10mm over book velocities

[owen58]

I recently loaded some 10mm Auto with 165gr hp pills over 14gr of AA9 in brand new Sig brass. Most data indicates that it should produce a velocity just over 1200fps. I was getting 1360fps (tried 2 chronos). This concerned me a bit. The last thing I need is a kaboom! I'm running a 6" barrel vs the 5" barrels used in the data. Do you guys with lots of experience think the additional barrel length could explain the extra 150fps? Anyone have similar results?

 

[Adam5]

That’s not much more than Hodgdon shows for that load.

 

[owen58]

That’s not much more than Hodgdon shows for that load.

True, at 1360 I'm not really concerned about any danger. But, I'm getting top velocity at a full grain under max. I'm curious what might happen at full charge.

 

[Steven037]

Crimp?

 

[Dieselt]

If you aren’t getting flat primers I wouldn’t worry about it

 

[owen58]

Crimp?

Lee factory crimp die.

 

[owen58]

If you aren’t getting flat primers I wouldn’t worry about it

That was my first thought...Thankfully, the primers look perfect. Surprised that an extra inch of barrel might be able to add 150fps.

 

[Twitch2120]

That was my first thought...Thankfully, the primers look perfect. Surprised that an extra inch of barrel might be able to add 150fps.

Never underestimate the power of an extra inch.

 

[Mk319]

I’ve read multiple places that the current loading for the 10mm are under loaded, and have found personally that load data is pretty tame compared to what it’s capable of. Just make sure your chamber is fully supported before you go trying to max your loads out. This is a 357 sig, but you get the idea.

 

[owen58]

I’ve read multiple places that the current loading for the 10mm are under loaded, and have found personally that load data is pretty tame compared to what it’s capable of. Just make sure your chamber is fully supported before you go trying to max your loads out. This is a 357 sig, but you get the idea.

View attachment 5895519

Yeah, I had some 40s that looked like that. Pretty scary.