Reloading for IDPA - advice on how close to make PF

[Quirk]

Hi, Just curious what the veterans of matches suggest for how 'tight' to make the PF threshold for a match? I'm shooting my first 'real' (sanctioned) match next weekend, wrapping up some handholds.  I'm shooting a different gun, an M&P Pro. This is shooting the same load moderately faster than my CZ 75 Shadow. What was 1020 fps ended up being 1080s-1090s in the M&P Pro. So I dropped the charge. 

For example, I chrono'd out these 124 gr bullets at the range: 1035-1045 fps today in Phoenix.  1008 fps is 125 PF.  Hard to imagine that conditions would be that different (central AZ now, to southern NM then) to risk not making PF?   

I'm not going to try to lighten them anymore, even if I could, b/c I have great accuracy and I've trained with this load. Just checking to make sure there is no real practical risk this would chrono to slow in a week?

C

[Bkreutz]

I never even get close, I load minor to 135 PF (and major to 172, but that's a different game). I never understood why people try to get so close. I've seen those same people fail chrono and it ruins their day.

[Bummy425]

I wouldnt lighten them at all. You wont notice the difference once the timer beeps! IMO, your biggest problem is switching platforms right before a match, especially moving from a heavy all steel gun to polymer. That plastic gun will dance all over compared to the cz. Have fun and good luck!

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[racknrider]

I run 130 PF out of my shortest barrel and use the same load in everything. 

As above I run 170-172 for CDP. 

[Quirk]

Thanks for the advice. I'll keep it where's it at. 

I've been shooting the M&P for 8 months, and the new lightened loads for 4 months....so I'm adjusted.

and yes I'm probably not going to underperform b/c my load was PF 128 rather than 125!  

 

C

[Hi-Power Jack]

12 hours ago, Quirk said:

  Hard to imagine that conditions would be that different (central AZ now, to southern NM then) to risk not making PF?   

"Conditions" are only one of three factors to consider ...   

Differences in Chrono's might make some difference, and

your current load is NOT 1035 - 1045 fps ....  if you shoot 20 rounds

you'll most likely find some rounds below 1005 fps.

And, as others have said above, you will NOT notice the difference

between PF 125.0 and 135.0.    Better to be safe and stay above

the PF Floor - or you're shooting for fun.

I fire 20 thru a chrono and want ALL 20 to be at least PF - usually

winds up being around PF 132 - 135 in average.     

[rowdyb]

whatever it takes for you to have a 90% confidence rating that any one bullet at random will make power factor. for me, that means 130pf.

shoot 20 rounds and record the pf for each one. then feed those twenty data points into an online calculator for standard deviation. look at the confidence rating for anything 125 or greater.

[v1911]

I keep mine at about 130-132pf. That allows me wiggle room for when I run them in my 4" guns and still make PF. 

[Quirk]

All my rounds were above 1008. I shot 14 rounds.  The minimum velocity was 1021, the max was 1080 (a rogue I think, the next fastest was 1060), the average was 1042 (my estimate above 1035-1045 was just that at the time, an estimate looking at the column of numbers before I had plugged them into Excel). I don't have all the other stats (the exact SD escapes my memory now). But I plugged them into Excel and calculated those numbers. I was most concerned that no shot was under 1008, and that was reassuring.   I was shooting all new starline brass at 1.060" OAL with precision delta 124 JHP, loaded with 3.7 gr of Titegroup. Before shooting I culled out any (and it was only a few, maybe 2) rounds that were not in the range of 1.055-1.065"...and most were within 0.003" of 1.060"

If their chrono is off, then i won't be alone in protesting, I assume. Don't they carefully calibrate or have backup chronos at big matches?

c

 

[MemphisMechanic]

You won't feel the difference (with the same bullet and powder) between the charge weights for 127 and 135 power factor.

Try it sometime. Load a mag going back and forth between the two and see for yourself.

But you'll never go home early at a major, the gun will run more consistently, and steel that's hit low has a better chance of going over.

Newbie gamers load to 127 PF trying to minimize recoil. Experienced ones load to 132-135 and know the gun will run 100% and that they can rest easy during the chrono  stage.

[Jim Watson]

I'll be shooting Tier 3 at the Mississippi state this Saturday with f = 134.  

When that lot is gone, I have some f = 132 and f = 135 for forthcoming sanctioned matches.  I have a supply of f = 130 for club shoots and practice.

[Rob Tompkins]

Another vote for 130-135 PF.  Gun is reliable, steel hits are stronger and more effective, and no worries at chrono.  If you really want low recoil got to 147 gr or even 160-165 gr bullets at 130-135PF.  A 140-145PF will start feeling harsh but 130+/- will bee just fine.

[Quirk]

That

1 hour ago, MemphisMechanic said:

You won't feel the difference (with the same bullet and powder) between the charge weights for 127 and 135 power factor.

Try it sometime. Load a mag going back and forth between the two and see for yourself.

But you'll never go home early at a major, the gun will run more consistently, and steel that's hit low has a better chance of going over.

Newbie gamers load to 127 PF trying to minimize recoil. Experienced ones load to 132-135 and know the gun will run 100% and that they can rest easy during the chrono  stage.

That's the info I was looking for, what do the match veterans do! 

