??? HELP???

[abw]

I have built.. a 223/5.56 S&w MP15 lower, Intacto arms upper and carrier bolt group, BHW 18" rifle gas system barrel SS 1:8 . Magpul furniture and Surplus arms and ammo gas block, YHM gas tube..Mil-spec buffer tube w 3 oz buffer weight..37 coils springs ( SSA kit) and the coil is 10 3/4 inches long. A2 flash hider. CMMG lower receiver kit.

day 1). took it to the range.-- Tight groups -yeah..
however wont cycle another round weak ejections.. Direction of ejection just to the 3-4 position but low. One even bounced off the table ( 55gr BH FMJ) Hmm Gas issue??

day 2) (culprit) Gas block had moved during install, so it is set now. Out to range.. Again single feed.. gas coming through carrier group bolt holes and out muzzle.. still no feed of next round, ejection stronger.. twice the weapon fed another round. However on empty chamber where it did not feed, it had dead trigger( no reset) and the chamber never locked back on empty chamber. Lots of recoil in shoulder..

day 3) back to armorer. Gas block ok in right position.. Armorer drills the gas tube block.. opens it up.. Back out to range---

The single feed issue again, however.. the trigger is reset every-time, but i have to manually charge it. no excess gas coming out of the bolt.. recoil not as pronounced..good ejections better than the last two days.. again 55 grain fmj.. Did not check lock back on magazine after last round..Did not want waste another round.
( I got it it to cycle correctly..)

Armor thinks the gas port on the barrel is to close to the barrel end of the rifle and the dwell time is to long.. He tells he thinks.. opening from-- port to barrel --it should be 5 1/2 inches and mine 5 1/4 inches.. ( skeptical) ( cheap route he will drill the gas black out a little more) I called to speak to andy or carl..However both out of office..which is cool.. NO call back yet..

I have vids of days 2 and 3 ...

Need help diagnosing issue.. gas issue or spring buffer issue..
Manually feeds fine.. 2 Magpul magazine used..and a regular mil-spec aluminum magazine used.. no problems at all manual feed..

[aspp]

Before drilling out the barrel, try a few different types of ammo. Also lube your bcg up, this can help when they are new/tight.

[abw]

We will drill out the gas tube apparently.. I have lubed the bcg really well. There seems to be no sticking on the gas tube, the gas key seems in alignment and the tube is straight to the barrel and level across..

The gas impression left at the barrel gas port in try 1 showed the gas block...no quite in alignment.. Possibly due (handguard ring + gas block)

Try 2 with gas block gas port ovalized shows block and port getting more gas, but not enough we think.. So the armorer contacted another g-smith they advised to carefully enlarge gas tube by..micrometers. So that next... We are not going to drill any barrel... I will refer to Carl or Andy before I ever put a bit on the barrel...



Is the Bhw barrels better suited for free float handguard or for handguard plate and delta assembly. Is that where I might have gone wrong on the build? The mic just off enough.

Ammo I have used some varmint load, 55 grain black hills, 55 grain Remington Pmc, all to no avail... I can't my hands on the 5.56. 77 gr but will after the new year. Shortages..

It should cycle at Minimum 55 gr...

[GLSHOOTER]

Dec 15, 2012 17:02:26 GMT -8 abw said:

We will drill out the gas tube apparently.. I have lubed the bcg really well. There seems to be no sticking on the gas tube, the gas key seems in alignment and the tube is straight to the barrel and level across..

The gas impression left at the barrel gas port in try 1 showed the gas block...no quite in alignment.. Possibly due (handguard ring + gas block)

Try 2 with gas block gas port ovalized shows block and port getting more gas, but not enough we think.. So the armorer contacted another g-smith they advised to carefully enlarge gas tube by..micrometers. So that next... We are not going to drill any barrel... I will refer to Carl or Andy before I ever put a bit on the barrel...



Is the BHW barrels better suited for free float handguard or for handguard plate and delta assembly. Is that where I might have gone wrong on the build? The mic just off enough.

Ammo I have used some varmint load, 55 grain black hills, 55 grain Remington Pmc, all to no avail... I can't my hands on the 5.56. 77 gr but will after the new year. Shortages..

It should cycle at Minimum 55 gr...

OK, first lets get me un-confused. You are drilling out the actual GAS TUBE or the GAS BLOCK passage up into the gas tube? I have no earthly idea how you drill a gas tube, There is simply nothing to enlarge.

IMHO doing either will do zip for you. The gas coming from the gas port in the tube is a steady amount. You can't get anymore gas coming out just because the block has a bigger hole. Dwell time of the bullet and gas behind the bullet will only squirt so much through that hole before the pressure drops. If anything opening the bottom of the gas block that mates to the hole will DROP the pressure going through the tube as you will be creating an expansion chamber that will bleed off the gas pressure/velocity and slow down the bolt movement. The fact that it is 1/4" closer to tr muzzle will meam a slightliy lower port pressure but the variance will be miniscule from the one drilled further back.

