First time out

[towerofpower93]

So I finally got a chance to take my 10" DI upper and 3 mags to the range and had some good times and bad times.

The first mag went great with the first couple rounds needing a tap to the forward assist to fully seat the bolt. Figured this was the metal working itself out on the tight spots. The remaining rounds fed, fired and ejected with no problems.

Then I move onto the second and third mags, no issues with the second mag but the third one won't let the bolt go forward to strip a round. The bolt smacks the back end of the round and unseats it from the mag, but the bolt carrier is held back and can't go into battery. I hand cycled this one 5-6 times with the same result each time. This mag also has dimples on the front corners of the mag right near the bottom. It appears that the bolt carrier is contacting the feedlips and I'm wondering what the standard fix is for this problem...flatten/file down the top of the feedlips or take some of the rib off the back of the mag to allow it to be seated lower and still locked into the magwell adapter.

So I swapped over the ammo from mag 3 to mags 2 and 1 and both of these mags would not strip a round after firing. Hand cycling would be fine and the round would fire, but a second round would not get stripped from the mag. Is this a dirty gun short stroking and not getting the bolt far enough to the rear in order to strip a round? The buffer spring is standard strength, the buffer for the first ~60 rounds was a Spikes ST-T2 tungsten buffer (slightly heavier than an H2 buffer) but when I swapped over to a standard H2 buffer (thinking the lighter weight may reduce the resistance) it still would not strip a second round.

Any and all help is appreciated.

Thanks

Eric

[HMC710]

Check all the mags, empty, in the upper. The left side feed lip is usually the culprit. Take a file and widen the opening by filing the left side. Do not shorten the feed lips. Make sure the ends are smooth and not sharp.
Look at the top of the adapter and see if there are any marks on the top of the feed ramp from the bolt lugs or the top of the adapter from the carrier.
Mag heights: Insert each mag into the adapter and pull down against the mag catch. Check the height of each one and compare #3 to the rest of them and let me know what you find.
Check your gas block. If you have a silver soldered block/gas tube, send it back and I will get you a tig welded one. Make sure your block didn't move forward closing off the gas port.
I use a light buffer with no weights in my upper. Your upper was tested using a standard carbine buffer and spring.
What ammo are you using and how was ejection?
Tim

[towerofpower93]

As far as ammo...I'm using this:

www.sportsmansguide.com/net/cb/1260-rds-762x25-mm-tokarev-ammo.aspx?a=170601

I just got mag #3 running with a couple swipes of a file and some hand cycling to let the high spot on the mag and the bolt get some "alone time" and work it out. They're talking now and have a plan for dual cusotdy of the dog:)

Ejection from the first mag was pretty good, can't give an exact figure as I was shooting under cover and the roof was catching them and tossing 'em back down. I did not look at the ejection for the last few mags, I will next time. How far up and to the right should a spent piece of brass fly from a 10" DI system when it's running smoothly? I'll be sure to get out in the open this weekend and get some hard data concerning this.

The gas block is still all the way to the rear and butted right up against the front of the chamber. I'm not sure what a silver soldered vs. tig wleded gas tube would look like to tell you if I got one or the other. I just received this the other day (Eric Beckman in VA) so I'm not sure when you stopped silver soldering and started tig welding, but the upper isn't all that old.

It seems there is quite a bit of residue/carbon in the quad rail directly above the joint where the gas tube comes out of the gas block and makes its sloping turn to the rear of the weapon...maybe it sprung a leak due to silver soldering?

let me know if you need pics and I'll get what I can.

Call if it's easier, I'll PM you my number.

Thanks

Eric

[HMC710]

You have one of the transition blocks. I made 6 that were silver soldered. Could be either one, either way we need to see what is going on. PM sent.

[towerofpower93]

Replied to the PM, but wanted to put this out so your product doesn't get dinged. I broke everything down again last night and discovered that I'd left my buffer tube filler in the lower from when I'd used my 9mm upper...doh!

Thinking that may have caused the short stroking after the upper got a little dirty from the first 50 or so rounds.

[HMC710]

Keep us posted, the soldered gas blocks need to be dinged