.41 Magnum bullets in a 10mm

[my_old_glock]

I wanted to see if resized .41 magnum bullets could be used in a 10mm cartridge. The reason is because a 41 magnum bullet is designed for higher velocities than 40S&W bullets, and they are available in heavier weights than regular 10mm/40S&W. I also have 3 bullet molds in 41 magnum. I do not remember what powder I used. Velocities are low, but oddly these felt like what I thought a 10mm should feel like. The regular 10mm 1200fps 155 XTP felt like a 40S&W. I used a Lee .401 bullet sizer. The only thing to note was that the bases of the resized bullet were not flat or even. They were slightly irregular because of the lead being forced from the sides to the base during resizing. This defect would probably reduce accuracy to some degree, but I doubt it would make a significant difference in a normal off the shelf gun. Remington makes jacketed soft point .41 magnum bullet that (I think) would be great for bear defense.

Picture below shows (from left to right):
1) Lee 210gr TL-SWC
2) Remington JHP
3) Lyman 215gr SWC
4) Lee 195gr SWC
5) Hornady 155 XTP (for size comparison)

I had to use 40S&W brass because I didn't have any 10mm brass.

Unsized bullets shown on top. Resized bullets in case. You can see the bands became longer after resizing.



Target distance was 10 yards. Gun shot from a bench/bag rest.

I only had 3 of the LEE 195 SWC to shoot. All others were 6 shots.

[The_Shadow]

Thanks for the report.  Very nicely done! 
I'd be willing to bet they would be more accurate if loaded in the 10mm cases...

What and how much powder were in your loads?

[my_old_glock]

Thanks for the report.  Very nicely done! 
I'd be willing to bet they would be more accurate if loaded in the 10mm cases...

What and how much powder were in your loads?

I do not remember which powder I used, or how much. I know they were all loaded with the same powder. I saved one to disassemble, so I should be able to find the powder weight at least.



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[sqlbullet]

You could avoid the issue of the base deforming if you used a nose punch and pushed through the lee die base first.  Might have to rigg it a little to get a nose punch set up, but should work.  I used to run my 175 grain SWC through base first with just the flat punch.

[gandog56]

.40 cal cases will not work in any of my 10mm guns. At least I think they wouldn't. Also, how do you even chamber a bullet with a diameter of .410" in a .400" chamber?

[sqlbullet]

.40 cal cases will not work in any of my 10mm guns. At least I think they wouldn't. Also, how do you even chamber a bullet with a diameter of .410" in a .400" chamber?

As he said in his original post, he runs the bullet through a .401" bullet sizing die.  So he ends up with a .401 diameter bullet that is the same size as any cast bullet.  Reduce 10% and work up.

[tommac919]

.40 cal cases will not work in any of my 10mm guns. At least I think they wouldn't.

As a test, I ran a box of 40sw thru my glock 20 all stock.... works fine.  But I don't think its a good idea on a reg basis as the 40sw is held by the extractor I believe. Easy to get a 40 barrel.

[The_Shadow]

The thing about the 10mm auto design is, they set the OAL at 1.2500" - 1.2600".  This was done to keep the grip shorter, in relation to the magazine well and magazine as a whole.  More to fit as many hands as possible.

The 41 Mag bullets being resized, still allows for the heavier weight bullets, but the OAL places more bullet inside the casing.

The Wide Flat Nose configuration in 200gr, 220gr, 230gr, was an attempt to have as much bullet weight up front in the effort to allow more space for the powder inside the casing without increasing the pressures drastically.

What was being noticed though was the wide nose increased the length of the tipping angle and jams occurred in some firearms.  Then some makers started to shorten the OAL to about the 1.2420" for reliable function, that increased the pressures and then powder charge weights were reduced to compensate.

Just as the FMJ and TMJ is the most compact design for the 10mm, they made the Hollow Points, which made the bullets longer in equal weights which take up the space for the powder.

The 10mm guys have played with the fudge factor of the OAL's, trying for the optimum maximum performance.  The best thing to happen was newer powders that provided safer performance and pressures.

When you look at the 9mm, 45ACP and the 40S&W OAL's the bullets are sticking out further buy their design. allowing the use of more powder in the space of the respective cartridges.

[sqlbullet]

It is funny...I have one 10mm gun that is sensitive to this.  My Para P16.

And it doesn't have to do with the OAL as much as how far past the case mouth but bullet body extends.  SWC designs have to be loaded with the shoulder right at the case mouth, maybe .050" beyond max.  That translates to COAL of 1.250" max or jam-o-matic.

But my 205 grain mountain mold  can be loaded all the way to 1.260+".  As long as it fits the magazine, it feed fine.  But the ogive on that bullet starts right at the case mouth.  Hollowpoint bullet designs vary from mfg. to mfg on what will/won't work seated out to 1.260".

[The_Shadow]

sqlbullet, It may just be that the leade to the rifling is shorter/tighter at the start where the end of chamber cut starts on out to the rifling.  Increasing the leade should help your bullets work better at the longer length.

This is from the 38Super Net and illustrates the issue you maybe experiencing.



Another is tipping angle that I was referring to in the previous post.



The info can be found here: http://38super.net/Pages/Overall%20Length.html

[sqlbullet]

Nope.  Mine is definitely a tipping point issue.  When it stops, it is exactly at figure B above.  And a slight tap to the slide gets it "over the hump"

[nickE10mm]

This thread is intriguing to me ... carry on ..... :popcorn:

[my_old_glock]

Thanks for the report.  Very nicely done! 
I'd be willing to bet they would be more accurate if loaded in the 10mm cases...

What and how much powder were in your loads?

I do not remember which powder I used, or how much. I know they were all loaded with the same powder. I saved one to disassemble, so I should be able to find the powder weight at least.


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I finally got around to disassembling one round and weighing the powder. It was 4.50gr measured, and 4.75gr calculated.

I plugged the weight into Quickloads software, but couldn't find a powder that would give me the 1160fps I had measured with the chronograph. The fastest powders I have (Solo1000, Red Dot, Tite-Group) don't give me 1160 fps. The powder I used was dark gray to almost black round disks/flakes. I thought it was AA#5 or AA#7, but those are ball/sphere shaped. I looked through the powders I have and the powder looks like either Unique or 800X. AT 4.75 grains of Unique the case volume is filled 110% with powder.





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[The_Shadow]

Did you have a picture of the pull down powder?

[my_old_glock]

Did you have a picture of the pull down powder?

I threw it out.

I am going to try the test again with real 10mm brass. I will keep track of what powder I use this time.


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