A couple buffer spring, and buffer questions:

[Magic_Salad0892]

I'm currently running a Spike's Tactical ST-T2 Buffer (4.2 oz.), and Sprinco ''RED'' Extra Power carbine action spring in an 11.5'' KAC Carbine.

I'm thinking of changing the setup a bit, but have a few questions before I pull the trigger (lol pun) on the change.

My self defence ammunition is 5.56x45mm Sierra 77 gr. SMK, while training ammunition is 62 gr. M855 clone, or Hornady 75 gr. 223.

I experience no short stroking using this setup. Suppressed, or not.

Question A: Does a stronger spring bring increased service life?
B: If I moved to a BCM H3 Carbine buffer would I get short stroking issues, and would be recoil, and cylic rate reduction be worth it?

Thanks for all the help, and for bearing my stupid questions in the past.

[mtdawg169]

If your barrel is a one off, chopped KAC barrel, it will be hard for folks to answer that question. Being a custom cut barrel and having no idea what size gas port was drilled in it, will make it hard to determine what spring & buffer combo will or will not work. Its not like an 11.5" Colt or BCM, where several people here would have first hand experience with that particular barrel or manufacturer as a reference point. You're probably just going to have to test it out through trial and error to see what works best.

All that being said, the ST-T2 is supposed to be near H2 weight. Some have been closer to H. Give the H3 a go and see what happens.

[BufordTJustice]

What I'm reading from your post is that you're looking for a reduction in cyclic rate and maybe a smoothing of the recoil impulse.

Maybe try this:

http://www.blackjackbuffers.com/index.php?main_page=product_info&cPath=65&products_id=188

I run a BCM 16" middy w/ Spike's FA Nickel Boron BCG, Tubbs flat-wire buffer spring, and ST-T2 buffer w/ this blackjack buffer tip installed (I have had one on my AKM clone for forever and figured I'd try it on my AR). The tip helped to further smooth the recoil impulse. My 16" really does shoot like a 20" rifle now....but having an FSC556 out front sure does help as well. ;)

Additionally, maybe trying the following enhanced buffer tube from PWS could have the same effect. I have zero experience with it, but have been eyeing it myself:

http://primaryweapons.com/store/pc/viewPrd.asp?idproduct=139&idcategory=21

I have wanted a rear sling attachment on my AR for a while...and possibly further smoothing the recoil impulse intrigues me....but the PWS buffer tube is not nearly as easy a switch-out as a buffer tip. The dead-blow buffer in the rear is stated to reduce the cyclic rate and smooth the recoil impulse. Only some bona-fide high-speed camera testing (on top of copious amounts of function testing) will either validate or invalidate this product....but PWS's willing-ness to innovate is undeniably sexy.

With the AR's limitation in bolt-carrier stroke (i.e. it's too short to run-out on springs without making contact with the rear of the receiver), using buffers that are softer than metal makes good sense...as long as it doesn't throw the system out of balance.

[mtdawg169]

I was thinking about this and it reminded of a discussion here a while back. Try a search for a thread written by Grant. I think it was titled something like "ultimate sbr" or something similar. It had a great discussion on several things Grant had done to an sbr upper to create a reliable & very soft shooting sbr. He experimented with buffers and even an enhanced bcg from LMT. I would bet that there is some relevant info in that thread.

As a side note, some guys are running H2 buffers in the BCM 14.5" middies (smaller gas ports), so I would think an H3 would be no problem on a carbine length gas. Its just that when more variables like after market springs are introduced, it's really hard to know exactly what will happen. I'm in the middle of an experiment right now, trying out a few different buffers & a couple springs in an SR15 E3. I'm just taking the trial & error approach to see what happens.

[SteveL]

I was thinking about this and it reminded of a discussion here a while back. Try a search for a thread written by Grant. I think it was titled something like "ultimate sbr" or something similar. It had a great discussion on several things Grant had done to an sbr upper to create a reliable & very soft shooting sbr. He experimented with buffers and even an enhanced bcg from LMT. I would bet that there is some relevant info in that thread.

As a side note, some guys are running H2 buffers in the BCM 14.5" middies (smaller gas ports), so I would think an H3 would be no problem on a carbine length gas. Its just that when more variables like after market springs are introduced, it's really hard to know exactly what will happen. I'm in the middle of an experiment right now, trying out a few different buffers & a couple springs in an SR15 E3. I'm just taking the trial & error approach to see what happens.

What prompted to change the setup in your KAC? Were you unhappy with its recoil characteristics?

[mtdawg169]

What prompted to change the setup in your KAC? Were you unhappy with its recoil characteristics?

I may not change it at all. Mostly just curiosity to see if it can run even smoother than it already does. In the end it will probably be a big waste of time considering that KAC has spent alot of time & $$ designing the E3 system to run on the standard carbine buffer, including lots of slow motion video to be sure that they run as well as possible.

Not to hijack, Magic_Salad, here is the thread I was referring to.

https://www.m4carbine.net/showthread.php?t=33743

[Magic_Salad0892]

Don't worry, I actually appreciate the link. I remember that thread.

