View Full Version : What set-up works best in a 11.5" upper???
Gents,
A good friend of mine (and his teammates) who work for a large state police dept on a tactical response team just had their 14.5" Bushmaster M4's re-barreled with 11.5" barrels. Not sure of the manufacturer of the barrels yet, but he says they are likely Bushmaster.
Just curious if there is a consensus on what set-up runs the best with the 11.5" barrels in-terms of buffer weight, extractor set-up, etc. For reference, they all have select fire lowers.
I will find out more on who the barrel manufacturer is, etc. this week.
I want to make sure his is set-up properly, since I get the idea I that his dept armorers are not "up to speed" on some of the finer details of properly setting-up their carbines.
Any solid advice is greatly appreciated.
Stay safe,
Nick
BufordTJustice
08-19-10, 04:51
Will suppressors be used? If so, will their use be constant or intermittent? The buffer weight will largely be determined by this and the (unknown) size of the gas ports.
I'd start with an H2 buffer if they are unsuppressed and an H3 if they are gonna be used with a can. You wanna go as heavy as you can get away with...but LEOs have a shitty record for maintenance and up-keep so having a margin for error is good also (I am an LEO). I have seen waaaaay too many of my buddies show up at the range (or an actual incident) with guns that are dry as a bone. :rolleyes:
BCM extractor upgrade kits on all the bolts (I would consider the use of the o-ring as well).
McFarland one-piece gas rings.
New BCM buffer springs.
That's all I got for ya. Hopefully some actual owners of SBRs will chime in. I know Grant and Gotm4 have a wealth of experience with them.
Nick,
Here is the problem. There may be several different answers because not every 11.5" is the same. Since it may be a Bushamster it is almost guaranteed to be overgassed.
Also, see what you can find out about their ammo.
I would start with an H2 and be ready for an H3. I also recommend not getting a crappy buffer, but rather a BCM or Colt.
I have an 11.5" BCM upper that I put together onto a BCM lower. I am using a BCM BCG and Mod 3 charging handle and have a Colt new style M4 extractor spring and insert. I am currently using an H2 buffer and it cycles 100% and locks back with all mags.
I can shoot Hornady 55gr. TAP (steel case), Federal 55gr., LC M855 and everything else with no issues. I shoot it both suppressed and un-suppressed, but generally run it with the can on.
I would have them contact Alan Dugger at Tactical Springs (Sprinco) in Austin, TX. I'd bet that his "Red" spring and an H2 or H3 buffer will make them run right. He has experience with lots of local, state, and federal LE departments.
I run a 9mm buffer with mine. I sometimes use a suppressor. It will run with an H2.
I always use the BCM extractor spring upgrade.
M16 BCG.
I've never had any issue out of mine. It's all Bushmaster except the BCG. I like Bravo Company full auto BCG's.
The commercial FSB is a pita. I use a .040 sight post available from Bushmaster. Then you can use a standard rear sight.
Our issued ammo was Fed 55gr. TRU.
It will run anything including Wolf.
BufordTJustice
08-19-10, 18:18
I would start with an H2 and be ready for an H3. I also recommend not getting a crappy buffer, but rather a BCM or Colt.
IG, I thought all buffers were the same. I mean no sarcasm...it just seemed like there wasn't much to screw up, right? What makes a colt or BCM buffer better than a cheaper buffer? No loaded questions here...I'm honestly curious.
Great info guys, thanks! I will be sure to pass it along....
Hopefully you got a good bunch... but test before handing out. Check the cyclic (too fast) and ejection (erratic or way out there) with your duty ammo.
I have seen BM 11.5" LE select fire guns 10/10 not work on auto.... every single one had bolt bounce issues. H3 buffers worked on most till could get Colt uppers.
DO NOT even think about using a 9mm buffer
Mcfarland gas rings cause more problems than solve.
Consider extractor spring upgrade(BCM or Colt improved), or throwing a "crane" o-ring or defender on it.
IMO BM has been criminally negligent in selling the over-gassed, malfunctioning, POS uppers to LE in the past. Hopefully the Cerebus management has sorted out the QA/QC problems with their newly acquired companies.
Some companies have been known to sell buffers that were not truly up to spec. Substituting different materials for the actual weights inside.
IG, I thought all buffers were the same. I mean no sarcasm...it just seemed like there wasn't much to screw up, right? What makes a colt or BCM buffer better than a cheaper buffer? No loaded questions here...I'm honestly curious.
Thank God Bushhamster doesn't make a 10.5, then we'd really be screwed.
BufordTJustice
08-21-10, 03:19
Some companies have been known to sell buffers that were not truly up to spec. Substituting different materials for the actual weights inside.
Wow. I had no idea people could be that cheap.
Thank you for the insight.
***UPDATE***
I got to take a look at my friends new upper. It is indeed a Bushmaster 11.5" HBAR barrel. They simply replaced their old 14.5" barrels with the new 11.5's. They also installed H2 buffers.
I have not got the chance to shoot it yet, but he said that he was having serious extraction problems during his initial test fire. His armorer then installed an O-ring on his extractor spring which cleared up the extraction problem for the rest of that session.
It sounds to me exactly what you guys have advised on the BM 11.5's, that it is waay over-gased. Do you think a heavier (H3) buffer would help?
This is the best piece of advice I can give you to pass on. Do not rely on a donut. It will work, but eventually they may start to have problems. Tell them to order a chamber reamer from Ned Christiansen and ream the chambers.
It will not harm their weapon. I did well over 180 of them in Iraq (lost count) on our guns and after that the problems all but stopped.
As extra insurance I would also get a BCM or similar Colt extractor spring and insert.
***UPDATE***
I got to take a look at my friends new upper. It is indeed a Bushmaster 11.5" HBAR barrel. They simply replaced their old 14.5" barrels with the new 11.5's. They also installed H2 buffers.
I have not got the chance to shoot it yet, but he said that he was having serious extraction problems during his initial test fire. His armorer then installed an O-ring on his extractor spring which cleared up the extraction problem for the rest of that session.
It sounds to me exactly what you guys have advised on the BM 11.5's, that it is waay over-gased. Do you think a heavier (H3) buffer would help?
IG,
Roger that. A local shop has one of Ned's reamers, or better yet, I may be going to one of Ned's armorers classes coming up soon.
Do you think an H3 will help any in the meantime?
This is the best piece of advice I can give you to pass on. Do not rely on a donut. It will work, but eventually they may start to have problems. Tell them to order a chamber reamer from Ned Christiansen and ream the chambers.
The heavier buffer will help slow it down but it isn't going to fix the issue. And you will have to test which one works best because it may not cycle correctly.
It will be hit or miss. I would buy at least 3 H2 and 3 H3's and then do a random test. Make sure that they use their training and duty loads to see if it will cycle and lock back properly.
In the testing we did with the BCM middy upper H3 was pushing the envelope.
IG,
Roger that. A local shop has one of Ned's reamers, or better yet, I may be going to one of Ned's armorers classes coming up soon.
Do you think an H3 will help any in the meantime?
glockshooter
09-06-10, 10:56
My issued swat rifle is the same 11.5" BM as the OP is talking about minus the select fire option. Mine has a H buffer and upgraded extractor setup. It is used suppressed (SWR can) and unsuppressed. We go mostly unsuppressed. Our training ammo is random brands and weights of fragible ammo. Our duty ammo is 55gr TAP. I have not seen any problems with any of our rifles but they are not new and are well broke in. I would obviously rather have a better rifle but I don't really have a choice. We are in the process of looking into new barrel and rail setups but that may take years.
Matt
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