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View Full Version : Frist time out with JP15. Had malfuntions, your thoughts?


sreiter
01-31-2010, 5:01 PM
THE GOOD: JP-15 UPPER ASSEMBLY
.223 WYLDE, 20" MEDIUM CONTOUR, 1:8 TWIST
COMPENSATOR, JP TACTICAL,
JPGS-3 GAS BLOCK, JP ADJUSTABLE, .936 BORE, ALUMINUM
JPBC-2 BOLT CARRIER, JP FULL MASS TACTICAL
Std .223 MIL SPEC .223/.204 BOLT ASSEMBLY

JP COMPLETE JP FIRE CONTROL SYSTEM WITH
TRIGGER, SPEED HAMMER AND OVERSIZED FITTED
PINS, INSTALLED
TRIGGER SPRING: YELLOW
HAMMER SPRING: RED
LPK-LTG LOWER RECEIVER PARTS KIT CONSISTING OF:
Trigger Guard Assembly, Selector Assembly,
Take-down/Pivot Pin Assemblies, Bolt Catch Assembly,
Magazine Catch Assembly, Grip-Bolt & Washer (Grip not
included) Buffer retainer and spring.
DPBS-09 RECEIVER EXTENSION TUBE, STANDARD
DPBS-10B BUFFER SPRING, STANDARD
DPBS-11 BUFFER ASSEMBLY, STANDARD
HPG HOGUE PISTOL GRIP
ACE-ARFX ACE ARFX SKELETON BUTT STOCK KIT

DPUR-19TL CHARGING HANDLE ASSEMBLY WITH BADGER
ORDNANCE TACTICAL LATCH

THE BAD:
i was shooting 55gr .223 federal, and 55gr 5.56 winchester

THE UGLY:

The weapon wouldn't feed a second round/ strip a round from the mag (10/30 pmag).

i could load 1 round via the charging handle, and fire. the trigger would reset (i know because i heard a click at least twice when it should have went bang)

I had 2 or 3 failure to eject. Almost the AR version of a stove pipe/ the brass half way ejected.

I tried someone elses metal 10/20 mag at the range same thing happened. I also tried the PMAG in my "1st time ever shooting it BCM upper" on a stag 15 lower with RRA LPK standard trigger, and it performed flawlessly.

Any thoughts on what woul cause the malfunction?

thanks in advance

elrcastor
01-31-2010, 5:31 PM
I'm assuming it was well lubed? I find sloppy wet works better. I use slip 2k.

wooger
01-31-2010, 5:35 PM
Turn up the gas.

bombadillo
01-31-2010, 5:46 PM
Yeah, my bet would be that the gas block is pinched way too tight for it to cycle hence the short stroking. If its not racking another round in, its not travelling back far enough. I have a LMOS BCG and buffer system and its awesome with the adjustable gas block. Back it out by about 2-3 full turns and see how it performs. Make the BCG sloppy wet and run the bore snake down a few times to get residual out but it should run fine i'd think. Also try a standard 10 round mag with it and see if its magazine problems. I highly doubt it is, but use a 10 rounder that is known to work not a converted mag.

aplinker
01-31-2010, 5:58 PM
1.) The rifle is new, sometimes it takes some time to work in.

2.) You bought a tuner hot-rod upper. Your gas system is adjustable and needs to be tuned to your load, especially since you're shooting some anemic stuff.

3.) You need to run WET.

4.) Your mags could be crap. Check others.

5.) You should have checked for conclusive short-stroking (i.e., does the bolt lock back when shooting just 1 round from a mag).


You have a lot of stuff to diagnose here...

sreiter
01-31-2010, 6:05 PM
Thanks all -

It was lubed, maybe i need to lube it even more. It was as wet as the BCM FA BCG.

Tried another mag, and that mag worked fine in the BCM, but it's always a possibility it didnt like that mag or the other I tried.

re: short stroke. i didnt just shoot 1 shot outta mag, however, I did run through about 30 rounds, and it did lock the bolt when the mag was empty.

hmmm - looks like i gotta learn to tune the gas block...I also have to learn to be patient until i get some real ammo

aplinker
01-31-2010, 6:09 PM
It's entirely possible it's overgassed, as well. If you hit the back of the extension hard enough you can slam back into battery, causing other issues.

