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Calculating PF - Bullets heavier than published


mpmo
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So, working up some loads with 147gn RN Blue Bullets, VV N320.  Decided to put them on the scale just to see how consistent they are.  There was not a single one that weighed less than 148, average was closer to 150, with some over 151.

 

So when I go to test on my chrono, what weight should I actually use?  Haven't attended anything other than Level 1 matches since I started shooting 7 months ago.  But there is a chance I might try to hit up at least 1 level 2 this coming year just for fun.  With chrono stages, how does it work?  Would I say my bullets are 150gn?  Should I try to get to 130PF with a 147 or 150 calculation?  

 

Shooting for 130PF.  

 

I'm sure I'm over thinking it.  It might not even be a 0.1gn powder difference right?!

 

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11 minutes ago, mpmo said:

So, working up some loads with 147gn RN Blue Bullets, VV N320.  Decided to put them on the scale just to see how consistent they are.  There was not a single one that weighed less than 148, average was closer to 150, with some over 151.

 

So when I go to test on my chrono, what weight should I actually use?  Haven't attended anything other than Level 1 matches since I started shooting 7 months ago.  But there is a chance I might try to hit up at least 1 level 2 this coming year just for fun.  With chrono stages, how does it work?  Would I say my bullets are 150gn?  Should I try to get to 130PF with a 147 or 150 calculation?  

 

Shooting for 130PF.  

 

I'm sure I'm over thinking it.  It might not even be a 0.1gn powder difference right?!

 

In a major match with chrono the bullets will be weighed. Whatever the actual weight is will be used to determine PF. FWIW bullet weight should be much closer to listed weight than what you are getting. Generally inside of a grain difference for better bullets.

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I’ve used various weights of blue bullets, they are consistently 2-3+ grains heavier than their listed weight. I was using the average of 10 bullets for my weight to compute PF. I also loaded to 135 PF, if I loaded to 130 I probably would have paid more attention to it. 

Edited by Rich406
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No lube grove bullets will actually weigh 1-2 grains more than stated weight.  The coating doesn't add more than .001 gr to the total.

 

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OP, I use BB 147's and they are always on the high side: 148-150gr. I like this, as it gives me a buffer in PF. But on my chrono session, I still use 147gr for calculations.

 

Last year, on all the level 2 matches I shot, they grab the magazines on me after I shot the stage before chrono. They weigh one bullet and shoot 3 rounds for average PF. I shoot for 130PF and always get 132-133PF, possibly because BB 147's are on the heavier side.

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As others said, use actual bullet weight when computing your power factor. Going for 130-135 in minor is pretty common and gives a margin of safety above the minimum.

 

At major matches I’ve had bullets pulled and weighed, and also just asked what grain bullet I was using. So could happen either way at the match.  If asked I’d just say the advertised weight. I’m typically 133-135pf, so would be well above minimum even with bullet weight variation. 

Edited by Tnbb33
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While I get more outliers from BB than most every other bullet I buy, I still shoot them (147grs)...have had some 6+ grains over advertised weights. I wish they would tighten it up a little.

 

Similar results as others (and would use 125gr when calculating PF, of course):

 

BB125gr.jpg.92822b934eae399882af87cc07d26e82.jpg

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