Grizzly MAG jamming

A

AK

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Sorry but I couldn't find anything specific in the search (yeah, I changed the date range).

I had the 18.5" MAG out this past weekend for the first time and was eager to put it through its paces. Nothing serious, just some clay busting and plinking. I was firing the cheap Federal #7.5 shot, 2 3/4", 2 3/4 DE target loads. I was finding that on every mag, I could pump off a shot or two and then it would jam. It appeared that as the shells were being fed up from the magazine, they would hit the top of the receiver and cant out of the ejection port slightly. Slamming the bolt closed would send the mouth of the shell square into the front edge of the ejection port. Some shells were slightly deformed as a result.

Now I know the Grizzly is supposed to be finnicky until it smooths out, though I bought this one second hand and it seems pretty smooth already. I also haven't read what the typical jam scenario involves; is this it? Doesn't seem like something that gets better the more you shoot it (especially since I can barely get it to do so in the first place!).

I'm a very busy man and I don't have time for guns that don't work. If they're faulty I get rid of them for something that does work. If this is a simple matter then I can deal with it, but if it involves grinding or polishing then I'll be happy to trade it to someone who wants to do that.

On a positive note the 8.5" Grizzly was a real hoot to bust off and fed the cheap target loads perfectly.
 
Thanks but I read that thread. I didn't catch in there where shells were being forced into the edge of the ejection port, just generic references to jamming which isn't very helpful. I hope the advice I get isn't "just keep shooting it". I'd hate to go through a flat of 12 ga only to discover my particular issue is NOT solved by "shooting it out".
 
AK said:
Thanks but I read that thread. I didn't catch in there where shells were being forced into the edge of the ejection port, just generic references to jamming which isn't very helpful. I hope the advice I get isn't "just keep shooting it". I'd hate to go through a flat of 12 ga only to discover my particular issue is NOT solved by "shooting it out".
Click to expand...

Some chamber are a little rough, they are fixed by a chamber polish & a chamfer, The mags Like the feed lips cleaned up with some emery cloth. I havent had one that didnt run flawless after a cleanup.
 
Are you haveing this issue with the original magazine that came with the gun or one of the extra mags?
The extra mags are known for turning the gun into a jam-o-matic. The problem isn't to hard to fix but it will involve a file and emery cloth or a dremel/die grinder.
If its the mag that came packaged with the gun then its an odd duck...
I did a bit of reshaping/polishing on the feed ramps and chamber area (nothing major) and with a tuned mag it feeds 2 3/4" & 3" shells perfectly.
 
Well I bought the gun second hand (was probably sold off because it's a jam-o-matic!) so I don't know what the story is on the mag, though I suspect it's the original as it only came with one. I had it out again the other week and same story, I found you had to very slowly and deliberately pump the action. Fast racking almost always caused a jam. The mag also has troubles loading the fifth round; as you're pushing down it feels like the follower gets stuck and you need to force it to get the fifth shell in.

I'm about at the point where I'm going to list this on the EE and trade it for a Mossberg or something. The mag is cool, but seriously, if it don't work 100% I don't want it.
 
have you tried any other ammo? My SN hates federal, it does something similar but only when ejecting, the shells hang up in the ejection port and block the fresh round from chambering. It does this every few rounds with both top gun and slugs, all types of Federal ammo. No other ammo has any problems.
 
This is a very common and frustrating problem that many have had. As some previous advice stated, you have to sand the lips on the mags. I have six mags and had to smooth the lips on every one.

It's a fun shotgun after this is done.

I still don't trust it as much as my Mossberg 590A1 SPX or my 870.
 
Don't sell it (unless you're doing a give away price-then PM me :)) they are good gun that just need a bit of love to bring out the reliability.
Heres my 2 cents on what I found with the mags;
The lips don't need polishing or smoothing, the problem on my mags (10 of them...) that caused all the jams was the lips are just a hair too long. As you rack the gun to chamber a round the front lip of the shell touches the flat face between the mag and the chamber, because the shell is plastic (fairly soft) it distorts a bit and jams the gun solid. If you shorten the mag lips (just a bit and a gentle roll of the radius) when you rack the gun as the shell is pushed forward and the nose of the shell starts to rise towards the chamber the rim of the shell clears the magazine lip and it glides into the chamber. This alone makes the gun flawless with 2 3/4" shells, for 3" shells you need to polish or feather in a mild ramp from the chamber to the magwell so there is no "flat spot".
I had ten mags to try first one style of repair and see how it worked then another mag for another thought of repair, the above description was the only way I found to make it run perfectly.
YMMV
 
