OCW opinions for a 6.5CM load

[User4302021]

I can't see the photos. Can anyone else?

 

[Echo Charlie]

Sorry not the best one with this tools

 

[Echo Charlie]

Still searching for a load started this test when 24" barrel had 130 shots.

Same components of previous tests:
Lapua SR primer cases once fired
N550 powder
CCI BR4
Hornady 147 grain ELD-M
COL: 2.880" (Maximum for magazine). Lands @ 2.913" (.033" Jump).

Distance to target 528 yards

first shots #1 to 5 with 39.2 grain
shots #6, 7 & 8 with 39.4 grain
Shots # 9, 10, & 11 with 39.6 grain
shots # 12, 13 & 14 with 39.8 grain

After this tested for COL

Charge of 39.4 grain
3 shots each COL: Maximum for magazine / .010" less / .020" less
Distance to target 109 yards

Any comments are appreciated.

 

[User4302021]

Any comments are appreciated.

I agree with the 39.4 grains.
The .005" seating increments (.15mm) are good. But when doing seating, 5 rounds is the minimum number to see the group shape.

You need to know if your group is stringing or not. 2 more rounds into each of those seating groups could change the picture dramatically.

 

[Echo Charlie]

Thanks Dog Rocket!
Considering the last test and as loads 39.4 and 39.6 grain grouped almost at the same height @ 500 yds why not load 39.5grain?

Did some 5 round groups @ 100m but was testing different primer and differences using new unfired cases.
Will also post them and further test the COL with 5 shots each COL with .005" seating increments.

 

[User4302021]

Thanks Dog Rocket!
Considering the last test and as loads 39.4 and 39.6 grain grouped almost at the same height @ 500 yds why not load 39.5grain?

You could do that.

My choice would depend on the temperature I shot this at. If it was relatively cold, I would choose 39.4, if it was relatively hot at the time, I might choose 39.6.

I don't think you would have an unfavorable result by splitting the difference at 39.5.

If you are so inclined, it would be interesting to see what a couple more .005" (.15mm) increments shorter would look like. But you are looking pretty good on a couple you have already done. Just gotta flesh them out a bit to see if they are actually gonna hold up.

 

[Echo Charlie]

You could do that.

My choice would depend on the temperature I shot this at. If it was relatively cold, I would choose 39.4, if it was relatively hot at the time, I might choose 39.6.

I don't think you would have an unfavorable result by splitting the difference at 39.5.

If you are so inclined, it would be interesting to see what a couple more .005" (.15mm) increments shorter would look like. But you are looking pretty good on a couple you have already done. Just gotta flesh them out a bit to see if they are actually gonna hold up.

Air temperature now is around the mean temperature this load will be used.
What interval you would consider test the COL?
From 2.880" (Maximum for magazine) to 2.800" its 16 groups of 5 shots. 80 rounds in total

 

[User4302021]

A .025"spread (6 groups at .005" intervals) should be enough to show you a whole cycle. You probably wouldn't see anything different, just more of the same if you went further.

I use full caliber seating depth as my minimum length, so no shorter than that. I don't go any further out than 75% of full seating depth. I don't want too little bullet in the case. However many .005" increments that difference works out to be, is usually the spread I use.

.010", or .020" off the lands means nothing to me if I have .25" of the bullet left in the case.

 

[User4302021]

A .025"spread (6 groups at .005" intervals) should be enough to show you a whole cycle. You probably wouldn't see anything different, just more of the same if you went further.

I use full caliber seating depth as my minimum length, so no shorter than that. I don't go any further out than 75% of full seating depth. I don't want too little bullet in the case. However many .005" increments that difference works out to be, is usually the spread I use.

.010", or .020" off the lands means nothing to me if I have .25" of the bullet left in the case.

I can't seem to edit, so I need to clarify. The difference between 100% and 75% seating depth are my extreme limits. I don't cover that whole spread. I start at full depth and run it out .025" from there unless I am prohibited by throat length or magazine length before I get there.

 

[Echo Charlie]

I can't seem to edit, so I need to clarify. The difference between 100% and 75% seating depth are my extreme limits. I don't cover that whole spread. I start at full depth and run it out .025" from there unless I am prohibited by throat length or magazine length before I get there.

So for this example - 6.5CM with 147 ELD M - you would probably start with a 2.800" COL and work up in .005" increments up to 2.825"

 

[User4302021]

So for this example - 6.5CM with 147 ELD M - you would probably start with a 2.800" COL and work up in .005" increments up to 2.825"

That is what I would do.