[Buzzdraw]

As others in this post mention you need to base your PF off your LIGHTEST bullet in the batch and the LOWEST velocity.  I'd suggest from a group of at least 10 rounds.  For 125 PF under that premise I don't run lower than 129.  For 165 PF around 170.  For 105 around 113.  If your current load is all over the place as far as extreme spread goes, I say work up one that has a low SD and ES.

Temperature and elevation as well as relative humidity affect PF.  To keep that to a minimum i select powders that are relatively insensitive to these.

I've run the chrono at major matches where guys tried sneaking by.  Some make it and some do not.  It stinks for them. 

[S&W686]

For minor I run around 130PF and major around 170PF. 

[MemphisMechanic]

Just doing 5 points over PF isn't enough for some ammo, but is a ton of cushion with other loads.

How CONSISTENT are your velocities? If you are working with a load with a very small standard deviation (velocities all within a few FPS of each other) then you could theoretically load to 125.1 powerfactor and be okay.

(until it's colder at the match or the humidity changes or their chrono reads slower than yours - but that's a different story...)

But if you have inconsistent charge weights and  OALs and a peaky powder,  you can easily see 100fps variations in velocity. That ammo could concieveably cause issues if you loaded to 130pf and they happened to choose a few of your slowest rounds.

Develop consistent, accurate ammo with everything well about 130 and you'll be very much good to go.

An additional benefit most don't catch at first? The powder burns more cleanly / completely in most cases when you're at least halfway up the range in the reloading manual. It keeps the gun cleaner, in addition to the increased force cycling your action a bit more briskly.

[Jim Watson]

When I chronograph ammo for power factor, my main entry is the average velocity and power factor... but I also note the lowest values.

I do not take ammo with even the low end below par to a match of any size.

[ttownracer]

Much wisdom from MemphisMechanic as usual.

Heed his advice and less regrets you will will have.


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[motosapiens]

19 hours ago, MemphisMechanic said:

You won't feel the difference (with the same bullet and powder) between the charge weights for 127 and 135 power factor.

Try it sometime. Load a mag going back and forth between the two and see for yourself.

 

I can definitely feel a difference between 127 and 135 pf. I have found I can feel differences about half of that in fact.

However, I have also found that I don't shoot any better or faster with the lighter load, so I'd rather just make sure the gun runs, steel falls, and I don't have to worry about chrono.

[MikeBurgess]

11 minutes ago, motosapiens said:

I can definitely feel a difference between 127 and 135 pf. I have found I can feel differences about half of that in fact.

However, I have also found that I don't shoot any better or faster with the lighter load, so I'd rather just make sure the gun runs, steel falls, and I don't have to worry about chrono.

Similar to this, I can feel the difference between heavy slow bullets and light fast bullets at similar power factors or ammo at different power factors (within reason) while shooting statically. what I have found for me is that after the beep in practice or competition, I cant tell the difference, I have mixed 115 factory 9mm with 170gr 9mm hand loads in mags during a match and all I noticed is some of the rounds were louder than the others. Basically I think we as a group pay way too much attention to the little things that really don't matter all that much. 

[Gooldylocks]

9 minutes ago, MikeBurgess said:

Similar to this, I can feel the difference between heavy slow bullets and light fast bullets at similar power factors or ammo at different power factors (within reason) while shooting statically. what I have found for me is that after the beep in practice or competition, I cant tell the difference, I have mixed 115 factory 9mm with 170gr 9mm hand loads in mags during a match and all I noticed is some of the rounds were louder than the others. Basically I think we as a group pay way too much attention to the little things that really don't matter all that much. 

Yup. People need to quit worrying so much and messing around with loads and stuff, just find one that runs and is decently accurate and safely (both safe pressure and safe margin of error) makes pf. Then load up a couple cases of them and go shoot em up. 

[MikeBurgess]

2 minutes ago, Gooldylocks said:

Yup. People need to quit worrying so much and messing around with loads and stuff, just find one that runs and is decently accurate and safely (both safe pressure and safe margin of error) makes pf. Then load up a couple cases of them and go shoot em up. 

 

[Gooldylocks]

5 minutes ago, MikeBurgess said:

Yup. People need to quit worrying so much and messing around with loads and stuff, just find one that runs and is decently accurate and safely (both safe pressure and safe margin of error) makes pf. Then load up a couple cases of them and go shoot em up. 

You shut up.

[IHAVEGAS]

20 hours ago, MemphisMechanic said:

steel that's hit low has a better chance of going over.

It is never good to be in the bottom rung on power factor when there is steel at a match, shooting 9 minor sometimes you are going to make good hits and get hosed even if you have a reasonable margin. 

That said, how light is your gun, how strong is your grip, is the recoil impulse a bang or more of a push, etc, etc, determines how sensitive you are to time lost for recoil control. 

For some reason 40 minor (180 grain) at about 140 pf seems as controllable to me as 9mm at 130. 

[MemphisMechanic]

37 minutes ago, motosapiens said:

I can definitely feel a difference between 127 and 135 pf. I have found I can feel differences about half of that in fact.

However, I have also found that I don't shoot any better or faster with the lighter load, so I'd rather just make sure the gun runs, steel falls, and I don't have to worry about chrono.

Okay okay, yes. Technically... you can feel it. Standing and shooting.

During a match? Nah.

Load something reliable and accurate and consistent and focus on practicing with it. Not chasing the perfect powder and bullet with load after load.

I think we're all saying the same thing.