Personally, I would close the gas all the way down, noting how far I moved. I would then open it just a hair and load one round. The bolt should not lock back (or you went too far). I'd continue opening until I just started to lock the bolt, then add maybe another 1/4 turn or so, for good measure.

Ejection distance/pattern is another clue.

Thanks all -

It was lubed, maybe i need to lube it even more. It was as wet as the BCM FA BCG.

Tried another mag, and that mag worked fine in the BCM, but it's always a possibility it didnt like that mag or the other I tried.

re: short stroke. i didnt just shoot 1 shot outta mag, however, I did run through about 30 rounds, and it did lock the bolt when the mag was empty.

hmmm - looks like i gotta learn to tune the gas block...I also have to learn to be patient until i get some real ammo

sreiter
01-31-2010, 6:15 PM
thanks plinker - you're talking a bit past my armor-level. hmmm, maybe one weekend I could meet you where-ever it is you shoot (piru?) and you could show/teach me. Beer and/or steak is on me (after we shoot of course)-

Josh3239
01-31-2010, 6:54 PM
I can go out to Piru and maybe help you out. Never worked with JP rifles or adjustable gas blocks on ARs but I have experience on other ARs and tuning the gas system on my M1 ;)

Also this compass or w/e you want to call it can help:
http://i4.photobucket.com/albums/y124/airsoft76/ejection.jpg

sreiter
01-31-2010, 7:13 PM
it was ejecting @9:00 -- damn range partner - lol

thanks - i'll give u a pm in two or so weeks. from what i recall - i think it was ejecting 2-3 o'clock

BigBamBoo
01-31-2010, 7:24 PM
..............

sreiter
01-31-2010, 7:29 PM
lol

stan, i've been just itch to shoot... i used a aimpoint for gods sake cause i havent decided on glass yet ... i just wanted to shoot

BigBamBoo
01-31-2010, 7:56 PM
............

sreiter
01-31-2010, 8:21 PM
actually i didnt see, the dvd, dont think one came with the rifle...or i thought i twas just the catalog of something and tossed it

BigBamBoo
01-31-2010, 9:04 PM
...........

sleepur606
01-31-2010, 9:08 PM
I know JP has a specific break in for setup of the adjustable gas block on their rifles/uppers/barrel kits.

A friend of mine has a 20" barrel from them and first time he took it out, he had to tune the gas block and it shot flawlessly. Second time, it wasn't lubed enough and was short stroking almost exactly as you're describing; trigger would reset, 95% of spent cases were removed, but a new round wasn't stripped and chambered. Last time out, he lubed it real well and retuned the gas block (500 rounds or so through the rifles) and it shoots near flawlessly again. I believe his 10 round mag was having feeding issues due to the follower tilting...not sure.

bombadillo
02-01-2010, 8:00 AM
Yeah, you may want to close it off altogether or you could open it up quite a bit and start backing it down. Without having to waste a bunch of ammo, I opened mine up quite bit and started backing it down until it short stroked. When it did, I started quarter turn by turn until it cycled nice and smooth without having function problems.

sreiter
02-01-2010, 8:57 AM
Thanks again for everyones suggestions. First steps. Jp dvd, good ammo, learn how to mess with the gass. Block.

sreiter
02-01-2010, 8:57 AM
Thanks again for everyones suggestions. First steps. Jp dvd, good ammo, learn how to mess with the gas Block.

sreiter
02-01-2010, 4:40 PM
spoke to J today - they suggest i mess with the gas block - they think its over gassed ...hmmm where did i hear that before????? thanks all -

BTW Stan, the guy there said federal american eagle is fine ammo for under 100 yards, and ok for under 300 just not as accurate as long as it isnt for a match.

he also suggests graphite in the mag AFTER its loaded - he said the cycling rate in general on a "race" gun is so fast, it might be faster then the follower, so cut down on the drag of the mag

norcal-ar
02-01-2010, 8:37 PM
my jp had the same issue and i changed the mag and problem solved.