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Old October 19, 2018, 18:54   #1
kroberts
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Buffer Question

I'm building a 9mm AR pistol, I've never built an AR from scratch before. The last part I need to buy is a buffer & spring. I'm using this brace...

https://www.sb-tactical.com/product/sbpdw/

The ad text states that it is "compatible with mil-spec bolt carrier groups and carbine buffers/springs" but SBtactical then offers a buffer/spring package with a special spring and 7.5 oz buffer. So what's the deal? Is this just marketing? Can I used a regular, off-the-shelf, 9mm AR buffer/spring kit or do I have to use a heavier package specifically for pistols?

Thanks in advance
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Old October 19, 2018, 19:24   #2
John A
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9mm is direct blowback and requires a heavier buffer.

I think that mine is about 5 1/2 ounces, but I also have a heavier buffer spring too.

edit: most carbine buffer springs start at 3.1 ounces and get heavier from there.

9mm definitely needs one heavier than that.

And you'll probably also want to buy one of these so you don't break your bolt catch because the 9mm case isn't as long as a 223 and doesn't require as much rearward travel. If the bolt moves back too far, will often batter and crack your bolt catch over time and likely break it off.

The little spacer doesn't allow it to move back as far, reducing the likelihood that will happen.

https://www.joeboboutfitters.com/New...fferspacer.htm

Last edited by John A; October 19, 2018 at 19:29.
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Old October 20, 2018, 10:37   #3
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Buy a dedicated 9mm buffer such as the one pictured. It is 8oz. and the proper length to not require a spacer. I have these in three different 9mm carbine/rifles and they work perfectly. You can play with springs all you want once you have the heavy buffer.

https://www.primaryarms.com/guntec-u...5-buffer-buf-9
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Old October 20, 2018, 17:35   #4
Uriah Lee
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Heavy buffers.com has about everything you might need in the way buffers for a pistol caliber carbine. That's suppressed or otherwise. Anything up to a 12 oz. unit.
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Old October 20, 2018, 17:54   #5
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Ditto, buy a complete buffer tube, spring and buffer made specifically for 9mm.
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Old October 20, 2018, 18:36   #6
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Quote:
Originally Posted by Uriah Lee View Post
Heavy buffers.com has about everything you might need in the way buffers for a pistol caliber carbine. That's suppressed or otherwise. Anything up to a 12 oz. unit.
And, boy is he proud of 'em.
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Old October 21, 2018, 12:44   #7
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I built up the pistol last night. Well, everything but the buffer. I'm really disappointed in the fit of the New Frontier upper and lower. Their finish is great. But the fit is sloppy and loose (just like I like my women). I know there are fixes for this but it's not like I'm using parts from two different manufacturers. The mag is loose too but that could be the magazine itself.

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Old October 21, 2018, 12:50   #8
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What magazine is that?
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Old October 21, 2018, 13:52   #9
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One of the most expensive 9mm magazines known to man. MP5.

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Old October 21, 2018, 14:38   #10
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I've bought a lot of buffers from Slash's (Heavy Buffers) and had good success.

Or, you can build you own with:

https://www.kakindustry.com/ar-15-pa...-buffer-system

An tune it right for you.
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Old October 21, 2018, 18:50   #11
Lee Carpentieri
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9mm AR-15 Buffers

Use a Colt 9mm Black Buffer. It's what I use in My Transferable Factory Colt M16A2 9mm. Also installed A 9mm Flat top with a DOE barrel assembly.
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Old October 21, 2018, 19:13   #12
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I have a Blitzkrieg hydraulic on mine. Love it but you pay for them.
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Old October 21, 2018, 20:39   #13
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Quote:
Originally Posted by Lee Carpentieri View Post
Use a Colt 9mm Black Buffer. It's what I use in My Transferable Factory Colt M16A2 9mm. Also installed A 9mm Flat top with a DOE barrel assembly.
Specialized Armament's site lists four different 9mm buffers. Which one do you use? They must be the same length as a standard 5.56 carbine buffer, since the site also shows a spacer for the buffer tube.
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Old October 23, 2018, 17:19   #14
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Quote:
Originally Posted by kroberts View Post
I'm building a 9mm AR pistol, I've never built an AR from scratch before. The last part I need to buy is a buffer & spring. I'm using this brace...

https://www.sb-tactical.com/product/sbpdw/

The ad text states that it is "compatible with mil-spec bolt carrier groups and carbine buffers/springs" but SBtactical then offers a buffer/spring package with a special spring and 7.5 oz buffer. So what's the deal? Is this just marketing? Can I used a regular, off-the-shelf, 9mm AR buffer/spring kit or do I have to use a heavier package specifically for pistols?

Thanks in advance
IMHO, it isn't just marketing... I finally used a 7.5oz buffer weight and Tubbs .308 Flatwire spring in my Colt Pattern.

Those cut down the bark and blast considerably. ( Even that is an understatement. )

HOWEVER, I am not a big fan of solid buffers, I prefer conventional "dead blow hammer" type buffers, the ones with the moving weights inside.

You will find, the 9x19 Carbine can handle wildly high buffer weights and heavy springs.

