time intervals between shots during load testing

[marchx]

What kind of impact has the barrel temperature during testing new load, different charges in seating depths etc. on validity of the test?

Obviously barrel's temperature increases with every consecutive shot. How much does this factor affect group pattern and size if you test e.g. 5 different seating depths shooting 3 rounds for each?

What time intervals between shots (series of shots) do you implement?

 

[markm87]

We just got the Garmin Chrono, and are tracking EVERYTHING. I'd love to see steady increase or decrease in velocity as barrel heats up, but it's simply all over the place.

Time intervals for us in AZ can be exhausting. In the summer, the barrel never cools off, so we just shoot as long as there's no suppressor mirage in the scope.

 

[Zero333]

Develop the load according to the way you're gonna be shooting it in real life matches etc..

 

[Bc'z]

^^^^ train like you fight^^^^

 

[mikecr]

With proper testing, barrel temps and seating depths are unconnected.

 

[dgeesaman]

Within reason, load test like you shoot it in practice. As the barrel gets hot, I find it doesn't affect much except the time spent on the bench and aggressiveness of the barrel wear.

Except:
* Hot cartridges create excessive barrel wear if you let the barrel get too hot.
* A hunting rifle that is shot for purpose in a dead cold state, is worth understanding how accurate the first cold bore shot is. That can't be learned with a warm barrel.
* A barrel chamber that's much warmer than ambient conditions can change the temperature of your chambered round and potentially increase the velocity and behavior of that shot. So if I might need to wait for a condition, I don't close the bolt to avoid heating up that round.
* Certain load development methods involve shooting your test loads round-robin, and for most cartridges and barrel weights that means going steady and not letting the barrel get too hot or too cold.
* You as a shooter have a tolerance and it's not load development if the shooting is more than you can be consistent with.

Changes in conditions are a real nuisance for load development and since I shoot short range I tend to shoot each load development group fairly quickly and let the gun cool in between groups. Long range shooters who are looking for patterns in the vertical probably won't do it that way.

 

[Coyotefurharvester]

When the flags are correct.

 

[K22]

Lots of good comments.

For me, the cold barrel shot is the money shot since I am a varmint / predator hunter. We don't get free sight in or fouling shots. So, my load development and range practice are all geared towards cold barrel shots. I avoid hot and overheated barrel shooting since this has no relevance to my use (eastern woodchuck and predator hunting) plus being hard on the accuracy life of the bore.

To effectively accomplish this, I do not do a lot of load development in one range session. I usually only will test two or at the most three 5 shot loads in one range session. I also try to pick a day and time of day when mirage and wind is minimal, and the temperature is moderate. Shooter fatigue is real, and one should avoid trying to test too many loads in one range session anyway.

With extruded powders most of the loads I have tested and selected shoot well both in hot and cold weather. However, the POI often changes due to air density changes. This I have verified this many times. In other words, if you sight in your varmint rifle in warm weather then later plan to hunt predators in the winter, one would be well served to recheck the sight in before going in the field. The reverse is also advised.

 

[Old Navy]

What kind of impact has the barrel temperature during testing new load, different charges in seating depths etc. on validity of the test?

Obviously barrel's temperature increases with every consecutive shot. How much does this factor affect group pattern and size if you test e.g. 5 different seating depths shooting 3 rounds for each?

What time intervals between shots (series of shots) do you implement?

I could do your test non stop with my 22XC but not with my 6.5X284 or my .284.

 

[Chris Edmondson]

What kind of impact has the barrel temperature during testing new load, different charges in seating depths etc. on validity of the test?

Obviously barrel's temperature increases with every consecutive shot. How much does this factor affect group pattern and size if you test e.g. 5 different seating depths shooting 3 rounds for each?

What time intervals between shots (series of shots) do you implement?

I've found 3 or 4 shots get's me past cold bore, not that cold bore is bad, just a bit unpredictable. From there, I'll run no more than three 5-shot groups in a row, then take a break. I do use a cordless fan to keep the air moving if ambient is hot, say 80F or so. More than three 5-shots in succession, things get dicey; vertical stringing.

Thanks to advice from a sage, I don't close the bolt on a hot chamber until it's trigger time.