.007 in OAL Issue with Overpressure?

[ilovevtac]

I normally load 1.142 OAL with 6.7 WAC and am making 172PF but due to the variations in brass.

 

Some of the ammo today came out to 1.135 OAL.

 

Would a difference of .007 cause an issue with Overpressure?

 

Thanks! 

[fbzero]

3 hours ago, ilovevtac said:

I normally load 1.142 OAL with 6.7 WAC and am making 172PF but due to the variations in brass.

 

Some of the ammo today came out to 1.135 OAL.

 

Would a difference of .007 cause an issue with Overpressure?

 

Thanks! 

In order for that to cause significant over-pressure, I think you'd have to be riding on the edge of what is safe in the first place.  I'd be terribly surprised if you went from no pressure signs to significantly over-pressure from that, given that most of these presses are only accurate to +/-0.003 anyway.

 

Edited May 10, 2019 by fbzero

[Hi-Power Jack]

You can cram a LOT of WAC into a case and be safe, and I don't think 1.135"

should be a problem, but really NOT positive. 

 

Doubt it's a problem, but not

sure.   Only because 1.135" is pretty short for a 9mm Major load.  And,

sounds like you have a fast barrel, making PF172 with only 6.7 gr WAC.

 

I presume that's a 124 gr JHP ?

[ilovevtac]

3 hours ago, Hi-Power Jack said:

You can cram a LOT of WAC into a case and be safe, and I don't think 1.135"

should be a problem, but really NOT positive. 

 

Doubt it's a problem, but not

sure.   Only because 1.135" is pretty short for a 9mm Major load.  And,

sounds like you have a fast barrel, making PF172 with only 6.7 gr WAC.

 

I presume that's a 124 gr JHP ?

 

Yeah I'm using 124GR MG JHP. It's for a CZ Czechmate (hence why it the OAL is a lot shorter than 2011's).

Fingers crossed there's no over pressure. What should I be looking for in terms of over pressure signs? 

[Hi-Power Jack]

The feel of recoil, the noise of the blast, distance the cases are thrown and the primers can give you some indication

of problems - but, none of them are exact science.

 

Look at the primers of your 1.142" loads and compare next to the first 1.135" you fire.

 

The primers should look the same.

 

Sounds fairly safe, but I'd check the recoil, noise, location of case and primer of the first one you shoot,

vs the other longer loads.     

Edited May 10, 2019 by Hi-Power Jack

[zzt]

On 5/10/2019 at 11:29 AM, ilovevtac said:

Yeah I'm using 124GR MG JHP. It's for a CZ Czechmate (hence why it the OAL is a lot shorter than 2011's).

 

A friend had his Czechmate barrel throated so he could use 1.165" ammo.  It runs fine.