45 colt to 44-40 in a rifle?

[Jackson Haller]

Hi all,

 Is it possible to rebarrel  or reline a 45 colt  lever action rifle like a Marlin '94 into a 44-40 caliber without having to change out the bolt as well? I'm looking at a Marlin short rifle in 45 colt, but really want it in a caliber that handles black powder well, like 44-40. Already have other lever actions in 44-40, but no Marlin.  I sold off a Century limited Marlin in 44-40 years ago, but really want a Marlin short rifle now.

Thanks!

 

[Tex Jones, SASS 2263]

Not sure, but I don't think you can use the same bolt.  Rim diameter on 45 Colt cartridge is .512" while the rim diameter on a 44-40 is .525".

[Colorado Coffinmaker]

I can't give you a positive yes or no.  However, Uberti Rifles and Winchester Rifles use the same bolt for both cartridges.  My immediate knee jerk reaction is you won't have to change the bolt.  No promises though. I will suggest however, since you are thinking Black Powder, the 45 Colt will run just a clean as a 44-40 IF, that is "IF" YOU ANNEAL your 45 Colt cases.  You will only have to anneal the upper third of the case for a good chamber seal. 

 

If you just "have to have" a Marlin in 44-40, the barrel can certainly be relined and re-chambered to 44-40.

[Boggus Deal #64218]

The bolt face could possibly be opened up. But I bet it would likely work. A barrel blank from Green Mountain should be easy to source. 

[H. K. Uriah, SASS #74619]

Might be easier to just get a rifle already in .44-40.

[Cheyenne Ranger, 48747L]

marlin 1894 44-40 For Sale – Buy marlin 1894 44-40 at GunBroker.com  

[Widder, SASS #59054]

According to my 2nd edition Richard LEE modern reloading book:

 

rim 44-40 is .525

rim .45 colt is .512

44-40 rim is .013 larger

 

case length 44-40 is 1.305

case length .45 colt is 1.285

44-40 case is .020 longer

 

Based on these numbers and having a little understanding of the Marlin 1894 action, you should be able to reline the barrel or get a new barrel, 

AND....... in keeping the firing pin hole center to the bolt and primer, you should be able to open up the bolt face with no discernible difference.....EXCEPT,

if it were me, I would cut off the small tab on the bolt face, but leave the bottom tabs...one on each side of the bolt.

AND, you may have to tweak the spring on the Extractor (weaken it) in order for it to have some slight movement to allow the larger size

rim to fit under it smoothly.

 

NOW, after stating all that, I just tested one of my .45 Colt Marlins by running some dummy rounds and empty brass thru it and it ran perfect.

BUT, my bolt face already has those mods that I listed (removal of the small tab on the bolt face and lightning the Extractor spring).

 

Again, my only concern is ensuring the firing pin is hitting center to your ammo, therefore probably requiring a little opening up the

bolt face just a few .000's

 

EDIT:  test your .45 Marlin with a primer only piece of 44-40 brass and see where your firing pin hits on the primer.

This will tell you more about your bolt face than anything I can suggest.

 

Nice project............. Good luck.

 

..........Widder

 

Edited November 7, 2025 by Widder, SASS #59054

[H. K. Uriah, SASS #74619]

Affordable Marlins are out there.

 

I got this one a couple of months ago for $600.   Yeah, it has no finish left, but it's in mechanically perfect condition.   Keep looking, and you'll find what you need.

 

 

 

[Rye Miles #13621]

2 hours ago, H. K. Uriah, SASS #74619 said:

Might be easier to just get a rifle already in .44-40.

This is the best advice so far! Why complicate your life?

[Cinch]

.0065 is pretty small. You might need to clearance your extractor? Probably not. 
 

You could chuck your 44-40’s in a cordless drill and touch someones emery board to the rim for 2 seconds.

Edited November 8, 2025 by Cinch

[Sedalia Dave]

11 hours ago, Cinch said:

.0065 is pretty small. You might need to clearance your extractor? Probably not. 
 

You could chuck your 44-40’s in a cordless drill and touch someones emery board to the rim for 2 seconds.

 

Please don't do that.  Someone else may end up with one of those cases and it could cause a failure to extract in their rifle.

