Quote from: sqlbullet on March 30 2020 10:19:02 AM MDT
So, even though that Mountain Mold page starts with 10mm/40, the as cast diameters have been pushed up to 45ACP sized bullets.

If you trim the diameter back down to .403", then the in-case length gets well above 0.500".  In my test at MM I came in at 0.567" inside the case with a 0.270 nose and a 270 grain bullet, two groove.  (Shadow is right, if max weight is the goal, go no lube groove and powder coat, but Mountain Mold doesn't allow you to delete lube grooves.)

Here is my take...

A 220 grain loaded within published data doesn't get above 1000 fps, and the reported pressure at max is nearly 37,000 psi.  So, a 220 grain gets you very subsonic.

Yeah. It was late and I had been messing with that mold site for awhile. Accidentally bumped up the diameter. It was just to give an idea. That site doesn't allow you to mock up PC-type rounds.

Quote from: The_Shadow on March 29 2020 01:50:08 PM MDT
Well if you want heavy without gaining length forget the lube groves, PC coat the bullets, also if bullets get too long you will likely see pressure spikes or the bulge where the bullet sits inside the case that may cause feeding issues... 

Yup, I stated in the OP that I coat bullets and was looking so no lube grooves or at most tumble grooves. Obviously I don't want to blow up one of my guns. Been there with a case head failure that trashed the frame of a new Glock in the middle of a stage during competition. That's why I'm looking around for as much information as I can to make educated starting guesses. I was hoping being a 10mm dedicated forum someone may have been down this rabbit hole before. Maybe not...

I worked this up on Mountain Molds...

Sorry. Wrong mold. That one was bumped up to 45 caliber by accident. It gives you an idea though.


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Hello fellow 10mm aficionados...

I'm looking to develop as heavy a 10mm subsonic round as possible. I realize this goes against the grain with most 10mm shooters  but I have a reason. I have a threaded barrel and suppressor for my GLOCK 20. This is my RV gun when I travel. My "one gun" for that purpose. Something for everything. I want a heavy cast boolit for subsonic use. The thinking is it'll be quiet but still penetration will still be good. A sledgehammer round if you will.

I'm looking for something 250-300 grains @1000fps. The higher the weight, the better. I'm not sure what is possible while remaining stable with the slow twist of 10mm. I'm sure others have had similar thoughts. Can't find a mold anywhere close to what I want. I have played with Mountain Molds design page but it's limited. I do some coated boolits, hi-tek and PC. So, I think a tumble lube or no lube groove design.

I don't know what will fit in the case with enough room for powder to get enough velocity...

Thoughts?


Edit: not interested in just using 180-220gr projectiles and calling it good...

Howdy from outside Raleigh NC! Long time shooter, competitor, reloader/caster, and fan of 10mm going back to one of my first CCW pistols in a S&W 1006... The only gun I ever regretted selling. Fast forward nearly 20 years after being into a little bit of everything gun-related and I finally got another 10mm. As a confirmed GLOCK fanboi I went with a Gen 4 20. It's been on my short list for years. I spend as much time as I can out in my Mercedes Sprinter RV and I am often in National Parks. So, I wanted a powerful, concealable handgun for critters on 4 legs and 2...

Anyhow, I spend my online time on Carolina Firearms Forum and Bushcraft USA mostly as I don't do social media. While doing some reloading/casting research on 10mm I came across this site and decided to jump in...