What is a comfortable margin for making minor?

[westczek]

What is a comfortable margin for making minor? I have crono'd a number of loads I could use for a match that will have a chronograph. Temperature should be similar t when I recorded the data. What should I consider?

I took readings of 5 rounds of incrementally heavier loads. Should I average all 5 velocities or just use the lowest 3? Based on this the loads I've been using are around a 136 power factor. Velocities of 853, 860 and 876 for and average of 863 with a 158 grn bullet ( weight range of 157-159).

Any thoughts would be appreciated.

Westczek

[yoshidaex]

At the very least, i'll go for 5 above the pf i'm trying to hit.

But i've noticed its best to find a load that runs the gun without any malfunctions.

So if a 135 pf load runs my gun 100%, i'll keep it at that pf.

[jasmap]

8-10 above the minimum PF of 125 is comfortable and helps to take down steel.

[twodownzero]

at least 8, 10 is better. Mine are 135-136 pf.

[Sarge]

10 for me as well.

[BlackSabbath]

I run 135 in my CZ Shadow.

[GForceLizard]

You should chrono more than 5 rounds. My chrono reads 10 round strings so I use 10. If you are loading 8-10PF above the 125PF then none of your 10 rounds should be under the 125PF.

[BayouSlide]

Definitely 10 round strings. Another good idea is to use brass with the same headstamp for major matches with chronos: it reduces another potential variable. You've already said you're chronoing under the same temps you expect at the match.

Under all those conditions, I would not be comfortable with a load that left any round under minor floor if I were shooting for 133 PF. I've seen similar chrono setups at matches vary from my chronos by a factor of 2-3 in either direction more often than not.

Curtis

[vluc]

10 rounds and at least a ten point difference over the minimum power factor. Add to that finding the load that makes your gun run the smoothest and you may be a few more points up.

[lugnut]

About 135 for me too... that way if you are off on a batch or your powder measure drifts you still should be ok. Plus my Glock runs better at 135.

[Flexmoney]

There is not need to chase the lightest mousefart load one can get away with.

I see so many shooters get all caught up in getting the lightest load and playing with springs...to chase some magically "softness". (grip and stance take care of all that)

Number one rule for me is the gun has gotta run. For that, I like to have a heavier recoil spring than most so that there is no problem with stripping a round from the magazine and feeding it into the chamber...plenty of spring energy to get the job done. (I often use a stock recoil spring in my Glocks, 17lb)

That also means I need enough power to drive the slide fully to the rear (sometimes with a bad one-handed grip). Therefore I run a bit higher power factor as well.

Another benefit of running a higher power factor for Minor is that you don't ever have to sweet it at the chrono stage. And, yet another huge benefit is that you can take down steel poppers better...it they are set a bit heavy or if you get an edge hit.

135-140 pf is what I'd suggest if you know that where you shoot happens to have the steel set well...usually. There are some places that I have shot that make it wise to bring the power up above that (usually not an USPSA match.)

[DWFAN]

I think the OP may be using a revolver.. just a guess based on his bullet weight and speed. So springs and running the gun may not be an issue.

Would Revo vs Auto change any of your responses ? I only ask because a lot of the Revo minor loads I see poseted fall between 128 and 132 pf..

[steel1212]

I'm with Flex, if its an auto my 9mm minor loads are around 135-138PF.

[G-ManBart]

Another vote for 135PF+. There's no real need to go over 135, unless that's where your gun runs best.

I do multiple 20 round strings. Sometimes I'll do a quick 10rd string just to see if a new load is in the ballpark, but when I really want to know, I run a 20rd string, let the gun cool a bit, then run another 20rd string. I do that under as many different weather conditions as possible (mostly temp), so there are no surprises when going to a match where it'll be hotter or cooler. R,

[Dan Burwell]

Here is my method however flawed: 3- 10 shot strings, one ambient temp, one from the freezer, one from the crockpot (my wife doesn't mind to much). The slowest round of each string must hit 130pf doing the math as if my bullet weight is one grain less than it is.

This way if I am shooting the frozen penguin match (Jan in northeast PA)or USPSA nats in Vegas I am covered and never sweat the chrono.

