Marlin Lever Action misfires- headspace?

[Rickk]

I am starting to get some misfires with a Marlin Guide Gun 45-70. I suspect excessive head space as with a round in the chamber and the lever closed, there is a small amount of movement if I push forward on the back of the bolt.

Am I looking in the right direction for a solution to the misfires? I don't really understand what locks the bolt in place. Surely not the little tip on the lever?

Is there a way to check headspace without buying a guage?

Thank you.
RickK

[docone31]

You have a rimmed case.
Perhaps it is primer or primer depth.
There are also bars on each side of the bolt that lock in place. I think. My 336 had them.
It might be headspace, how much firing has it had?
I wonder if it might not have some crud deep in the bolt also.

[John Taylor]

You can check head space with masking tape. Put a layer on the base of the shell and trim the edge with a file. Keep adding layers till the lever will not close all the way then take a layer off and check the rest with a micrometer. If you can fit more than two layers you got a problem.

[looseprojectile]

First thing that pops into my head is--- how clean is the firing pin bore in the bolt?
Very cold oil and grease will freeze up a firing pin. If you don't know how the bolt locks up you probably haven't taken out the bolt to clean it. Did this just start happening since it got cold?
I would go so far as to advise you to take off the buttstock and wash out the whole action with solvent or hot soapy water. The hammer pivot bolt may be gunked up also. Clean and dry it, blow it out with compressed air and don't oil it till the spring thaw. Hope you get it running. Hope you don't have something broken.

Life is good

[docone31]

Ahhh, the old oil gets thick in the cold trick!
I always used silicone spray rather than gun oil, especially in colder weather.
It can make a difference.

[Rickk]

Ok, I checked the headspace using tape. I don't have any masking tape, but being this is Alaska there is always plenty of duct tape around. Two layers the bolt would close. Three it wouldn't. Three layers measure .008. So I assume the headspace must be around .005-006. Does that sound right?

Actually I have had the bolt out numerous times. No heavy oil ever used. I guess the cold weather dampened my brain as I was unable to see the locking bolt just in front of the trigger until now. No, I saw it, just didn't understand how it worked.

[MtGun44]

I'm sure that the firing pin protrudes much more than .006". I seriously doubt that
headspace is bad enough to cause misfires with a rimmed cartridge.

I'd look at cleaning the firing pin and the hole it runs in, plus there is a portion that
drops out for safety in the rear, make sure it is working properly and coming fully into
position with the lever closed all the way. The lever IS closed all the way, isn't it?

Bill

[Rickk]

mtgun44-Yes, the lever is closing all the way. But the little thingie in the back that, as you say, drops out of the way seems a little "sticky" It appears there is a roll pin that hold the whole thing in the bolt. If I can get it out I will clean the whole shebang real good.
Thanks

[John Taylor]

I have had a few come in with bent levers which keeps the two piece firing pin from lining up, causing miss fires.

[Rickk]

John,
Bent levers? Sideways or so that the action did not close all the way? Do you think my .006 headspace is about right?
I took the firing pin out and gave it a good bath. Didn't seem to bad. However there was a slight burr on what I guess you would call the rear firing pin. It would hang up slightly when pushing it up in place. Used a fine stone gingerly and it works much better now. Shot about 20 rounds this morning with no misfires. Won't feel real good until I do a few more. Thanks for the help everyone.

[phaessler]

Hmmm... so many good suggestions. Have had it happen to me also, in .45-70 too. Marlin 1895 too, found Starline brass to be the culprit, the primer pockets were so deep (0.010-0.012") that light hits were the norm, then a little bit of dirt (i.e. hunting, rain, dust) misfires began to happen. Stack-up of issues, but changed brass just the same.

Pete

[Rickk]

Pete,
Wow, I had been thinking about getting some new brass and was looking at Starline. I wonder if they have made changes by now? My brass is old WW and Rem.

[Bigscot]

How does it shoot factory ammo? Does it still misfire?

I have a Marlin in 35 rem and with handloads I get some misfires. Sometimes I can shoot them again and they will work, sometimes not.

I tried a box of factory and all 20 went bang the 1st time. I think and hope the sizing die may be off. However, some of the brass I had was bought here and was already resized when I loaded them and had the same problem with them.

Bigscot

[JesterGrin_1]

Are your rounds factory rounds or did you reload them? And if so what primer did you use?

Another thing might be that your hammer spring is a bit weak.But that would be an easy fix. All you have to do is find a flat washer that will fit where the spring is and add one washer at a time till it fires fine. You can keep the rifle this way or simply order a new hammer spring.

[John Taylor]

John,
Bent levers? Sideways or so that the action did not close all the way? Do you think my .006 headspace is about right?
I took the firing pin out and gave it a good bath. Didn't seem to bad. However there was a slight burr on what I guess you would call the rear firing pin. It would hang up slightly when pushing it up in place. Used a fine stone gingerly and it works much better now. Shot about 20 rounds this morning with no misfires. Won't feel real good until I do a few more. Thanks for the help everyone.

.006" head space should be no problem. You might try setting the hammer against the firing pin with the lever about 1/2 " down and close it slow. The hammer should push the pin forward a small amount just as the lever reaches the lower tang or a fraction before. This will show that the locking lug is going far enough up to line up the firing pin. If you don't see a forward movement of the firing pin then the lever may have a slight bend.

[Bullshop Junior]

Is the lever closing all the way?? Close the lever and see if you can see light all the way across under it. If you can, then I am probably wrong. If you can not, it means that the lever is hitting the stock or tang before it closes all the way, and that is not allowing the two piece firing pin to work correctly. The lever has tp be closed ALL the way for it to work.

[flhroy]

Rickk how old is the rifle? The reason I ask is I have an older Marlin 39A that was doing the same thing. I thought it was a firing pin thing but for some reason I decided to take off the butt stock. I couldn't believe how dirty it was in there. All of that crud must have really ate up a lot of energy produced by the spring that drives the firing pin because after cleaning it up I haven't had a FTF. Might be something worth taking a look at.

[Rickk]

First, thanks to everyone who took the time to post a response. This forum has been just great and a great help in several areas already.

The problem turned out to be the bent lever as several of you suggested. It was hitting the lower tang before the bolt was all the way closed. Apparently this caused a slight burr on the rear firing pin. After straightening the bolt and stoning the burr off the pin I have not had another misfire.

I did take the butt stock off and everything looked real nice and clean in there. It appears to me that the hammer spring is almost entirely compressed at full-cock to the point it would only handle a very thin shim if any if one wanted to increase the power.

Thanks again. This has been my faithful defender against grizzlies and it was sort of spooky when it didn't go bang!