OCW test results

[jdgray]

Decided to run a OCW test on my R700 LTR .223, and have some questions. Loading 69gr SMKs, Varget, CCI400s, Lapua brass.
Shooting off a frt rest, prone, rear bag. Anyways, my old go to load for this rifle was 24gr, usually shoots .5moa pretty consistantly, but got a hair to go the rest of the load spectrum. Best group was at 24.6- 24.9, and at 3rds, 25.5, and 26.1 were bug holes! I admit, I was getting scope eye from the shooting, and may blame some of that on me....
And why were my groups getting lower, the hotter they shot? My 24gr load is 2760fps Avg, from years ago, I did not worry about the chrony on this test. Were should I go from here in your opinions?

 

[AtOne]

Re: OCW test results

Personally I'd load up 24.5 to 24.9 in .1gr. increments and test again.

I think you'll find your ideal load right in there and more than likely it will be right around the 24.6 load.

Once you decide which one works the best you can then adjust the seating depth to fine tune it.

Good luck with it !

 

[jdgray]

Re: OCW test results

Thanks! After running the test, I read Newberrys OCW, and seen he runs 3rd groups not 5. Any thoughts on why the groups got lower not higher? That dont seem right....

 

[shoot4fun]

Re: OCW test results

Not casting stones but it looks to me like there may be some shooter induced influence on your test. OCW should be done slowly, methodically and in a manner that would allow you to shoot your best. I think you should maybe think about redoing the test but cut it in half to reduce fatigue issues you mentioned. In other words, shoot the same charges but do four of them instead of all eight. Then back off a bit before doing the rest. I really think you could see a good node toward the high end.

 

[jdgray]

Re: OCW test results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shoot4fun</div><div class="ubbcode-body">Not casting stones but it looks to me like there may be some shooter induced influence on your test. OCW should be done slowly, methodically and in a manner that would allow you to shoot your best. I think you should maybe think about redoing the test but cut it in half to reduce fatigue issues you mentioned. In other words, shoot the same charges but do four of them instead of all eight. Then back off a bit before doing the rest. I really think you could see a good node toward the high end.
</div></div>

Yeah, if I would have stopped after 3rds, it was looking real good on the top end! No pressure signs at 26.1 either, with room to go higher. After 1.5hrs behind the scope, I was ready to quit!!

 

[DroidSniper]

Re: OCW test results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jdgray</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shoot4fun</div><div class="ubbcode-body">Not casting stones but it looks to me like there may be some shooter induced influence on your test. OCW should be done slowly, methodically and in a manner that would allow you to shoot your best. I think you should maybe think about redoing the test but cut it in half to reduce fatigue issues you mentioned. In other words, shoot the same charges but do four of them instead of all eight. Then back off a bit before doing the rest. I really think you could see a good node toward the high end.
</div></div>

Yeah, if I would have stopped after 3rds, it was looking real good on the top end! No pressure signs at 26.1 either, with room to go higher. After 1.5hrs behind the scope, I was ready to quit!! </div></div>

That is exactly why he recommends 3 round groups. Also the first stage overall group size isn't going to tell you the story. You are looking for three group with a center within 1 MOA or less. This is your node. If you find it necessary you can shrink loads further by small powder or very small seating adjustment.

A lot more info can be found here http://practicalrifler.6.forumer.com/ including the man who came up with the OCW method himself.

I spent a year pissing around with my win mag and was lucky to get under MOA loads. I spent a day on OCW and got a load barely above 1/4 MOA.

 

[.50 Cal Cow]

Re: OCW test results

Also big thing that seems important would be doing the groups round robin. This would give you confirmation on rounds dropping as a result of barrel temp or powder charge.

 

[MitchAlsup]

Re: OCW test results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jdgray</div><div class="ubbcode-body">And why were my groups getting lower, the hotter they shot? </div></div>

Barrel harmonics. That is the bullet left the barrel while it was pointing slightly downward compared to the lighter loadings.

 

[jdgray]

Re: OCW test results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jchapman</div><div class="ubbcode-body">Also big thing that seems important would be doing the groups round robin. This would give you confirmation on rounds dropping as a result of barrel temp or powder charge. </div></div>
They were shot round robbin..

 

[jdgray]

Re: OCW test results

I reread Dan Newberry OCW, and am gonna redo the test with 3 rds, also my charge weights came out higer using his exact data, ranging from 24.8 up to 26.4. Thats 21 total rounds vs the 40 that wore out my vision. So much for going off memory!!