Load development question.

[GRiNGo]

Hi, I'm starting load development for my new Tikka 260. I only have one bullet and three powders on hand so this is where I started. I will order more components if necessary. The bullet I have is 140gr A-max and the powders are RL-15, H4831 and H4895. I started with H4831 and RL-15. I achieved 3/4" 3 shot groups at both 44 and 45 grs of H4831 and a 1/2" group with 36 grs of RL-15. This is at 100 meters. Now my questions are, with the RL-15 it is probably a little fast and this is why the case volume is not full, so is it bad to not have your case close to full if you are getting good results? Also I think the felt recoil was a little less with RL-15, can I assume without using a crony that my velocity was also less? Is there a program that could give me a "guesstimate" on velocity?
I do have a friend that I can borrow some H4350 from as that seems to be the goto powder for this caliber and is in what I think is about the right spot on the burn rate chart. But I had such a good first result with RL-15 I may have to continue to check it out.
I will shoot more than 3 shot groups now that I have found some "sweet spots" so no blasting me about 20 shot groups please.
If there is any other info you need let me know, and thanks for any input. Oh, I used Remington brass, and Federal 210M primers.
-Chad

 

[Duck_Hunter]

Your reloading manual or go to the manufacturers website and look up some load data should give you a guesstimate, but your best bet is to pic up a chrony and see for yourself. Here's some info from the hodgdon site, Varget has a close burn rate to RL-15, and the partition is not going to have as high a B.C. as the A-max, not to mention likely differing barrel lengths, etc. so take it for what its worth.
140 GR. NOS PART Hodgdon Varget .264" 2.780" 34.0 2469 53,300 PSI 36.0 2578 59,400 PSI

 

[Boomer]

Provided your velocity is in the right ball park range and the load proves accurate, it doesn't much matter if there is air space in the case. If you were shooting long range you might have some issues if there were large variations in velocity, but at ranges under 300 yards you should get good accuracy even if there was a fairly large extreme spread.

Judging velocity by felt recoil can fool you. Either guestimate the velocity from the information in your loading manual or like Duck Hunter said, get a Chroney. Another method is to sight in for 100 yards and shoot at a 300 yard target. Match up your 300 yard drop with the drop tables for your bullet and you should get a pretty good idea of the velocity.

 

[cosmic]

In my experiences, rifles tend to tune to a specific bullet weight. If you've got a good bullet, and it seems you do, then playing around with powders is just "icing on the cake."
FWIW - For the average shooter 1/2 MOA is about as good as it gets. Depending upon your shooting skill, you may waste a lot of ammo trying to get the rifle to shoot better than this...