all three are between 1.500 - 1.505, and the nibs are nice, square on the bottom, and pronounced.
Originally Posted by Matt_X
Here's what I did to resolve the FTF. Maybe it will help.
interesting. I thought my failure to feed's were from the nose of the round wedging in the chamber. I could be wrong. Yours looks like the bolt slips off the back of the round after pushing it partway. I need to see if I can manually reproduce the problem - will either remove the firing pin or disassemble some rounds and make dummies.
Definately seems to be worth the effort to trying to replicate the FTF and from there see which of the causes or are the most likely.
I recently saw some late WW2 era dummy rounds for sale on-line, either as whole box or in groups of 10 cartidges. Let me know if you want to look through for the website.
Definately seems to be worth the effort to trying to replicate the FTF
On my list for the weekend. I don't feel like wasting rounds taking them apart to make dummies...so I was going to remove the firing pin instead. Found this neat little trick.
My NPM only has one notch? Guess I need to read up more on the variations. Fun Fun!
Matt: I love to read about people working out problems. Great job.
First, I would have to say that any magazine tolerances are probably aimed toward the loose side. If the magazine doesn't fit the weapon it is useless. My personal experiences are that the 30 rd mags are barely ok unless you have the late model mag release. Which I don't. Fully loaded with about 28 rounds, they weigh a lot and the whole thing depends on two tiny nibs of an extremely crappy design. The magazine is the Achilles heel of the carbine, that's probably why they made tens of millions of them. They are a wear item. I have a few genuine AI and SEY Mags and I just don't use them anymore. Fully loaded they remove the lightness and handiness of the carbine, like putting a stock pouch on one. They just naturally flop around, look cool but we are not at war with them. The 15s are so much better for any number of reasons. The carbines are amazing weapons, their design is wonderful but when they made them into machine guns they took away their best attributes.
Look at the magazines for an M14 or M16, much stronger and a much better release system. The M14 has a mag release like an AK plus you can recharge an empty magazine while is is in the rifle with stripper clips. Had the carbine been developed as an automatic from the start, the magazines would have probably been much different.
tried over a hundred times to reproduce, and can't get it. However, from what I remember on range day, the failures were all on left rounds...and looked like the round "wedged" crooked in the chamber. After trying to reproduce, I thought maybe either the lip of the magazine might have a burr or be shaped down, catching the round, or maybe the mouth of the case is catching on the edge of the chamber?
Although I couldn't produce the failure manually, I set up a stop on the oprod...it kind of looks like this when the failure happens... Attachment 121214
After watching the thing feed manually...I don't think the magazine position in the wells or any looseness are the fault
Going to the range with some friends Friday...I'll try to get a good picture when the failure reveals itself.
Good range day with my friend. We went to his range, which is only 25 yards. I took the mags I had been using, as well as the new Korean made ones, and let him have fun with a box of 50 rounds.
Sure enough, on the 4th round the failure showed itself with the USGI magazines, then almost always every other round (seems to only effect the left side rounds.
The malfunction only happened once on the Korean mags, and only on the third to last round of the magazine (last round feeds from the left of the follower).
I took pictures, and they all looked the same... Attachment 121461
The bolt pics up the round, pushes it forward part way, then before the base of the round pops up from under the magazine's lip, the bolt slips off the top and wedges on top of the round. I think bolt slippage occurs just a hair before the round is fully out of the magazine. When I pull the bolt back to clear, the round pops up.
I think I can try...
1) tearing down the mags, cleaning inside again, and spraying some dry teflon lube inside and on the follower.
2) polishing the edges of the feed lips, especially the front part.
3) opening the front corners of the feed lips slightly if (1) and (2) fail
4) the slight amount of vertical play in the magazines seems to be isolated to the trigger gaurd pin. I can try shimming it with a small piece of aluminum tape on the underside of the pin.
My friend shoots righty. As I watched him, every round ejected the same at 4:30 - 5 o'clock, and I easily caught the brass in my hat. I shot one mag as a lefty, and every shot either went just past my right ear, or hit my forehead. One problem at a time
I've got an idea what it might be and I don't believe it's been mentioned yet in this thread. Look to see if your trigger pin is being tightly held in place by the width of the opening in the stock. If it slips just enough to allow the pin to disengage the trigger housing at one end, what you've shown can happen. I don't have time to explain it right now, but I'll post pictures below and a link to my thread that should explain it. If the trigger pin is a sloppy fit in the TH or in the trigger, I suppose it would do the same thing. - Bob
Hmmm! I can't find a link to my thread. Maybe I just imagined that I made one on this "jamming" with my Underwood? Painter777 could probably find it for me. He knows how to search this forum better than I do!
Look to see if your trigger pin is being tightly held in place by the width of the opening in the stock. If it slips just enough to allow the pin to disengage the trigger housing at one end, what you've shown can happen
Thanks. I'll give it a look. Are you suggesting stock inletting might be loose enough the pin could slip out partway? I suppose the pin's hole could be sloppy enough to cause the same issue too. I haven't been able to reproduce by hand...so maybe it's the jarring of the recoil jiggles the pin.
Maybe I just imagined that I made one on this "jamming" with my Underwood?
Hey Ole Timer,
If your talking about the Underwood you got 2 or 3 years ago..... Same one that had the loose gas piston nut on it that you took apart to look for lead fouling in it.
You posted about the Trigger housing pin in this thread- reply #13 concerning the possible binding Hammer/Trigger housing:
While reading it I'd advice reading JackP's reply #4 on page 1 (Very good info passed along and often overlooked).
GI Bob, Your reply is on page 2:
I don't know if this has been mentioned but,since you have had all the magazines apart, are you sure the magazine springs are in the correct way? It's easy to accidentally put them in the wrong way.I know if magazine springs are put in backwards, it can make rounds do funny things.
Originally Posted by USGI
PM
