Load testing

[IA_shooter]

So what is the conventional/professional wisdom concerning load testing as it pertains to how long to wait between shots and shot groups while testing loads? I have a series of 5 loads, 5 rounds each I want to test this morning using Hornady 75 grain BTHP and Varget in my 223. I don't see this discussed much and would love some insight from y'all. Thanks.

 

[Bc'z]

Shoot 5 n let it cool to at least warm.
Take a nother gun with you to shoot between firings so as you give it a chance to cool.

 

[IA_shooter]

Well, not much for responses before I left this morning but I did my load testing shooting round robin style, one of each charge at each target and taking my time between shots, then waited 10 minutes and shot another round reversing the charges from highest charge to lowest charge. Went back and forth that way and got these results in the pic.

Chronoed everything with my Pro Chrono and 23.5 grains had the lowest overall fps deviation and also shot the best group overall and the factory Hornady Black ammo I shot came in a close second for lowest speed deviation and grouped almost as well. Probably because the factory ammo was the closest to average speed as the 23.5 grain group at just a tad faster by only about 20-25 fps average and the one shot farthest to the right in that group was actually my fault more than anything.

 

[K22]

For load development, I like to shoot five shot groups from a cool to cold barrel. Depending on ambient temp, I generally wait at least 5 minutes between shots. Also, I don't attempt to do too much load testing in one range session so as to not let fatigue or lack of concentration affect my testing. I normally don't test more that three combo's (5 shots each) in each range session.

Incidentally, those are some since groups on targets 1,3 and 4.

 

[Dusty Stevens]

Dont wait between shots on one group. Shoot them as fast as you can so the conditions cant change. In 5 minutes between shots there is no way youre going to shoot a good group or get any useful info

 

[grovey]

I only do load development in 3 or 4 mph winds tops. I shoot three shot groups the first time around and fire them fairly quick. Wait 5 mins repeat. Usually I switch guns after the second group, and repeat the process with that gun if I'm doing development with that one too. With time and my wind requirements I usually have more than one to play with. To each his own, but I won't shoot them in the order you did. Seems like the conditions would change to much.

 

[corsair4360]

I usually have 2 or three rifles to shoot, letting each one cool off after a three shot string (for hunting rifles), five shot strings fired more slowly for long range target rifles. The rifles cooling off are vertical in the rifle rack, until they are cool to the touch, which can take quite a while when ambient temperatures are above 75(F) or so degrees Did that Friday morning at the range with a 7mm Rem Mag (my brothers) and a 270 WSM, which I have since figured out has severe throat erosion and therefore is on the list to get re-barreled so my 338 Win Mag gets primary duty this fall on elk, with my backup rifle being a 30-06 1917 Enfield which was extensively customized in the 1970's and re-barreled 2 years ago.

 

[Intheshop]

Am finishing up a cast,varmint blaster 7-08 load.37g Varget behind a swaged(meplat)285-130R Lee,cast "real hard" and water dropped.

Anyway,the load has made it through all the early stages..... now it's,step out shop door to send 5 as fast as I can work the bolt.Gather up the brass,go back inside.Repeat a cpl times a day,every day.... once there,start picking crummy weather.Especially rain and high humidity.Within a week or so it's,park whatever hunting rig that was being drug around and go kill something with the new load.Wash/repeat.

 

[IA_shooter]

I only do load development in 3 or 4 mph winds tops. I shoot three shot groups the first time around and fire them fairly quick. Wait 5 mins repeat. Usually I switch guns after the second group, and repeat the process with that gun if I'm doing development with that one too. With time and my wind requirements I usually have more than one to play with. To each his own, but I won't shoot them in the order you did. Seems like the conditions would change to much.

My 100 yard test range I have set up is almost completely surrounded by the woods and is fairly wind protected so I'm not too concerned about condition changes. Here's a view of my range.

 

[Dusty Stevens]

My 100 yard test range I have set up is almost completely surrounded by the woods and is fairly wind protected so I'm not too concerned about condition changes. Here's a view of my range.

I think that if you actually put flags up it would be an eye opener in that tunnel

 

[ClassCat]

I think that if you actually put flags up it would be an eye opener in that tunnel

Dusty nailed it. YOU NEED FLAGS !

 

[boltfluter]

I would drop the round robin style for what you are doing. To much movement of the rifle IMO. Makes it very hard to shoot groups even with a great load.

Paul

 

[T-shooter]

The conditions for each shot should be as similar as possible including barrel temp. I usually fire about 3 warm-up rounds, let the barrel cool and absorb the heat for a minute or so and then start shooting groups. I usually use a barrel cooler blowing air through the chamber and out the barrel and keep direct sunshine off the barrel as much as you can while cooling. Depending on the outside temperature, 30-60 seconds is all that's necessary. My gauge for temperature is if I can hold the barrel without it being uncomfortably hot, roughly 100° - 105°. I use the round robin style most of the time. Do everything exactly the same. If the wind picks up, wait on it to calm down. If you get a flier or it doesn't feel right, shoot that one over and discard the previous shot. It would also be good to chronograph and keep track of each shot. Keep your ammo out of the sun where it can get hot and don't leave a round in the chamber very long before firing.

 

[KenOath]

Always use flags.. My general rule is 2-3 foulers, then 2x5 shot groups then let Barrel cool for a timed 5mins with a barrel cool fan inserted, then repeat..In general no more than 40rnds 8 groups.

 

[Puzzaz01]

Dusty nailed it. YOU NEED FLAGS !

+1