38-55 max load in a re-bored Marlin 336

[Deep Six]

I'm loading the NOE copy of the gas-checked Lyman 379449. The book load for 38-55 with this boolit is something like 24-25 gr of IMR 4198 at 28k cup. This load shoots exceptionally well in my rifle but it is very mild. Report and recoil are only a small fraction of what it was as a 30-30 with factory ammo. I'm wondering how much higher I can go with the 336. Obviously the 336 action is plenty strong (I've done the research to see that it is a 45 ksi action). I looked at 375 win book loads but nobody lists the 379449 boolit in a 375 win load. I'm sure some of you have tested this boolit with IMR 4198 and established a consensus limit in a 336 action. I have loaded rounds at 25.5, 26.0, 26.5, and 27.0 gr to work up to and will probably shoot them this weekend. 27.0 gr appears to be 100% powder capacity. Anyone ever gone past 27.0? Also, approximately what velocities am I looking at for this boolit with 25-27 gr of 4198?

[9.3X62AL]

Dunno about going "high velocity" with the 38/55. Not so much because the rifles can't absorb the pressure, but brass might be the limiting factor. I load for my rebored Win 94 at the 1300-1350 FPS level with the Lee 250 grain plain base, and no issues with pistol powders or with RL-7. Moving on with 250 grain gas-checked 250s (Both Lyman #375449 and the RCBS 37-250), 1500-1550 fps was fine using IMR 4198 and RL-7. Bumping things into the 1700-1750 FPS speed zone with RL-7 and both bullets caused loose primer pockets on the cases' first firing. Brass is new Starline bought as the older 2.125" length, then trimmed to 2.080" after consult with barrel guru (JES Reboring). Grooves are .376", bullets sized @ .377", 92/6/2 alloy throughout. Load data was sourced from Ken Water's "Pet Loads" compendium.

[cwheel]

First lets start out saying I think the Marlin action, especially in a newer rifle is quite different than my Winchester 94 that was made in 1917. I need to work within safety limits of this my older rifle with a bore that could be much better, 20" barrel. After spending much time on working up loads for this rifle, I settled on a 265 gr. gas check bullet ( 375296 ) and 29 gr. of 3031 @ 1600 fps. through the chrony. Needed to size bullets to .381 to get acceptable accuracy out of this rifle with a larger bore. Cases were all trimmed @ 2.080. I did try faster loads, but accuracy was best in this rifle @1600 fps. Because this rifle is primarily used for hunting, so there was no point ( for me ) working up target loads for this rifle, although some lower pressure and speed loads could work out to be more accurate. With a 20" barrel, with these loads, I can hold a slightly over 3" group @100 yards even with these old eyes and iron sights. Groups were fired from a cold bore and cooled after 3 shots. Recoil noted with this load was on par with a model 94 in 30:30. At least with my rifle, I don't think I'll be comfortable loading above this level in my older 94, a different rifle, different action, things could be much different.
Chris

[Jedman]

I have a M 336 rebored to 38-55 by JES and my favorite load so far has been 32.5 grs. of IMR 4198 behind a 220 gr. jacketed bullet. It will shoot consistent 3 shot groups of 1.2" @ 100 yards with a 4 X scope. I haven't experimented with cast bullets enough to find what it likes yet.

Jedman

[ben lurkin]

There's no question the action is up to the task as others have pointed out. Regarding the case, it is basically a necked up 30-30 case. The 30-30 is loaded as high as 36k cup. If you look at the starting loads for the 375 Winchester on the Hodgdon.com website, they are all in that same 36k range. Use that as your ceiling for the 38-55. That is what I have done in my model 94 Win. No issues on my end from doing so.

[Catshooter]

I have about 1700 round through my Win 94 (post '64) in 38-55. My Lyman 375449 lubed & checked weighs in at 285 gr. I use 30.0 grains of AA 2230 and that gives me right about 1750 fps. I use Win brass. Twenty six inch barrel. Zero leading. Of course this is my loads, lead, and gun, your results may vary and of course, you need to work up your loads.

I think that I'm not really at the top but I've never gone higher. There's no doubt in my mind that the round has gone off in my seven and a half pound rifle! :)


Cat

[9.3X62AL]

Perhaps I got a lot of "soft" brass from Starline. Don't know. What I DO know is that I will be running the ammo at the 1500-1550 FPS bracket at top end. The 38/55 has been grassing deer and other like-sized or larger game animals for quite a long time with 250 grainers in the 1300 FPS ZIP Code, and 1500 FPS with bullets of that weight won't do the recipients much good at all when cast as a BruceB Soft Point.

[FergusonTO35]

Some people report perfect success using stouter loads in .375 WCF brass in modern (post-WWII) .38-55 rifles as the chamber dimensions are close enough. Likewise, others report that .38-55 ammo works just fine in their .375 rifles. Of course, the manufacturers warn against this practice.

[quail4jake]

I'm really excited to hear that you rebored to .38-55. My first rifle was a Marlin '93 26" half oct. half mag in .38-55 and I want it back! I know case length and bore diameter are variable in the .38-55, what size does JES rebore to? Is there a modern standard for .38-55?

[SSGOldfart]

I'm really excited to hear that you rebored to .38-55. My first rifle was a Marlin '93 26" half oct. half mag in .38-55 and I want it back! I know case length and bore diameter are variable in the .38-55, what size does JES rebore to? Is there a modern standard for .38-55?
Yep andI thank it's called a38-55 Win.

[9.3X62AL]

JES groove diameter in my re-bored 38/55 is .376". "Modern standard" in any caliber is something of a standing joke, really. Gotta slug or pin-gauge EVERY barrel to get a firm answer.

[Deep Six]

Still haven't got around to shooting my work-up loads due to deer season and work. Maybe this weekend.... Also picked up a nice 9.3x57 Husqvarna I made some beginning loads for. I should take both back to the range at the same time....

[Deep Six]

Finally got out shooting today. Tried loads from 25 up to 26.5 gr. All shot nice tight groups and showed no signs of pressure issues. I did check seating new primers on the fired brass and they were a little loose on the 26.5 brass. I also found a book load in Lyman 49 for the 375 win with the 379449 and it shows 25.5 gr IMR 4198 as max, so maybe 26.5 really is too much, even in the longer 38-55 case.

Also shot the 9.3x57. Shoots well but that is a lot of caliber in a very lightweight rifle with a plastic butt plate. Only fired six out of it and my shoulder is still sore.