AR noob needs help!

J

jory

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Hey guys,

I recently purchased a used DDM4V5 upper and a new BCM complete lower for it, slapped it together, and called it a rifle.

I took it out for the first time on the weekend to see what all the fuss about AR's is about, and ran into some issues that I need help with. Here are some details:

DDM4V5 upper- used (2000rnd)
BCM Mod 0 lower- new
Aguila 55gr .223
1x magpul PMAG
2x aluminium Beowulf mags

Issues:

1. The bolt will lock back after the last round of my beowulf mags, but not far enough to grab a round from a fresh mag. It will not lock back after the last round from a PMAG
2. Occasionally between rounds it will not travel back far enough to grab the next (short stroking)
3. There were a few times that I manually cycled the bolt with the charging handle, but it still did not strip the next round until I REALLY gave the magazine a good smack. When I inserted a new mag I made absolute sure it was seated in there very well, but sometimes I couldn't even manually cycle it far enough back to grab the next round
4. The gun seemed to recoil way more than it should have, and there was a distinct humming sound coming from the buffer tube area after every round- it sounds like a spring vibrating in the tube.

Again, i'm VERY new to this, so it's likely a very stupid/simple problem. I just need some tips on where to start.

Thanks!
 
Without looking at the rifle I'm going to guess that you need to replace the gas rings in the BCG. It's a cheap and easy fix you can do yourself in a few minutes. Also check that your gas key is tight on the top of the carrier and that the gas tube looks like it's in decent shape where the gas key slips over it inside the receiver
And as pitbull said, it needs to be well lubed, doesn't need to be dripping but the AR doesn't like to be run dry.

Is it locking back on the boltface or is the bolt catch grabbing the front of the carrier?

Good luck
 
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Whats your buffer weight and what gas length you have on the upper?
(That needs to be paired properly)

I think your upper is mid length and your lower buffer is a heavy or extra heavy carbine buffer.

Disclaimer** I am not a doctor
 
The gun was NOT well lubed- probably under lubed in fact from what you guys are explaining. I'm hoping it's that easy of a fix.

The bolt catch was grabbing the front of the carrier. Once it locked "open" the bolt was still obstructing the view inside the dust cover by an inch and a bit. I had to use the charging handle to pull it back the rest of the way to lock the bolt open.

DDm4V5 is a mid length gas system, and I just realized now after checking the web that the BCM Mod 0 lower comes with a milspec carbon buffer system: http://shop.bravocompanymfg.com/AR1...oup-Stock-Mod-0-Black-p/lrg-stk-mod-0-blk.htm

I suppose that could be my issue.
 
I'm starting to wonder if the upper has been taking apart in the past. If it has then it could be possible that the gas block is not aligned with the gas hole on the barrel causing it to be under gased. Check the gas block , see if it's loose
 
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He has problem by even manually cycling the rifle.

Find a different lower, and try again. If the upper works with a different lower, the lower is the problem.

Do this before start randomly throwing parts in.

There were a few times that I manually cycled the bolt with the charging handle, but it still did not strip the next round until I REALLY gave the magazine a good smack. When I inserted a new mag I made absolute sure it was seated in there very well, but sometimes I couldn't even manually cycle it far enough back to grab the next round
Click to expand...
 
Added to some of these suggestions try different ammo. I would suggest purchasing a few alternate brands and in particular NATO 5.56 ammo that will generate higher levels of gas.
 
jory said:
The gun was NOT well lubed- probably under lubed in fact from what you guys are explaining. I'm hoping it's that easy of a fix.

The bolt catch was grabbing the front of the carrier. Once it locked "open" the bolt was still obstructing the view inside the dust cover by an inch and a bit. I had to use the charging handle to pull it back the rest of the way to lock the bolt open.

DDm4V5 is a mid length gas system, and I just realized now after checking the web that the BCM Mod 0 lower comes with a milspec carbon buffer system: http://shop.bravocompanymfg.com/AR1...oup-Stock-Mod-0-Black-p/lrg-stk-mod-0-blk.htm

I suppose that could be my issue.
Click to expand...


That lower uses a H buffer which should work fine with that mid length system. So I might start with GreenTips suggestion.
 
The answer to #4 is yes. They have recoil. Hellish, uncontrollable recoil.... Not really, but there is definitely some and a "boing" sound is completely normal.
For many $$$ you can buy a silent spring system that will not work any different than what you have now.
 
I've been reading up on this, and I've found mixed opinions on my buffer setup with this upper. The mod 0 lower looks like it's set up for carbines, not mid length uppers like I have.
 
You can try the L5AWM and a Sprinco tactical spring.

The action will become smoother with time. Keep shooting.

I keep the BCG well lubricated.

All my setups have worked with that combination and a crane O-Ring.
 
Update:

I lubed the piss out of the bolt and bolt carrier group, and didn't have a single short stroke all day!

However, the bolt hold open on my last round is hit or miss between all my different mag varieties. Why would this happen?
 
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