Most efficient way to test pistol loads for accuracy

[wdfwguy]

I've been experimenting with some new powders, looking for a 9mm minor (~130 PF) load.

I ran some rounds over the chrono, enough to find that velocity window for all of the powders.  Now, I plan to run 10 rounds of each over the chrono again, and shoot some groups.

Is there a sweet spot of rounds per group, and number of groups that gives you a good indicator of accuracy, without wasting ammo?  Three, five rounds groups?  Two, ten round groups, etc?

[Wobbly]

We have generally favored 8-10 rounds at each load. This is generally done with a single brand of brass, primer and bullet, with the only difference being the powder weight.



Loads are generally no more than 0.2gr per increment. I prefer small individual targets that can be studied when I get back to the bench. Such a target is the TQ-2, which measures about 5x7". So these are small enough to keep in a card file box for later comparisons.



Additionally, at anything from "plinking" up to 130PF, you're probably going to find that you'll need to re-spring your pistol for best results with your new load. This because most CZ's are sprung from the factory for max power SD loads, unless your pistol is a competition pistol from the start.

Wolff Gun Springs.... https://www.gunsprings.com/


PS. We highly advise that you include Alliant Sport Pistol in your testing.

Hope this helps. 

[Wobbly]

Is there a sweet spot of rounds per group, and number of groups that gives you a good indicator of accuracy, without wasting ammo?

There is no such thing as "wasted ammo" if you really want to achieve good test results. I would submit that a true waste would enter the picture after you loaded 5000 rounds and then found out that a load you did not test performed better !

 

[noylj]

I load 10 rounds and shoot 5 round groups.
I never shoot for accuracy at less than 25 yards for pistols or 100 yards for rifles.
Use a rest of some sort.

[wdfwguy]

Gun is already sprung for 130pf loads.  And Sport Pistol is my go-to powder, I'm just running low and thought I'd try some other powders.

So, I started with my regular SP load, then shot 4 other powders over a chrono.  I loaded 2 or 3 loads for each powder, just trying to find the charge that would give me 128-132pf.

Now that I have that, I'm going to load some rounds using each different powder.  Then chrono and shoot some groups. 

[bang bang]

What it comes down to is YOU, the shooter and reloader. 

You can change if you want.  Its not like that load will be set in stone and the reloading police will make you reload only that round.  Something to keep in mind.

FWIW, several years ago i was doing some testing with various ammo.  alot of Bulk and some target stuff on my bolt 22 rifles.  I didnt care what the outcome, but i wanted to see how each rifle varied with the various ammo i had at that time.  You could definitely see some rifles/ammo combo were better than the other, but i could not say that there was 1 ammo that worked best for ALL of the rifles.  I also made notes on the shooting conditions such as no cleaning between rounds  and no "fouling" of that brand after another brand was shot.  shoot 5 rounds of A brand and then the same for B, C...ect.

I choose 5 rounds since since my ammo came in even numbers, like 50, 100 or 250....

And fwiw, i used 5 shot groups.  I had some bulk ammo to "break in" or "season" the barrel and to align scope, but it was like 1 mag full.  No rests or cooling down between shots, just start shooting.  Some rifles had scope and some not.  If a rifle could accept a scope i moved that scope from rifle to rifle.  Some rifles were only open sights.

and fwiw, a friend ask me to replicate some 300 WIN mag.  using Nosler bullets.  he had some factory he wanted to replicate.  So i used some factory to get an idea on speed.  that was the only way i could find something to load to.  but what i did was to get that "average" speed using a chrono.  Then i loaded up 5 rounds of each using various powder weights.   The velocity that was factory was sort of in between the book min/max.   But what i did was to start at the low and work my way up.  I forget the increment, but i just guess on an increment to use so i could get somewhere and not fast and not slow.   Also, after shooting several powder variations you will get an idea if you can bump up your charge increment.  I have to drive 30+ minutes to get to the range so i loaded up more to test.   I didnt change seating depth, crimp or anything else.  But what i did was to shoot via chrono and then look at the pattern if anything.  It was really apparent in the first 3 shots if i had something good or not.  So what i did was to not finish shooting the other 2 rounds.  Or if i wanted to "foul" the gun i could use those. 

You know what you want, so if you want, use that as your "standard". 