RUPZUK said:
Don't sell it (unless you're doing a give away price-then PM me :)) they are good gun that just need a bit of love to bring out the reliability.
Heres my 2 cents on what I found with the mags;
The lips don't need polishing or smoothing, the problem on my mags (10 of them...) that caused all the jams was the lips are just a hair too long. As you rack the gun to chamber a round the front lip of the shell touches the flat face between the mag and the chamber, because the shell is plastic (fairly soft) it distorts a bit and jams the gun solid. If you shorten the mag lips (just a bit and a gentle roll of the radius) when you rack the gun as the shell is pushed forward and the nose of the shell starts to rise towards the chamber the rim of the shell clears the magazine lip and it glides into the chamber. This alone makes the gun flawless with 2 3/4" shells, for 3" shells you need to polish or feather in a mild ramp from the chamber to the magwell so there is no "flat spot".
I had ten mags to try first one style of repair and see how it worked then another mag for another thought of repair, the above description was the only way I found to make it run perfectly.
YMMV
Click to expand...

Interesting. Maybe that's why it took so long for some mags when I did it. Sooner or later I hit the right spot. Could you post a pic or a more detailed explaination of where you are doing the work on the mag?

TIA
 
OK, Thursday came early, it's my Friday anyway...
So first pic (hey, I found one more to do...), notice the shape of the edge (arrow points to it) how it is almost a Z shape.
grizzleymag002.jpg

This incorrect (IMO - YMMV) profile makes the lip too long, the result is the nose of the shell hits the flat part of the gun between the magazine and the chamber but the shell rim is still captive to the mag lips so the gun jams.
AND THAT SUCKS!!!!
The next pic shows the modification that has worked perfectly (for me - YMMV), I turned the Z radius into a gentle slope. What this allows is as the shell moves forward towards the chamber it is allowed to rise slightly as the shell rim starts passing through this new radius and that allows the nose of the shell to elevate into the chamber without jaming. Not much grinding is required to get it to work right - remove a little at a time equally on both sides until it cycles perfectly. You might want to try different cycling speeds and force applied to ensure it is reliable 100% of the time.
grizzleymag003.jpg

I don't have a pic of the mod I did between the mag and the chamber as it is very difficult to photo but a emery wheel on a die grinder (fine grit) can do it in seconds (don't grind too much - just a very slight angle, and I mean slight). If you've seen a ramped pistol barrel, you know what to do.:)
STANDARD DISCLAIMER: I'm not a gunsmith nor do I play one on TV...
Cheers
Rick
 
RUPZUK said:
OK, Thursday came early, it's my Friday anyway...
So first pic (hey, I found one more to do...), notice the shape of the edge (arrow points to it) how it is almost a Z shape.
grizzleymag002.jpg

This incorrect (IMO - YMMV) profile makes the lip too long, the result is the nose of the shell hits the flat part of the gun between the magazine and the chamber but the shell rim is still captive to the mag lips so the gun jams.
AND THAT SUCKS!!!!
The next pic shows the modification that has worked perfectly (for me - YMMV), I turned the Z radius into a gentle slope. What this allows is as the shell moves forward towards the chamber it is allowed to rise slightly as the shell rim starts passing through this new radius and that allows the nose of the shell to elevate into the chamber without jaming. Not much grinding is required to get it to work right - remove a little at a time equally on both sides until it cycles perfectly. You might want to try different cycling speeds and force applied to ensure it is reliable 100% of the time.
grizzleymag003.jpg

I don't have a pic of the mod I did between the mag and the chamber as it is very difficult to photo but a emery wheel on a die grinder (fine grit) can do it in seconds (don't grind too much - just a very slight angle, and I mean slight). If you've seen a ramped pistol barrel, you know what to do.:)
STANDARD DISCLAIMER: I'm not a gunsmith nor do I play one on TV...
Cheers
Rick
Click to expand...

Interesting. Thanks.
 
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