Home Forums Reloading Big Game Rifles 2 shot development

here is some information on 2-shot testing.

http://www.public.iastate.edu/%7Ejessie/PPB/PPB_files/Page760.htm

I think this is what its all about. Like I said, I just read it and interpreted it the way I saw it - the idea of using two shots as a start.

I think the idea was to start testing with two shots, and like Fireball said if they are not close then move on.

I did this last night. I started load development with some new Hornady bullets in my 7-08. I had already found a load with Sierra bullets, so I knew kind of where to start. I loaded some up and shot them into a decent group. I did shoot 3 times - just couldnt help myself.

Then, I decided instead of playing with powder charge, I would play with OAL. I started with .020" off so I shortened it up to .015" off. The first shot was way high and left. Honestly, I thought to myself I should stop there and seat the other bullets deeper, but I just wondered if it was one of those magical fliers. So I shot another.

That one hit low and left. At that point this whole conversation made sense to me. I did not even bother shooting the third and went back to the shop to seat it deeper.

On the other hand, if/when I do shoot two in tight together it just makes sense to shoot another one in there to see what happens. And I suppose, if that 3rd flies in there close it makes sense to send another one in to see what happens. So on and so forth.

But I am almost next to positive the original thought that I read was for those loads that don't get anywhere close to each other with the first two shots. Relatively speaking of course. I suppose you would have to have a base line to say what close vs far away is.

Interesting article, but I think its a tad off of what load development would be. That deals more with load testing, which I could totally see. Using two shots to not only tell how far apart they hit, but how far away from POA they hit.

But for load development, POA is kind of relative because as you reach different nodes with powder/OAL your POI changes, but groups can remain the same. I saw a good example of this last night. I had two groups that measure almost identical as far as size goes, but the POI changed because I changed OAL.

I cant tell you how many groups I have had "ruined" when the third one, all of a sudden dashes off to the left or right an inch or more.

Even if the group is horrid after 2 rounds, I always shoot the third one. If nothing else, for more trigger time.

During load development, or just practice/testing?

I'm all about trigger time. But when I am developing a load I want to do so wisely and logically.

Load development.

If u load 20 rounds, I'm firing the 20 rounds. Unless of course pressure is involved.

Makes sense to me. Find a load that will at minimum put two bullets close and go from there. If you can't at least get there as a starting point why waist gunpowder and lead continuing on.

I've always used 3 shot groups myself as I figure the only thing a 5 shot group will tell someone like me is my factory barrel is still indeed a factory barrel.

Sometimes in my opinion a 3 shot group will also reveal a factory barrel on the 3rd shot

Overall I can see the reasoning and a place for two shot load development although it would depend on what sort of hunting rig one is useing. For instance a custom varmint rifle a two shot load development might be a waist of time and effort.






Trystan

I'd say two shots can't prove a load to be good but can go a long way toward demonstrating that a load is NOT good, and gives a rough idea where the zone IS NOT. I use this method myself when I am trying something new and looking for charge limits.

It seems like a good way to weed out the junk and save a little bit on components. I typically run 3 shot groups because it give a little more proof of the good loads, but the bad ones just burn more powder. This may be a good way to go for the first round of testing.

I think what people are missing. A guy is shooting a hunting rifle, he shoots 2. Lets the barrel cool. Shoots 2. etc. This 2 shot group process gives plenty of data on a loads ability to consistently kill stuff. Some light weight rifles just will not shoot 3-5 shot groups. But who cares. It's a hunting rifle. I have hunting rifles. I need them to put the 1st bullet where I want it. I have a 7mm rem mag that will put 2 into under 1" at 300 yards. Shoot a 5 shot group at 100 yards and it is 2" let it cool completely go back to the 300 yard target. 2 inside 1" again. Heavy barrel rifles have a different objective than a light barrel. I have a 223 that will put 4 under 1-1/2" at 300 yards. 5th shot always adds 1" to group. Why shoot the 5th? just set it aside to cool. Then shoot 4 more. It is a hunting rifle loaded with hunting bullets. Why would I care about groups outside the barrels good group zone. Then there is the large case capacity rifle group. Think about a 300 weatherby with 90 grains of powder. 2 round testing makes complete sense. Barrels get hot fast when you are burning 80-90 grains of powder. Shoot 2 let it cool.