Wobbly has a photo of a target. To me, a target is worth a thousand words.  but what i do is to print labels with info on them and stick them near the bullseye or where im shooting.  I also make notes on my excel.  If you want you can take photo and link to load used.

If you want to learn something, look up DOE -  Design of Experiments.  Its math. but you can look at maybe doing a DOE. Since you only have 1 variable if you use just changing powder charge.  I dont like math, so i will leave that to someone that has dreams about it.

last comment.  sometimes people dont want to learn or they want the quick and dirty answer.  with the www its easy now.  but if you do some testing you may find that "sweet spot" in x many rounds to determine if that combo is good enough.  Dont forget about the person behind that trigger too.  Sometimes egos get in the way.  So if you screwed that shot, just make note and continue. 

good luck and have fun.

[recoilguy]

Is there a sweet spot of rounds per group, and number of groups that gives you a good indicator of accuracy, without wasting ammo?

There is no such thing as "wasted ammo" if you really want to achieve good test results. I would submit that a true waste would enter the picture after you loaded 5000 rounds and then found out that a load you did not test performed better !

 

right on

[M1A4ME]

Load in 10 round groups starting low and working up in 0.2 (sometimes 0.3) grain increments.  Can't remember getting within 1/2 of max for pistol loads or rifle loads.

I shoot the pistols at about 12 yds. off hand.  Two 5 shot groups.  I can generally tell if I've got a good group going and screw one up.  Not always.  Sometimes I think a round should have been with the rest when it wasn't.  Every now and then one is in the group when I thought it would be a little low.

I write the load info/range, etc. on the targets when I bring them back to the table and look'em over at home.  If I have a promising group or two I'll load of some more of for the next trip and make a note in the logbook which of the loads did the best, if any.

For the rifle I do the same except shoot them at 25 yds. from a rest (I'm lousy off hand with a rifle since I've gotten older.  If I still worried about hitting groundhogs in the head out in a field somewhere I'd shoot the .223 loads at 100 yds. to see where they hit at vs. POA.  I do that, too, if I have a BDC scope so it's POI and POA are on at 100 and the "hope" it's good on out there if the scope is right.  No place to shoot farther than 100 yds. these days.

[newageroman]

Here's how I did my recent test groups.
plastic box of 50 ammo test loads 5x10
10 slots for each +.2 grains
starting and ending loads decided before loading based on convenience.
Draw it out on paper, tape to inside lid.
Bench and bags with clays at 50 yds and the chrono - 5 shots is enough to narrow the field for initial testing.

[Dan_69GTX]

Greetings    wdfwguy

You got some good info here.

Can you take some time and fill out your info?  Such as - where are you? etc.

I used to shoot the handgun on a rest to test for accuracy.  I now use a ransom rest.  If you find someone who has one (or your club might) - see if you can borrow it (or rent it for a few of their favorite beverages).  Properly used, they will take YEARS and YEARS to wear out.

Anything you do, just stay consistent to lessen the variations.

FWIW - in MY guns I find they all like their own load - so, if you NEED 130PF - start there and work a little higher to see if there is a sweet spot for your gun.  If I find one I think the gun really likes, I load up another 2 tests and do it again - to verify consistency.

For testing I normally use 10 shots if the gun can't hold that many then the capacity of the gun.

[bang bang]

Here's how I did my recent test groups.
plastic box of 50 ammo test loads 5x10
10 slots for each +.2 grains
starting and ending loads decided before loading based on convenience.
Draw it out on paper, tape to inside lid.
Bench and bags with clays at 50 yds and the chrono - 5 shots is enough to narrow the field for initial testing.

thats more or less what i did.

But i also used a spreadsheet and printed it. 

I used to shoot the handgun on a rest to test for accuracy.  I now use a ransom rest.  If you find someone who has one (or your club might) - see if you can borrow it (or rent it for a few of their favorite beverages).  Properly used, they will take YEARS and YEARS to wear out.

Anything you do, just stay consistent to lessen the variations.

Hopefully a rest or something is used to take out as much variation from the shooter.

and consistency is key. 

[otto]

"Most efficient way to test pistol loads for accuracy"

That depends on your marksmanship and distance from target.  I'm assuming you don't own a RR. 
What level of accuracy do you consider acceptable?    The more specifics you can provide will result in better answers.