Looking for a little more power from my 450 Marlin. (I never liked that long belt anyway). So the 450 measures .528 at the belt. A .416 Ruger measures .532 at the base. So it should clean up a .450 Marlin chamber.

So if we take a .416 Ruger case, shorten it to the same length as the .450 Marlin, then open it up to 45 caliber we can get a few more grains of powder in there without reducing chamber wall thickness to less than it is now at the front of the belt.

Comments?

But if you are using a Marlin lever gun would the new round be over pressured?

sure --

if you are trying to replace the 458 2" /american/marlin with a beltless version, you will likely gain about 4-6% capacity - which would net 1 to 1.5% gain in vel, at the same pressure in the same basic case design ... 2" straight wall case to 2" straight wall case, no other real changes, that's about what you can expect...

it MAY NOT totally clean up the 450 marlin chamber, but that won't really matter

you would then need to spend about
$250 for a chamber reamer
$200 for a die reamer
$50 for a headspace gage

and then whatever your gunsmithing costs are, for barrel marking, rechambering, dies...

500-700 bucks - meanwhile, you might also go ahead and buy a replacement barrel (or use a replacement OEM barrel/takeoff) to be able to set the gun back to original, if you ever plan to sell it

call that another 100 -- so, 600 to 800 bucks, 1 to 1.5% increase in vel, and you get to be shed of that pesky belt --

btw, if you get anything more vel than 1/4 of the % gain in capacity, you are running at higher pressure , unless you make fundamental changes in case design --- like straight walled to bottlenecked.

of course you should look here first

http://www.b-mriflesandcartridges.com/

Or one could buy a 458WM with a 20 inch barrel.

Tx to all who responded.

1 - I was not planning on loading to higher pressures than the 450 Marlin.

2 - Not sure of the case capacity increase, the Marlin case has much more taper than the Ruger case and so I was hoping to get more than 4-6% increase in capacity.

3 - I was just going to rechamber, rebarreling would significantly raise the cost.

4 - Did talk with B&M about another project, I think all their rounds are based on RUM cases and are too large in diameter for the Marlin lever guns.

i think the max increase you'd see is about 6% - the belted cases are .511 in front of the belt - the ruger should be about .525 or so -- might be as high as .530, assuming near zero taper through the web ... unless you have a shoulder, you would actually have MORE taper to make the "neck" dimension --

though you always have the opportunity for a a ghost shoulder..

i could do a half reamer, i reckon, and save a bit more - but yeah, its not going to be much to fit the tight envelope to work in the marlin

A vote for the B&M
If you get work done to the gun to feed longer carts, you could do the the 2.25" version with 45-70 bullets.

quote:

Originally posted by boom stick:
A vote for the B&M
If you get work done to the gun to feed longer carts, you could do the the 2.25" version with 45-70 bullets.

boomie getting the itch again?

Wildcatting is like herpes. It never goes away... It just goes in remission

quote:

Originally posted by boom stick:
Wildcatting is like herpes. It never goes away... It just goes in remission

Nice!

Here is what I did. Buy a Browning BLR in .450 Marlin. Have the throat lengthened right near .3". This will give you an increase in powder room...AND an action designed to handle over 60K in pressure. The BLR's WSM magazines feed the .450 case very well, although you might have to tweak the feed lips slightly. No, you won't have a .458 Win Mag, but close enough for anything on this continent and most things in Africa.

Boomie,
I'm at a loss on the 2.25" case in the Marlin .45-70 rifles. I thought the Marlin was limited in action length. That is what caused the problem with Marlins and Hornady spritzers. Could you enlighten me?

Not Boomie, But....

Note: we are now talking about a Browning BLR. The BLR is made for 308 length rounds that are 2.8 inches max. The Marlin is made for 45/70 length rounds that are 2.51 inches max.

What we are doing by lengthing the throat over SAMMI spec is getting more powder room

You would use factory dies and brass. In a bolt rifle you would use a standard reamer and head space gauges. Just lengthen the throat with a throater to use the added magazine length.

B&M uses the improved 348 Winchester case for lever action Marlins and Winchester rifles typically in .500 caliber (think the Alaskan cartridge here except with .500 caliber caliber bullets vs .510 for the Alaskan); loaded cartridges are held to 2.55" COAL.

quote:

Originally posted by swarf:
Not Boomie, But....

Note: we are now talking about a Browning BLR. The BLR is made for 308 length rounds that are 2.8 inches max. The Marlin is made for 45/70 length rounds that are 2.51 inches max.

What we are doing by lengthing the throat over SAMMI spec is getting more powder room

You would use factory dies and brass. In a bolt rifle you would use a standard reamer and head space gauges. Just lengthen the throat with a throater to use the added magazine length.

Boomie and prof242 were referencing the Browning BLR short action which does accommodate the 2.8" COAL cartridges. By lengthening the 450 Marlin freebore one is able to seat bullets for a 2.8" COAL vs the SAAMI 2.55" specification.

sjmci,

The limiting factors for you Marlin lever action rifle are:
1) COAL 2.55" maximum
2) PSI <48K
No matter the dart ridge case you potentially adopt you cannot escape the case length and pressure maximums the rifle will safely accommodate.

Understanding the preceding limitations, you have two options to eliminate the belted case. They are:
1) Create your wildcat cartridge as noted by yourself and other commentators. Or,
2) Send your Marlin to SSK Industries and have it re-chambered to the 458 B&M SA.
http://sskindustries.com/
This is a lower pressure RSAUM derivative cartridge designed for use in AR based modern semi-auto rifles. The 458 B&M SA chamber reamer should completely cleanup your 450 Marlin chamber. The 458 B&M SA cartridge case dimensions are not greater than that of the .510 caliber 50 Alaskan or .500 caliber 50 B&M Alaskan cartridge case, and the 458 B&M SA uses the same bolt face dimensions as your 450 Marlin. The cartridge will headspace off the shoulder vs the belt (450 Marlin) or the rim (348 Winchester derivative Alaskan).

Reloading dies should be available from SSK Industries; if not you can check with B&M.

Neither of your options are cheap. That said the 458 B&M SA option will be cheaper as SSK already has the finish reamer and gauges as well as the knowledge and skill to accomplish the work (they have built many 50 Alaskan and 50 B&M Alaskan rifles on the Marlin lever action rifle).

Just something to think about.