IMHO, one of the most important thing to do is make sure you don't have excess BCG overtravel.... excess bolt overtravel tends to break bolt catches in a Colt Pattern 9x19... keep the distance limited to about 3/16" between the bolt face and bolt catch. ( YMMV with your setup. )
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Old October 25, 2018, 05:44   #15
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This is a good choice for a 9mm buffer... Pretty close to the Colt 2 piece 9mm buffer...

https://www.jsesurplus.com/rockriver9mmbuffer.aspx
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Old October 25, 2018, 11:06   #16
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Above was mentioned Tubbs Flatwire springs and Slash Heavy buffers. No experience with them in 9mm but both have worked miracles in other AR builds.
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Old October 25, 2018, 21:23   #17
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Colt 9mm Black buffers

I use the factory original. The problem with the Colt 9x19 mm weapon is the fact is it's only rated for up to 124Grn ammo, NO Hot ammo and NO +P ammo. One of my Nephew's who's a LEO and his agency was using Colt 9x19 semi auto carbines kept breaking the bolt release levers. He came to me for 2 of them and I supplied him and another officer with replacement bolt release levers as they were both using 158grn +p loads in the Colts which is a really BIG non no with the Colt 9mm carbines, But that was several years ago. Of coarse I haven't been on Ken's website in 5 years.
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Old October 26, 2018, 08:50   #18
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Quote:
Originally Posted by Lee Carpentieri View Post
I use the factory original. The problem with the Colt 9x19 mm weapon is the fact is it's only rated for up to 124Grn ammo, NO Hot ammo and NO +P ammo. One of my Nephew's who's a LEO and his agency was using Colt 9x19 semi auto carbines kept breaking the bolt release levers. He came to me for 2 of them and I supplied him and another officer with replacement bolt release levers as they were both using 158grn +p loads in the Colts which is a really BIG non no with the Colt 9mm carbines, But that was several years ago. Of coarse I haven't been on Ken's website in 5 years.
Broken bolt stops are a result of over-travel with the 9mm AR's.

Buffer spacers will reduce that tremendously. I routinely shoot 165 gr bullets in mine. Admittedly, since it is a suppressed gun, I have no desire to shoot +p in mine.

Before these were available, A lot of guys used a handful of quarters stacked in the back of the buffer tube.

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Old October 26, 2018, 09:46   #19
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Bolt hold opens usually break from bolt overrun so measure maximum travel on all my bolts to make sure bolt is not travelling too far rearward in a particular buffer tube/buffer combination have selected for a build. Do not want it to have room to gain momentum and slam the BHO too hard. Often a BHO is too tall, engages improperly and needs to be shaved plus add in some of the cheap Chinese made BHO's are weak and break because they suck. I normally buy DPMS when find on sale six to a dozen at a time because are a known quality and often find them on really good sales. Last week ran out of BHO's from not keeping up with inventory so ordered six DPMS from Brownell's because of a sale (cheap but not as cheap as can find thus why didn't order a dozen) and free shipping.

Having six shipping wasn't helping me on the rifle was one part from finishing so ran to LGS and asked who made their bulk BHO's in their individual parts box to a shoulder shrug. Had some in unmarked bags with no idea if came from China cast from pot metal or were machined from unobtainium in space and had the ability to stop a train. Because their selection of BHO's were all over the map, the only ones they had that identified them as U.S. made from quality vendors came in slick point of sale packaging in kits with BHO and all associated parts starting at $10 bucks. Have several dozen Colt BHO springs with detents and buy roll pins in 50 count bulk packs. Had half dozen $4.99 DPMS units shipping but paid $11.99 for a kit just to rob a BHO would trust and used the parts that came with it to keep my Colt supply unmixed with other suppliers.

I trial fitted my BHO and placed a thin spacer in back of tube to get my preferred maximum rearward travel and rebound till the parts slam into each other. Examinined the fit and stoned a few spots so it had no places where fit was overly snug then checked it's interaction with bolt, shaved a fuzz off the height then sprayed it with a rattle can of Cerakote and put under a heat lamp for half hour before assembling. 99% of all BHO's are most likely installed without any fitting but a broken BHO at inopportune time could suck so I hand fit mine like most parts. Below is a discussion thread that should help the 9mm pistol builder crowd.

https://forums.brianenos.com/topic/2...avel-distance/
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Old October 26, 2018, 11:57   #20
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These 9mm ar pistols sure sound complicated...
Think I'll stick with my old oly sten mag beater 9mm carbine that shoots anything and everything, loves my +p+ 160gr lead reloads, dosent have a mag catch to brake and uses regular AR parts with a piece of dowel in the tube
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Old October 27, 2018, 17:11   #21
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Not complicated if buy parts already proven to get along with each other. Plenty of threads that outline successful builds.
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Old November 09, 2018, 14:16   #22
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My colt mag ar9 has always eaten everything fed it, with whatever buffer and spring i stuck in it. I'm using one of heavy buffers's buffers now.
Mags are ets and metalforms, the ets mags needed one of the feed lips filed off a bit to makem work.

I've read of alot of guys having problems with ar9's, guess i got lucky.
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