[Captain Clark]

14 hours ago, Cinch said:

.0065 is pretty small. You might need to clearance your extractor? Probably not. 
 

You could chuck your 44-40’s in a cordless drill and touch someones emery board to the rim for 2 seconds.

Another pitfall of  lost brass matches….

[Jackson Haller]

Well, the 45 colt short rifle turned out to be a Remington made one and I was not willing to take a chance on it, given the quality control problems with them that I've read about.  I think I will try to find a 44-40  (all were JM made) Marlin Cowboy, either 24 inch length or even better, 20 inch.  Yes, needle in haystack, but I'm patient!

[H. K. Uriah, SASS #74619]

Interesting thing happened to me today.   I stopped by the local Cabela's and they had about a dozen used Marlins for sale.   Most were .30-30's, 1 .45-70, and one .44-40.

The .45-70 and one of the .30-30's had the cross bolt safety.   None of these others did.  And the prices were very reasonable.   Now, yeah, only one of them was in a SASS main match caliber, but the point is; haunt your local gun shops.   You'll never know what you will find.

[Jackson Haller]

PM sent H. K. Uriah

Edited November 8, 2025 by Jackson Haller

[Cinch]

On 11/8/2025 at 5:03 AM, Sedalia Dave said:

 

Please don't do that.  Someone else may end up with one of those cases and it could cause a failure to extract in their rifle.

The point is it will work. The difference in case size is not all on one side. Place a 44-40 on top of a .45 and see. 
 

I have experience with this as my buddy and I both had new marlins back in the day. His girlfriend wanted to shoot a stage so went to my gun cart and grabbed my .45. She then loaded 10 rounds of .44 WCF in it and shot the stage. 
 

My buddy realized what happen when picking brass. I grabbed my .45 and shot the next stage. No quivering lip emojis or hand wringing. 
 

When the brass got picked up it had changed. I took a little imperial sizing wax to run them. I won’t tell those with weak knees about the kid firing.270 Weatherby’s in a 300 Weatherby…

[Griff]

20 minutes ago, Cinch said:

The point is it will work. The difference in case size is not all on one side. Place a 44-40 on top of a .45 and see. 
 

I have experience with this as my buddy and I both had new marlins back in the day. His girlfriend wanted to shoot a stage so went to my gun cart and grabbed my .45. She then loaded 10 rounds of .44 WCF in it and shot the stage. 
 

My buddy realized what happen when picking brass. I grabbed my .45 and shot the next stage. No quivering lip emojis or hand wringing. 

That it will work is NOT the point.  Permanently altering your brass is one thing.  But, when that brass may end up in the hands of others, who are ignorant of the changes you made, it will likely cause problems down the road.  No hand-wringing or lip quivering, just plain fact.  Many a .44-40 has been shot thru a 45 Colt with nary a consequence except a fat, non bottle-neck case.  In fact, a number of 45 Colt BP shooters use .44-40 brass in order to have better sealing rifle chambers due the thinner case mouths.  But, you'll find that works better with the more open bolt & chamber design of the toggle link rifles.  Frankly, the bolt will not likely be a problem.  My Ubertis, both '73s & Henry all accept .44-40 ammo in the chamber.  However, the Marlin has a "hood" over the rim area of the receiver that aligns the case with the chamber.  Again, an area that a good machinist should be able to relieve to allow the .44-40 rim to seat properly aligned with the bore.  

 

To the OP, I have an older Marlin, originally a 44 Magnum that I converted to use C45S in, I just tried a .44-40 case in it.  It will close and eject the round, but... closing the bolt fully takes more effort than it does with a properly sized rim.  It wouldn't take much to alter the 45 Colt bolt to accept .44-40 cases with ease.  In measuring my .44-40 Starline case rims I find they run between .520" down to .518".  That falls in the SAAMI spec. of .525"-.010".  My Starline C45S & 45 Colt case rims run between .509"-.507"... again, with the SAAMI spec of .510"-.010".

[Bailey Creek,5759]

Look at VTI Gun Parts.

Purchase a 44-40 Barrel. New bolt. Swapping Barrels is easy to do.

A local smith can do that.

