Problem with belt cartridge

[Mada]

So I finally went out to the range today to test out my reloads.

I used:
Remington brass
Winchester WLRM primers
H4831
and Hornady 139 BTSPs

I loaded from 56.0gr to 64.0gr in 1.0gr increments

And this is what I have

 

[Mada]

My best group was the 56g at .619minutes

57.0g was measured to 1.113 lengthwise

58.0g was measured .564 without the straggler up left, What I think is that after the 4th shot, the 5th shot is thrown off. Could it be because of the barrel heating?

59.0 g wasnt included as the group wasnt as good

60.0g had a decent 3 shot group that measured .483, but had two stragglers both right and left of the groups, Im curious to what could of caused it

61.0g isnt shown

62.0g has a 1.279 group measuring vertically

63.0g has 1.113 measuring farthest to farthest

 

[Mada]

And last:

64.0g which had one pattern on the left that is just one hole, but as you can see the whole grouping is really thrown around. I didnt measure the MOA of this group as it wouldve been useless, but I was wondering what you guys think could be the problem.

 

[Mada]

This is my first load so I'm asking what you think I should work with to improve, what grain should I work around with to try and find that right load.

Im really liking the 64.0g because of the two shot/ one hole pattern.



Critique me, please

 

[bman73]

go back to 56 grains and play with seating depth

 

[Mada]

alllrighty

 

[Mada]

Do you guys do 3 round test groups or 5? If not, what is it you do?

 

[jimbires]

I'll load 4 or 5 of each , but I usually shoot groups of 3 . if three shots are grouping wide there is no sense shooting 5 . jim

 

[rscott5028]

3 shots per load is fine for working up.

Then, pick your one or two best groups and try multiple 3 shot groups without changing anything to be sure it's repeatable.

Next, take the best load and repeat the whole process while changing the seating depth and holding everything else constant.

-- richard

 

[Mada]

So the COL of my bullets seated to the cannelure is ~3.250.
Touching the rifling its ~3.320

I've made test rounds with COL, seating deeper in .010 increments such as:

3.320 (kissing)
3.310
3.300
3.290


and then some more normal 56.0gr with cannelure seating.

seems good?