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40 S&W OAL or powder change


jimbullet
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I have been using win231 and an OAL of 1.169 on a CMJ FP 180gr which produced a power factor of 175, suitable of IPSC standard division.

 

I had to change the bullets due to low stock to a FMJ FP 180 gr and without changing anything on my press, as I am hoping to get the CMJs once they become available, I noticed that the OAL has reduced to 1.149 and I believe this has caused the spike in my velocity reaching 1,030 fps or a power factor of 185.

 

I am thinking not to adjust my press so that when I get back to the CMJs it will be back to the OAL of 1.169 and I once again have my match ammo ready. 

 

 I guess the angle of how the Flat point on the FMJ is causing this to seat more deeper thus creating higher pressures. 

 

Question is this

1. Is it safe to run a 40 S&W at 1030 fps resulting to a power factor of 185 or is this going to beat up the gun badly therefore maybe I should just dial the powder less?

 

 

 

 

 

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The different shape of the bullet will affect the oal. I always adjust my dies to suit the profile and maintain similar oal.  Both approaches should work to decrease pf but it depends on the oal you gun likes for feeding purposes. Though im generally switching between 180s and 200s and I maintain a similar oal for reliability and just change the powder dump.

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It doesn't take much time to adjust the OAL - takes couple minutes to dial it back

to 1.169" when you switch back.

 

I'd try to load your new bullets longer - make sure you try 

The Plunk Test first.

 

Heck, if necessary, I'd even adjust the powder charge down

to stay around PF 175 (that seems high enough to me).

 

Not that much effort to change both.

 

You didn't mention which gun you're using - if it's a S_I, it

won't be damaged by PF 185, but it's so easy to get back

to PF 175, I'd prefer to do that - if the rounds feed properly

and the accuracy is there.

 

If it's NOT a S_I, then I'd be even more eager to downsize

the PF.

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51 minutes ago, Novagunner said:

The different shape of the bullet will affect the oal. I always adjust my dies to suit the profile and maintain similar oal.  Both approaches should work to decrease pf but it depends on the oal you gun likes for feeding purposes. Though im generally switching between 180s and 200s and I maintain a similar oal for reliability and just change the powder dump.

By switching - does your OAL change like mine or I suppose both your 180 and 200 have the same profile and therefore no need to adjust the seating die?

 

I am using a 2011 STI pistol  and a Dillon square deal.

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I also noticed that the new projectiles I have has a diameter of 0.3995 which is slightly slimmer that the CMJs I was used to which was 0.400 but when I tried to load dummy rounds the crimped them to a diameter at the lip of the case at 0.420, I could press the projectile by hand and the bullet would slip right into the case. So I had to adjust my crimp which is now 0.418. What crimp measurement do you have? 

 

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OAL tends to be adjust for function. Powder for velocity. You probably need to do both.
To the question you asked though. 185 pf isnt too high and can easily be done at below max pressure with slower powders.
185 pf with 231 powder probably has you over pressure.

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