35/303 British or .35 Remington rimmed

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rm_rang

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Hey guys

I have a project I’d like to take on but need to work out what’s better or if it’s even possible

I want to take an old martini enfield in .303 British and rechamber/rebore it to either 35/303 or .35 Remington rimmed.

The reason for the choice of these two calibers is that they both utilize .303 cases to I wouldn’t have to change the bolt face, extractor exc just rechamber and rebore.

So from my research these two wildcats exist but I’m not sure how I would go about forming the brass for 35/303? It seems like for the .35 Remington rimmed I would just start by trimming down the .303 case to .35 rem length and feed it into a .35 rem sizing die and trim again after. Once it’s fire formed it would be all set.

This seems like more work than the .35/303 might be but I can’t find any dies specifically for this caliber. The best I can find says I need to use a combination of dies to achieve the 35/303 and that would be much more work after all than .35 Remington rimmed.

In both cases it sounds like I could utilize .35 rem load data

If you guys have any experience in this please let me know your thoughts or advice

Thanks!
 
Depends which 35/303 you decide to go with but the one I had dealings with you just expanded the neck up to 35 and ran it into the 35/303 FL die. The shoulder will expand on first firing. Case was given a minor trim. I used a tapered expander I made on my lathe. The case is rimmed so you don’t have to worry about forming a shoulder for the case to headspace on. The 35/303 makes more since to me. Actually less work. 35 rimmed you cut your cases, form them and trim. Your going to ream chamber and associated work which is about the same. 35/303 gets my vote.
 
I am doing that "change" on a different set of cases, but same process - using advice from this website and other places. I am starting with an 8x57 case. I use a series of expanders and eventually get it to nearly "straight walled". Then start re-sizing it in a 9.3x57 die - size it, try in the rifle, turn in the die a bit, try again, repeat until the case just so allows the bolt to close snugly. It is relying on the newly formed "false shoulder" to hold it tightly in the chamber with minimum end play. The first full power firing will blow the case shoulder out to fully match the existing chamber. From then on, a matter of gently "touching" that new shoulder when re-sizing, to ensure there is minimal end play. You could use the same process on your project - ignore that rim - use the snug fit of the case within the chamber to handle "head space". I do not have GO or NOGO gauges for a 9.3x57, nor do I really care about that number - this process is creating brass that snugly fit into this chamber. The down side is that I have no way of knowing how this rifle will work with factory 9.3x57 ammo, if such a thing exists, nor is there any assurance that my ammo will fit into another 9.3x57, or if their ammo will fit into my rifle. Not a concern for me.

As far as finding a sizing die - I have never had it done, but would suspect that whomever can re-bore and re-rifle your barrel, and then cut a new chamber, could use that same chambering reamer to cut you a sizing die? Die would have to be externally threaded, etc., need to figure out expander ball, etc. but that is always a possibility? Goes to the issue of any non-standard chambering - how would you know that a "store bought" sizing die is the same dimensions as the chambering reamer used in your rifle? - So far as I know, there is nothing similar to SAAMI standards to tell the reamer maker or the die maker what sizes or angles to use on their product?
 
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I'd go .338-.303 Ken Waters did that to a Westley Richards slant magazine 98 mauser that was shot out. C+H will make a set of dies if it is not already in stock.
 
As long as the bore is greater than 8.3mm land to land it would work for my purposes.
Who is c+h or ken waters? Would they be able to do the work to the rifle as well as supply the dies for the .338/303 conversion?
 
All Ken Waters loads that worked in his guns worked likewise in mine and saved a pile of time and wasted components.
 
The .35 Winchester is new on my radar. Would the case dimensions allow for it to be rechambered from .303 British? Or is it quite literally the same dimensions with the exception of the neck/throat?
 
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rm_rang said:
Hey guys
I have a project I’d like to take on but need to work out what’s better or if it’s even possible.
I want to take an old martini enfield in .303 British and rechamber/rebore it to either 35/303 or .35 Remington rimmed.
The reason for the choice of these two calibers is that they both utilize .303 cases to I wouldn’t have to change the bolt face, extractor exc just rechamber and rebore.

Not to be picky, but I'm still trying to figure out where the bolt face would be in a Martini Enfield action ??
Or maybe that should have read Lee Enfield ??
Click to expand...
 
Might there be a problem if a .303 martini barrel were rebored to .35 and the chamber neck and leade reamed up? The balance of the .303 chamber and headspace would remain the same, for better or for worse.
 
That's how my friend, Duncan's, 35-303 Br was done.

A6EA74D1-02E7-4B6A-AD28-26BF25125545.jpg

Start with an oversize and corroded bore, send it to the Man, then shorten the barrel to 20 inches, reinstall the front sight, add a cheap plastic stock, load 250 Speers over IMR3031, and go hunting with your handy sows-ear carbine thumper.

It feeds like a fat boy at a buffet, and is drilled and tapped for a scope, but he prefers to use it as you see it.

There are a couple of 375-303s up here as well.

Ted
 

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I'm not sure of your intended purpose of this venture is. Is it for hunting? what game? Range?

IMHO the 35 Rem Rimmed would be a good choice, lots of Contenders in 35 Rem were converted to rimmed to solve the headspace issues. If your rifle is mostly or entirely for shooting cast, no need to go to any bigger case. I had a Martini in 303 Br that shot fantastic, but wasn't stocked for me and I sold it. I like the 303 Br cartridge, lots of history and a pretty versatile round. Boring is somewhat cheaper than rebarreling, but if the caliber you end up with is not something you like, you won't be happy. I've had a few custom rifles made and some I sold after firing less than a box of ammo, just didn't like them. A 35 Rem should recoil much like a 303 Br, a 35-303 (a fairly common wildcat) will recoil a bit more. I'd avoid a 35 Winchester, a very good caliber, but the brass is longer than 303 Br or 30-40 Krag, so not cheap or easy to get. You could go to a shorter necked version and use 30-40 brass

Going the 35 Rem Rimmed will require setting the barrel back, another expense to consider.

If you want big, why not a 405 Winchester.

It would be nice if you posted a picture of you rifle, sometimes the rifle will have a "look" that will be the best fit. Bottom line it has to something that you'd like and shoot. The nicest conversion I saw was in Ruger #1, a 375 Rimmless Nitro Express (AKA the 9.5x57MS, 9.5x56MS or 9.5x56.5MS). Of course the #1 does not need a rimmed cartridge.

I don't know the outside diameter of your barrel, but that may dictate how big a bore you want.

Interesting project, and looking forward to seeing some pictures.

Nitro
 
Thanks for all the info guys!

I actually haven’t got the rifle yet. I wanted to do some research and get some info before I start investing.

Now that you have said 35/303 is fairly common it makes me wonder why I can’t find any chamber reamers or does for that wild cat. That would probably be the easiest way to go by the sounds of it.
 
Might be possible to find a 'smith with a reamer.
You may need to special order a reamer.
If the original .303 chamber is to be retained, the neck and throat area will need to be reamed up for .35. A reamer to do this job would look not unlike a pistol caliber reamer.
If a complete fresh chamber is to be cut, then a reamer capable of cutting all parts of the chamber would be needed.
If you compare cartridge cases fired in a military .303 chamber with those fired in a SAAMI spec chamber, the difference is noteworthy.
It might be an idea to call Manson, and explain what you want to do.
 
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