336 rebarrel thoughts

[Tiswell]

My first post here. Hello from Maryland. Some counties in our state have gone to allowing straight walled cartridges. I had an old and ugly 336 in 30-30. I sent it away and had it rebored to 375 Winchester. Out of 5 shots, 3 to 4 of them will group in about 2 inches and then it throws one or two well out of the group. Both with reloads and Buffalo Bore 38-55 loads. The smith said it will chamber and shoot both 375 and 38-55. The dispersion is predominately vertical and can be 5 to 8 inches from the group high or low. I have tried two different scopes, a Vortex and a Leupold, rechecked scope base and rings screws for tightness. At this point I have removed the forend and magazine tube and plan to shoot it naked while resting on the action and see what happens. If it is still squirrelly I plan to firelap it.

Any thoughts or similar experiences that you figured out? Any one know a qualified lever action smith that will tackle a rebarrel? It seems like some of the long time levergun smiths have retired.

Thanks, Bill

[JimB..]

I had John Taylor, who is a user on this forum, rebarrel an 1894 for me. Work looks great, screwed up my back so haven’t been able to shoot it yet. Wait time was about 5 months as I recall.

[725]

With a vertical string, try adjusting your powder load. Probably go lower if you are shooting .375 Win level loads. If you groups had been a horizontal string, I would have suggested varying the C.O.A.L., but vertical strings have usually meant powder for me. YMMV. Good luck.

[pietro]

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Welcome to the board, and have a great Holiday season !

[magnumuser]

No offenses here, but my head is scratching really hard trying to figure out how this re bore job was actually done..

30-30 has about 22,000 CUP LESS chamber pressure then .375 winchester. And the reciever/frame of a 338 should not have enough metal in it to be safe..... And just found several articles on the 375 winchester that state you cannot fire 38-55 in the .375 winchester because 38-55 is LONGER case length.

[John Taylor]

The 38-55 is slightly longer. The 375 is a little fatter from the thicker brass. The 375 will chamber in a 38-55 chamber in most cases but may have a higher than normal pressure because the chamber is smaller in diameter where the bullet is. Also the 375 ( 55,000 ) is loaded much hotter than the 38-55 ( 30,000 ).

[Moleman-]

No offenses here, but my head is scratching really hard trying to figure out how this re bore job was actually done..

30-30 has about 22,000 CUP LESS chamber pressure then .375 winchester. And the reciever/frame of a 338 should not have enough metal in it to be safe..... And just found several articles on the 375 winchester that state you cannot fire 38-55 in the .375 winchester because 38-55 is LONGER case length.

The 336 was offered in 375 Win from the factory. Assuming it's to SAAMI specs, if you compare at the SAAMI specs for 375Win and 38-55 you will see that they went with an unusually long chamber on the 375 Win. Long enough to accept a standard length 38-55.

[Tiswell]

Magnumuser,
As I understand it, the action should be strong enough. As Moleman stated, 375 win was offered in a 336. The 336 375's that I have seen in images appear to have the larger diameter barrel and correspondingly bulkier forend like the 444 and 45-70. I have a 444 and although I like it very much, when you pick up the rebored 30-30 it feels like a totally different gun, much more agile in the hand. Although the gun does not posses an attractive finish,it is more appealing to my eye with the full length mag tube. The rebore guy says it is safe to shoot 375's out of the rebored 30-30 barrel. The barrel was remarked by him to 375WIN and he has done more than a few of these. Having said all of that, I am a reloader and don't plan to push it anywhere near the limit for 375.

[FergusonTO35]

Are you using .38-55 or .375 data? I would start with basic .38-55 data and slowly work your way up. Every gun I own is way more accurate with a charges somewhat lighter than the norm, including my .45-70, two .308's, and all five of my .30-30's. 'Nother thing: how warm is your barrel getting? Some rifles simply will not tolerate a hot or even warm barrel, my dad's Browning BLR is like that. May want to try firing a three shot group and then let it cool all the way down, as in not even slightly warm, and see what happens. If a rifle will produce a nice three shot group starting with a cold barrel that is all I require personally.

[Dan Cash]

Vertical stringing is caused by either a non uniform ignition/burn rate of propellant or physical pressure on the barrel. 336 rifles which I have had occasion to work with have, in a few cases shown the magazine tube to be pressing on the barrel in the chamber area.

Remove the forend and reattach the magazine tube. Observe if the tube is contacting the barrel in the first few inches forward of the receiver. The 336 barrel is relieved in this area to allow the barrel to clear the magazine tube. In some cases, the reliefe cut lis not sufficient to clear. If your gun is binding, remove a sufficient amount of metal from the barrel to alow a sheet of typing paper to pass freely between barrel and magazine tube when the tube is installed.

While the forend and magazine tube are removed, you might fire a few rounds from a rest. If the ammo is good, you may be amazed how accurate the rifle is.