Then if you wanted to change it back to 45 Colt you could. 

Or sell 45 Barrel and Bolt here on SASSS Classifieds.

[Cinch]

4 hours ago, Griff said:

That it will work is NOT the point.  Permanently altering your brass is one thing.  

Working is the point. .0065 is such a small difference one could make the rim smaller in 3 seconds with an emery board. I wouldn’t waste my time. 
 

anyone that fired such brass would never know either. You will never see it from your house.

[Widder, SASS #59054]

Because .0065 is such a small difference AND Marlin never had a reputation for being 'precise' in some of their tolerances,

its possible (actually probable) that the .45 Colt bolt face is already in a 'Go' tolerance for the 44-40.

 

My 'guess' is that once the 44-40 round is chambered and the bolt is closed, the FP will hit correctly to ignite the primer.

 

The 'hood' at the top of the receiver (mentioned by Griff) could present a problem, but as I previously stated with my .45 Marlin, the dummy

44-40 rounds cycled clean and empties ejected strong.   I encountered no cycling issues.

 

Heck, I've encountered greater problems with rifles set up using the proper ammo in them.   

 

..........Widder

 

[Smokin Gator SASS #29736]

26 minutes ago, Widder, SASS #59054 said:

Because .0065 is such a small difference AND Marlin never had a reputation for being 'precise' in some of their tolerances,

its possible (actually probable) that the .45 Colt bolt face is already in a 'Go' tolerance for the 44-40.

 

My 'guess' is that once the 44-40 round is chambered and the bolt is closed, the FP will hit correctly to ignite the primer.

 

The 'hood' at the top of the receiver (mentioned by Griff) could present a problem, but as I previously stated with my .45 Marlin, the dummy

44-40 rounds cycled clean and empties ejected strong.   I encountered no cycling issues.

 

Heck, I've encountered greater problems with rifles set up using the proper ammo in them.   

 

..........Widder

 

 

I'm not even remotely close to being a gunsmith. But just thinking about it I figured that once the 44-40 round was chambered it would have to be centered for a good hit on the primer. Assuming of course that it would cycle through the action in the first place. Just made sense to me.

[Widder, SASS #59054]

47 minutes ago, Smokin Gator SASS #29736 said:

 

I'm not even remotely close to being a gunsmith. But just thinking about it I figured that once the 44-40 round was chambered it would have to be centered for a good hit on the primer. Assuming of course that it would cycle through the action in the first place. Just made sense to me.

 

Good thinking.

And I was thinking the same.   But with all the Marlin's I have worked on, there were a high number where the FP didn't actually hit center

but noticeably off  center a little. 

If we complicate that with a bolt face that might be off, any 'extra' variance (like changing out the barrel to a new caliber and

chamber size) could create inconsistencies on primer ignition.

 

Its just one of those thoughts that go thru my head when I think about certain changes in the Marlin.   My brain tries to figure out

all possible 'positives' and 'negatives'.

I was taught a long time ago that for every action, there will be a reaction.   Sometimes, those actions create a negative reaction.

 

EDIT:  yes, its just a 'guess' of mine that the FP will hit correctly to ignite the primer.

 

Best regards,

 

..........Widder

 

Edited November 9, 2025 by Widder, SASS #59054

[Savvy Jack]

On 11/7/2025 at 1:21 PM, Jackson Haller said:

Hi all,

 Is it possible to rebarrel  or reline a 45 colt  lever action rifle like a Marlin '94 into a 44-40 caliber without having to change out the bolt as well? I'm looking at a Marlin short rifle in 45 colt, but really want it in a caliber that handles black powder well, like 44-40. Already have other lever actions in 44-40, but no Marlin.  I sold off a Century limited Marlin in 44-40 years ago, but really want a Marlin short rifle now.

Thanks!

 

 

It is probably possible, but could still open a whole nother can-o-warms with a Marlin...parts can not be had except by the manufacture. I tried once. I have the last three Marlins I will ever own due to parts availability.

However, the Uberti 73' bolt is used for the 45 Colt, 44 Special, 44-40...and more than likely the 44 Mag option. There is a bolt kit that can be currently purchased. The carrier block is also the same for all...and the 38-40.