So I sent the following email to the guys at Tubbs and was wondering if anyone our here had any thoughts or insight:

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Good Morning,

I'm planning on using one of your springs in a 12.5in AR w/ midlength gas system with a dedicated suppressor living on it. I was looking for your technical insight for on you springs considering my application.

In watching your video comparing different springs (here: https://www.youtube.com/watch?v=8fMVZbrnvu8&t=153s) right at the very end you have the AR10/42 coil spring. The loadings bolt closed and open on a CAR buffer tube w/ your flatwire springs were as follows:

AR15 Flat Wire Spring: 10.5lbs (bolt closed) / 16.3lbs (Bolt Open)
AR10 Flat Wire Spring: 13lbs / 16.7lbs

In your video you mentioned you want as maximum load retarding the bolt opening and minimum load with the bolt open so that way you don't make your muzzle dip. If there is minimal difference between the two springs when the bolt is open (16.3 vs 16.7lbs) why would I not go with the AR10 spring?

This generates some thoughts on my end based on my assumptions:

1) Wouldn't that help increase reliability over a wider variety of cartridges?
2) Wouldn't this theoretically help with perceived recoil since it would take longer for the bolt to overcome the spring pressure and take longer for the whole recoil process to occur?
3) Wouldn't the heavier spring be better for suprpessed use since it's keeping the bolt closed longer/better?
I4) t seems that you get a lot of benefits of keeping the bolt closed better w/o paying the penalty of an overly strong spring by going with you AR10 vs AR15 springs.

What are your thoughts given my application. I want the rifle to operate as smooth as possible with minimal recoil, but not compromise reliability. I also don't want too powerful of a spring where it pushes my muzzle off target. Which spring should I go with and why? Any insight on this topic would be greatly appreciated. Thanks!

I use heavier buffers and standard springs.

take a look at this
https://geissele.com/super-42-braided-wire-buffer-spring-and-buffer-combo.html

I see where you are coming from, I also had the same thoughts. I was over thinking this. I experimented with the Tubb AR10 spring, cutting off coils etc. All of my mid length gas now have the Tubb carbine with H2 buffer except my 14.5 Stealth and I use H3. I'm shooting IMI primarily.

Most all of my carbine length gas, 10.5 & 11.5, 14.5 barrels , have Tubb carbine with H2 except my 7.62x39 10.5 barrel I use H3. My (new production) DD 10.5 barrel can run an H3 but I use an H2, I kinda like that kick. I shoot primarily IMI ammo.

With my Colt SOCOM 14.5 barrel, with an AFAB muzzle (my present select fire rifle) with Tubb carbine when shooting auto with IMI I'll use H3 and it will shoot so flat, keeping on a B-27 target at 50 yards takes very little practice. Shooting Wolf etc. .223 ammo I'll use an H2 buffer.

Shooting a PSA 16" barrel, mid length gas, with Surefire Procomp brake, Tubb carbine, H2 buffer, IMI ammo, recoil feels like a 22 LR.

I would experiment with it, keep a log book noting barrel, muzzle device, gas length, ammo, spring, buffer combos, that's half the fun of this.

I bought one, ended up cutting it down a bit. Love the linear rate of flat coils.

This. IMO if you want a short barrel, expect more recoil. If it's not smoothed out enough with an h3 or adjustable gas, then look for a new barrel length. My 10.3s kick. My 20in is smooth as butter.

Double tap

I use a ar10/308 tubbs spring in an lwrc di but with a vltor A5 buffer and larue ar10 carbine buffer tube.  If used with a ar15 length buffer tube I think you will completely compressing the spring before the buffer bottoms out.  If you are trimming coils I think you are defeating the purpose.

Just because it fits doesn’t mean its the best...



The ar10 carbine platform generally uses a buffer tube about 1” longer then the ar15. Put a tubbs ar10 buffer spring into an ar15 carbine buffer system and while the entire stack might not bottomed out most of the coils will be in full compression.  Which means part of the spring will be working harder or more often then the rest of the spring as well as lowering the load rate as now less coils are working. Also its better for spring life to be run in the “middle” as in not in full compression or not in full extension...

