Thread: OCW Load Testing

So what method / procedure are you using now @Puffin ?

I'm treating the bullet type as the primary variable and starting with medium loads of 2-3 obvious choice powders, not more. If the bullet doesn’t show promise straight away I’ll discard that bullet from contention. That, but mainly a SS match grade barrel competently chambered with due attention given to the throat and crown, that's my current thinking as an initial go-to solution for tighter groups, expensive but allows results to be fast-tracked.

OCW as described by Newberry (as I understand it) addresses the contribution to POI dispersion due to the inevitable variation in loading parameters and looks to find a way to minimise this, which is fine if that is a significant contributor to group size, but if the dispersion is mainly due to something else then it won’t be possible to see the OCW effect. And this is where the problem usual is in that it is all too easy - particularly with some shooters partiality for 3-shot groups - to convince yourself you have found the optimum point in an OCW test sequence only to then try and rationalise the reason why a different load shoots better the next time at the range.

And on my other favourite related topic ( because I can’t help myself ) why, why, why, is there any acceptance of 3-shot groups as an indicator of anything other than that the bullet is coming out of the barrel in roughly the right direction ? Noise from the rifle followed by statistical noise on the target.

…well I’m done here, and feeling a lot better for it.

hehe, i'm definately coming at it from a very different angle

usually trying to find a load that works in a second hand, half shot out rifle of dubious chambering

Originally Posted by ebf

usually trying to find a load that works in a second hand, half shot out rifle of dubious chambering

...in which case there is even more chance that group dispersion will be due to factors other than those addressed by OCW.

For those contemplating trying to improve group size using OCW consider the following:

- if you very very carefully assemble 7-8 rounds to get as close to identical charge weights, neck tension, COAL, primer seating consistency etc etc and the resulting group is significantly smaller than when normal care is applied then it may be worthwhile trying to find a OCW node, as that is what finding a OCW barrel "whipping" node is trying to achieve; a smaller group than would otherwise result from shot-to-shot loading variations if not at a node.

- when not at a node the dispersion of the shots should lie along a line (that links adjacent nodes). If not trending along a line then the dominant reason for the dispersion cannot be the barrel whip.

I'm not saying that there aren't reasons why differing charge weights may result in different group sizes, only that the underlying principle that Newberry is trying to address with OCW is one around barrel "whip", and it pays to know what you are trying to improve before embarking on a method that may have only coincidental bearing on that issue. That is my position on most of the OCW testing that is reported on this forum.

Experimentation on thrashed-out barrels might be better spent trying some different hardness and weights of flat-based bullets.

Open to debate of course ( when I can find time to get on here) so bring it on…

..and by next roar you'll be frustated with the whole thing, thrown half the stuff out, using a teapsoon and a half of 2206H and a corlokt!.....

.....And the deer died happily ever after!

When you say "projectile shows promise" what are you basing that on ? Consistent velocity, group size ?

Are you moving more to an Audette style string with velocity nodes or something else ?

To me the bottom line is that unless you are doing a pure velocity analysis every single load development technique requires prescision shooting.

Originally Posted by ebf

When you say "projectile shows promise" what are you basing that on ? Consistent velocity, group size ?

Group size; under moa straight away.

Originally Posted by ebf

Are you moving more to an Audette style string with velocity nodes or something else ?

Eben, my last three posts all attempted to say that I didn't think barrel whip was a significant contributing factor to my group size, so I wouldn't be replacing OCW with another method ( Audette ladder) that attempts to minimise the effect of barrel whip on group sizes !

Originally Posted by ebf

To me the bottom line is that unless you are doing a pure velocity analysis every single load development technique requires prescision shooting.

I agree. The original comment from PerazziSC3 was " you really need a rifle/scope/shooter combo (capable) of shooting very very tight groups to get a good indication of nodes ", and setting aside for now shooter & scope capability I just don’t think the rifles used by most shooters attempting OCW testing are capable of the level of precision required. Newberry is starting with precision rifles and attempting to make them more tolerant of load variation. He approaches OCW with a view that EVERY load in these rifles are capable of small groups if he could remove all round-to-round variation in his reloading technique. Finding and then loading for a “node” as he describes it is an improvement only in that it permits round-to-round inconsistency with the least detrimental effect on group size. People read his article and then use the same method to try and identify the smallest group from their rifles over a range of test charge weights - it is not the same thing.

Ok, so now we get to the interesting bit.

Your argument about targeting the most likely culprit for dispersion is very good.

There are of course multiple factors all happening at the same time.

So we use solid rests to account for shooter skill, round robin techniques to negate barrel heat effect on velocity etc.

Maybe I should ask the question this way:

For the following 2 scenarios, what do you believe is the factor that would have the major impact on group size (hence the one to design the test around):

1) High end target barrel, well chambered, not likely to be 'whippy' - you've pretty much answered this one already by saying projectile type
2) typical thinner profile hunting barrel

Bullet type as the initial variable is my personal pick for both, but in 2. always limited by the barrel. If having tried a number of bullets with moderate loads unsuccessfully in an off-the-shelf hunting rifle I would opt now to replace the barrel after perhaps some very limited experimentation with powder type, charge, jump, primer - variables that I'd use as more for fine-tuning. Applying this to trying to improve the performance of factory rifles that show up in OCW test reports shooting 1.5-2moa groups, OCW has little chance of making any gains, finding a preferred bullet a much better chance, changing to a True-flite UM in combination with favoured bullets almost guaranteed.
All personal opinion, and there will always be rifles out there that will do their own thing.

You had me hook, line and sinker........till you mentioned true-flite

However, if I ignoring that gigantic hole in your logic, I agree with everything else

Tx puffin, interesting thread.

I guess I am one of those guys who believes that you can get just about any barrel to shoot significantly better by hand loading. So far I have been lucky enough to work out an acceptable load just messing with charge and jump mostly. Some projectiles like the Berger VLDs take a lot more work and experimentation, but that to me is the fun part.

Also kinda depends on what your criteria are for precision...

Originally Posted by Proudkiwi

You had me hook, line and sinker........till you mentioned true-flite

Finally got a decent bite with a change in bait, slamming the application of OCW alone was not delivering.

Take two...

Originally Posted by The Bloke

Take two...

Nice one.
So what is your current hunting load?
I'd be keen to hear how you get on with the magnetospeed also.

Factory ammo.

Simply put, I don't get out to the range to shoot the rifle as much as I would like, so it's a little bit of a slow process. However, I plan to make up another set of loads based around what I found out with the second lot and confirm.

Really, any of them would be fine for hunting. That's not the point.

Though, to further mix things up, I have also just picked up a Rem700 Varmint in 308 as a budget precision build... busy times!