Long-load the M610

[sparkyv]

I want to push the velocity higher in my M610, but I'm not ready to ream it out to a magnum just yet.  I've read where some have long-loaded the 10mm auto cartridge with some degree of success, but my searches for details  on this topic have been futile.  I would like some suggestions and thoughts on the matter as well as pitfalls. I recognize the possibility of "prairie dogging" projectiles to less opportunity to crimp less effectively, but would appreciate any feedback.

[The_Shadow]

You might want to experiment using W296 / H-110 powder and actually apply a good crimp if you load long.  That could possible yield you some good velocities while keeping pressures decent!
I would suggest studying 41 mag and 357 mag data to find a load close for the bullet weight you want to use to get a slightly compressed load...
Good luck and post your results to include the COL, powder weights for velocity obtained.

[sparkyv]

Thank you, sir.

[CtYankee]

Let me play Devil's Advocate.  the 10mm Magnum case is ¼" longer than the 10mm Auto so you're not going to be able to set bullets out enough to equal its powder capacity. A good deal of the bullet's resistance to initial movement is from neck tension not crimp (expecially taper crimp). Unless you are using heavy bullets (200gr+), or you're seating bullets without expanding the cases you will have reduced neck tension. I tried seating a 200 gr GDHP to half its normal seating depth, I gained less than .02" of case capacity. I put a heavy taper crimp on it (dummy cartridges - no powder) and found that I could disassemble it in my impact puller much easier than those seated to standard depth: however, that doesn't mean that the bullets didn't have enough resistance. I'm not sure that the 10mm Auto case will allow enough H110 (even w/ bullets seated long) to show any improvement. If a 610 can headspace off the moonclips you might be able to use a roll crimp - you can buy a cannelure tool from CH4D for $130.  You can increase the velocity potentialof the 10mm Auto, but I don't think that you'll hit 10mm Magnum velocity unless you ream it to 10mm Magnum. It depends on what you want. I use my GP100 for ICORE competition and load for a power factor of 130-125. I know I can hit 1150 fps with a 200 gr bullets and maybe get to 1200 fps, that seems adaquate for me.

[sparkyv]

Thanks for the contraperspective; I appreciate all POV.  I'm a natural tinkerer and am just in the investigative phase, but if I gained less than .02" of case capacity, H110 efforts may be in vain.  If there's not enough neck tension, then I'll load up only one round at a time.  Totally impractical, but good enough to pass over the chrony. I didn't expect to reach 10mm Mag performance,  just want to wring out a bit more.

[Bimmer]

I was hesitant to ream my cylinder for 10mm Mag, but it was actually quite easy... 

If you really want more oomph, then go for it. 

Caveat:  I wasn't able to replicate the velocities that Taffin reported (not even close). 

I lost interest in going further when I started splitting cases with 200gr Gold Dots at ?1,200fps. 

Some of that may be due to my sloppy DIY reaming job, but some of that is just the limits of a 6-1/2" barrel.  (IIRC, Taffin was testing using an 8" autoloader.) 

[sparkyv]

I've put this project on hold as my new M617 is inbound and am looking forward to putting her through its paces.

[FN in MT237]

   OR..... Just get a .41 mag?  A lot easier.

[Mike D]

I want to push the velocity higher in my M610, but I'm not ready to ream it out to a magnum just yet.  I've read where some have long-loaded the 10mm auto cartridge with some degree of success, but my searches for details  on this topic have been futile.  I would like some suggestions and thoughts on the matter as well as pitfalls. I recognize the possibility of "prairie dogging" projectiles to less opportunity to crimp less effectively, but would appreciate any feedback.

You can always buy an extra cylinder and ream it out.







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[sparkyv]

I thought the extra cylinder would require hand-fitting.  I'm pretty sure the hand has to be worked match the cylinder, so swapping between the two calibers is not a trivial task.

[Mike D]

I thought the extra cylinder would require hand-fitting.  I'm pretty sure the hand has to be worked match the cylinder, so swapping between the two calibers is not a trivial task.

I thought that applied to single actions only.


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[sparkyv]

Have you successfully obtained a second cylinder for your M610 and it fit without modification, MikeD?

[Mike D]

Have you successfully obtained a second cylinder for your M610 and it fit without modification, MikeD?

I have not. Since I?ve not had the cylinder reamed yet, I?ve not done anything with it.


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