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How close to 125 power factor should I get

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I've been slowly eliminating the use of store bought ammo in favor of my reloads.

I'm about ready to go to a match where I think I will be chronoed, but I really have very limited experience (almost none) in sanctioned matches.

it will be (quietly), an IDPA match (sorry, I know people on here don't like them, but we don't have USPSA anywhere close to here.)

I'm running 147 grain plated bullets at an average speed of 881 ft per second, which should be 129.5 power factor (3.1 grains Bullseye, test at 63 degrees).

My standard deviation though, is 20, so I guess I'm running with about a 4% chance (if my memory of math is correct) of hitting 124 PF.

I would think that would be good enough.

Do I need to worry about temperature, humidity changes, or anything else?

Do they usually test rounds before you shoot or after you start?

Any advice?

Thanks in advance,

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Bump it a bit, if it is within published data. You can't tell the difference between 133 and 127 PF ammo, but the chrono man can and going under is a bad bad thing!!!

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Even with your standard deviation you will still come in higher than the minimum. I would think that unless you have a lot of powder spillage on several rounds that you're going to be just fine. If it was me, I'd leave it alone. (But I'm from Nevada, a gambling state!) :goof:

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In minor going a little warmer never hurt. I run mine about 135, you will find a spot in what you like and what runs effectively. It might be 130, it might be 140. Try loads and see if you can discern a difference. Now for major my loads are only 169-170 Chronographed in the cold, no reason to go any higher, I am only but so brave.

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I like to fire 20 shots over the chrono, and have Every One

of them at PF 125. :cheers:

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I run at 130 but my deviation is less. I don't like running it to tight because you never know with Chrono. After seeing some folks at Nationals a few years back not make Major because they were pushing the limit I decided to not put myself in that position especially when trying to make minor

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Going sub-minor sucks. I like 135PF.

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Somewhere between 130-135 I call it good. Plus, it will knock down steel better, or so I tell myself.

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When I develop loads, I first load to whatever power factor I choose with a margin for outside influences (altitude, temperature, chrono variations). I go 5 over minimum so 130 for minor and 170 for major. Then I play around with the loads to see which is the most accurate and feels the best in my gun. I ended up with 136 in minor and 172 in major. I don't shoot of a rest or bags, just freestyle group of 6 (mainly because in a match I don't shoot off a rest so why use that for load development) and pick the load I like the best from the freestyle rapid fire. That tells me more about followup shots.

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Somewhere between 130-135 I call it good. Plus, it will knock down steel better, or so I tell myself.

Same here. I can tell the difference between 122 and 135. But between 130 and 135, pretty hard to tell. I usually end up between 129 and 131.

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Somewhere between 130-135 I call it good. Plus, it will knock down steel better, or so I tell myself.

Same here. I can tell the difference between 122 and 135. But between 130 and 135, pretty hard to tell. I usually end up between 129 and 131.

Same here.

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If you go to the chrono worried about making PF you are just stupid.

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I've been slowly eliminating the use of store bought ammo in favor of my reloads.

I'm about ready to go to a match where I think I will be chronoed, but I really have very limited experience (almost none) in sanctioned matches.

it will be (quietly), an IDPA match (sorry, I know people on here don't like them, but we don't have USPSA anywhere close to here.)

I'm running 147 grain plated bullets at an average speed of 881 ft per second, which should be 129.5 power factor (3.1 grains Bullseye, test at 63 degrees).

My standard deviation though, is 20, so I guess I'm running with about a 4% chance (if my memory of math is correct) of hitting 124 PF.

I would think that would be good enough.

Do I need to worry about temperature, humidity changes, or anything else?

Do they usually test rounds before you shoot or after you start?

Any advice?

Thanks in advance,

1 SD 68%, 2 SD 95% 3 SD 99.7%

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If you go to the chrono worried about making PF you are just stupid.

I was not worried, but I wanted to see how close I could get once. 165.03, on the 6th bullet fired shooting major. :roflol:

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If you go to the chrono worried about making PF you are just stupid.

