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How close to 125 power factor should I get

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Also one thing I don't see mentioned is accuracy. Yes most if not all, myself included prefer 130 pf however, in my case running 135 bayous and n320 135 pf is actually noticeably more accurate than 130pf. When running 147 bayou over n310 I run 128pf since it's more accurate than 130 or 135pf. with vv powders my SD is less than 8 so I have no worries.

Moral of the story keep accuracy in mind because slower is not necessarily better and many times may be worse. Slightly faster with proper spring setup in the gun can make all the difference.

Edited by tcazes

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I make sure that 10 out of 10 are at 125 or more on 2 different chronos. Last time I worked up a load I got there at a 127.5 average.

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If you live in South Texas on the Beach 1 foot above sea level and it summer time and over 100 degrees.

You chrono your loads and it makes power factor of 125.1

You are headed to Rocky Mountain High Shoot and its 25 degree there, you will not make power factor.

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If you live in South Texas on the Beach 1 foot above sea level and it summer time and over 100 degrees.

You chrono your loads and it makes power factor of 125.1

You are headed to Rocky Mountain High Shoot and its 25 degree there, you will not make power factor.

Which is the reason my 9mm loads make 137 and I recommend a minimum of 132/133.

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I find that all my CZ s shoot better at 135 than 130 where the groups open up some. Found this tendency with multiple different powders.....

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At "super-close to Minor floor", a lot of loads will suffer from accuracy issues because of Load Density, unless you're running a VERY fluffy powder. There is a LOT of empty space in the case and just a little powder. That is not very conducive to consistent pressures and velocities.

I owned a 38 Super Limited/ESP Gun that wouldn't shoot 15 inch groups at 15 yards with Minor power factor loads, but if you bumped it up to about 160 or so, it was a tackdriver. A lot of people have found issues when trying to load 185 grain bullets in a .45 ACP also, like Extreme Spreads in the 150 fps range. That's astronomically high when you're only going for 925 fps or so...

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Weigh your bullets to know the real weight. Fire 5 shots over the chrono, delete the highest and lowest velocities, get the average of the remainging 3 and calculate the Factor. If you are between 5 and 7 points above minimum you will always be fine.

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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...

Why don't you just make sure your magazines are legal length? We checked magazines with a gauge on a stage, and some random checks elsewhere.

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Weigh your bullets to know the real weight. Fire 5 shots over the chrono, delete the highest and lowest velocities, get the average of the remainging 3 and calculate the Factor. If you are between 5 and 7 points above minimum you will always be fine.

Do not discard any value, because they are very relevant. You may go to a match and find that all of the loads are on the low side and you're DQ'd.

Run 10 rds over the chono and you will have a better idea how your loads are doing. I run chrono at some major matches in the NE.

Strive for 133 - 135 and no lower, and then you can be sure that a trip isn't wasted.

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I choose a velocity that is about three standard deviations (for a 15-20 shot group) above the minimum velocity to make PF.

For my current 9mm pet load, that puts me around 131 PF.

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I choose a velocity that is about three standard deviations (for a 15-20 shot group) above the minimum velocity to make PF.

For my current 9mm pet load, that puts me around 131 PF.

Could you please provide your load data and the press you are using.

A S.D. of 2 is excellent.

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Read the rules: 8.3.2 Official Chronograph Procedure

In the end, ONLY TWO of SIX rounds needs to meet PF.

I say cut it as close as you want.

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Read the rules: 8.3.2 Official Chronograph Procedure

In the end, ONLY TWO of SIX rounds needs to meet PF.

I say cut it as close as you want.

And then go home because the temperature/humidity were different on the day you shot.

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I choose a velocity that is about three standard deviations (for a 15-20 shot group) above the minimum velocity to make PF.

For my current 9mm pet load, that puts me around 131 PF.

Could you please provide your load data and the press you are using.

A S.D. of 2 is excellent.

3.2gr Titegroup

147gr X-treme RN plated (.356)

WSP

OAL 1.150-1.160"

XL 650

(use at your own risk blah blah)

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Read the rules: 8.3.2 Official Chronograph Procedure

In the end, ONLY TWO of SIX rounds needs to meet PF.

I say cut it as close as you want.

8.3.2?

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Read the rules: 8.3.2 Official Chronograph Procedure

In the end, ONLY TWO of SIX rounds needs to meet PF.

I say cut it as close as you want.