Tubbs website doesn’t show the spring rate but does show the load rate.  So the figures you see for the ar10 could be infact the exact same spring (same spring rate) but with more coils giving it a higher load rate.  Cutting down a ar10 spring would in effect make it the same as the ar15 tubbs spring.  Also since using a short buffer tube with a longer spring that has the same spring rate might cause coil bind or coils that are in full compression there by just taking up space and causing the rest of the spring to make up the work load in less area.  With a progressive rate spring one could benefit by putting the spring in a more compressed state.

This is why in general for the softest shooting rifle most will use a rifle length buffer system, or a vltor a5 system with less tuning/work..

Also I wouldn’t recommend a shorter buffer (2.5”) with a longer spring more chance for coil bind since there is less buffer to act or be a center guide as the spring travels.  Could cause the spring to wear out much faster.

That indeed is the case. Mr Tubb said that one could cut down the AR10 spring to make a carbine spring, difference is the length.

In David Tubb's video: https://www.youtube.com/watch?v=8fMVZbrnvu8
He shows that doesn't happen. He has a milled out CAR buffer tube and shoves his AR10 Flat spring in there and it does NOT completely compress HIS spring.

Like Tejas1836 posted, David Tubb does says you can trim coils to achieve your desired results.  However, I don't like trimming coils either, mainly because it looks ugly unless you have a way of 'closing' the spring.

Watched the video.  Great it doesn’t completely compress the spring.  My comment two post up said just because it fits doesn’t mean its the best.  Sounds like there is 8 additional coils.  The spring rate is the same per coil.  In watching the video you can see ar15 tubbs spring when compressed there is approximately 1/8” gap between each coil.  For the ar10 tubbs spring there is maybe a 1/16” gap. So while only adding 8 coils the spring is compressing further as well as remaining in a more compressed state the entire time it is in use.  While the longer ar10 spring maybe good for tuning down to a rate of a tubbs ar15.  I don’t think it is as ideal to run the tubbs ar10 spring in a ar15 carbine setup.  And spring life will suffer, which maybe it will only last 250,000 compression cycles instead of 500,000...

If you want to run the tubbs ar10 spring with a std ar15 carbine length buffer, I would recommend a ar10 buffer tube with a buffer spacer.



This setup would allow the spring the additional room it was originally designed for and the load rate should remain the same. As well as running std, h1, h2, h3, 9mm buffers, or remove the spacer and run A5 buffers giving a person even more tuning options.

Been doing that for years.
Picture below is using a 556 Tubb flat spring, in A5 buffer, tube Griffin SOB collapsible stock buffer and one of a few custom plugs I had made years ago before New Frontier Armory came out with theirs.


I know Tubb mentioned putting his AR10 flat spring in a carbine stock but I personally use an A5 just for the reasons you mentioned.  
My current favorite configuration is to use the 556 Tubb flat spring in an A5 tube and the 9mm Kyshot buffer.  The 9mm Kynshot buffer works great in almost all my configurations.
Pictured below is heavybuffers.com A5 buffer.


9mm Kynshot hydraulic buffer is about the same length compressed.
s

Extended length


I've done some full auto testing here: http://c3junkie.com/?page_id=654

I primarily use the 556 Tubb in the A5 tube in almost all of my configurations.  I only use the AR10 Tubb flat spring on configurations that require more force to strip rounds off and that would be my 7.62x39 setups running from unmodified AK drums w/ the MGI modular lower and with the belt fed Shrike which needs more power to strip rounds off the links.

My favorite mag fed 556 setup is my 12.5 Mid.  With the 556 Tubb flat spring, A5 tube, 9mm Hydraulic I get 669 RPM and can still easily pull single round bursts in full auto.


Out of curiosity I tried the 308 Tubb flat wire spring and was surprised at the almost identical RoF.


