First OCW Test W/ 6.5C

[LaserGuidedPinky]

Hello,

I decided to do an OCW test for the 6.5 using H4350, 140gr Bergers, Lapua brass, seated .03" off the lands. I started at 40.2gr to 41.2gr. Looking at my target, there's not really a bad group other than one, but don't know which area to test. I was thinking 40.5gr, what do you think? 40.6gr was a good group so going by that, should I even do a seating test? Or stay with .03" off lands? The 41.gr area was already at 2880fps, but nothing abnormal. Brass grew to same size as always and no weird stuff with the bolt.

 

[Ned Ludd]

40.4, 40.6, and 40.8 all have the same rwlative POI, so you're probably good with 40.6, assuming that the fill ratio, velocity/stats, etc., at 40.6 gr were all acceptable to you.

As far as seating depth testing, yes, .030" off the lands shot tight. But you have no way of knowing whether .030" off might be right at the leading edge of an optimal seating depth window, at the trailing edge, or somewhere in between. A good example of why this is important would be because if .030" off turns out to be right at the trailing edge of an optimnal seating depth window, the load could go out of tune very quickly. Doing a seating depth test is really not that much effort, and then you'll know. I'd seat bullets at the middle or leading edge of the optimal window, which will give the most room for land erosion before the load goes out of tune and seating depth needs to be re-visited.

 

[Mike TackleBerry]

I almost always start my testing with my bullets at jam + .010, Unless they absolutely have to be mag fed then I'll start at .015 off the mag lip! This way I know where I'm at in the window.

 

[LaserGuidedPinky]

40.4, 40.6, and 40.8 all have the same rwlative POI, so you're probably good with 40.6, assuming that the fill ratio, velocity/stats, etc., at 40.6 gr were all acceptable to you.

As far as seating depth testing, yes, .030" off the lands shot tight. But you have no way of knowing whether .030" off might be right at the leading edge of an optimal seating depth window, at the trailing edge, or somewhere in between. A good example of why this is important would be because if .030" off turns out to be right at the trailing edge of an optimnal seating depth window, the load could go out of tune very quickly. Doing a seating depth test is really not that much effort, and then you'll know. I'd seat bullets at the middle or leading edge of the optimal window, which will give the most room for land erosion before the load goes out of tune and seating depth needs to be re-visited.

Thanks for the great info. I'm not sure about the fill ratio, I'd like to get it a little more, but I don't think H4350 would allow that. I'm still learning that part. I understand the concept, but I'm still green and have no idea how to go about choosing a powder. I have 4831SC, Staball 6.5, R16 and H4350. Enough of each to last me a few years, I went nuts this year. The perosn I shoot with does great with 4831 and it's the one I want to try next, but I want to use H4350 and see how low I can get the numbers. Im one of those that get too caught up with sds and es. Im trying to stop that!

Im thinking about doing the seating test with 40.6gr then and then take it to 600yds to see if all holds up.

 

[LaserGuidedPinky]

I almost always start my testing with my bullets at jam + .010, Unless they absolutely have to be mag fed then I'll start at .015 off the mag lip! This way I know where I'm at in the window.

That part I have down. The one that I have a hard time with is the powder charge. I start at .15" off because .03" always works for me. Across 4 different rifles now, but with Bergers. Thanks.

 

[Mike TackleBerry]

That part I have down. The one that I have a hard time with is the powder charge. I start at .15" off because .03" always works for me. Across 4 different rifles now, but with Bergers. Thanks.

.15 jump is a huge jump.

 

[LaserGuidedPinky]

.15 jump is a huge jump.

I see. I'll have to try starting on the lands. Thanks.

 

[Mike TackleBerry]

I see. I'll have to try starting on the lands. Thanks.

Are you single-feeding or mag-feeding the rounds?

 

[Zero333]

40.6 looks good to me.

Usually when I do an OCW test, I do the test twice to make sure it's repeatable. and not just a fluke.

 

[mullmann]

40.6 looks good and try a seating depth test. I learned years ago to look for repeatability. These groups were a couple days apart. This was a load I settled on and confirmed it.

 

[LaserGuidedPinky]

Are you single-feeding or mag-feeding the rounds?

I do both. The magazine will hold up to the land loads.

 

[LaserGuidedPinky]

40.6 looks good and try a seating depth test. I learned years ago to look for repeatability. These groups were a couple days apart. This was a load I settled on and confirmed it.

Good idea, I'll do that. Thanks.

 

[Dave M.]

.15 jump is a huge jump.

I’m guessing he means 15 thousandths