10mm Reloads - Sanity Check

[Caboose]

Hi, I'm relatively new to loading 10mm, and none of my friends do, so I found this place and decided to ask for a sanity check on what I'm doing. As usual, my manual doesn't have the exact bullet I'm loading (165gr Blue Bullet RNFP) so I started low and worked up for similar bullet weights using Power Pistol and Blue Dot. I'm using the Lyman 49th Edition, and I wanted to get to 1200 fps, which doesn't seem like a stretch for 10mm w/ 165s.

So I worked up a Power Pistol load first:
- 7.9 gr, 1130 fps
- 8.1 gr, 1150 fps
- 8.3 gr, 1175 fps
- 8.5 gr, 1185 fps
- 8.7 gr, 1210 fps

Do these seem reasonable?That last load with Power Pistol launched 5 bullets within 10fps of each other. Then came the Blue Dot, which I regularly had +/- 25 fps with (is this normal for a G20.4?).

- 9.1 gr, ~1039 fps
- 9.3 gr, ~1071 fps
- 9.5 gr, ~1087 fps
- 9.9 gr, ~1103 fps
- 10.2 gr, ~1112 fps
- 10.4 gr, ~1173 fps

It could be my imagination, but these Blue Dot loads seemed to have a lot of blast and recoil for the velocities I was seeing. Also, I have 2 scales I check against each other especially when I get near a book max. I was seeing differences of up to 0.2gr with Blue Dot (maybe that explains the velocity variation). Am I on track here, and do these numbers seem reasonable to you guys that have loaded a lot more 10 than me? The brass looks fine, resizes fine, no flattened primers. I did put a Brass Stacker 22 lb spring in.

[Graybeard]

What was the COAL on these?

[Caboose]

1.279"

[Graybeard]

Wow, 1.260 is max length for 10mm. I'm surprised they fed and cycled.

1200fps is indeed no big deal w/165gr bullets. You got there with the PP because it's a faster burning powder and more forgiving of the extra internal case volume with the 165gr bullets loaded over length.

BlueDot, because of it's slower burning rate, wasn't burning completely with the extra internal case volume. You probably didn't have any more recoil, but did have a much bigger fireball when shooting those. Your 10.4gr BD load should launch a 180gr bullet as fast, or a little faster, while still being well under max pressure.

BD doesn't meter as well as PP, so that may have been part of your spread issue. Being over length with a short bullet to begin with was probably the bigger factor.

I tend to get better results with 180gr bullets and up.

Hope this helps.

[The_Shadow]

Caboose, welcome to the forum!  Looking at the COL you listed does show why the velocities are slightly lower that what I would expect.
I use COL of 1.2500 for most all of my 10mm ammo.  This helps to build the pressure needed for performance.  I powder tends to burn better with the higher pressures as well.  I take that the Blue Bullet is a poly coated lead and as such lead alloy data is good for their use.

Your readings look good and would even be higher with your COL being shorter...

The reason for the 45ACP using 1.275" was because of the 230 grain FMJ being long and you would see shorter numbers for FP and HP styles.

[sqlbullet]

As graybeard says, the blue dot was loud and firebally because of the unburned powder.  Reduce the COAL and keep working up. 

10.4 is the starting load for a 165 grain Gold Dot, with a COAL of 1.255".  Your bullet will be shorter, and probably have less bearing surface and friction, though it should seal the bore a bit better.  These factors means you have additional "headroom" in your load.  Blue Dot should get you to between 1275 and 1300 fps with this bullet, if loaded to 1.255".  At your length you might see 1350.

[Caboose]

Thanks for the info, guys. Yes, they are poly coated bullets. I got to this COAL by making some dummies and doing the "plunk" test. They actually plunked at even longer COALs just fine. Then I pushed them in until they would fit in the mag, and I've had no reliability issues. I decided the extra length was some margin for error in terms of pressure as I worked loads up. Sometime this weekend I'll load a new batch and push them in a little more and see what happens with Blue Dot. So far, 10mm has been fun. Even these loads make my 9mm +P carry ammo out of a G26 seem wimpy.

[The_Shadow]

Also using slower burning powders, the extra case to bullet tension helps burn the power and prevent bullet setback.
It may not seem like much but wit Blue Dot it will help.

[Caboose]

OK, looks like 1.263" is as deep as I can go with these bullets. Any shorter and I'll be taper crimping air at the case mouth. Loading some up with Blue Dot that is measuring 10.5-10.7 grains per throw.

[gjarcher]

If flash is an issue, try Alliant BE-86. Burn rate falls between Unique and Power Pistol. BE-86 meters very well, similar to Power Pistol.

http://www.alliantpowder.com/reloaders/RecipePrint.aspx?gtypeid=1&weight=165&shellid=30&bulletid=41&bdid=1246

http://www.alliantpowder.com/reloaders/RecipePrint.aspx?gtypeid=1&weight=165&shellid=30&bulletid=330&bdid=1249

[sqlbullet]

And...

BE-86 is the fastest of the powders Alliant lists for 165 grain at 1344.

[Caboose]

Thanks. When I burn up the rest of this Blue Dot I'll check out BE86. Alliant powders are typically available locally. I do like how Power Pistol meters, it's very consistent.

[Graybeard]

You could switch bullets and use your BlueDot with them, too. The profile of the blue bullets is somewhat similar to a LSWC. The reduced diameter above the power band allowed for the plunk test to work at the greater lengths that you mentioned. It would have plunked until the power band hit the rifling.

Something like the Berry's 165gr HBRN heavy plate would be a safe choice for your load work up. They can be seated much further, and take the speed of a jacketed bullet. They also have more bearing surface/neck tension (as Shadow mentioned). They are a bit more expensive, though.

Interestingly, it looks to me like the Blue Bullets you're using would be perfect for a gun with a 40/10 chamber. Like they were designed for it.

[Caboose]

I have a few thousand of these Blue 165s (I use them for .40 minor loads mainly), maybe I'll check into a different bullet after those are all gone. I shoot a lot of steel so I prefer to stay away from anything plated or jacketed. I got a piece of jacket in the face once from properly set steel, not fun.

What's a 40/10 chamber?

[Graybeard]

I participate in steel shoots quite often. Getting hit with stray bullet bits isn't fun, but it is why we wear eye protection. I've never really noticed plated bullets to offer up more shrapnel than straight lead. In fact, one of the worst ones was lead. I had to dig that one out of my finger with a pocket knife.

A 40/10 chamber involves using .40S&W brass loaded to 10mm lengths and with 10mm powder charges. The chamber is cut to headspace as a .40 but the rifling starts as if it were a 10mm. It's really only useful on race guns. Easy to make major power factor and the extra gas feeds the compensator/brake. Guys who like it argue that .40 brass is cheaper, small primers, mitigates recoil better than a .40 or a 10mm. The goal isn't to achieve the speed of a 10mm or bullseye accuracy, just a fast shooting, low recoiling .40 that makes major.

Hence my comment. A poly coated bullet that can only be loaded long by design, using lead data, and gives you a big gas ball with slower powders was practically made for this.