OCW "after" the test question

[KevinSC]

Hello all,

I have recently used the OCW test to establish a load in my 6.5 Creedmor with good results. However, when I did the test it was almost twenty degrees cooler out and now that it's heating up my load is showing signs of over pressure. Considering the progressions that it took to get to this load, what step or steps should I use to to find a lower "node"?

Kevin

 

[Aimsmall55]

What powder are you using

 

[KevinSC]

That load was with RL17

 

[EMorr]

Do you have a chrono, if you do did you chrono the load when you decided on your node? My first idea would be (if you have access to a chrono) to back off the load untill you are at the velocity of your original node and then see what results you get.

If you don't have access to a chrono I think the simplest thing would be to back off a grain or two until you are no longer showing pressure signs and then re-work a short OCW test around that charge weight.

 

[Dan Newberry]

If you properly identified the OCW, your next lower node should be 3 percent less powder than what you've come up with now. Try a group or two with that amount, and report back and we can go from there.

Dan

 

[steve123]

Ditch the R-17 and use H4350 or H4831.

 

[KevinSC]

Dan,

Here is a pic of the original results. If I understand your method correctly, I ended up going with the 40.5 as the middle charge. Do you concurr, or am I not reading the results correctly?

Thanks,

Kevin

 

[KevinSC]

Ditch the R-17 and use H4350 or H4831.

Haha, if only it were so easy to just do that. H4350 might as well be from another planet right now.

 

[Dan Newberry]

First of all... the rifle is extremely accurate--that's well evident.

The scatter nodes are are 40.5 and 41.7, at the usual 3 percent spacing.

That means the accuracy nodes are 41.0 grains, and dropping 3 percent, we get 39.8 grains.

Load up some at 39.8 grains and rock on... that should take care of the problem. You could still run 41 grains in cold weather, if you can avoid pressure signs.

Dan