[Nobade]

I used to have a 336 rebored to 38-55 that would do exactly that. I used it for cowboy long range silhouette matches and it was pretty entertaining on the rams because as it heated up the aim point had to change for every shot. I got pretty good at predicting where to hold but eventually sold it off. My theory is, there is a great deal of residual stress in those factory barrels. By making it as thin as that rebore does, it allows the barrel to warp when it gets hot, enough to really notice. Couple that with being a levergun with a forend and a magazine tube hanging off the bottom to bind things up and you get what you are seeing. I tested that rifle quite a bit to verify this, and it was quite repeatable. Start shooting with it cold and it went right where it was aimed. Maintain a steady rate of fire and every shot was higher. Let it sit and cool off and it went back to POA. It grouped great as long as you didn't let it get hot. This convinced me that at least for a competition rifle I will use a new barrel blank if I want to turn a 30-30 into a 38-55. It would be just fine for a hunting gun, since you don't typically shoot groups on the side of a deer.

As an aside, I have tried making octagon barrels from factory Remington 700 heavy barrels. You would not believe how much they will bend and twist up as they are cut. The residual stress in factory made button rifled barrels is considerable. Just fluting them is sometimes bad enough. I won't do that any more either.

[Tiswell]

Thanks to all that replied! Dan Cash, all good points and my barrel was every so slightly under rotated. I was able to turn it a degree or two to get the magazine tube clearance in better alignment and now the rear sight dovetail is parallel with the top of the receiver as well. As previously mentioned I tried the Buffalo bore 38-55 ammo and some reloads. My reloads used a reasonable charge of charge of AA 1680 which should have had a 180 grain bullet doing 2300 fps, but I didn't chrono shots thus far. Going forward I will chrono all shots just to have more info to bring to bear to try to figure this out. Thanks again to all and Merry Christmas!

[Shawlerbrook]

Welcome ! Dan Cash gave some great advice and the Marlin 336 can handle both the 375 and 38 55.

[john.k]

There is a utube of Marlin 336 actions being made ,and the reciever is heated bright red hot by some open process ,that didnt seem to have the expected induction coils ,and IMHO may have been a resistance process .......anyhoo,the point is there was no quench ,so it appears the reciever is made of an air hardening alloy steel....The extreme thin-ness of the barrel tenon with 45-70 and the belted 45s do indicate some very high strength alloy steel used.

[RickinTN]

I would suggest trying some loads at standard 38-55 levels to see if the problem goes away. I have a feeling you are pushing things a bit.
Rick

[Tripplebeards]

If theses groups are with cast boolits. I’d tell you to switch over to a lee factory collet crimp die. Sounds like my first go with cast when I first started out. I was shooting 100 yard groups the size of pie plates with fliers. I changed my crimp from roll crimping to a nice tight, even, seal that I applied with a lee collet crimp and the same “pie plate group” ladder testing went from “pie plate groups” down to the largest group 1.75” all the way down to sub MOA.

[farmbif]

dont know what powder op is using but my best powders for the 375 win are 1680, imr4198 and reloder7.
I have a marlin 375 and I cant tell the receiver apart from a 336 30-30. it's definitely not the larger stronger 1895 receiver.
have you tried different weight bullets and working loads up with different powders?

[John Taylor]

The 38-55 brass is 2.1295" long but some are 2.085". The 375 is 2.020" long. I have the chamber reamers for the original 38-55 and the 375.

[Bigslug]

Try filling the gap between the barrel and mag tube with pliable-when-gasket material, then bed the forend/barrel and forend/receiver contacts. Sounds like you've got something that's not settling identically shot to shot. Short of one of the "tactical" tubular handguards, you can't free-float it like a bolt gun, so try to lock it down.

[Tripplebeards]

I load my 35 Remington long enough that the boolit contacts the microgrooves when I chamber it. You can see the grooves on the cartridge I chambered. The barrel slugged at .357 and I size at .3595. That’s an example of a light crimp with with the Lee collet factory crimp die as well.



When I first started loading for it I had a few rounds that I didn’t fire. Light primer strikes. They all went off in the second try. I figured it was one of two things. Either my primers weren’t seated deep enough or my shoulders were bumped back to far allowing my case to shift forward when the firing pin hit the primer. I bought a RCBS hand primer tool to make sure they all were seated deep and a hornady case comparator. After measuring the shoulders on my fired cases I adjusted my FL sizing die to bump the shoulders back .002”’s. I also stretched my spring that the lever catch sits on. It seemed like my lever wasn’t locking closed. I also polished my trigger group and got it down to a hair over 3 pounds. Closer to 3.5 if I remember. After doing all those things I have had zero fail to fires to date and a ridiculous increase in accuracy as you can see in avatar. The accuracy with cast boolits is just as good as my target guns with jacketed ammo at 100 yards. It still shoots MOA at 200 yards. My local range only goes to 200 yards or I would have tested my group sizes out to as far as the next county even though I can’t shoot past a 150 yards in my woods. Maybe your already doing all of the above steps. If not give them a try. I won’t waste my time loading any cast boolits if I’m not using a lee factory crimp die. I just can’t get any type of what would consider acceptable accuracy (sub MOA) past 25 yards without using that particular crimp.


Eventually I’ll find a 375 win JM some day and have fun casting up some loads for it.