Which Charge weight should I use?

[186thFCo]

Hello everyone, I'm not experienced with load development and I would like your opinion. While shooting through my crono I found two areas of interest and would like to know which I should pursue. The first was that the charge weights of 42.2gr and 42.5gr had almost equal average MV of 2634fps and 2635fps and SD's of 9.7 and 9.3. The grouping on these weren't great 1.04 MOA and .88 MOA. These are all five shots per charge weight BTW.

The other string of fire I liked had a charge weight of 43.0 gr of powder and and produced a group of .44 MOA and had an SD of 3.8. Again only a five shot group.

In a perfect world I would look at both and make rounds at 42.3 gr of powder, slitting the difference between the two charge weights that had very close MV's and try to tighten the groups up with seating depth. Also seeing if the 43.0 gr would repeat. However I don't have time to try both because I have a PRS match June 1st and I only can make it to the range one more time to test, so I need to pick one or the other, load a few tonight so a can test tomorrow and try to make the best of it.

I pick a hell of a time to not use factory ammo. Thanks for the help

 

[diggler1833]

I'd go 43gr. Not enough of a charge weight difference between 42.5 @ .88 MOA and 43 @ .44 MOA for your load to fall way the hell off the second time around (ie. You shoot a 1 MOA+ group if you tried again), and you may just be getting into a good window (have to test more to verify).

My guess is that 43gr ran again will give you somewhere between that .44 and .88, and be more than adequate for a PRS match.

Best of luck.

 

[secondofangle2]

This is all statistical noise

I’d focus on making sure you’re far enough below max pressure that you have wiggle room with temp changes and power lot/humidity variation

 

[straightshooter1]

Hello everyone, I'm not experienced with load development and I would like your opinion. While shooting through my crono I found two areas of interest and would like to know which I should pursue. The first was that the charge weights of 42.2gr and 42.5gr had almost equal average MV of 2634fps and 2635fps and SD's of 9.7 and 9.3. The grouping on these weren't great 1.04 MOA and .88 MOA. These are all five shots per charge weight BTW.

The other string of fire I liked had a charge weight of 43.0 gr of powder and and produced a group of .44 MOA and had an SD of 3.8. Again only a five shot group.

In a perfect world I would look at both and make rounds at 42.3 gr of powder, slitting the difference between the two charge weights that had very close MV's and try to tighten the groups up with seating depth. Also seeing if the 43.0 gr would repeat. However I don't have time to try both because I have a PRS match June 1st and I only can make it to the range one more time to test, so I need to pick one or the other, load a few tonight so a can test tomorrow and try to make the best of it.

I pick a hell of a time to not use factory ammo. Thanks for the help

What powder are you using? Is this a .308?

That you recorded the same velocity with 42.2 and 42.5, just doesn't really mean anything. The important thing is what you're getting on paper. So, that 43.0 grs sounds much better than the other two loads. But, as you've suggested, the only way to know is to test it again to see if you get a similar result.

 

[186thFCo]

6.5 CM, staball 6.5, Hornady brass, cci BR-2’s

 

[straightshooter1]

6.5 CM, staball 6.5, Hornady brass, cci BR-2’s

Hopefully, that load is working for you. Seems to me, when you get around to it, you might test to see where your pressure limit is, as it appears to me you've got plenty of room for more case fill, which might help with your SD's (just a thought that occurs to me).