Stoeger M3K issue

[Andrew863]

I have had this gun for a couple years and have probably 1k rounds threw it. The day I got it I cleaned and de burred all the small stuff, added a 8rd Noridic comp tube and follower and took it to the range. Shot 200 rds of heavy loads and it ran like a champ. With light loads I have always been able to shoot 2 maybe 3 boxes and then start running into every 10 or 20 rounds it will not go all the way into battery. It don't mater if I use the cheap Federal bulk pack or good AA's it always the same. I tried to polish everything that has any friction the gun was smooth as silk but I still have the issue from time to time. I took the gun and had the bolt and carrier coated with micro slick dry film. Again the gun is silky smooth but still have the issue from time to time and the crazy thing is I can run the 1145 FPS loads in this gun fine but the not going into battery issue still happens even with 1200 FPS loads.  I hope someone can help me with this issue. I love the gun but man it gets annoying constantly checking to make sure it went all the way into battery and getting a click from time to time.

[kurtm]

Did you by chance polish the cam pin slot in the bolt carrier? Knock the edge off that kind of flat spot on the carrier where the cam pin hits when it first is closing?

[Andrew863]

1 hour ago, kurtm said:

Did you by chance polish the cam pin slot in the bolt carrier? Knock the edge off that kind of flat spot on the carrier where the cam pin hits when it first is closing?

So I assume your talking about the spot on the bolt itself that the pin rotates in the slot. What are u doing to that area. Mine is super smooth already but I haven't done anything to that spot but it is coated with micro slick. 

[kurtm]

Yes, where the bolt rotates. Don't do anything in there! Some guys try to re profile that area so it rotates real smooth. Problem is, if it doesn't have that hesitation in it, it can bounce back out of battery because when it closes it compresses the inertia spring a bit. Sounds to me like it is suffering bolt bounce. Quick test. Lock it back, hold it horizontal right in front of your face and trip the bolt release. Watch the bolt slam forward, if it bounces back at all that's your problem. It should close and not move back at all. If it does something in your camming system is worn. Also make sure that the retaining pin for your ejector is tapped all the way in and not dragging.

Edited May 27, 2020 by kurtm

[Andrew863]

9 hours ago, kurtm said:

Yes, where the bolt rotates. Don't do anything in there! Some guys try to re profile that area so it rotates real smooth. Problem is, if it doesn't have that hesitation in it, it can bounce back out of battery because when it closes it compresses the inertia spring a bit. Sounds to me like it is suffering bolt bounce. Quick test. Lock it back, hold it horizontal right in front of your face and trip the bolt release. Watch the bolt slam forward, if it bounces back at all that's your problem. It should close and not move back at all. If it does something in your camming system is worn. Also make sure that the retaining pin for your ejector is tapped all the way in and not dragging.

Never thought of that for some reason. I always check for bounce in ar's not sure why that didn't cross my mind here. When I get home later i'll get some super slow mo's with my phone and see if it is bouncing out of battery. It's like a light bulb come one as soon as I read this. That make all the sense in the world. I have been chasing the other direction the whole time I have had this gun. The only thing that gives me just a little doubt is it only happens after a box of 2 when the gun is dirty. With that said it could also be because the gun grease and oil I use is warm and the viscosity is down allowing the bolt to slightly speed up from time to time allowing it to bounce out of battery. Say this it the case you think I need to get a recoil spring?

[kurtm]

I really don't know. I know on Benellis a heavier spring made it worse because it compresses the inertia spring even more. On that.gun, the guy had dremmeled the slot in the carrier so there was no step at all. It closed really smoothly, no hitch at all, but it had a very madining intermittent click. It took me almost a week to find the cause, because he said he hadn't done any thing to the gun except polish a couple rough spots. After that it's the first thing I check for the feeder inertia click!

[Andrew863]

33 minutes ago, kurtm said:

I really don't know. I know on Benellis a heavier spring made it worse because it compresses the inertia spring even more. On that.gun, the guy had dremmeled the slot in the carrier so there was no step at all. It closed really smoothly, no hitch at all, but it had a very madining intermittent click. It took me almost a week to find the cause, because he said he hadn't done any thing to the gun except polish a couple rough spots. After that it's the first thing I check for the feeder inertia click!

Thanks again. I for sure still have that step and havent touched any of that. I have polished the extractor and the ramp on the barrel for the extractor and the carrier that rides on the mag tube but all of that has micro slick other then the extractor. Might try one of the lighter recoil springs from moa. 