First off, does the bolt slide smoothly in and out of the BC? Do you have to force it open and closed? Have you lubed the snot out of the bolt? Is there a chance that he BCG is dragging as it goes back into the buffer tube? Does it slide in there smooth as a baby's butt or like a Tonka Truck over a graveled sand box? I would grab a known, well fuctioning, lower and try that on my upper.

The location of your port is the same on any of the BHW barrels and is determined by the length of a standard gas tube. 5 1/4" vs 5 1/2" might well be based on measurements to the crown of the threaded portion vs the step on the barrel at the back of the flash hider. The dwell time of the pressure on an 18" tube with the location of that hole is more than adequate for the operation of the bolt. If anything the shorter length you measured would DECREASE the pressure curve not INCREASE the dwell time.

Has your 'smith commented on the size of the gas port? I suspect there is something that is slowing the BCG down and that is the cause. Keep us posted as he works his way through his theories.

Greg

PS: The barrels will run a FF tube or the regular furniture with no difference in performance other than accuracy.

[pasttense]

I like to check simple stuff first . are there three gas ring on the back of the bolt . is the gas tube open ( unobstructed ) at the bolt end. if you blow in the gas port of the BCG with the bolt removed can you here or witness air passing. The gas tube is a seemed tube any splits. hope something helps
Good Luck Paul

[pasttense]

One more thought maybe two. Not meaning any judgment but not knowing your experience level. please don't be insulted .
but is it the right length gas tube. is it mated properly to the BCG gas port. Paul

[joebush]

My thoughts on your issue:

Lube Lube Lube. Sloppy wet for break in. I have had multiple experiences at the range helping guys with new AR's get them to function, the primary issue so far has been not enough lube. Lube in the holes in the BCG, lube the bearing surfaces, lube the bolt lugs.

I also have an 18" BHW barrel with a rifle length gas system. No issues here, but plenty of lube in the BCG and upper receiver during break in. Some may call it excessive but I had no issues.

I used Federal XM855 for barrel break in.

Just an odd thought, could your magazine be rubbing the bolt carrier? Have you tried different magazines?

[abw]

Ok. I talked with Carl. Thank you so much for your advice and insight.

1. We didn't drill or ream out the gas tube..the gas tube and gas block were checked for leaks.. The armorer took solvent blew it down the tube under pressure and it bubbled back between the gas block and the gas tube hole..So he "slipped sleeved it" --

2.. we changed the BCG out.. not the BCG.. the borrowed BCG would not even function when fire no cycling at all.. We used my BCG in the other rifle well and it functioned with no issue.

So back to realignment of the gas block. That seemed to work-- to get fire, ejection, cycle back, load to battery. ---5 shot string ( hiccup) 6 shot string (hiccup)

hiccup-- empty mag and the BCG will not stay back.. Checked the bolt catch manually...works every time.

the bolt catch ---cmmg -- is new part, no wear, no stress, looks and performs fine. manually..I have used three different mags, all followers function, and no hangups. USGI, MAgpul, non military issue alum..

At this point..I'm frustrated.. I cannot even fathom using as a patrol carbine yet.

I think the best option, is to purchase after payday a jp gas adjustable block and new gas tube. reinstall..then test it. I have used the BH 55 grain ,223 ammo-
and Remington UMC 55 mc l223r3 <not the best but in pinch it what was available with all the crazy going on..


So this is where we sit.. Those folks that are helping me--thank you so much.. what are opinions now or suggestions..

Joebush what are you running for gas block?

the ammo we will use as agency will be duty. 5.56 77grain and the practice ammo will be 223 77grain both from black hills. We love their ammo..

[GLSHOOTER]

I would pick up a gas block from Battle Tested Equipment. I have met the owner and he is making some of the slickest standard and adjustable blocks in the country. The owner, George, is a shooter as are all his workers. They are supplying past to major builders across the country that you see all the time n the various boards.

His URL is: bte-usa.com/. The prices are better than a JP even though I buy JP's at dealer and have bought 8-10 in the last year. BTE will be flying on all my builds from here on out. I have been shooting their adjustable mini-block and it is running super. Ritch has one also and he is having parallel results.

If you order one via phone or write a note to them tel them you got the information from the Black Hole board.

Greg

PS: He also makes some super bullet charging handles that make my mouth water!!

[aspp]

Wilson Combat is also producing a slick adjustable gas block.

