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9mm buffer springs


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The primary role of the spacer/quarters is to reduce bolt travel and save bolt catches. Quarters add a slight amount of preload to the spring but it isn't much. 

I am using a Wolff XP spring. I don't know if a rifle spring would reach coil bind and limit travel or not, but if you are after a stiffer spring weight there are plenty of manufacturers out there who make a stiffer spring. 

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2 hours ago, MikeRush said:

The primary role of the spacer/quarters is to reduce bolt travel and save bolt catches. Quarters add a slight amount of preload to the spring but it isn't much. 

I am using a Wolff XP spring. I don't know if a rifle spring would reach coil bind and limit travel or not, but if you are after a stiffer spring weight there are plenty of manufacturers out there who make a stiffer spring. 

I was going to try some sort of XP spring, that's what got me thinking along the line of a rifle spring.  I understand it has something like 8-10 more coils...

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possibly not your answer... I went with a rifle buffer tube and rifle buffer to experiment with heavier weights as my unscientific testing showed less scope movement up to about 7.5oz... I had tried a maximum of 9oz buffer.. with the 7.5, I finalized on a standard .308 rifle spring (.079 diameter wire)... I shoot my carbine stocks at the same length of pull as my primary 3 gun rifle that has an A1 stock... with a standard partial lead filled rifle buffer, and NFA end cap bumper, .308 spring, my NFA 17oz bolt clears the bolt hold open by about 3/16"... I do not use a last round bolt hold open...

DIY rifle buffer weights

filled with #7 1/2 lead shot  6.0oz

1/2" brass rod and a couple turns of electrician's tape  6.2oz

5/8" brass rod 7.0oz

filled solid lead 9.0oz
my NFA bolt is slightly convex, so I drilled out the front end of the sold lead buffer until I reached 7.5oz

Edited by Les Snyder
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16 hours ago, mikeor70 said:

Not quite there as in?  I'm contemplating an AR10 carbine spring in mine as well.  

The carrier goes further than I want it to.  I'm still using the quarters, even with a 9mm specific buffer.  But I'm only using $1 of quarters, not $1.75.

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On 9/28/2016 at 6:09 AM, jrswanson1 said:

I'm using an AR-10 carbine spring and it's not quite there.  I have not tried the rifle spring yet.

Not quite there as in?  I'm contemplating a

 

11 hours ago, jrswanson1 said:

The carrier goes further than I want it to.  I'm still using the quarters, even with a 9mm specific buffer.  But I'm only using $1 of quarters, not $1.75.

n AR10 carbine spring in mine as well.  

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Tried an AR-10 carbine spring today and reduced the spacers to $1.00. The spring is definitely stiffer but I only ran it with an H2 buffer.  

 

I don't know how much more I'm going to monkey with this lower, springs and buffer combo.  I am supposed to be working on a PCC gun for my wife, but she has yet to surrender her lower, so my experimentation has been entirely on my lower.  Also I'm getting an AR-15 rifle spring to throw in the mix soon too.

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My wife's lower had issues with the mag block, so I played a little more with the lowwer I have been working with.  

 

I have settled on an AR-10 carbine buffer spring, 9mm buffer, and $1.75 spacer.  It's not like a .22, but it is good enough for USPSA.  I was hoping to have a little more leeway in the tuning, my .223 upper on this lower does shoot like a .22 with the proper ammo, but I have the gas system and a comp/brake to enter the mix on tuning.

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I did some more tweaking tiday and went back to the AR15 carbine spring with an H2 buffer.  I tried a combination of AR10 and AR 15 carbine springs mixed with carbine, H2 and 9mm buffers.  

 

With a target set at 15 yards, I did some timed double taps.  I found ultimately with the AR15 carbine spring and the H2 buffer my times were a little faster by about .1 sec and the hits were about 1"-1.5"  vs 2"-3" with the other combinations. The noticeable recoil was negligibly less too.  Other advantages are it's much easier to charge the bolt, and since there are more coils on on this spring there is  overtravel.

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Using a Wolff XP carbine buffer spring with a Spikes extended heavy buffer.  It may be my imagination but I think it shoots a little softer and cleaner now.  Used to use a std. carbine spring and CMMG 9mm buffer.     

Edited by blaster113
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Wonder if someone tried to go lighter and use a heavier spring what the effects would be? I think the heavy stuff was used to hold the bolt closed longer to let the pressure decrease in the barrel before it started moving. The Bolt and buffer combined being heavy took longer to get moving. But this also slams harder coming back and the more momentum you feel or see in the sights.

A lighter system would have less felt recoil and less sight movement in theory. The question is how far can we go. So if using a std Bolt, remove the weight, run a carbine buffer and heavy spring. If using the JP SCS, could change the tungsten weights out for stainless to lessen the weight. 

BE interesting to see it in slow-motion to see what the timing impulse is of the bolt in movement and to see if you get any bounce when it comes back. Since these are mostly using glock mags, if we think about the glock system you just have the weight of the slide, which might should equal the weight of the bolt and buffer?

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Do the Glock mags require less spring force to strip and chamber the round? I'm using a Colt set up.  I tried the heavier spring with a carbine buffer and my times were a lottle slower with a looser grouping.  Also charging the rifle with the heavier spring required a lot more strength.

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  • 3 years later...

