So I had had an interesting failure. Or rather, I may have figured out a long-ish running issue I’ve been having. I have been experiencing multiple failures to feed for a while now. This is on a F/A gun completed by Group Industries (pre-Vector).
I don’t think it has been an issue of weak ammo, as the failures usually happen on the first shot of a burst. So it’s like the cartridge was having trouble initially getting stripped from the magazine. I would get the cartridge part way into the chamber, but stopping part way in. But to take the ammo out of the equation, I have been using FMJ-RN 124 gr. NATO ammo from Igman. I haven’t run it over the Chrono yet, but it seems like the gun runs faster with it than with typical ammo.
I thought maybe it was due to tired surplus mags, but I bought some new Uzi Pro mags and still had the same issue.
So when I pull the trigger, I will occasionally get one that doesn’t feed all the way into the chamber. It isn’t nose-diving into the bottom of the barrel. Rather, the bullet is started into the chamber but gets hung up at an angle, with the bolt part way forward. The gun has a BWE feedramp, installed by Richard Hoffman.
I had been shooting a surplus military barrel with the typical chamber, with the typical end prep. I switched to the original Group Industries barrel, which has a bit more of a funnel profile at the chamber end, but the issue continued.
Looking closely at several of the malfunctions, the cartridge case head seems to go about half way up the lower lip on the breech face and would hang up there. It kind of looked like the rim was getting caught on the cutout for the ejector. Examining the bolt breech face, I don’t see anything that appears to be out of spec. I was using a surplus military bolt that I’d gotten from somewhere. It was either a surplus bolt I had gotten from BWE, or it could have been an IMI bolt that came with with an Izzy parts kit I have.
In any event, I swapped one surplus bolt for another and suddenly the gun ran flawlessly. For several magazines. I did not have a timer with me to check rate of fire, but the gun felt like it was running faster as well. I may have to clock the two bolts and see if there is a measurable difference in ROF. I may also try using a stone to round the edges on the ejector cutout. Although as noted, I don’t see any real difference between this one and any of my other bolts.
Kind of strange. Anyone else ever run into an issue like this?
I don’t think it has been an issue of weak ammo, as the failures usually happen on the first shot of a burst. So it’s like the cartridge was having trouble initially getting stripped from the magazine. I would get the cartridge part way into the chamber, but stopping part way in. But to take the ammo out of the equation, I have been using FMJ-RN 124 gr. NATO ammo from Igman. I haven’t run it over the Chrono yet, but it seems like the gun runs faster with it than with typical ammo.
I thought maybe it was due to tired surplus mags, but I bought some new Uzi Pro mags and still had the same issue.
So when I pull the trigger, I will occasionally get one that doesn’t feed all the way into the chamber. It isn’t nose-diving into the bottom of the barrel. Rather, the bullet is started into the chamber but gets hung up at an angle, with the bolt part way forward. The gun has a BWE feedramp, installed by Richard Hoffman.
I had been shooting a surplus military barrel with the typical chamber, with the typical end prep. I switched to the original Group Industries barrel, which has a bit more of a funnel profile at the chamber end, but the issue continued.
Looking closely at several of the malfunctions, the cartridge case head seems to go about half way up the lower lip on the breech face and would hang up there. It kind of looked like the rim was getting caught on the cutout for the ejector. Examining the bolt breech face, I don’t see anything that appears to be out of spec. I was using a surplus military bolt that I’d gotten from somewhere. It was either a surplus bolt I had gotten from BWE, or it could have been an IMI bolt that came with with an Izzy parts kit I have.
In any event, I swapped one surplus bolt for another and suddenly the gun ran flawlessly. For several magazines. I did not have a timer with me to check rate of fire, but the gun felt like it was running faster as well. I may have to clock the two bolts and see if there is a measurable difference in ROF. I may also try using a stone to round the edges on the ejector cutout. Although as noted, I don’t see any real difference between this one and any of my other bolts.
Kind of strange. Anyone else ever run into an issue like this?
