Heavy 10mm load

[NavyVet1959]

Well, I've mentioned a new load that I stumbled across in other threads, but I thought I might as well make a new thread on it anyway.

Alliant Longshot -- 8.4 gr
OAL: 1.2660"
Bullet: Lee TL-410-210-SWC resized to 0.401" w/o lube, powdercoated; ASBB*2, Harbor Freight flat black; resized to 0.401" again; with a 50:50 Pb:WW alloy, the bullets drop at around around 216 gr
Using .40SW brass loaded to 10mm OAL.

1237 fps; 747 ft-lbs

After resizing the .41 mag bullet to 10mm, the SWC basically becomes a WFN. The lube grooves nearly disappear.

http://images.spambob.net/navy-vet-1959/lee-tl410-210-swc-resized-10mm-loaded-320w.jpg
http://images.spambob.net/navy-vet-1959/lee-tl410-210-swc-resized-10mm-loaded.jpg

Shot it in a Glock 29 (without a mag, just in case it blew up in my hand) and it felt a bit snappy. Shot it in a RIA 10mm (M1911) (with a full mag) and it felt comfortable.

I guess I need to try it with a G20 next to see if it was just the shorter grip on the G29 that made it feel snappy.

[Greg S]

I noted your comment the other day concerning the use of 40 S&W brass in full house loads. Have you disected/split a 40 and 10 to compare case webs? Are you running a factory or aftermarket barrel in the glocks? I tried pushing cast 180s in a Sig 229 with 800x and was getting some buppies (baby guppies) and backed off. With the extended 10mm oal and large metplat to get support in the leade it would be interesting. You did state basically same same accurracy with 40 or 10 brass on other loads if i recall correctly.

[rosewood]

The max pressure for a 40 and 10mm are about the same, so I would imagine the brass would have the same thickness webbing. Also, with the 40 being a small pistol primer, it has more brass back there than the 10mm does. Only issue I see is these cartridges are supposed to head space off the rim, this makes you head space off the extractor. But if you drive the cast boolit into the lands, it might take care of that.

[NavyVet1959]

I noted your comment the other day concerning the use of 40 S&W brass in full house loads. Have you disected/split a 40 and 10 to compare case webs? Are you running a factory or aftermarket barrel in the glocks? I tried pushing cast 180s in a Sig 229 with 800x and was getting some buppies (baby guppies) and backed off. With the extended 10mm oal and large metplat to get support in the leade it would be interesting. You did state basically same same accurracy with 40 or 10 brass on other loads if i recall correctly.

I did not notice any issues with the brass when I was shooting the 175gr loads with Alliant Promo. 6.2 gr gives 1194 fps (554 ft-lbs) according to Lyman #48.

Supposedly, this is the load that Underwood Ammo was using in their 220 gr Hard Cast Flat Nose product at one point. Their "220 gr" bullet also comes in at 216 gr.

http://10mm-firearms.com/factory-10mm-ammo-pull-downs/underwood-220gr-cast-wfn-1230-fps-pull-down

Some later pulldown examinations of the Underwood ammo showed 8.6 gr of Longshot, but there wasn't enough of a velocity gain for me to bother with it. I figured that was just 0.2 gr of margin I have in case my powder measure is not consistent. :) Underwood also appears to have used 800X at some point.