All of chrono procedures I've been through went the same. You go to the station, you give them your ammo (I usually unload one of my mags), they remove one bullet and weigh it, they chrono three shots, average your velocity, and give you your power factor. If your PF is marginal, one low outlier can bring you under. If you don't make the PF on your three, they do additional testing but I've never seen it done so I am not sure what the protocol is.
I've heard of random ammo samples requests but never witnessed one.

I personally shoot factory 9 mm ammo and never had issues with chrono. American Eagle 115 grain usually clicks at 132; 124 and 147 grain, as well as 150 Syntech clock at 140 but the latter shoots softer.

 

Thanks for the reply and info YVK. I am also shooting factory 9mm. I am only reloading right now for the wife's 45acp ammo as she is shooting single stack division and 45 costs more. If they are only testing a random 3 generally, then I am probably ok with my current reloads with having the lowest at 164 (just under major power factor 165) out of 15 rounds or so. Some more chrono needed, but just want to understand my margin for error. Sounds like with my average at 170 and one failing out of 15 rounds just barely, I am on target with the current formula to not fail if they are taking an average. Thanks again for the reply.

 

I don't know if this is still the procedure, but in the past, at Nationals or such, they would pull eight rounds at some point, labeling it as yours.

When you (or your squad) report to the chrono station, they have pulled one bullet and weighed it. They then will acquire your gun and an empty magazine to test fire. Three rounds are fired and averaged for the velocity, then the power factor with the weight of the bullet they pulled.

If the first three do not make it, the second three are fired. They used to take the best three velocities and use that average with the bullet weight.

If that still does not make it, you have the choice to have then fire the final round, or pull the bullet to see if the new bullet weight will make it.

 

This^^

If your don't make PF with the initial 3 x the pulled bullet weight....
Each of the next 3 chrono'd shots will be re-figured with the previous after each shot and the 3 highest velocity results will be used.
If you still fail to make PF after each one of the additional 3 results, the 7th round will be your option...weigh the bullet and recalculate using the previous top 3 results or chrono it.

 

I would bump up a little to get a little headroom. It won't make much difference in felt recoil.
Just curious, what's your major load for the missus?

 

Thanks for the info Reloader and thanks for the advice Oldfut808. As far as the current load Oldfut808; with 230gr round nose copper plated, W231 powder, bullet length (OAL) 1.26, width .472, powder grains at 5.3gr. Much softer than factory and averaging 170 power factor with a small sampling. This is a competition sub section though (not reloading), so any additional responses, please comment about competition power factor testing procedures and related. Still learning. Never seen ammo tested at a match yet. Is there a lot of differences in how that goes on or when?

 

When the PF was 175, most of us loaded to 185. It's a small bit of insurance. Temperature can make a difference, usually not in my favor.

 

If you're cutting it that close that you are worried, you should bump it anyway.

At most matches they ask you at the first stage for 8 of your rounds. They will weigh one and test 3. If you pass you're good, otherwise they will shoot 3 more. If you still don't make it you have the choice to re-weigh #8, or shoot that one also. They will take your best 3 shots and average those to get your power factor.

At the section match here that I've been a CRO at for three years we pulled mags off of people belts after the first stage, so they weren't able to choose their 8 perfect rounds to give the chrono man. You see some interesting reactions when you do that. It's funny when someone declares major and goes subminor.

 

All of the above.….

It gets a little ridiculous that some people will obsess over just barely making "Major" in order to get some perceived reduction on felt recoil and somehow this translates to better scores.

Be extra vigilant at reloading and practice, train, practice, train and repeat!

Practice and training far outweighs any "benefit" of a few power factor points.

Smiles,

 

We have only shot level one matches over the past year and have never seen a match official test someones ammo with a chrono. We will attend our first level two match, a sectional in mid August. Maybe they don't test at level two either. I have no idea.

Pretty sure you will have a chrono stage there. Every Area match I attended had a chrono. Never at a local match. They take a sample of 8 from you. Pull the bullet and weigh it from one. Shoot 3 and average it for your power factor.

Also be aware that your chrono at home may not jive with the one at the match. As stated already its always a good idea to bump your load up a little just to be safe. I recommend 5% velocity target, over minimum power factor for your bullet weight. For instance,

9mm 124g @ 1009 fps = 125.12 pf

up the velocity 5% to 1059 fps = 131.37 pf

45 200g @ 825 fps = 165 pf

up the velocity 5% to 866 fps = 173.2 pf

Thats the formula I use and I have never failed a chrono.

 

If you are averaging 170, I would stop worrying about it, especially if your lowest out of 15 was 164. With those numbers it is statistically near impossible to go minor, considering that you only need your best 3 out of 7 to make pf. Most people are not very good at math tho, so they use formulas like going 5% higher or whatever, without taking into account the standard deviation of their load, or any sort of probability calculation.

