messing with the feed ramp

Metric · July 22, 2020, 10:48 PM

Someone I know has a Beretta 71 that the previous owner screwed with, before selling it off.

The 71 is the most reliable .22 pistol platform that I've seen. But this one was attacked by a bubba with a dremel tool. The aluminum frame was apparently "polished" (aggressively) where it fits against the barrel's feed ramp. Since metal was removed from the frame, this created a tiny gap with a slightly "overhanging" feed ramp.

Not surprisingly, the overhanging feed ramp now catches bullets as they are feeding out of the magazine, and shaves a bit off them and/or causes jams (failures to feed).

This, of course, is extremely annoying. It looks to me as though there is only one realistic fix -- taking an equal amount of metal off the feed ramp to eliminate the "overhang."

I have never done this before, and I'm well aware of the possibility of screwing things up even more. But I want to know if it's effectively "next to impossible" to do it right, or if some work with a needle file and then polishing could possibly help.

The overhang is very small, and with the best possible ammo (mini-mag) it creates a jam perhaps once every 10 shots, on average. With other ammo, jams are much more common. It's very easy to see how that overhanging ramp is shaving bullets.

What would you do?

FrankenMauser · July 23, 2020, 10:47 AM

Have a skilled TiG welder replace the metal that was removed.
Then return the feed ramp to its original shape, as well as possible.

Metric · July 23, 2020, 07:03 PM

We decided to risk it. I broke out a needle file and re-shaped the feed ramp to eliminate the slight overhang, then polished. Haven't shot it yet but it will now hand-cycle everything flawlessly (ammo that was giving guaranteed jams every mag when hand-cycled before).

Will try shooting over the weekend.

FrankenMauser · July 24, 2020, 11:33 AM

I hope it works out.

Metric · July 24, 2020, 06:17 PM

Thanks for your thoughts and responses Franken, I'll update the thread after I've tested. I'm pretty sure it will be improved, but my main uncertainty is whether it's completely fixed or still throwing the occasional failure to feed.

tangolima · July 25, 2020, 12:12 PM

Polishing deep into aluminum frame is a permanent damage done. The metal is soft. It requires the hard anodized layer to work as a pistol frame. I'm afraid the new frame ramp will wear rather quickly.

The barrel ramp may be cut back to eliminate the over hang, which is a no no. The barrel must be behind the edge of the frame ramp enough to feed well, and the frame needs to have sharp, not rounded, edge. But grinding back barrel ramp too much will reduce support to the brass head. Ruptured brass may result.

Building up the frame ramp may be a better choice, if you can tig weld aluminum. But it will still lack the anodization.

-TL

Sent from my SM-N960U using Tapatalk

Metric · July 25, 2020, 03:22 PM

Tested with ~200 rounds of ~6 varieties this morning, from lead bulk ammo to premium hyper-velocity. Also had four shooters participate. Zero failures to feed with any of them (I did encounter one dud in the bulk ammo, but not much to be done about that).

The overhang was quite small, just enough to reliably snag bullets on every mag, so the barrel ramp did not need a massive change. That's the reason I went ahead with it -- it wasn't a radical operation.

I will watch for accelerated wear on the polished part of the frame, but I wouldn't expect the directing of 22LR bullets to require a high-hardness surface -- the force of the recoil spring is quite mild, and the bullets are soft. It's easy to imagine a different story with something like pointy FMJ centerfire rifle ammo.

sparkyv · July 26, 2020, 02:54 PM

Well-done, Metric.

July 22, 2020, 10:48 PM	#1
Metric Senior Member Join Date: December 4, 2016 Posts: 339	messing with the feed ramp Someone I know has a Beretta 71 that the previous owner screwed with, before selling it off. The 71 is the most reliable .22 pistol platform that I've seen. But this one was attacked by a bubba with a dremel tool. The aluminum frame was apparently "polished" (aggressively) where it fits against the barrel's feed ramp. Since metal was removed from the frame, this created a tiny gap with a slightly "overhanging" feed ramp. Not surprisingly, the overhanging feed ramp now catches bullets as they are feeding out of the magazine, and shaves a bit off them and/or causes jams (failures to feed). This, of course, is extremely annoying. It looks to me as though there is only one realistic fix -- taking an equal amount of metal off the feed ramp to eliminate the "overhang." I have never done this before, and I'm well aware of the possibility of screwing things up even more. But I want to know if it's effectively "next to impossible" to do it right, or if some work with a needle file and then polishing could possibly help. The overhang is very small, and with the best possible ammo (mini-mag) it creates a jam perhaps once every 10 shots, on average. With other ammo, jams are much more common. It's very easy to see how that overhanging ramp is shaving bullets. What would you do?

July 23, 2020, 10:47 AM	#2
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	Have a skilled TiG welder replace the metal that was removed. Then return the feed ramp to its original shape, as well as possible. __________________ Don't even try it. It's even worse than the internet would lead you to believe.

July 24, 2020, 11:33 AM	#4
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	I hope it works out. __________________ Don't even try it. It's even worse than the internet would lead you to believe.

July 26, 2020, 02:54 PM	#8
sparkyv Senior Member Join Date: May 2, 2015 Location: Deepinnaheartta,Texas Posts: 318	Well-done, Metric. __________________ μολὼν λαβέ NRA Life Member

July 23, 2020, 07:03 PM	#3
Metric Senior Member Join Date: December 4, 2016 Posts: 339	We decided to risk it. I broke out a needle file and re-shaped the feed ramp to eliminate the slight overhang, then polished. Haven't shot it yet but it will now hand-cycle everything flawlessly (ammo that was giving guaranteed jams every mag when hand-cycled before). Will try shooting over the weekend.

July 24, 2020, 06:17 PM	#5
Metric Senior Member Join Date: December 4, 2016 Posts: 339	Thanks for your thoughts and responses Franken, I'll update the thread after I've tested. I'm pretty sure it will be improved, but my main uncertainty is whether it's completely fixed or still throwing the occasional failure to feed.

July 25, 2020, 12:12 PM	#6
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,816	Polishing deep into aluminum frame is a permanent damage done. The metal is soft. It requires the hard anodized layer to work as a pistol frame. I'm afraid the new frame ramp will wear rather quickly. The barrel ramp may be cut back to eliminate the over hang, which is a no no. The barrel must be behind the edge of the frame ramp enough to feed well, and the frame needs to have sharp, not rounded, edge. But grinding back barrel ramp too much will reduce support to the brass head. Ruptured brass may result. Building up the frame ramp may be a better choice, if you can tig weld aluminum. But it will still lack the anodization. -TL Sent from my SM-N960U using Tapatalk

July 25, 2020, 03:22 PM	#7
Metric Senior Member Join Date: December 4, 2016 Posts: 339	Tested with ~200 rounds of ~6 varieties this morning, from lead bulk ammo to premium hyper-velocity. Also had four shooters participate. Zero failures to feed with any of them (I did encounter one dud in the bulk ammo, but not much to be done about that). The overhang was quite small, just enough to reliably snag bullets on every mag, so the barrel ramp did not need a massive change. That's the reason I went ahead with it -- it wasn't a radical operation. I will watch for accelerated wear on the polished part of the frame, but I wouldn't expect the directing of 22LR bullets to require a high-hardness surface -- the force of the recoil spring is quite mild, and the bullets are soft. It's easy to imagine a different story with something like pointy FMJ centerfire rifle ammo.