Looking for help reading my ocw test

R

Ryno308

Private
Minuteman
Jan 20, 2025
4
1
British Columbia
#1
Hey everyone, first time poster long time lingering.

I'm looking for some help interpreting my ocw test I just completed.

20" barrel 308 1-10

175 SMK
Varget
Br2
FC brass
No Chrono unfortunately

I decided to load up some 44.5 and 44.2 based on this test but I'm not entirely confident I read the results correct.

The group consisting of 44.4 I pulled the high shot. Slipped off the bag right as I fired. The next group felt good but a similar impact to the previous makes me think it wasn't me maybe it was.

Anyone with more expertise is love the help

I also loaded up some 45gr as the shape was decent so I'm tuning that in with seating depth.
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Last edited:
#2
you need to shoot this test all at the same point of aim at like 400 yards. and you only need one round at every increment you want to use. or 2 if you want to shoot the test twice on 2 different targets.
 
#5
First off you have a "node" in the 44.1 to 44.7 gn range as the average POI is very close to the same. At 100 yds this shows consistency in the barrel point of aim at bullet release. Within that "node" there is probably a finer charge so shooting it again with ).2 grain increment will help refine your charge and verify this result. I typically load this second test slightly differently being starting at 44.2 and shooting 44.4 and 44.6 gn. Don't be fooled by that very tight group at 44.1. As for shooting at distance you can check your selected charge after you tie that down. When you shoot at distance you will be seeing the velocity variation as opposed to the barrel affect only. That's the theory behind OCW. If you shoot these test round robin the groups will typically open up some as its difficult for us mortals to repeat our setup consistently.

As for seating depth, I don't know what rifle/chamber you may have but if this is a Remington 700 you are well away from the lands and I wouldn't mess with doing anything as the lands are a mile away. I have found chasing any refinement in mine is pretty much a waste of time and components.

As for the chronograph, you don't need it to find a node. Once you find it you can use the chronograph to help refine your loading process to improve your standard deviation. Velocity variation at 100yds has little effect on the POI. A 100 fps variation at 100yds might move the POI about 0.2".

Good luck
 
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#6
Doom said:
First off you have a "node" in the 44.1 to 44.7 gn range as the average POI is very close to the same. At 100 yds this shows consistency in the barrel point of aim at bullet release. Within that "node" there is probably a finer charge so shooting it again with ).2 grain increment will help refine your charge and verify this result. I typically load this second test slightly differently being starting at 44.2 and shooting 44.4 and 44.6 gn. Don't be fooled by that very tight group at 44.1. As for shooting at distance you can check your selected charge after you tie that down. When you shoot at distance you will be seeing the velocity variation as opposed to the barrel affect only. That's the theory behind OCW. If you shoot these test round robin the groups will typically open up some as its difficult for us mortals to repeat our setup consistently.

As for seating depth, I don't know what rifle/chamber you may have but if this is a Remington 700 you are well away from the lands and I wouldn't mess with doing anything as the lands are a mile away. I have found chasing any refinement in mine is pretty much a waste of time and components.

As for the chronograph, you don't need it to find a node. Once you find it you can use the chronograph to help refine your loading process to improve your standard deviation. Velocity variation at 100yds has little effect on the POI. A 100 fps variation at 100yds might move the POI about 0.2".

Good luck
Click to expand...
Excellent response thankyou doom!

The rifle is a Springfield Armory Waypoint 2020 with the BSF carbon barrel. These were all seated at 2.250 BTO which I remember correctly is .040 off the lands. I can go all the way to .05 and still be in mag length. I read somewhere in here that the smk tends to like some jump so I just picked a number close to the FGMM and went with it.

Im glad to hear that's my nide from others. I'm pretty new to reloading but have done a disgusting amount of research on the topic. I though the node was in the that range aswell given it opens in below and above the 44.1-.44.7 range.

What are you thoughts on trying to get the 45gr to tighten up? With the 20" barrel I'd to get a half decent velocity. But without a Chrono I have no idea at the moment. My plan is the to try and reach the 2600 mark.

I'm sure I can tighten it up right close to the lands but that's not my objective. I'd like to stay off them for reliability in the field as I do plan to take some deer with these rounds this year. My climate is pretty nasty during deer season and it's one less thing I have to worry about.

Thanks
 
#8
Doom said:
2600 is going to be hard on you and the cases. I wouldn't try it with Federal Brass. Not saying it can't be done. I think you are in the 2550 neighborhood. Would another 50 fps make a difference?
Click to expand...
You know your right, 50 isn't a deal vreaker. I do have some of the hornady match brass I could try along with just buying lapua. I'm my gun, I've worked up to 47gr with no pressure issues pushing the 168 Berger VLD. I couldn't get that bullet to shoot right while maintaining mag length. I may be able to borrow a Chrono for my next round of testing. Going try another ocw in the range you mentioned above.

Also working up a 165 SGK as a proper hunting bullet load. Ocw is to come for that too.
 
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