Marlin Pump Question

[TommyKid]

I recently purchased some 2.5" low pressure RST shells to shoot out of my Model 21. This gun is a recent purchase and this was the first time I was going to fire it. I had previously used a snap cap in the gun to check some of the functionality prior to purchase and everything seemed fine. The bolt would not lock with the RST shells, however. As this happened today, I have yet to try any other low pressure shells in the gun. I was curious to see if anyone else has had a problem like this and exactly what ammo you use in your Marlin pump. I'm not sure if the issue is the gun or the choice of ammo.
Thanks,
Tom

[Jim Susemihl]

After reading your question I was in my local gun shop and they had some RST 2.5" 16ga shells in stock so I bought a box to try their function in one of my 16ga Marlin pumps. They functioned as well as the 2.75" shells. I have not shot them but they do feed through the action just fine. I'll try some 12ga shells if they get some in and let you know how they do.
Regards, Jim

[TommyKid]

Jim,
Thanks for the reply. Yeah, I figured it must be something wrong with the gun. I tried to see if some Federal 2 3/4 shells would lock up in the gun and they did not. Unfortunately, my go-to gunsmith took one look at the gun and told me he would never touch another Marlin pump as he said they are just a nightmare to work on. He said there are too many small parts and he doesn't like working on them. To each his own, I guess.
Best regards,
Tom

Anyone else have any ideas??

[Jim Susemihl]

Tom, I was at the gun store on Saturday and they did have some 2.5" 12ga shells so I bought some to try in my 12ga guns. They also functioned well. My guess is that your shell stop is not holding the shells as it should. Have you taken the gun apart and given it a really good cleaning and lubing? I do this with every one of mine. I currently have 13 Marlin pumps and all but a couple function as they should and pass all of the safety checks as required. I understand what you say about a gunsmith who will not work on a Marlin. They are less complicated than many of the current guns and are way less complicated than a Wrenchchester 1897 and most gunsmiths don't mind working on them. I think it is the legal thing about working on a shotgun that the manufacturer has said are unsafe to shoot. If you have a copy of Marauder's instructions for taking a Marlin hammer pump apart and for checking the safety features, and if you have any gunsmithing savy at all, you can take one apart, clean it, and reassemble it and make it function. I do not have the web site for him saved any more but I am sure that someone on this site can tell you how to find him. I printed his instructions a few years ago and they stay at my work bench all the time now. There are things to look for like some of the spring loaded plungers that help control the action of some parts as well as the tension of some of the small springs that also control the function of parts. In particular are the recoil safety lock for the bolt and the safety sear that will not let the hammer drop if the gun is not locked up fully. I have had to replace springs on these parts to get things working properly. My idea is that if you are going to work with one of these guns you should understand what every part in it does and be able to make sure that it does what it is supposed to do. That is the only way to be safe if you ever want to shoot it. I hope this helps and if you have any other concerns I'll see if I can answer them. If not, I'll go take one of my guns apart and see if I can figure it out.
Regards, Jim

[TommyKid]

Jim,
I have not taken the gun apart as of yet. I did read and print out Marauder's instructions, though. That's how I was able to check the safety features of the gun prior to purchase. I was planning on taking on this project over the spring/summer. I was really hoping that my gunsmith would take on the project as I have to admit being a bit apprehensive about diving into it on my own. Regardless, I should be able to work on it myself, so I will carefully follow Marauder's instructions and take it slowly. I greatly appreciate your input.
Best regards,
Tom