OCW opinions for a 6.5CM load

[Echo Charlie]

Would you please give me your opinion about this 6.5CM load?
Any comments are appreciated.

Lapua SR primer cases.
CCI BR4.
Vihtavuori N550 powder
147grain ELD match
24" barrel
COL: 2.880" (Maximum for magazine). Lands @ 2.913" (.033" Jump).

1st test done @ 100 meter.
Before this test fired 10 shots with N150/140ELD_M to harm and foul the barrel.
New cases (0 firing).
Oheler 35P didnt read velocity of the 38 grain charge

Photo of the case loaded with 41.5 grain.
Cratered primer and also visible a light round ejector hole mark around the last "A" of LAPUA lettering. This case measured a slightly larger OD near the base than the other ones.
Not noticed signs on the other cases and no bolt lift increased force.

 

[Echo Charlie]

Then decided to do another test at 400 meter
Cases fired once. Fire-formed to chamber and sized to reduce headspace .002".
6 shots for the first charge (39.4 grain) and 3 shots for the remaining charges.
First shot the 6 with 39.4 and then the rest.
Air Temperature: 77ºF
No over pressure signs.
Oheler 35P didn't read velocities of all 40 grain charges and two of 39.4.

The guy near the target to take note of impacts got a bit confused and we had a few doubts. Anyway, below a photo of target with the groups signed with different colors.

 

[Echo Charlie]

When I did this test @ 400 meter hadn't studied properly the all data of the first test, as I did above, and probably just searched for higher velocity instead of searching in the best window.

 

[Barrelnut]

Seems there is a relative flat spot in velocity with charges 39, 39.5, and 39.7. that is a good sign. I would probably start looking there.

 

[Echo Charlie]

Lastly decided to do another test @ 500 meter.
Cases fired once. Fire-formed to chamber and sized to reduce headspace .002".
Air Temperature: 63ºF
No over pressure signs.
Oheler 35P didn't read velocities of all 40 grain charges and two of 39.4.

2 shots to warm and foul the barrel (dots #1 & 2) then 3 shots each charge round Robin.
No photo of target but made this representation of POI to scale.

 

[Korhil78]

May I ask what rifle you are shooting?

 

[User4302021]

Would you please give me your opinion about this 6.5CM load?
Any comments are appreciated.

Lapua SR primer cases.
CCI BR4.
Vihtavuori N550 powder
147grain ELD match
24" barrel
COL: 2.880" (Maximum for magazine). Lands @ 2.913" (.033" Jump).

1st test done @ 100 meter.
Before this test fired 10 shots with N150/140ELD_M to harm and foul the barrel.
New cases (0 firing).
Oheler 35P didnt read velocity of the 38 grain charge
View attachment 130831
Photo of the case loaded with 41.5 grain.
Cratered primer and also visible a light round ejector hole mark around the last "A" of LAPUA lettering. This case measured a slightly larger OD near the base than the other ones.
Not noticed signs on the other cases and no bolt lift increased force.
View attachment 130836

View attachment 130832

View attachment 130834

View attachment 130837

Tests done with virgin brass are unlikely to yield any usable data.

Looking at all your data, I'm betting your most tunable node is going to be from 39.2 to 39.6 grains.

I'm not familiar with N550 at all, but from the sources I did find, your max charge with this combination is probably somewhere around 40 grains. Your velocities seem to confirm that. That could explain the inconsistency you have above that charge weight.

 

[Echo Charlie]

May I ask what rifle you are shooting?

Bergara B14 HMR 6.5CM 24" barrel 1:8"

 

[Echo Charlie]

Tests done with virgin brass are unlikely to yield any usable data.

Looking at all your data, I'm betting your most tunable node is going to be from 39.2 to 39.6 grains.

I'm not familiar with N550 at all, but from the sources I did find, your max charge with this combination is probably somewhere around 40 grains. Your velocities seem to confirm that. That could explain the inconsistency you have above that charge weight.

Thank you Dog Rocket.
Now that I have a better picture from the data collect with this tests I might consider back the loads for better consistency and less velocity. Usually we can not have the best of 2 worlds. We need to choose one or the other

Anyway bullet should remain above transonic up to 1,300-1,600 yards and cases and barrel will have longer lives.

 

[hwy1strat]

Is this a new rifle? And, are you set on using N550?

 

[Echo Charlie]

Is this a new rifle? And, are you set on using N550?

Yes. New rifle.
Not limited to N550 but almost.
Where I live its difficult to get powders.
Now I can get a few Vihtavuori, Maxam GDB 111, and a few Vectan

 

[hwy1strat]

Yes. New rifle.
Not limited to N550 but almost.
Where I live its difficult to get powders.
Now I can get a few Vihtavuori, Maxam GDB 111, and a few Vectan

My 6.5 creedmoor started pretty slow and it seemed to take about 150 rounds before it really sped up. I was shooting 140's around 2680 at first and now I'm pushing them right at 2800. Mine is a 26" barrel for what it's worth though. Anyway, I would expect you to get more velocity out of it as you shoot more through it. Normally, on a new rifle, I put about 100 rounds through it before I start load development so I don't have to worry about it speeding up while I'm trying to find the velocity node. But that is just my method. Maybe it doesn't matter.

I'm sure you have heard that H4350 is a good powder. I have had great success with it and very good velocity out of it. Maybe worth trying if you can get a hold of it. I have never used N550 though

 

[ar10ar15man]

i do not understand. this is a 6.5 cm
no load development required, any bullet and powder and shoots little groups at 1000 yards.

Would you please give me your opinion about this 6.5CM load?
Any comments are appreciated.

Lapua SR primer cases.
CCI BR4.
Vihtavuori N550 powder
147grain ELD match
24" barrel
COL: 2.880" (Maximum for magazine). Lands @ 2.913" (.033" Jump).

1st test done @ 100 meter.
Before this test fired 10 shots with N150/140ELD_M to harm and foul the barrel.
New cases (0 firing).
Oheler 35P didnt read velocity of the 38 grain charge
View attachment 130831
Photo of the case loaded with 41.5 grain.
Cratered primer and also visible a light round ejector hole mark around the last "A" of LAPUA lettering. This case measured a slightly larger OD near the base than the other ones.
Not noticed signs on the other cases and no bolt lift increased force.
View attachment 130836

View attachment 130832

View attachment 130834

View attachment 130837

 

[Echo Charlie]

I was shooting 140's around 2680 at first and now I'm pushing them right at 2800.

120 fps more? That's a lot. Thanks for the input.
I was expecting some increase but not that much.
Wanted a 26" barrel but none was available to our market.
Mine has 131 rounds on the clock.
Hard to almost impossible to get US powders.