For what it is worth this usually yields around a 135-140pf.

[Sarge]

135-140 pf is what I'd suggest if you know that where you shoot happens to have the steel set well...usually.

Reeaally!

[G-ManBart]

Here is my method however flawed: 3- 10 shot strings, one ambient temp, one from the freezer, one from the crockpot (my wife doesn't mind to much). The slowest round of each string must hit 130pf doing the math as if my bullet weight is one grain less than it is.

This way if I am shooting the frozen penguin match (Jan in northeast PA)or USPSA nats in Vegas I am covered and never sweat the chrono.

For what it is worth this usually yields around a 135-140pf.

Can a Mod please turn something from this into a new avatar line...it's really too good to pass up! "Minor Crockpot" has a ring to it....

[Aircooled6racer]

Hello: I like to be at 131PF so it will not be minor at any temps. Thanks, Eric

[bbbean]

If you miss your PF for major, you lose a few points, but you're still in the running if you shoot As. If you miss your PF shooting minor, you're just getting to practice with a bunch of other guys. I might run a very consistent 170 PF load for Major, but would hate to run anything under 135 or so for minor.

[Rob Tompkins]

Don't forget to accuracy test your load.

The most accurate load will not always be at the "ideal" PF, whatever you determine that to be. For me, accuracy is #1 consderation, then does it run the gun (non-issue with a revolver), and finaly does it make PF and by what margin.

As to PF, I look at as big a sample as practical but IMHO 10 rnds min. Consider extream spread (ES), standard deviation (SD), average, min vel, etc. For me if the (avg vel - 2 x SD) > min PF, its ok.

Edited September 7, 2010 by Rob Tompkins

[westczek]

Bonus points to DWFAN, I am a revolver shooter, one of the few not using a S&W 625 and 45 ACP it would seam. I use 38 special in a 6 inch S&W 686, so recoil isn't much of an issue. You know, no mater how high a power factor, I can't get the ammo to cycle my wheel gun

Thanks for all the advice on this issue and ideas about methodolgy. I have three 5 shot strings for one of the lighter loads and even the lowest velocity shot is above than 130 power factor.

Westczek

[DWFAN]

Bonus points to DWFAN, I am a revolver shooter, one of the few not using a S&W 625 and 45 ACP it would seam. I use 38 special in a 6 inch S&W 686, so recoil isn't much of an issue. You know, no mater how high a power factor, I can't get the ammo to cycle my wheel gun

Thanks for all the advice on this issue and ideas about methodolgy. I have three 5 shot strings for one of the lighter loads and even the lowest velocity shot is above than 130 power factor.

Westczek

Whats your load if you dont mind sharing? (Im still searching since I just got a new to me 686ssr to play in IDPA with)

[westczek]

DWFAN,

I'm running a 6" barreled 686 for what it's worth. Your velocity will be less in 686 SSR, but I have no 4" barrel data. I've been using this for the last year. If you crimp it tigt enough it averages around 900 fps with about 60 fps range.

158 grn LRN moly coat (Black bullets Int)

Remington or Federal brass

Federal primers

4.8 grn Unique

OAL 1.45

Taper crimp

I have also been working on a load with same specs, but wih Solo 1000, looks promising, but not a lot of data yet. I worked it up to 4.2 grn Solo 1000. Only 5 rounds 861, 845, 844, 874 and 856 fps. Lots of published data for Unique, but not for Solo 1000.

Westczek

[Flexmoney]

I think the OP may be using a revolver.. just a guess based on his bullet weight and speed. So springs and running the gun may not be an issue.

Would Revo vs Auto change any of your responses ? I only ask because a lot of the Revo minor loads I see poseted fall between 128 and 132 pf..

I have run chrono at a few Major matches. Two shooters (at different matches) that I recall not making their declared power factor... were shooting revolvers.

7pf over the floor is a minimum, IMO.

Icarus.

[Flexmoney]

135-140 pf is what I'd suggest if you know that where you shoot happens to have the steel set well...usually.

Reeaally!

Yes...that was for you.