I generally load major to 168-170, minor to mid 130's (to knock down steel, not because I'm worried about going sub-minor), and I've never had an issue. My SD is almost always in the single digits tho, so I have great confidence that I'm not going to get 6 out of 7 rounds that are drastically low.

Now the one thing you might want to take into account is if you haven't been chrono'd before, you don't really know if yours is going to read the same as the one at the match. Mine always gives the same figures (within a percent) as the ones at the 20 or so major matches I've shot, but I also make sure my chrono is in the shade when I test. If i put it in the sun, it typically reads higher..... so I don't do that.

Another thing worth taking into account is if you have a backup gun, you want to know if it is different than your primary. My backup gun is 2-3 pf slower than my primary, so when I discovered a broken ejector the night before Area 1, I was sweating it a little knowing that my 167 pf rounds might be cutting it close in the backup. Turned out I only needed 4 bullets to get a best 3 that was over 165 (165.4 or thereabouts), so all was good, but that's why I load to over 168 with the primary gun now.

 

If you are averaging 170, I would stop worrying about it, especially if your lowest out of 15 was 164. With those numbers it is statistically near impossible to go minor, considering that you only need your best 3 out of 7 to make pf. Most people are not very good at math tho, so they use formulas like going 5% higher or whatever, without taking into account the standard deviation of their load, or any sort of probability calculation.

So educate those of us who are not very good at math. How do you take into account the standard deviation of your load, and give us an example of how you do a probability calculation for your loads.

 

Originally IDPA was a bit different.
For convenience, they usually shot your ammo in your gun, but you were entitled for it to be tested in the longest barrel available in your Division.
Ammo that was fine ca f=131 in my Colt was below 125 in my Sig Sauer. Fortunately the chrono station gun was a Colt and my loads passed handily in it.
They don't do that any more.

I never had any trouble making .45 Major for IPSC, USPSA, or IDPA CDP.

 

I only ever saw one local club do power factoring at their matches, and not every month at that. Everybody likes to shoot, hardly anyone likes to WORK matches.

 

Some matches will at random collect ammo, or after a specific stage. Some will take what you give them others will choose a mag after you've shot a stage. Our local club will chrono ammo at our monthly match when there is an upcoming big match. This gives shooters who don't have one to see what their pf is. You don't want to travel, hotel, etc. and not make it through chrono. They will also make sure your gun fits in the box and test safety function if applicable. Also holster and mag pouch position.

 

I have seen less than 5 random chrono checks at local matches in the past 20 years I have been playing USPSA/IDPA/ICORE/ect.

 

I meant to say they may randomly collect ammo at major matches, not local. Some majors will let you know they will do chrono after a specific stage, while others won't tell you when they'll collect your ammo. But we have chronod ammo at locals just before major matches so shooters can check their ammo.

 

Thanks for all the replies and great information from everyone. I did some reloading tonight and I did bump it up grain wise ever so slightly though I was probably ok without doing that. It was very slightly though.

One post mentioned, and I paraphrase or rather summarize here, learning to shoot is the main thing and not trying to get as close as possible to power factor. I agree 100%, just the wife who is skinny and weak arms, refuses to switch to the softer 9mm and divisions for that, and insists on shooting 45acp. She likes big dogs and big calibers. Part of it is the single stack pistols simply fit her small hands better. At our age though (early 50's, the recoil is punishing from the 45). Though she won't admit yet. It is why I switched to 9mm these days. Love it. But anyhow, just trying to help her recoil out as best as possible while staying USPSA legal. Will be experimenting with 185gr and 200gr bullets in the near future. Again, thanks for all the great info on how USPSA goes about testing at matches and when. Very informative for us newbies.

 

No matter where the match, out-of-state chronos read slower than at home.

 

No Kiddin'



No kiddin'! The formula for power factor should "factor in" distance from home!

It seems if I ever had gun or ammo issues it was always the matches farthest from home with really high match fees to boot! Making that ride home really long!

Smiles,

 

I ran out of recoil tolerance some time ago. I didn't want to shelve or sell off my .45s, so I went to .45 Minor. Low recoil and the big holes will gain a point every now and then.
I have nine shot magazines that will fit The Box for IDPA and SS. Some made by cutting down ten shot magazines, some by a particular combination of tube, follower and spring.
I think it would also be possible to use ten shot magazines in L-10 Minor, but I will have to measure a magazine to be sure.
ETA Yup, well under 170mm..

 

I ran out of recoil tolerance some time ago. I didn't want to shelve or sell off my .45s, so I went to .45 Minor. Low recoil and the big holes will gain a point every now and then.

Interesting Jim. I had not thought of downloading 45 to minor and going that route. I started USPSA shooting a 9mm 1911. Soft shooter it was, but of course with scoring major vs minor, you gotta be one accurate SOB to really compete. So I personally switched to production division. This is about the wife though of course. The wife is actually very accurate, and downloading a 45 to take advantage of the close call shots with a wider bullet is a very interesting approach. Not going to happen, but a very interesting approach I had not thought of. Thanks for your reply.