scope on a "return to zero" mount that I swap on for target shooing; the EoTech is pretty much for HD). I had intended to swap back the Slash buffer, put the scope on, mark targets, etc. and try to do a more scientific test, but that will have to wait. I'm heading to the shop to clean up the carbine and closely examine the buffer for any problems. Hope to try a much more detailed experiment soon, but wanted to let you all know the old Endine did indeed work with no malfs.

Regards, Jim

Let us know

Always interested in whatever smooths these 9's out

Yes

Greetings,

Will do! If we get decent weather Wed I'll have my neighbor come over to help and try a much more scientific test. I too am interested in getting the 9mm AR optimized to minimum physical "recoil bounce", yet still maintain 100% reliability. I need to check and see if I have any standard carbine length springs in the parts bin to try as well. If not, I can scavenge one temporarily from another AR.

Regards, Jim

tried the lead filled rifle buffer ( 9oz) today, and I think I went past the point of diminishing returns... with my 133pf pistol 147 load, the 9oz buffer was worse than the 6.2oz buffer  with standard rifle spring...  drilled out some of the lead to get a 7.5oz buffer, a tad heavier than SBR 7-11 reported with a sold brass slug... will give it a test tomorrow...

edit... the 7.5oz buffer with the 26oz NFA bolt seems like the ticket with my 16" PCC...will try to get a good chronograph result tomorrow

Is that supposed to be 16oz NFA bolt?

I was using a Cousin's digital scale, and may have read it incorrectly, but don't think so... 1# 10oz is what I wrote down for the NFA modular bolt...I don't have a scale at the house other than the powder scale to confirm

Weird, website says 16oz

My bolt is 15.something ounces and it's almost solid steel

Do they have different "back halfs" for the modular bolt?

I was thinking about the whole 9mm bolt travel thing and how it's way more travel than what is actually necessary to chamber and extract.

So I tore down my hipoint 9mm and weighed the "slide" and it's roughly 26oz. (Need a better scale)

The recoil spring is miniscule compared to an AR spring, maybe ½" x 6"

The recoil "buffer" is a ¼" thick piece of rubber.

So...

I figured out how much bolt travel was needed to reset the hammer and figured I could shorten the stroke by about 2"

I made a 1" long 1" diameter rubber "plug" and sandwiched it between two ½" thick 2" diameter delron spacers.

I gave it a try and it worked! I had a few different springs and buffer weight combinations to try but I ran out of light

The biggest difference I noticed was that the recoil was more of a straight back push and staying on target was easier

Went through pretty much the same process, settled on the hydraulic buffer. Works for me anyway. https://www.blitzkriegcomponents.com/ProductDetails.asp?ProductCode=RB5007

Very happy with mine.

OK...I think I'm through ...  NFA 17oz bolt, with a 7.5oz rifle length buffer and tube, and a standard DPMS .308 spring with NFA bumper....thanks everyone for the input... regards Les L747

lasnyder so how is the recoil or (rifle shake) on your final set up?

formula 11e...still recoils, but the shake has been reduced....I've switched from a Vortex SPARC dot to the Vortex Spitfire 1x... with its adjustable focus, I can get a clear dot which helps with my astigmatism...at this point, I'm getting a slight vertical bobble (will work on the comp) and about 2" side to side movement for  double tap at 25yd....my goal was half the "A" zone of a USPSA target, and at this point I'm close enough... working on the loads as I think I'll try some of the coated Bayou 135s... still need to chrono the loads in my G34 as I plan on one load for both guns.. thanks for the interest .. Les