AR15 issues

My AR isn't particularly reliable, I get a lot of failures to feed where the BCG either rides over the round entirely not picking it up, or it half picks it up but the round nosedives into the barrel extension.


Carbine gas, 14.5", compensator, rifle buffer system, well lubed. Have tried 2 BCGs (Daniel Defense Milspec and DPMS), the DD one seems a little more reliable (Possibly due to being sllllightly heavier). Have tried several different mags, 2 types of factory ammo (60gr Belmont, 55gr Hornady (brass cased)). The Belmot seemed a little more reliable.


I suspect it's overgassed but I'm not really sure. Any thoughts?


The fact that I have an upper with M4 feedramps and a barrel extension without them can't be helping. The barrel work was done by Dan Hardy, I've though of sending the rifle up to him to fix it but I'd like to be able to use the damn thing while I'm here on break from work.

Fuck custom rifles, next time I'm just going to deal with the customs hassle and get the barrel I want factory from the USA

Would like to try a PRI adjustable low profile gas block if someone has one they can bear to part with....

Tried putting upward pressure on the mag while rattling off rounds to test it.

My H&K used to do it with a shitty mag.

Just blend the extension to the upper with a dremel or something

Where does it throw the brass?

Attachment 312

Tried several different mags, magpul followers and shit


Ejection is to about 6feet to 2 o'clock with DD BCG... interesting. Adjustable gas block I guess??


Or send it back to Dan and say "Fix"

What's an SSS spring?

Personally I'd remove the gas block, measure the hole in it (from gas port), get a wee plug made up and press into it and drill hole 1/2 the size and test.
Work it up with jet drills till you get what you want.


The can will add bolt speed to it also so want it to operate just ok with no can on, then with can it will be sweeeeeeeet.

SSS spring is Superior Shooting Solutions
I think its a flat coil spring you can cut to suit

I want it to function properly with and without can and with any factory ammo (Like a rifle should) so I guess I'll send it to Dan and say "it's fucked, make it work"

Oh well another 2 months with no rifle

Now how the fuck are you going to come shooting up the valley Gimp? No .223 and your fucked!

Certainly does sound like too much gas getting through. Adjustable block would sort that. Try advertising around the forums & email the usual suspects who sell AR stuff. Serious Shooters had them but are showing out of stock. If you are really desperate you could try squeezing the gas tube a little to restrict the volume getting through. Just a little at a time as theres no going back. Good idea to have a spare tube before you start cos theres a good chance you will wreck it without fixing the problem.. A tip from Bubba gunsmiths Inc.

jp adjustable gas block - there was one on trademe recently but it may have gone

I'd say either a shitty magazine or over gassed. Or both. The gas port hole in your barrel could have been drilled to wide. What do your feed ramps look like?

http://i1135.photobucket.com/albums/.../feedramps.jpg

Having your rifle over gassed will do nothing for bolt life either

Plug it and drill the hole 2mm.
Thats the size of the gasport in all my carbine barrels in which most went on to replace Hardy barrels with big port.
2mm vs 3mm - 3mm isnt 50% more its 100% more area

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Originally Posted by Beavis

I'd say either a shitty magazine or over gassed. Or both. The gas port hole in your barrel could have been drilled to wide. What do your feed ramps look like?

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Originally Posted by gimp

Have tried several different mags,

The fact that I have an upper with M4 feedramps and a barrel extension without them can't be helping.

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Originally Posted by Wirehunt

Now how the fuck are you going to come shooting up the valley Gimp? No .223 and your fucked!

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It works most of the time. Fired the last few mags of the day with no problems

Quote:

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Originally Posted by muzr257

jp adjustable gas block - there was one on trademe recently but it may have gone

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I need the PRI one or a similar lowpro one to fit under my handguard

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Originally Posted by Spanners

Plug it and drill the hole 2mm.
Thats the size of the gasport in all my carbine barrels in which most went on to replace Hardy barrels with big port.
2mm vs 3mm - 3mm isnt 50% more its 100% more area

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How do I plug it? I've heard of people welding them but that doesn't seem like a great idea.

To make an adjustable gas block you'd just have to drill + tap it for a set screw that would screw in/out adusting the amount of gas that can get through... right?

You could just solder the gastube at the block end and just 2mm drill it.

Man I might try that

...got any spare gas tubes?


I'll measure my gas port in a bit

think so

I have a PRI low-profile adjustable gas block on the way, so hopefully that will solve my problem here.


Alternatively, does someone have an H3 buffer lying around?

G'Day Fella's,
gimp, I'm a bit late to this thread but with a shorter barreled AR, I have seen what they call a "Pig Tail" gas tube.
These gas tubes come back from the gas block then wrap around the outside of the barrel a couple of times, prior to going into the upper receiver.
What they are doing is extending the length of the gas tube on short barreled rifles, there by slowing down the cyclic speed of the bolt carrier.

I just went and Googled AR15M16PigTailGasTube and up it came with a picture and details of the part from Brownells in the US.

Now fella's, I'd like to say I was some kind of authority on Black Guns, but because of some slimy political animal (FJWH), this is not the case!!!

Hope that helps

Doh!
Homer

A pigs tail will change dwell timing more than cyclic rate - although they are both related. Gimps probs are the result of a gunsmith that over drills gas ports all the time

G'Day Spanners,

Is it possible to drill and tap the current gas port and then install an Hex grub screw with a smaller gas port diameter?
Or maybe, install a hollow "Spring Pin" in the current port hole?

Doh!
Homer

It's easier to solder the barrel end of the gas tube and drill that hole the right size or to suit

Spanners, it sounds like you blokes have a good handle on the situation!

Merry Christmas
JB/Homer

Update: I am now about 90% sure that it is UNDERgassing, as it functions 100% with suppressor, 75% with compensator, 0% with no muzzle device.


This means I have bought a useless adjustable gas block, however it also means that it's a way easier fix.


Ejection is actually to ~4 o'clock as observed at the range today.

4 o'clock is about perfect

Does it lock open on last round?

You havnt got something stupid like a carbine buffer or spring in it do you??

Have you measured the shoulder to gas port centre on the barre; and the gasblock back to hole centre?

Remember that a 'normal' AR with handguard front cap spaces the gasblcok the thickness of the cap fwd. If you use this same block without the front cap, then you are a mm or 2 too far back and the holes may not line up properly


Whats your loads?

With suppressor on it functions 100% perfectly, picking up rounds, locking back etc. Without any muzzle device, it doesn't pick up next round or lock back on empty mag.

Rifle stock, rifle buffer and spring.


3 types of factory ammo - Norma, Hornady (55gr) and Belmont (60gr).


The hole in the gasblock is centred over the gas port.

Gas port is ~1.4mm diameter.

BINGO - bigger pls 1.7
My M4 barrels (same as what US Army using) 14.5" are 2mm and a touch overgassed with my hot ammo, then again they might want to throw brass fwd to get it out of guys way beside you

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Originally Posted by Spanners

BINGO - bigger pls 1.7

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Thats about 1/16" if you have imperial drills