I just purchased a 308 recoil spring and a carbine buffer spacer from Joebobsoutfitters.com for my 9mm build with 16" bbl. They arrive Wednesday. Now after studying and watching youtube comments on this combination comes the concern will this interfere with the choice of ammo? I plan to mostly use 124 gr and 147 gr ammo but 115 grain ammo would be nice to use at times. Any thoughts on the subject?

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What Buffer and what tube are you using?  I almost always find something else besides buffer combinations is causing ammo sensitivity . If its

Properly setup it should run any bullet weight.

 

 

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The XM177 clone has a standard carbine buffer tube, buffer and spring in it with a hard polymer spacer placed at the back of the tube.

 

As someone previously mentioned, nothing to do with function/recoil, just trying to insure the bolt does not destroy the bolt stop when forward movement is stopped after the last round is fired from the magazine.

 

The AR 9MM pistol has a pistol buffer tube, carbine buffer and spring.  It has three metal washers at the back of the buffer tube for the same purpose of not hammering the bolt catch when it stops the bolt after the last round.

 

Both have operated 100% with either Federal 115 grain FMJ, a small amount of the dirty/nasty Winchester 115 grain FMJ, and the 115 grain hollow points I use in my 9MM pistols.

 

I haven't tried 124's or 147's in either one.

 

I really can't say about recoil vs. the .223's.  I really don't pay much attention to the recoil of AR15 type weapons.  I think even my .308 GII is pretty decent compared to the M1A/M1 Garand/12 ga. pump.

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Using a carbine buffer, and I mean a standard length mil spec style carbine buffer.......the AR15 rifle spring is waaaaay to long and will go to solid upon recoil. Will it work for 9mm? possibly, but sending a spring to solid with dramatically shorten the life of the spring and it will weaken quickly. Like in under 500 rounds. Funny thing.....that fancy new VR80 shotgun, they tell you to break it in for the first 250-500 rounds with high energy rounds. WHY?......well, for a couple reasons, but the main one is people notice that after break in.....the shotgun seems to be a lot easier to charge......hmmmm......well if you dive into it, you find that the factory spring is going solid and when I say solid, I mean.....compress the spring all you can until you can't get it any shorter solid. Basically, you are wearing out the spring. So......can you use a rifle spring in a carbine buffer tube? YES YOU CAN, will it go solid and an wear out faster with a traditiona mil spec length carbine buffer....YES IT WILL.

 

FYI......in case you are wondering, over here at TACCOm, with the 3 stage adjustable buffer system, we did engineer the system so that you can run a rifle spring in the carbine buffer tube......so you may ask.....isn't that spring going solid? NOPE.....our buffer is longer than carbine length so the added benefit is that out of the box you get a shorter stroke as well. and with the included short stroke stop, you even get less compression and longer life......of course we no longer use a rifle spring, rather we use pre-load washers with a carbine spring......but you can use a rifle spring in a taccom 3 stage buffer system.

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46 minutes ago, M1A4ME said:

They've got a name/term for that with valve springs in engine heads.  You call it going "solid" but I can't remember (at this moment) what they call it with valve springs but the end result is the same - it ruins the spring real fast.

 

It's called coil bind.

 

Nolan

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Reently completed a pistol 9mm AR.  7.5 oz buffer, longer supposedly for 9mm, 7.5" barrel.  I tested 3 different buffer spring: JP tuned 223 carbine spring, 308 rifle spring, Tubb 308 spring.  The standard 308 spring kept the bolt from going all the way to the rear, and was also the harshest on recoil and bolt reset; I assume coil bind, but the reset was excessive. The JP tuned spring was pretty good, no real complaints.  The Tubb 308 spring had the softest (most pleasant for recovery) feel of all 3.  Not by much over the JP 223 spring, but I could feel it.  Did not use the timer to test.  I'm still tinkering.  The trigger is a CMC 3.5 lb 9mm unit. 

 

My understanding with blowback systems is that the springs, buffers (if used in that system), and hammer spring all have an effect on how quickly the bolt opens.  Obviously, a system that keeps the bolt closed as long as necessary is desired, with the trade off being heavier springs and/or buffers. A delayed roller system, like the HK systems, is probably the best 9mm carbine shooting I've done.  The MP5 made anyone look like an expert.

 

BTW, the JP and Tubb springs allowed the buffer to fully enter the buffer tube.  After reading this thread, I now understand why people try to limit travel.  Perhaps one of those polymer buffer spacers at the back of the buffer tube would be a better idea than a stack of quarters.  I'm surprised my buffer allows full retraction of the bolt, as it's supposed to be longer than a standard carbine buffer, and restrict full cycling of the bolt.

 

I'm still playing around.  I'm hoping to find a nice compromise so the return to battery isn't so jarring.  The Tubb spring is supposed to have more seat pressure than open pressure, whereas the JP is supposedly 7% stiffer through it's range.  THat is what I felt when comparing the two.

 

Another question, not related to this subject: I'm using a standard AR upper and dedicated 9mm lower.  No last round hold open feature.  I found the manufacturer of the lower has a "matching" upper with the feature and side charging.  Does anyone have feedback on those issues?  It'd be nice to have the LRHO feature, and the side charger appears to keep the pistol engaged on target while manipulating the bolt, but I don't want to spend the 200+ if not really necessary.  I will, though, if the features are worth the cost.  I just don't know due to lack of experience in the matter.

Edited by soflarick
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