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How close to minimum PF are you comfortable with?


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How close to the minimum PF are you guys comfortable with?

Working with Promo for 40 major, I loaded up some 4.4gr, 4.6gr. and 4.8gr. with an OAL of 1.135. PF was 169, 172 and 180 respectively.

Would you be ok with a 169 PF?. The lowest velocity was 928, so all of the rounds individually made the minimum. How much chrono work would you need to be confident at the chrono stage. I got my data from 1 session at 70 degrees. Should I be testing at different temps?

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How close to the minimum PF are you guys comfortable with?

If you are entering major competitions, I'd certainly want to

test at least 20 rounds at various temperatures, and have

each and every round at least make Major. :surprise:

If you're NOT shooting major comp's I'd be happy where

you are right now, without any further testing - you're

definitely close. :bow: :bow: :bow:

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Minor - 130, Major - 170

Agree

I run WST that a lot of people say is reverse Temp. sensitive, I've not seen more than a 2 1/2 % difference at any temp but for peace of mind I run it at 171-172Pf

Never gone below 169.8 "I think" at any chrono.

IT sucks to go minor so lean to the 170+ side

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It really depends on the caliber, the powder used and the consistency. I tested a lot of powders across a wide temperature range and found that most were temp sensitive. Many were extremely so. VV N310 comes to mind.

My Major loads all return single digit SDs across 20 round strings. With consistency like that, I'm happy with 170PF at 45 deg, the coldest I've shot matches at. Even the slowest shot in the string makes Major.

I've settled on Solo1000 for 45 Major. My load gives 170PF at 47 deg, 172PF at 66 deg, and top out at 174-175 in Summer.

I use e3 for 40 Major. It has no discernible temp sensitivity, so I load to 172PF.

Also, be aware that chrono technique affects the results. Whoever is testing your loads may be a bozo. Different chronos will return different readings from the exact same gun and load. So it pays to build in a little margin for error. One guy at the club is always angling for an edge. He loads just above 165PF figuring he is back on target a split second faster that way. He got chrono'd and bumped to Minor. He's a race through and spray kind of guy, so shooting an almost Major load with Minor scoring is not an advantage. Why take a chance?

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I generally run right around 168-169 for major and whatever turns out for minor under 135 with the bullet/powder combo I am working with at that moment.

Every round doesn't actually have to make major to make it at the chrono...

Edited by wgj3
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Thanks guys.

Until now I have only shot local matches. This July we're going up to Ryan Rocks which will have a chrono stage. I went through 8lbs of Unique in what I

"thought" (just a guess really, no chrono) was a major PF load. Not so much. Now that I have a chrono I thought I should probably use it. On the flip side, I don't want to spend all of my time shooting through it.

These loads have to work in 2 different guns as well. A Glock 22 and a Glock 35. I only ran these Promo loads through the 22. My earlier tests say that 35 will be 40-60 fps faster. I will verify the 35 when I'm happy with the 22.

I will also pull the chrono out when it's warmer/cooler out. For now I think I'll try another 20 rounds of the 169 pf load to see if there is enough consistency to be comfortable.

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Major 172+, Minor 134+ tested at the hottest and coldest you can.

Make sure you have a good accurate chrono.

I like to load my Serious Match Ammo as a single batch. Then test several times. You just don't want to have to worry about it at a Money Match or a Nationals.

Club matches I'll load the same loads in mixed brass but don't get too concerned over it.

For the bigger matches though don't trust the scales to be right. I've seen guys who load say 4.8 titegroup in a 40 and it makes it fine, then they load up another batch with a different lot or the powder bar has been changed and reset and gone minor cause the load was just under the pf.

Most of us can't tell the difference, or use it, between a 174 and a 169 or a 169 and a 164.

There was a good article on this subject and standard deviation in Front Sight last issue.

Edited by pskys2
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Just remember, if you go minor you still shoot for score , if you go sub minor you are shooting for fun. Going minor isn't a good feeling, but if you know early enough in the match you can adjust your approach

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There was a good article on this subject and standard deviation in Front Sight last issue.

The Jan/Feb 2015 Front Sight has this article "The Power of Statistics". It is written by Joel Whittington.

The short version of the article is that the Standard Deviation of your ammo needs to be considered. You may want to read it. ;)

Later,

Chuck

PS: You don't get DQ'ed for not making PF. Cnote covered it pretty well!

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I think there is a difference between results showing DQ when a shooter doesn't make minor and saying you DQ'ed a shooter for not making minor.

Regardless of what the results say you are not DQ'ed in the literal sense for going sub minor

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If you want to apply statistics to your own situation, take a look at my post (#44) in the previous thread http://www.brianenos.com/forums/index.php?/topic/92433-What's-your-Power-Factor-margin-of-error

Wow! Thanks! I searched for an hour and never came across that thread.

I didn't even think to weigh the bullets. :blush:

As long as the bullets are in the ballpark it looks like I'll be good.

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The only real problem with my spreadsheet is that it assumes that all chronographs are 100% accurate and give exactly the same answer for each bullet. This is obviously not true - there will be some statistical variability from chronograph to chronograph. However, I only have one - so I don't know the size of the variability expected. It is therefore good to allow a little bit extra, in case the match chrony gives a slightly lower reading than your own.

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Some powders you may be able to push it and stay closer to the baseline. Promo will generate less energy in colder weather, though.

I try for +5 as a minimum, but +7 is probably sage advice. Advice I will take, too.

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Guess I like playing with fire. I load for 167-168 major. I've never gone under. Been close, had a bullet weighed, had to take extra shots.... but made it. Well, with 40 in a Limited gun anyway.

Once I went minor in open, shooting an older gun set up for 175-180PF.... after the rules lowered to 165pf. Oops. Wasn't a case of planning to low... I meant to be 175+ but made a bullet change last minute (ran out) without chrono time before the match. Lets just say 124gr bullets shouldn't weigh 115gr. Weigh your bullets. 164pf is embarrassing for an open gun when you were planning for 178pf.

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