It's best to speak with Jesse about what your expectations are for usage. In your rifle, the cartridges are basically twins and Jesse can help you decide the best way to chamber (if there is a difference) and the best barrel stamp. Personally, I think that some folks are more "worried" seeing 38-55 about cartridge performance as compared to the .375. In reality, in your rifle, performance would be the same for any reloader. That's why I'd lean towards .375 with a chamber capable for 38-55.

Good luck 👍 JES did a great conversion for me, changing a new M70 Super Grade from the original .308 to .358.

 

My 375Win model 94 shoots standard length 38-55's just as well as 375's. Some 38-55 bores are 0.379-0.381, needing larger diameter bullets for accuracy. I have 265gr 0.379-0.380 LFNGC lubed bullets shooting in both rifles with no accuracy issues. Chamber it for 38-55 and you can run either cartridge.

 

I have a 375 SC and a 1896 Winchester Hi-Wall in .38-55.
My 375 SC shoots both cartridges equally well. The Hi-Wall doesn't like the .375 too much! Just as well, don't want to stretch that antique Hi-Wall frame!
I bought a bag of brass from a guy once who had me try 29 Gr. of RL7 under a 200 Gr. cast flat nose.
It works in both cases, .375 and .38-55, but I see that it is way under the common RL7 load. I keep that load for the older Hi-Wall.
Health issues are keeping me from shooting the 375 SC much, but I do believe that if I was homeless, that .375 would still be with me. Sweetest shooting rifle of all the Marlins I own!

 

I have multiple 38-55s , one 375, and a 35/30-30(35 Rem bullets in a necked up 30-30 case) which I am sure was done by JES before I got it. In all reality there is very little performance difference between the three. 38-55 cases are available but kinda salty. 375 brass may be difficult to obtain at times but 30-30 brass is literally available for free by picking it up off the ground in a lot of places. The main drawback most cite as a drawback to the 35/30-30 is reloading dies are custom buuuut I use a combination of easily obtained dies to load mine with no ill effects. 357 mag dies to neck size and seat and a Lee factory crimp die to ,,,well crimp. Just a thought.

 

If it were me, I would decide based on availability of ammo/reloading components. My choice has been the 375 Winchester. I have six riles chambered for that cartridge. - T.S.

 

If you go the 375 Winchester route, watch out for Starline brass. It is very thick and you lose a lot of case capacity and velocity. On some loads I was hitting pressure signs 4 gr and 150 fps under max.

I have had two rifles from JES, both converted to 358 Norma Magnum. He does good work.

 

Jess did my Glenfield 30A awhile back and said he would chamber it to shoot either. He asked me how I wanted it caliber stamped and I told him to pick. He stamped it 38-55. I use 375 Starline brass but load cast bullets to 38-55 levels but it will handle any reasonable 375 load. It's a joy to shoot. You won't be disappointed with Jesse's work!

 

Jessie has done 4 356 win conversions and this 38-55 with a 16 1/4” barrel. I am a big fan. Anything he does will be done right and shoot well.

 

My 38-55 model 94(formerly a 30-30) can be loaded hot enough to kick with that steel buttplate.
I run a .377” Lee 250 gr at 1500 fps for hunting, the same bullet around 1200 fps for plinking.
I don’t need to venture into the .375 Winchester territory!
Jessie included some loads to try in the 3 groove .375” bore he did for me.
But I can’t find jacketed flat nose bullets so it’s a moot point.


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May I suggest a rebore to 360 Buckhammer? - TR

 

I thought 35/30 and 360 BH were the same round only now I can buy factory brass if I need to.....Toplot

 

Meee Too..JES rebored my tired mdl 36 30/30 to 38-55 and my '93 SRC to 35/30 Both bought online with described good bores. NOT by my standards! I shoot cast lead in everything from 22 K Hornet to 50/70s but these two from JES are my most accurate lead slingers. Just my 2 cents, the 38-55 looks way more cool on the bbl. On my CFs I try to have any chamber mods stamped in a obscure place and leave the orig alone. Most are just AIs anyway so no problems there.

 

I have a Marlin 375 in (obviously) .375 Win, and shoot 200 grain Sierras over 35 grains of RE7. My buddy has the exact same rifle and shoots nothing but .38-55 with homecast bullets in his. Honestly, i don't see any real difference as long as you pick your shots. I DO suspect he has more overall fun with his due to casting his own bullets, etc

 

I’ve got a 30-30 I’m planning to send down to JES for a rebore to one of these two chambering options. I’ve read everything I can find that Paco Kelly wrote about these two rounds as well as Tim Sundle of Buffalo Bore’s article.
After reading all that, I’m still undecided. I’ll be cutting down the barrel to my preferred 16” length. Whats everyone’s opinions on these two rounds?

