10.5" Barrel questions

[Ben O]

I recently built a 10.5" barrel 5.56 AR pistol. I was recommended to buy a H3 buffer. Upon assembly and testing within 100 rounds, I had 4 failures to eject, light primer strikes, and failure to battery. I have researched more regarding this but I am getting a ton of mixed messages. I will inevitably be getting a can for this rifle. I am assuming at this point I should have gone with the H2 buffer. Any help is much appreciated. I am also firing 55g to 62g and generally stay in this ball park of ammo.

Read More

 

[papersoldier]

I used an H2 buffer in my 10.5" 5.56 (with 62g green tip) before switching to a JP Enterprises Captured Spring and didn't have any of the problems you're experiencing. It may not hurt to try out the H2 to see if your heavy buffer is the issue.

 

[erslll]

I used an H3 buffer in my 11.5" .223 Wilde and haven't had any problems. My suggestion would be more lube and get it good and broke in.

 

[slimmer13]

I recently built a 10.5" barrel 5.56 AR pistol. I was recommended to buy a H3 buffer. Upon assembly and testing within 100 rounds, I had 4 failures to eject, light primer strikes, and failure to battery. I have researched more regarding this but I am getting a ton of mixed messages. I will inevitably be getting a can for this rifle. I am assuming at this point I should have gone with the H2 buffer. Any help is much appreciated. I am also firing 55g to 62g and generally stay in this ball park of ammo.

Sounds like you have more going on than buffer issues. Is the hammer spring installed correctly? If its upside down it could cause light primer strikes.

Also, on new builds, there is occasionally burrs and machine marks that need smoothed out. This could cause things to hang up.

 

[titsonritz]

Upon assembly and testing within 100 rounds, I had 4 failures to eject, light primer strikes, and failure to battery.

That statement would suggest you have more problems than an H3 buffer.

 

[Ops]

ive used a h and standard buffer in my 10.5's never noticed an issue. I pound steel case through them like butter. I did switch to a amerspec smb H buffer in a couple and it doesn't twang as much but runs great

 

[Member 34319]

Consider that most if not every Palmetto Build is shipped with a plain ole carbine buffer, I'd say you have too much weight shooting unsuppressed. I've had 3-4 shorter builds by them and they all ran fine. I was running a carbine and switched to an H2 when I got my YHM Turbo on my latest 11.5".

 

[Ben O]

I read all your replies and thank you very much for the input. Upon checking my trigger assembly, I did put the hammer spring upside down - jackass 101 (effin Fudd). I will probably pick up an h2 buffer but I do plan on running a can eventually. Any issues running h2 with a can?
I bought all parts from aeroprecision based out of Tacoma if any of ya'll are interested. I paid $850 approximately for upper reciever (assembled, was cheaper than buying in assembled at the time during their labor day sale), all lower parts standard milspec, magpul pistol grip with storage, mlok afg and sba3 brace. The h2 buffer, buffer spring, tube, castle nut, spacer, and mlok sling attachment ran an extra $90 plus 4 extra take down detent springs. The aero upper and lower snug together very nicely unlike my SW MP15-2
Which has some gaps in the lower and upper when assembled.

 

[titsonritz]

The aero upper and lower snug together very nicely unlike my SW MP15-2

Before buying anything else, I suggest pulling the buffer out of your MP15 and trying it out

 

[Ben O]

Before buying anything else, I suggest pulling the buffer out of your MP15 and trying it out

I was thinking the same thing and trying to run the h3 in my mp15 due to the twang of the spring and the lack of smooth firing compared to this 10.5." can't hurt right? Either way I may end up build a 6.5 creed or 308 which calls for an h3 if I am not mistaken

 

[Jcon268]

I recently built a 10.5" barrel 5.56 AR pistol. I was recommended to buy a H3 buffer. Upon assembly and testing within 100 rounds, I had 4 failures to eject, light primer strikes, and failure to battery. I have researched more regarding this but I am getting a ton of mixed messages. I will inevitably be getting a can for this rifle. I am assuming at this point I should have gone with the H2 buffer. Any help is much appreciated. I am also firing 55g to 62g and generally stay in this ball park of ammo.

I use a H2 with blue extra power Sprinco spring in mine no issues. What buffer/pistol tube are you using? That can make a difference too as some of the tubes are shorter and don't allow the spring to compress fully to cycle the bolt. I experiences that problem and then switched back to my longer KAK pistol tailhook tube and no issues whatsoever.

By the way the H2 should work suppressed too but the H3 might help at that point.

 

[Stomper]

With the exception of the KNS retainers, both of these have standard fare internals and buffer assemblies, and not one single malfunction from day one.

 

[Tomahawk67]

Run the heaviest buffer that will lock back the bolt on the weakest ammo you will use in that gun. If you are going to run it both suppressed and unsuppressed , It would most likely be the buffer that locks back without the can on.

 

[Ben O]

Before buying anything else, I suggest pulling the buffer out of your MP15 and trying it out

I tried this when I got off work, mind that I haven't cycled rounds through either yet, I swapped the buffer and spring in my mp15-2 and the 10.5. I also tried each buffer on each spring in both with negative feel.
I kept the stock spring and buffer from the mp15-2 and the milspec spring with he H3.
Upon pulling the charging handle back and letting it rack dry on both I experience the "spring twang" on both now but on the 10.5 the pull is lighter on the charge and on the mp15-2 16" it is a bit heavier - obviously, yet both feel smoother overall after manual dry charge handle pulls.

The mp15 stock buffer in weight feels like a 3.5 oz and the spring is lighter and longer by a 1/2" then the milspec spring I purchased with the h3 which is stiffer and the h3 obviously being 2oz heavier.

I'm going to run some rounds through this weekend and smell, sniff, and tell. I have a feeling the H3 plus the milspec spring will feel better on the mp15 but I think I will be putting the stock mp15 buffer aside and sailing into an h2 or a buffer with a 4.5oz weight due to my "can wants."

 

[Ben O]

I use a H2 with blue extra power Sprinco spring in mine no issues. What buffer/pistol tube are you using? That can make a difference too as some of the tubes are shorter and don't allow the spring to compress fully to cycle the bolt. I experiences that problem and then switched back to my longer KAK pistol tailhook tube and no issues whatsoever.

By the way the H2 should work suppressed too but the H3 might help at that point.

The brace is a SBA3. Tube came with it. I may have figured out my issue. Either way, I had a stench that I wanted to run a 4.5-4.9 oz buffer.
My aim is to pull off a ratchet can 4.5" - 6" max length can and no issues.

 

[Ben O]

I truly appreciate all the feedback.

 

[Ben O]

Little update regarding 10.5" if any are interested. I replaced the H3 with an H2. All is well, 100%. I ended up buying a Sig Romeo4S the 2MOA ballistic dot/circle setup. I may have well stole the dot, $200 off msrp.
I have not messed around with swapping all these buffers with my mp15-2 yet.
I am currently looking in to running a piston system in this 10.5." The Adam's kits will not fit with my free float. Currently, it's looking like "superlative" kits are the only solid option. Any recommendations?