OCW method - second rifle test

@414gates @414gates 3 years ago

Because I was able to achieve what I consider to be a good result with my first OCW test, I tried the same test on a second target rifle.

This is a 375 RUM, using 300 grain Peregrine Rangemasters, with N570 and Federal 215 Match primers.

Again, I have a full two percent spread where the group centers are almost identical. 102, 103 and 104 grains. The left-most shot on the 102 is indicative of a pulled shot - Dan Newberry says if the flyer is not in the direction of the previous or next charge weight group center, it's a shooter induced error.

I will re-shoot this at 102.5, 103 and 103.5 to verify that the group centers remain the same. If that works out, I can work on the seating depth.

It's been very interesting for me to see the OCW test in action, and get what seems to me to be a conclusive result.

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@414gates @414gates OP

and 104 grains is the most expansion I want to have on the brass.

***************************
could you please tell us more about this ?
Perhaps even start a thread detailing this matter of expansion, what, why and how.

You can refer here :

Measuring for pressure .

@T @treeman

and 104 grains is the most expansion I want to have on the brass.

***************************
could you please tell us more about this ?
Perhaps even start a thread detailing this matter of expansion, what, why and how.

@T @tripodmvr

What distance was the chrony at?

@414gates @414gates OP

The speeds I recorded on the day looked odd, it's possible that between the identical numbers the reading wasn't picked up due to muzzle blast.

These numbers were round robin, so in order of the columns, not rows : 2337, 2337, 2777, 2777, then column two, etc.

101 - 2737, 2789, 2766
102 - 2737, 2777, 2789
103 - 2777, 2777, 2770
104 - 2777, 2803, 2842

I'm really not concerned with the velocity yet, I did tests previously measuring virgin brass after firing with a 1/10,000 micrometer, and the N570 gave highest velocity for the least case head expansion, and 104 grains is the most expansion I want to have on the brass.

@T @tripodmvr

I think you know that I have been into Quick Load for a long while. It would be interesting to evaluate your results using QL to see if there is a correlation between the two methods. Did you record speed whilst shooting? If so, I can do calculations to try and assist with load development.