[Deleted]

Let me try to help you out.
First forget about the gas system for a second.
Did you try with another lower that is known to work reliably in another AR?
If you try this and it works then you know other place where you need to look at.
One could say your system is under-gassed but before we draw any conclusions we also need to make sure the lower, magazine or the buffer are not putting the brakes on the carrier group.
Everything that happens in fast motion one can replicate in slow motion as far as charging the rifle slowing and looking for any frictions. The bolt should be unlocking very easily w/o obstruction. I would test this without and with the lower on.
Then a hammer spring that has excessive force with a hammer that is out of spec or full of machine marks or rough cuts is going to slow down that initial push (I have seen them).
So while it is logical to start at the port I don't think it is a dwell time issue and before getting into any conclusions it is logical to follow the gas forces but not only looking for where gas pressure might be missing due to leaking or not being there in the first place but look at the internals and make sure there is nothing there slowing the group.
Charging an upper should feel very smooth and uniform force w/o any spots where it feels harder or slowing due to friction or other forces.
Make sure the bolt lugs do not make contact with the magazine lips due to dropping the magazine or something else.
An adjustable block is going to do little for you as normally you use them to reduce the amount of gas.
Try cycling the system with M193 LC nato rounds that are pretty hot. But a well tuned AR should cycle with anything, even PCM bonce that are very mild.
Try this ammo and try another lower. if you want to call me send me a PM and I will be happy to discuss with you. Everything can be fixed the issue is to identify first where the real root cause is.

[GLSHOOTER]

Dec 21, 2012 13:43:51 GMT -8 @sergiomartinez said:

Let me try to help you out.
First forget about the gas system for a second.
Did you try with another lower that is known to work reliably in another AR?
If you try this and it works then you know other place where you need to look at.
One could say your system is under-gassed but before we draw any conclusions we also need to make sure the lower, magazine or the buffer are not putting the brakes on the carrier group.
Everything that happens in fast motion one can replicate in slow motion as far as charging the rifle slowing and looking for any frictions. The bolt should be unlocking very easily w/o obstruction. I would test this without and with the lower on.
Then a hammer spring that has excessive force with a hammer that is out of spec or full of machine marks or rough cuts is going to slow down that initial push (I have seen them).
So while it is logical to start at the port I don't think it is a dwell time issue and before getting into any conclusions it is logical to follow the gas forces but not only looking for where gas pressure might be missing due to leaking or not being there in the first place but look at the internals and make sure there is nothing there slowing the group.
Charging an upper should feel very smooth and uniform force w/o any spots where it feels harder or slowing due to friction or other forces.
Make sure the bolt lugs do not make contact with the magazine lips due to dropping the magazine or something else.
An adjustable block is going to do little for you as normally you use them to reduce the amount of gas.
Try cycling the system with M193 LC nato rounds that are pretty hot. But a well tuned AR should cycle with anything, even PCM bonce that are very mild.
Try this ammo and try another lower. if you want to call me send me a PM and I will be happy to discuss with you. Everything can be fixed the issue is to identify first where the real root cause is.

Good advice. Kind of like what I told him about seven posts ago.

Greg

[texcl]

I just built an 18" rifle length ar (blackhole barrel of course) and have no issues. I don't even really lube my bolt but it is nickel boron plated. I also use a standard A2 stock assembly but recently built a M-4 style lower and slapped this upper on it to test it, it has been flawless on both and even when brand new never jammed or even had an inkling that it wanted to. Sound to me like something is binding or your gas block is no good. I would get a YHM block and see if that helps, I use the low profile block by YHM it runs around $20 and have no issues. I've heard that those S&W's aren't really mil-spec and there are lots of issues with things not fitting correctly. Could also be an incorrect buffer and spring I suppose.

[abw]

I spoke to BTE. I need to know what the barrels gas port opening is in thousandths as it comes out of the factory. He is concerned that even with BTE block there will not be enough gas vs dwell.. I have my ar here but do not have the tool to measure it out. I hope my armorer will stop by.. but anyways what should be the size of the opening.

[abw]

Dec 21, 2012 13:43:51 GMT -8 @sergiomartinez said:

Let me try to help you out.
First forget about the gas system for a second.
Did you try with another lower that is known to work reliably in another AR? Yes
If you try this and it works then you know other place where you need to look at.
One could say your system is under-gassed but before we draw any conclusions we also need to make sure the lower, magazine or the buffer are not putting the brakes on the carrier group.
Everything that happens in fast motion one can replicate in slow motion as far as charging the rifle slowing and looking for any frictions. The bolt should be unlocking very easily w/o obstruction. I would test this without and with the lower on. We have done this as well.
Then a hammer spring that has excessive force with a hammer that is out of spec or full of machine marks or rough cuts is going to slow down that initial push (I have seen them).
So while it is logical to start at the port I don't think it is a dwell time issue and before getting into any conclusions it is logical to follow the gas forces but not only looking for where gas pressure might be missing due to leaking or not being there in the first place but look at the internals and make sure there is nothing there slowing the group.
Charging an upper should feel very smooth and uniform force w/o any spots where it feels harder or slowing due to friction or other forces.
Make sure the bolt lugs do not make contact with the magazine lips due to dropping the magazine or something else. Nope
An adjustable block is going to do little for you as normally you use them to reduce the amount of gas.
Try cycling the system with M193 LC nato rounds that are pretty hot. But a well tuned AR should cycle with anything, even PCM bonce that are very mild.
Try this ammo and try another lower. if you want to call me send me a PM and I will be happy to discuss with you. Everything can be fixed the issue is to identify first where the real root cause is.