Help analysing OCW data please.

[Mungo]

I am going to repeat the OCW method in the near future, 7 years after doing it last. Due to upgrading some case preperation equipment.

I wonder if I will get the same results as previously ......

£10 says it doesn’t…

 

[kenbro]

For me, & this is me just saying what I’ve found has worked for me over the years & I'm by no means a statistician or reloading guru, your increments are way too course.

I find the optimum barrel time for the length of barrel & then use QuickLoad to identify the powder weight that gets me the closest to that time.

I then load five rounds each starting at that powder weight and going up & down two steps at 0.1gn increments.

I’ve not done non lead bullets yet but with traditional cup & core I load one batch at 10 thou off the lands & then a second batch at 20 thou off the lands. So in total I have 50 rounds loaded. It sounds a lot. You,ve just shot 21 rounds - so only 4 less than my first batch at 10 thou jump, & don’t have a clear idea of where you go next.

Using this method I worked up the following load for an AI AT in one sitting - I’d shot the rounds with 10 thou jump & had found a good load in that at under 0.5moa so nearly didn’t bother to shoot the other 25 & was going to go home & pull them. However, I decided I should really see how they shot if only to see just how ‘tolerant’ the barrel was. I was pleased I did as the little hole below is 5 rounds of .308W loaded with a Sierra 2155 bullet.

Incidentally for load testing I keep the target simple - rows of 15mm black patches on the back of a large pistol/gallery target which I find make a simple clean aiming mark. I then stick a couple of minutes of elevation on the scope so the bullets don’t hit the aiming mark but instead leave it clear for the next shot to be aimed.

View attachment 427311


I’ll be developing a load for my 308 using Sako 162gn Powerhead blade but won’t be bothering with jump initial, I’ll just load to factory length & do a test based on powder weights as above. The fun will come when I do the development for the 6.5x47 as there’s no factory ammo to use as a starting point!

What distance do you do your development shots at?
Cheers, Ken.

 

[kenbro]

Absolutely pick a good gun (you have). Pick good powder primers and bullets and pick a desired velocity load that is safe. Make up 10 rounds (with copper a 60-120thou jump is good lead stick to sammi spec) and check if they shoot well (under 1 moa) and show no pressure signs and that’s it…. move on with your life. If they shoot terribly and it’s not a fault of gun or gunner then change bullets or powder or primer in that order.
It’s seems to be well established by way cleverer people than me that all the other testing we used to do is chasing ghosts. Prove it to yourself do the same test again and see if they look the same I bet they won’t. I don’t mean to be harsh but I’ve wasted 1000 of hours and £ doing all this and I’m trying to save you from it!

Me too, I’ve worn barrels out developing loads!!!!

 

[Donkey Basher]

What distance do you do your development shots at?
Cheers, Ken.

@kenbro I’ve always done my development at 100 yards, mainly because that was the range I had easy access to at the time (BSRC so don’t get me started on NRA/BSR running it now… ). I’ve not had cause to try load development at any greater distance & given the potential for outside influence to distort the results, ie wind, mirage, etc. I’ve never really seen the need either. Back when I was shooting seriously, I had a 6mmBR built & did load development based on factory ammunition dimensions (the chamber was cut to suit Norma Diamondline) but using N140 instead of Norma 205B(?), all at 100 yards. That combination would shoot touching groups at 300 yards when I was doing my bit right!

 

[lambic]

I am going to repeat the OCW method in the near future, 7 years after doing it last. Due to upgrading some case preperation equipment.

I wonder if I will get the same results as previously ....

£10 says it doesn’t…

I'm afraid I'd almost certainly lose £10