8.3.2 “Are You Ready?” – The lack of any negative response from the competitor indicates that he fully understands the requirements of the course of fire and is ready to proceed. If the competitor is not ready at the “Are You Ready?” command, he must indicate to the Range Officer that he is not ready.

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Competitor Ammunition Testing Procedure

33. Ammunition must be tested using the competitor’s firearm. Prior to and/or during testing, the competitor’s firearm and the component parts thereof must not be altered or modified in any way from the condition it is being used (or will be used) at the match. Violations will be subject to Section 10.6.

34. Conventions to be used for all measurements:

a. if more than one chronograph is in use, the highest velocity recorded by any of the chronographs shall be used for each respective shot.

b. if more than one scale is in use concurrently, the highest weight mea-sured by the scales shall be used for each respective bullet weighed

35. From the eight sample rounds drawn by Match Officials, one bullet is weighed to determine the actual bullet weight and three bullets are fired over the chronograph. Digits displayed on the official match bullet scales and chronograph will be used at face value, irrespective of the number of decimal places indicated on the measuring device used at the match.

36. Power factor is calculated using the bullet weight and the average velocity of the three rounds fired, according to the following formula:

Power Factor = bullet weight (grains) x average velocity (feet per second) / 1000

The final result will ignore all decimal places (e.g. for USPSA purposes, a result of 124.9999 is not 125).

37. If the resultant power factor fails to meet the declared power factor floor, another three rounds will be fired over the chronograph. The power factor will be recalculated using the bullet weight and the average velocity of the three highest velocity rounds from the six rounds fired.

38. If the power factor is still insufficient, the competitor may elect to have:

a. the final bullet pulled and weighed and, if heavier than the first bullet, the power factor calculation in Paragraph 36 will be recalculated using the heavier bullet weight, or

b. the final round fired over the chronograph and the power factor recal-culated using the first bullet weight, and the average velocity of the three highest velocity rounds from the seven rounds fired.

39 If the resultant power factor fails to meet the Major power factor floor of the relevant Division, the competitor’s entire match scores will be recalculated as Minor, if achieved.

73 USPSA Handgun Rules, February 2014 Edition

40. If the resultant power factor fails to meet the minimum power factor floor for the relevant Division, the competitor may continue shooting the match, but not for score or match recognition.

41. Due to the different methods used by certain chronograph brands to calcu-late Power Factor, any power factor results produced by the Chrono Station chronograph are considered interim results and subject to confirmation.

a. The only official power factor results are produced and/or confirmed by using the formula specified in Item 36 or via the EzWinScore scoring program.

b. Specifically, power factors generated by a chronograph which indicate exactly 125.0 or 165.0 shall be subject to confirmation since these values could be the result of the “rounding up” of digits after the first decimal place.

42. If a competitor’s match ammunition is retested, or if any authorized replace-ment ammunition is used, and different power factors are recorded when tested according to these rules, the lower power factor must be applied to all courses of fire, including those already completed by the competitor.

43. The scores of a competitor who, for any reason, fails to present his firearm for testing at the designated time and location and/or who fails to provide sample rounds for testing whenever requested by a Match Official will be removed from the match results.

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I don't know what rule book you are using, but the current one V1.2 and rule 8.3.2 is the chrono procedure.

I suggest that you download the current one from IDPA.com.

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Read the rules: 8.3.2 Official Chronograph Procedure

In the end, ONLY TWO of SIX rounds needs to meet PF.

I say cut it as close as you want.

And then go home because the temperature/humidity were different on the day you shot.

That is a risk each shooter must consider in determining how close to cut the PF. Personally I run at ~130-132PF because that is where I get good accurcy with the bullets I choose to load in my gun the way I shoot - not because I'm really that concerend about making PF. For IDPA a 127 or 128PF is not that risky if you test with a good chrono at nominal kinds of conditions. You do have to be aware of all kinds of factor variations (chrono, weather, altitude, brass, bullet weight, etc.) in making a call as to what PF you are comfortable with.

My point is that not every round tested has to make PF and the average dosen't have to make PF, only two of six have to make PF. If recoil is such a big deal to you and you can live with the risk, load to whatever you are ok with even if its 125.1PF.

Edited by Rob Tompkins

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Read the rules: 8.3.2 Official Chronograph Procedure

In the end, ONLY TWO of SIX rounds needs to meet PF.

I say cut it as close as you want.

8.3.2?

Oops, wrong game...

That made me laugh! ;-)

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