Marlin 1894 started jamming

[ColinR]

I bought this Marlin 1894SS about 4 years ago. Immediately on receipt it showed signs that the timing was off (Scraping and gouging cartridges during the loading cycle) and was sent back to Edgar Bros who completely rectified the problem - lovely smooth consistent cycling with lead and FMJ, in fact anything I put through it.

Suddenly it is failing to lift the cartridge, jamming the lever at the extreme of its movement with the cartridge jammed between the rear of the carrier and the receiver just above the magazine tube. This appears to be due to cartridge length, but testing it with cartridges loaded with lead bullets that worked fine previously now causes the same fault. I put through a batch of FMJ and they worked flawlessly.

The FMJ's are probably 0.020" shorter than the lead, but neither the FMJ or the lead exceed the length of cartridges that always worked fine.

This rifle has probably only had 2 or 3K rounds through it. Nothing appears worn, it just seems it has become very sensitive to COL and only reliably cycling cartridges with a shorter COL than those used previously. Just to be sure I loaded up some new brass with the lead bullets (from the same Batch) I have always use, seated to the same length (to the crimp groove) and they jam. The cases are under SAAMI length and the OAL is within plus or minus 0.001" to 0.003" of cartridges that previously worked fine with the same bullet from the same batch.

I am at a loss to understand why suddenly this rifle requires shorter cartridges (OAL) to perform correctly. What could have changed? I've had it fully stripped and cleaned and cannot see any wear, but something has changed. Does this ring any bells??

[Sim G]

Known around the "net" as the "Marlin Jam"....

This is where the sharp edge of the cam on the lever, causes camming surface on the cartridge lifter to have a groove worn in to it at the end of the full lever movement forward. Eventually this goove with catch the cam and lock it solid. The fix is relatively easy but requires a certain skill level.

Firstly, radius the front of the snail cam for a fairly broad 60 degree radius. Polish the camming surface of the lifter to remove the groove. Then heat the noise of the lifter till red hot and tap the nose up around 3 thou.

Alternatively, increase the radius of the cam as described, then inlet a harder steel into the lifter, effectively replacing the camming surface which is scored. Some have had great results with jigsaw blades.

Or, radius the cam, replace the lifter. The easiest method in operation, but those carriers are now very, very rare as spares....

[saddler]

My mate does a new carrier on an exchange basis, usually by return of post....

Forgot what he charges but he's done most of Marlins in the club, if not most in Scotland!
ALL the Scottish Gallery Rifle team have his modification done.

PM me for info

[ColinR]

Known around the "net" as the "Marlin Jam"....

This is where the sharp edge of the cam on the lever, causes camming surface on the cartridge lifter to have a groove worn in to it at the end of the full lever movement forward. Eventually this goove with catch the cam and lock it solid. The fix is relatively easy but requires a certain skill level.

Firstly, radius the front of the snail cam for a fairly broad 60 degree radius. Polish the camming surface of the lifter to remove the groove. Then heat the noise of the lifter till red hot and tap the nose up around 3 thou.

Alternatively, increase the radius of the cam as described, then inlet a harder steel into the lifter, effectively replacing the camming surface which is scored. Some have had great results with jigsaw blades.

Or, radius the cam, replace the lifter. The easiest method in operation, but those carriers are now very, very rare as spares....

Thanks for that. I have ordered a carrier from Marlin Spares - they say they have 44 in stock! However, I can see the groove you mention on the carrier and the sharp edge of the cam causing it. I will first try polishing and radiusing and if that fails I'll fit the new carrier. The groove in the carrier seems little more than a surface mark, may be a couple of thou deep if that - presumably the jamming only happens when there is a cartridge on the carrier as it cycles fine when unloaded. It just surprises me that this happened suddenly.
Seems Saddler might have a solution too which I will explore.

[WelshShooter]

Yes, definitely the marlin jam. Mine happened around 350 rounds since I bought it (it was used with an unknown round count too) and all I did was polish out the groove and radius the "snail shape" cam on the lever. I've fired an extra 3,500 rounds since without a reoccurence of the problem. Get some snap caps or if you handload make up some dummy rounds with no powder or primers. Once you've done the polishing, cycle through around 50 dummy rounds to make sure that it's all working fine.

P.S. I too bought a spare carrier from Marlin Spares but it arrived already blued and the one I had wasn't, so there wasn't a good fit. For me it was easier to work on the carrier I had rather than remove the bluing on the spare. At least I have a spare if I need one...

[25Pdr]

I use a small amount of Grease on the offending area on the carrier, it is the type used for constant velocity joints on cars, contains Molybdenum, suppose any type is better than just oil though.

Well over 20K rounds and no sign of wear.

[Chapuis]

P.S. I too bought a spare carrier from Marlin Spares but it arrived already blued and the one I had wasn't, so there wasn't a good fit. For me it was easier to work on the carrier I had rather than remove the bluing on the spare. At least I have a spare if I need one...

I'm curious why remove the bluing? Its only a surface finish microns deep if that.

[WelshShooter]

P.S. I too bought a spare carrier from Marlin Spares but it arrived already blued and the one I had wasn't, so there wasn't a good fit. For me it was easier to work on the carrier I had rather than remove the bluing on the spare. At least I have a spare if I need one...

I'm curious why remove the bluing? Its only a surface finish microns deep if that.

I'll get a picture of it (if I find it!) when I get home. It depends on how it was blued but if I recall correctly the edges of the part looked "rounded" which would imply that the coating was a bit thicker than a few microns.

[ColinR]

It turns out it wasn't the carrier at all although I did radius the cam and polished the camming surface on the carrier, which has resulted in a much smoother action. The problem was the last batch of lead bullets which had an inconsistent length - some as much as 0.020" longer. This does not seem much but I have discovered that the Marlin won't handle cartridges over 1.580" and I was loading to 1.575". 1.590" just won't go! Don't know why this last batch was so inconsistent as they are the same bullets I have used all along in this rifle with no problems. They have a crimp groove and I always load with the brass level with the front edge of the groove and roll crimp. Seems this last batch is longer from the edge of the crimp groove to the tip. Having solved the problem I'm now looking for a lead bullet 158 grain flat point without a crimp groove.

[WelshShooter]

Ah, that's a good point. I use 158gr lead Truncated Cones (or known as Flat Point) and with an overall length of 1.590" these feed fine in my Marlin. Where do you source your lead bullets from? I've had mine from Tim Hannam which have always been good. When my supply runs out I'll try some from shellhouse to see how good these are, the price is quite reasonable however I don't know the price of shipping.