Marlin 1894 started jamming

[ColinR]

Since I bought the Marlin four years ago I have always used GM Hardcast 158 grain truncated cone which have always fed perfectly through this rifle but for some reason the last box are jamming up as they make the cartridge too long - all + 1.590" to 1.605" COL which just won't go through this gun. I load tight to the crimp groove. I thought the cases might have stretched but they are all 1.280" or v close thereabouts. I even tried some brand new Magtech cases (all at 1.280") but still they come out too long. Seems the bullet dimensions have changed because nothing in the loading procedure has. I just loaded up a batch to 1.575" which means the case is further up the bullet and does not crimp into the bullet crimp groove. I'm now putting a light taper crimp on them instead - they load and shoot fine but I would prefer to have a bullet of the right length so I can go back to roll crimping into the proper crimp groove. I am loathe to try GM again and given the sensitivity of this rifle to COL I'll need some samples before buying a batch of anything new.

When I have the time I'll strip the rifle down again to see if there is any obstruction that can be relieved around the exit of the magazine tube, I'll also look to see if it is possible to relieve the carrier where the base of the cartridge locates. I have looked at and tried every loading procedure and it is now v clear that the GM bullets have changed in some inexplicable way.

[ColinR]

Shellhouse are very kindly sending me some samples of their 158 grain flat point, so it will be good to see how they compare. More expensive than GM but if they are more consistent that will be a bonus.

[WelshShooter]

Shellhouse are very kindly sending me some samples of their 158 grain flat point, so it will be good to see how they compare. More expensive than GM but if they are more consistent that will be a bonus.

Very nice! Please update this thread with your findings and how they work for you. I'd really appreciate it as I'm looking to buy some of these when my current supply runs out.

[Daryll]

Like ColinR I've also always used the GM Hardcast 158 grain truncated cone, with no problems, but a few weeks ago I wanted to make up some ammo for a club comp, so went all out to make it as accurate as possible, to the extent of weighing the bullets for the first time... the result was a surprise....!!

For 158gn bullets, they ranged from 155 to 160gn... I expected (maybe unrealistically?) them to be a lot more consistent than that.

So assuming they're the same diameter, (swaged?) but different weights, their lengths must vary..?

[WelshShooter]

Daryll, if they are cast then I suppose cutting the "sprue" differently might make the difference in mass. 5gr is 0.323 gram so cutting the sprue differently each time could be the cause for this. I've never cast so please point me out if correct.

Also, with flat points you shouldn't get any deviation in overall length if you use the correct seating stem. I have a seat stem with a flat top that gives very repeatable overall lengths, I imagine if you are using a tapered stem then any "extra height" in a flat point bullet will account for an additional overall length.

[ColinR]

This Marlin is really sensitive to COL and in the past GN truncated cone have worked flawlessly. The last batch were just a few thou too long. Consensus amongst .357 Marlin gallery shooters is a COL of max 1.580" in a magnum case of 1.280". GM bullets are now loading to 1.600" when loaded tight to the front of the crimp groove.

Shellhouse bullets have been extremely helpful and sent me a sample batch of both their 158 grain RNFP and Truncated cone FP. The TCFP loaded to >1.600" and would not cycle while the RNFP loaded to 1.550" and worked perfectly, Now I prefer the TCFP to the RNFP, but I am unprepared to trim the cases by >0.020" or seat the bullets deeper beyond the crimp groove so I have to taper crimp.

I cannot be the only one with this problem, but it seems the bullet manufacturers are unaware/ignoring the problem. If Shellhouse or GM would produce a TCFP with the crimp groove moved slightly forward by 0.020" the problem would be solved for all these tight Marlins. PPU 158 grain FMJ TCFP with crimp groove load perfectly to 1.580" and function flawlessly

When I have time I will strip it down and see if I can slightly relieve the receiver above the mag tube exit (where the bullet jams) and failing that remove a little metal from the carrier where the cartridge rim locates to v slightly increase the length of the cartridge it can accommodate. So much easier if the bullet manufacturers would take this problem on board.

[ColinR]

Like ColinR I've also always used the GM Hardcast 158 grain truncated cone, with no problems, but a few weeks ago I wanted to make up some ammo for a club comp, so went all out to make it as accurate as possible, to the extent of weighing the bullets for the first time... the result was a surprise....!!

For 158gn bullets, they ranged from 155 to 160gn... I expected (maybe unrealistically?) them to be a lot more consistent than that.

So assuming they're the same diameter, (swaged?) but different weights, their lengths must vary..?

Daryll - I just weighed the batch of TCFP sent by Shellhouse. They all weigh heavy from 159.5 grain to 160.6 grain, but clearly are more consistent than you found with GM - GM you say vary by 5 grains while the 25 samples from Shellhouse only vary by just over 1 grain. I have asked Shellhouse if they would consider making a 158 grain TCFP with the crimp groove moved forward towards the tip of the bullet by 0.020" which it seems will solve the problems in many .357 Marlins that can only load at a COL of 1.580" or thereabouts. Currently the Shellhouse TCFP load to >1.600" COL which consistently jam. You would not think that 0.020" would make that much difference, but it is the difference between working 100% reliably and not working at all.

[Sim G]

Why are you not just loading to COL anyway, despite where the cannelure is? With even commercial hard cast bullets, a suitable roll crimp can be applied anywhere on the shank of the bullet, it is not a necessity to crimp in the groove, but as you've found, COL is critical with some Marlins.

[ColinR]

Sim I was always of the opinion that if there was a dedicated crimp groove you used that for a roll crimp and anywhere else was a taper crimp, but you suggest otherwise, which would solve my problem. Is a roll crimp in these circumstances still better than a taper crimp?

[Sim G]

No, you don't have to rely on the crimp groove. I've roll crimped many a cast bullet well below the groove when I was loading .38 special for one of my Marlins as the COL had to make magnum length. Likewise, I've used factory produced cast bullets for completely different cartridges and there's no way a manufacturer can offer something so precise as different postponed grooves for different cartridge combinations.

I've even used a Lee factory crimp die to crimp jacketed bullets without a cannelure as that particular die forms the cannelure as well.

Taper crimping is for semi auto pistols that head space on the case mouth.

Rolled crimped below the groove isn't as pretty though, but crimped above the groove they look no different.