[Andrew863]

8 hours ago, kurtm said:

I really don't know. I know on Benellis a heavier spring made it worse because it compresses the inertia spring even more. On that.gun, the guy had dremmeled the slot in the carrier so there was no step at all. It closed really smoothly, no hitch at all, but it had a very madining intermittent click. It took me almost a week to find the cause, because he said he hadn't done any thing to the gun except polish a couple rough spots. After that it's the first thing I check for the feeder inertia click!

Well you hit the nail on the head. Got a super slow mo of it locking and unlocking completely then going back into battery with a tiny bounce and no rotation after that. I think I'm going to order the low power recoil spring maybe. Not really sure what to try. I tried pulling the plastic spacer behind the recoil spring to remove tension and it still bounced about as bad as with it. So I'm not sure what to do. I havent messed with the locking lugs or really anything that should affect this. Might should have sent this thing back when I first got it. 

[kurtm]

I'm thinking new locking pin and carrier, but I'm not a stoeger guy. All I am is a guy who has done a little playing with inertia guns.

[Andrew863]

11 hours ago, kurtm said:

I'm thinking new locking pin and carrier, but I'm not a stoeger guy. All I am is a guy who has done a little playing with inertia guns.

I'm going to have to do some research and see what I come up with. I just dont see how the carrier could be wore out. It's done this from day one unless it was out of spec when I bought it new. I'm going to play with some springs and see if I can figure this out. A complete bolt and carrier online is 150 so atleast they are cheap for a stoeger. 

[kurtm]

I think it's the locking head/locking pin....bolt. I think all the rotation on a Stoeger is done by the bolt head and pin put in the carrier, but I haven't played Stoeger in a long time.

[Andrew863]

6 minutes ago, kurtm said:

I think it's the locking head/locking pin....bolt. I think all the rotation on a Stoeger is done by the bolt head and pin put in the carrier, but I haven't played Stoeger in a long time.

Yea sir that is correct. The locking head( AKA the bolt)  and the locking pin that holds it in the carrier is what controls the rotation. The carrier just holds the pin that makes the locking head rotate. I may give that a shot. U can get a new locking head for 30 and the pin is like 10. For 40 it's worth a shot. I may go ahead and order a inertia spring and recoil spring while I'm at it. One thing nice are parts for these things are super cheap. I bet a a complete Benelli bolt on there was 600. Thanks again u have been a huge help in getting me going in the right direction!

[Andrew863]

1 hour ago, kurtm said:

I think it's the locking head/locking pin....bolt. I think all the rotation on a Stoeger is done by the bolt head and pin put in the carrier, but I haven't played Stoeger in a long time.

So I just talked to a Benelli/Stoger gunsmith. He asked a bunch of questions and finally got him to understand I have checked all the small stuff. Then he said there is a ramp on the barrel for the extractor and there is a groove that the extractor goes in. He said is that groove wore. Well my extractor has not gone in that groove since i have had the gun. I thought that was just extra threads from the barrel extension. He said they will have to cut that grove in the barrel. I'm a tool maker and can do it but the gun is only 3 years old I'm just going to let it go back to them and see what they say. I have never sent a gun back to the factory but i would rather let them do it and maybe they will cover the other parts if it's not. 

[kurtm]

Hmmmmm, was it Carter Miller by chance?

[Andrew863]

1 hour ago, kurtm said:

Hmmmmm, was it Carter Miller by chance?

Pat Cottingham was one and not sure the other guy. Does the Benelli have a groove the the extractor grips when the bolts closes?

[Andrew863]

On 5/28/2020 at 5:30 PM, kurtm said:

Hmmmmm, was it Carter Miller by chance?

Figure i'll toss out a little update. So I went to Uncle Lee's AKA buds guns shop and looked at 10 to 20 Benelli's and Stoeger's and none of them had this cut that the guy on the phone had talked about. He had to have been talking about the ramp that the extractor rides on. He made it sound like the tip of the extractor claw would have a small groove on the ramp to grip but out of several guns none of them had this. So I had a friend of mine that had just purchased a Stoeger P3500. Its insane how close they are to the semi auto version. Anyway I took the bolt head and cam pin out of that and put it in the m3k and it cut the bolt bounce in half. I then used the complete carrier and that made the problem go away at least in slow mo video. The only difference in the pump version is that it didn't have the hole for the bolt handle, so i just locked the bolt back by hand and then dropped it on a loaded round. So I have ordered all the internals other then the action bar, firing pin and trigger group. Surely this will take care of the issue or get me going in the right direction. If this don't take care of the bounce I will try the MOA weight that welds onto the action bar. I wish I could upload some of the slo mo vids to show you the issues and the progress where it is with the pump bolt and carrier. Do these guns have a small amount of bounce all the time? I just cant see how it wouldn't. Wish they had a buffer of some type like a AR.