I have owned 375 in both a Winchester 94 Big Bore and Ruger No 3. Of the two a would go with 38-55. 375 Ammo is hard to come by and as Tim’s article states you almost the same performance at less pressure and a more readily available around, with guns still being manufactured in that caliber! Ammo and bullets selection are your biggest problems. 200gr SD isn’t optimal and the 255 is spot on but you just can’t push the bullet fast enough to get reliable expansions past 110 yards. 375 was designed for jacketed bullets, and though there is a cast offering I can’t recommend it, more on that later.
Winchester does a run of 375 from time to time in a 200gr then you have Buffalo Bore excellent 255gr round but the is a 100 yard point blank round, if thats what you’re looking for. If you’re using anything but a Ruger No 3 do not use Reeds 220gr. I had that load developed by them and though I specifically told them it was for a 94, the rounds are over pressured for that action. Their 235 gr hard cast OAL is wrong and will not feed in a 94. Reeds 200gr are fine to be fair.
My solution? I got rid of the both 375 and there was a Winchester 1894 manufactured in 1906 with a 26” Octagon barrel with dual aperture tang sights in 32 Win that called me name! With that barrel length I have the 200+yard gun I was looking for with close enough to the same down range performance. Your mileage may vary!

 

35-30 would be my pick … lifetime brass
I have had a 38-55 by Jes … great work … I used 38-55 with increased pressure.. loads ( starting 375 win Loads )
Easy shooter
Shot one Doe with 250gr HC
Worked as advertised

But again the 35-30 would be my pick
With the 360 introduction, should be plenty of bullets

 

Moose ears called it. Most of the original 375’s chambers were cut long enough to handle 38-55. Of I didn’t have a bunch of old 375 brass I would get the longer 38-55. I’m pretty sure star line is selling two lengths of brass for the 38-55 now. I’m pretty sure you want the shorter length if it’s going in a 375 chamber.

 

While my choice would still be the dual chamber with a .375 stamp, I used BB 38-55 to take this Ky buck in 2015. There's virtually no difference when hand loading and even BB could only squeeze 50 FPS more out of the heavy .375 above the older heavy 38-55 that I used in my .375s. The reason I'd opt for the .375 stamp over the 38-55 is because some folks might equate that 38-55 stamp to the pressure/ballistics of an older BP 38-55 and not be aware of the difference that a newer production 38-55 brings.

 

I'd choose the JES 375 Win rebore and barrel stamp, as mentioned above. He did my tired old Glenfield 30A back in 2016 and it's a great rifle. I went with the 3 groove 375 Win and it's a very accurate rifle with 200gr Sierra FN over 35gr H4198.

 

I can't come up with JES on Google. I'd like to contact him. Please identify him more clearly.

 

Here ya go

Home - Reboring by J E S

A WebsiteBuilder Website

35caliber.com

 

try 35caliber.com

 

JES Rifle reboring
WWW.35Caliber.com
541-942-1342

 

I’ve got a 30-30 I’m planning to send down to JES for a rebore to one of these two chambering options. I’ve read everything I can find that Paco Kelly wrote about these two rounds as well as Tim Sundle of Buffalo Bore’s article.
After reading all that, I’m still undecided. I’ll be cutting down the barrel to my preferred 16” length. Whats everyone’s opinions on these two rounds?

Simple, consider your choice of bullet. If cast bullets only, 38-55 can handle all the pressure you need. If jacketed, 375 Win. To get the potential out of a jacketed bullet, you need the thicker 375 brass and higher pressures. You can always tame down the 375 to shoot cast. Not the other way around with the 38-55.

 

Am I missing something here? Do folks here really think that a JES rebore in a modern 336 30-30 has a difference in pressure for reloading? His rebore in a modern rifle with modern steel is virtually the same and merely stamped differently. If someone wants to check the BB site, they will find that the exact same .377 bullet is used in both their heavy 38-55 load AND their .375 load. Folks, in a modern rifle, they are twins. Since the introduction of the .375, chambers have been made to accommodate the 38-55 too. I've owned four Marlin .375s and have run 38-55 thru all of them, including heavy 38-55 from BB.

I've voted twice here already for the common chamber and a stamp of .375 in a modern convert. Why?
Because someone might shy away from a 38-55 stamp, thinking it cannot handle warmer .375 loads. It will/can.

 

That’s a great explanation! Thanks for spelling it out 🙏