Nah, what's really stupid is bringing the big stick with the grip tape on the basepad at an Area match! Funny that all the other open shooters had 140's in their hands ...

Meanwhile, back at the subject. Don't forget to weigh your bullets and figure in that SD also! Especially with more "economy" projectiles...

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Nah, what's really stupid is bringing the big stick with the grip tape on the basepad at an Area match! Funny that all the other open shooters had 140's in their hands ...

^ Is that really a thing? I mean, is grip tape really making or breaking the big stick? Serious question.

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Nah, what's really stupid is bringing the big stick with the grip tape on the basepad at an Area match! Funny that all the other open shooters had 140's in their hands ...

^ Is that really a thing? I mean, is grip tape really making or breaking the big stick? Serious question.

Yup. The chrono dude put it into the mag gauge and it would not fit. Shooting for no score since he was already in open. This has happened to limited shooters also. Every other open shooter in line had a 140 in their hand for the chrono...

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Somewhere between 130-135 I call it good. Plus, it will knock down steel better, or so I tell myself.

Agreed. Also, in my (very limited) experience it seems that the accuracy and variability is less in that range. Granted, I've only tried BE and TG in 9mm using a limited number of different projectiles but other threads seem to support this theory as well.

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As a chronographer for some major IDPA matches, I recommend a minimum of 7 or 8 over for all divisions.

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We chrono before major matches and usually bump it up at least +5 from the minimum just to make sure we make it. You'd hardly notice the difference. Also keep in mind that not all chronos are all the same. Just because you read 125 20x over on your chrono doesn't mean you'll get that on another chrono as those have variance as well.

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Nah, what's really stupid is bringing the big stick with the grip tape on the basepad at an Area match! Funny that all the other open shooters had 140's in their hands ...

^ Is that really a thing? I mean, is grip tape really making or breaking the big stick? Serious question.

Yup. The chrono dude put it into the mag gauge and it would not fit. Shooting for no score since he was already in open. This has happened to limited shooters also. Every other open shooter in line had a 140 in their hand for the chrono...

Incredible! I'll take this as a heads up. Thanks you!

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Thanks for the advice. The most frustrating thing was that it was only one round in my data set that really killed the standard deviation. Otherwise, I wouldn't have even worried about it.

I've boosted up a test batch a little and am going to try again. Worst case, if I can't get enough ingredients for enough new rounds, I'll just use commercial ones.

Thanks again.

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I boosted it up .2 grains and while it was all in the 130's, the spread is huge.

From what I've read elsewhere, I also am thinking Bullseye may just be too fast for 147 grain bullets.

I ran some of my lighter rounds through again and at 92 degrees F, their average PF was low enough that it would worry me.

It did great with very little deviation at 40 degrees, Ok with a little more spread at 62 degrees, and not so great at 92 degrees.

My logs are telling me to drop back to 124 grain and use the recipe I used with them, but I can't get them in time.

I've had trouble finding powder this last year and have used Bullseye, Autocomp, HP-38, , even 800X, basically whatever I could find that you could locate a recipe for.

Oh well, I think this time, I'm just going to wimp out again and bring commercial 115 grain ammo.

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Nah, what's really stupid is bringing the big stick with the grip tape on the basepad at an Area match! Funny that all the other open shooters had 140's in their hands ...

^ Is that really a thing? I mean, is grip tape really making or breaking the big stick? Serious question.

Yup. The chrono dude put it into the mag gauge and it would not fit. Shooting for no score since he was already in open. This has happened to limited shooters also. Every other open shooter in line had a 140 in their hand for the chrono...

Incredible! I'll take this as a heads up. Thanks you!

Many, many, many 170 mags will need a little filing on the back of the lips or I see some with the base pads sanded a little. Very easy to have mags that are too long and not even know it until.......

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I agree with the chrono readings being different. I worked up a load for the Desert Classic this year. Over my chrono it was a 132 p.f. Over the match chronology it was 135 p.f. so it's better to stay 5 or more above minimum and not have to worry about it.

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