[AdamM]

I had the same bounce back issue on my m3k. I found the issue to be how sharp the radius on the carrier to the pin was. I also did the slow-mo to see the bounce back. I used a dremmel to smooth it out and now works perfectly. If you work the bolt very slowly by hand, you could feel it hang up a bit at that point. Now it feels smooth when hand cycling very slowly.

On thing that worked temporarily was to use a heavy grease on the carrier and pin. If that fixes the issue for several hundred rounds, you have the same issue. I still use grease instead of oil.

[Andrew863]

1 hour ago, AdamM said:

I had the same bounce back issue on my m3k. I found the issue to be how sharp the radius on the carrier to the pin was. I also did the slow-mo to see the bounce back. I used a dremmel to smooth it out and now works perfectly. If you work the bolt very slowly by hand, you could feel it hang up a bit at that point. Now it feels smooth when hand cycling very slowly.

On thing that worked temporarily was to use a heavy grease on the carrier and pin. If that fixes the issue for several hundred rounds, you have the same issue. I still use grease instead of oil.

So from what I understand removing that shoulder that the cam pin rides in will speed up the carrier and cause more bolt bounce. I have ordered all the internals so I will have a spare to play with. Maybe u can explain what your thinking but it seems backwards to me but I'm all ears. 

[AdamM]

It's just a slight radius on the corner and  then polish.  If you cycle very slowly by hand and it feels like it is sticking when it is trying to rotate where it locks the bolt face into place.  I believe that it gets stuck there and when it does finally make it over-the-hump, that is why it bounce back afterwards.  Try using some grease, like wheel-bearing grease, on the ramp and pin, and see if your issue goes away for a few hundred rounds.  Easy to test before doing any grinding.

[GunCat]

12 hours ago, Andrew863 said:

Figure i'll toss out a little update. So I went to Uncle Lee's AKA buds guns shop and looked at 10 to 20 Benelli's and Stoeger's ........

If you are were at Uncle Lee's in Kentucky you were only one county away from me. I bet we know some of the same people. Give me a shout if you don't get it sorted out and I'll be glad to help.

[Andrew863]

On 6/2/2020 at 6:59 PM, GunCat said:

If you are were at Uncle Lee's in Kentucky you were only one county away from me. I bet we know some of the same people. Give me a shout if you don't get it sorted out and I'll be glad to help.

So where I'm  at now. I have replaced all the internals. Complete bolt and bolt head,  pins and springs. The trigger group and firing pin are the only stock pieces in the gun. Doing a slow mo video it still has a small bolt bounce but from what I can tell they all have some ( correct me if I'm wrong) but the bolt no longer rotates out of battery just has a small bounce. I'm considering adding the weight that moa puts on there carriers to see if that helps and maybe the low recoil spring from them but I dont see that helping me at all. 

[kurtm]

I don't know about all Stogies, but a lot of them do bounce a tiny bit. As long as it doesn't fully unlock your fine. I think you will find that the light springs don't help, and can in some cases hinder. I would no sooner put in a lighter recoil spring in a shotgun than I would soak it in salt water for a year.

[Andrew863]

1 hour ago, kurtm said:

I don't know about all Stogies, but a lot of them do bounce a tiny bit. As long as it doesn't fully unlock your fine. I think you will find that the light springs don't help, and can in some cases hinder. I would no sooner put in a lighter recoil spring in a shotgun than I would soak it in salt water for a year.

Yea the more I thought about it the worse the idea seemed. I did a slow mo video with a 3in slug and it has no bounce at all. So the added weight helped. So I'm thinking about adding the weight on the carrier if I have any more issues. Were having a clay shoot this weekend so I'm going to give it a test. I'll shoot 300-400 rds that will let me know one way or another. Thanks everyone and especially kurtm for all the help. 

[Pistolpete9]

Good info!  Looking forward to your data!  Thanks guys

[GunCat]

Is the magazine tube bushing in place on your gun? It is the first part to go onto the magazine tube when reassembling the recoil spring, bolt, etc - fits between the spring and receiver. I've seen a gun or 2 without the bushing (probably lost in disassemble) and the bolt bounce issue was increased.