For contrast, here is what an H2 buffer and standard White Sprinco spring does.  At 782 RPM, much harder to pull singles.


JP SCS H2 was almost the same as the white Sprinco and H2 at 761 RPM.  

I was wondering when you’d pop in haha. Sounds like the 5.56 spring is the way to go based on your testing since we have almost identical rifles.

Seperate question amphibian, in your email to me, you said that instead of switching to an A5 buffet tube, it maybe just as good to use the Tubbs flat wire with a “5.56L” Kynshot hydraulic buffer? In your blog you mentioned you weren’t as big of a fan on the regular 5.56 Kynshot models. Can you elaborate on that a bit?

Is there a big/measureable/noticeable difference between the CAR buffer tube w/ 5.56 Kynshot vs the A5 w/ 9mm Kynshot based on your experiences?

BOTACH has the 5.56 models in stock for like $90 vs $120+ on the 9mm and they’re out of stock...plus I obviously already have the CAR buffer tube.

+1.

I tried screwing around with different springs but had numerous problems.  Went back to this and had no issues after.

I think going with a heavy buffer is what most people should do.  Most people aren't tinkering with machine guns either.
That is where you start noticing problems with things breaking and what is more controllable....a byproduct of it is that whatever works in full auto can typically see a benefit for semi auto.
In my Shrike belt fed upper, I never went heavier than an H2 but after a lot of full auto, sheared the impact lug of the carrier off.  The inventor told me to remember that whenever you go heavy on the buffer on a 'piston' system that you are putting more stress on the op rod and impact lug on the carrier on a 'piston' system.

Granted, I don't really like 'piston' systems on the AR platform so not really much of an issue.

Then there is the FM9 belt fed upper that is straight blowback.  Heavy buffer just makes the whole thing too bouncy for my tastes.

Now what is considered 'heavy' is all relative.  To me, I don't think of the H2 as really heavy......[/b]but of course I know anything with an 'H' is heavy.  I know H means 1 tungsten, H2 is two and H3 is three tungsten.
The reason I don't think of H2 of being really heavy is because I am always testing in full auto and the H2 weight (with reciprocating internal weights) is the minimum you need to mitigate bolt bounce in full auto.  Go lighter and you start getting light primer hits and no more full auto.  So for me, that is the baseline.  H2 = 4.5 oz, H3 = 5.3 oz.  I think once you start going over 6oz then that is really heavy and when you go too heavy, the gun no longer shoots flat and gets bouncy.
Bear in mind, I'm generalizing here.  I know some are going to say I use XYZ and it is the best thing ever.  Great!!  
I've always said the great thing about the AR platform is so much you can do with it.  The bad thing about the AR platform is so much you can do with it.
Meaning you can have an awesome build for your exact requirements, tastes but you can also jack stuff up.

I want to get the gun to shoot flat, smooth and preferably a lower rate of fire in full auto.  People that aren't shooting machine guns don't care about the last thing of course.

My buffer tube, buffer and spring selection are done with all 3 of those goals in mind.  Gas port selection and whether or not you are suppressed or not also plays are major part which I factor in.

Data from my site goes over all this: http://c3junkie.com/?page_id=654

Standard MK18 w/ .070" gas port, H2 buffer and standard power spring = 1136 RPM, too fast, hard to control and bouncy


Say you move to the A5 system 5.3 oz buffer (default A5 weight) and Vltor supplied Rifle spring 1056 RPM, smoother but still fast.


Controlling the port size helps.  .052 Gas port


.052 w/ default A5 config


Same .052 port but around 200 RPM reduction from the two configurations above.  This hydraulic buffer is 5.9 oz vs the 5.3 oz A5 buffer which is the same BTW as an H3 buffer.
The hydraulic buffer combined with the Tubb flat spring smooths out the initial recoil impulse and helps maintain flatness and clearly a huge reduction in the cyclic rate.  
Forget about full auto, I see an immediate difference over the other two in semi, however many people may not notice a difference if they don't shoot a lot and simply only care that the gun functions and not concerned with flatness and smoothness.