Great read it is. :)

I should add that I am now running a KAC URX II 7'' Carbine FF Rail + Noveske Switchblock.

The GP size is .071. (I'm 99.999% sure that's the GP size.)

(When I first edited the post I thought it was .081 Colt 11.5'' Milspec GP size.) It matches a Noveske barrel a friend of mine left with me. - Waiting for his lower to be SBR'd.)

I'd like to bring up two points actually:

Would it be more beneficial for me to run an H3 and Blue Spring? (I'd love to get Grant here on this one. Or KevinB being that I'm running a KAC suppressor.)

Anybody know the GP sizes on a Switchblock?

[Robb Jensen]

I would use a high quality standard rate CAR buffer spring from KAC, BCM or Colt along with KAC CAR buffer or BCM H buffer at the heaviest.

The slo-mo video post about buffer proves that the Spidey buffer is a waste of money.....many for some reason drink that Koolaid.

[J Krammes]

Here is a great thread to read with some great videos. https://www.m4carbine.net/showthread.php?t=59176

In my 10.5" Noveske, I use a standard carbine spring and an H buffer (w/ auto carrier). It runs great. No cycling issues at all from Wolf 55gr to XM193. I have only put 30 rounds through it with a suppressor on, but it functioned fine.

Jeremy

[Magic_Salad0892]

I would use a high quality standard rate CAR buffer spring from KAC, BCM or Colt along with KAC CAR buffer or BCM H buffer at the heaviest.

The slo-mo video post about buffer proves that the Spidey buffer is a waste of money.....many for some reason drink that Koolaid.

I saw that. -_-

Do you think that the BCM H3 + Sprinco standard power spring would work reliably? With NATO pressure ammo?

[Robb Jensen]

I saw that. -_-

Do you think that the BCM H3 + Sprinco standard power spring would work reliably? With NATO pressure ammo?

It might work. But like I said, I'd use the KAC buffer or at heaviest a BCM H. KAC knows how to build a good rifle. If it needed a super heavy buffer it would come with one.

[Magic_Salad0892]

Yeah, but they didn't build that buffer setup for the 11.5'' with .071'' gas port + Noveske SB.

What do they run on the 11.5'' SR-16 CQB?

Also:

I have purchased three Sprinco blue springs, and 3 BCM H3 buffers.

I'll post how it runs after 1K rounds.

Thought I'd post these threads/pages for relevance as they contain useful information, and helped me out.

''Best suppressed SBR ever?'' by Grant (A million thanks for helping me. I didn't know I'd be a DI guy when reading this the first time.)

https://www.m4carbine.net/showthread.php?t=33743

The Big M4 Myth: “Fouling caused by the direct impingement gas system makes the M4/M4A1 Carbine unreliable.” by Mike Pannone

http://www.defensereview.com/the-big-m4-myth-fouling-caused-by-the-direct-impingement-gas-system-makes-the-m4-unreliable/

[Robb Jensen]

Yeah, but they didn't build that buffer setup for the 11.5'' with .071'' gas port + Noveske SB.

What do they run on the 11.5'' SR-16 CQB?

Also:

I have purchased three Sprinco blue springs, and 3 BCM H3 buffers.

I'll post how it runs after 1K rounds.

Thought I'd post these threads/pages for relevance as they contain useful information, and helped me out.

''Best suppressed SBR ever?'' by Grant (A million thanks for helping me. I didn't know I'd be a DI guy when reading this the first time.)

https://www.m4carbine.net/showthread.php?t=33743

The Big M4 Myth: “Fouling caused by the direct impingement gas system makes the M4/M4A1 Carbine unreliable.” by Mike Pannone

http://www.defensereview.com/the-big-m4-myth-fouling-caused-by-the-direct-impingement-gas-system-makes-the-m4-unreliable/


.071" is what Noveske and LMT use on 10.5" barrels. On 11.5" barrels it should be even more reliable due to the longer time the bullet is in the barrel. Both companies recommend H buffers. A Noveske switchblock doesn't magically add more gas on the normal open setting. It only restricts some gas on the suppressed setting. I'd still recommend nothing heavier than a H buffer with a normal rate chrome silicon buffer spring.
You can over buffer a gun just as you can have an overgassed gun.
On my 10.5" SBR I'm using a Colt M4 SOCOM barrel cut to 10.5" gas port left at .062" along with a standard BCM bolt, LMT enhanced carrier and a BCM H buffer. It shoots soft suppressed and unsuppressed REALLY soft and still locks back on an empty mag. Even softer using a H3 but won't lock back on an empty mag when unsupressed with a H3.

[Magic_Salad0892]

What spring are you running?

Is .071'' a better port diameter than .063'' or is .063'' for dedicated suppressed rifles?

I'll dig up my KAC buffer, and play with standard H buffer and see what happens.

[SteveL]

I may not change it at all. Mostly just curiosity to see if it can run even smoother than it already does. In the end it will probably be a big waste of time considering that KAC has spent alot of time & $$ designing the E3 system to run on the standard carbine buffer, including lots of slow motion video to be sure that they run as well as possible.

I'll still be curious to read your thoughts/conclusions when you're finished experimenting.