OCW method and seating depth

[RobertH]

Hi all,

I am going to try this method for my .223 using 60 Gr V-max and Vihtavuori N133, and note that on Dan Newberry's site, which I quote "The seating depth for all test loads should of course be the same. I normally seat the bullet a caliber's depth into the case, or to magazine length--whichever is shorter. I don't believe loading to approach the lands is necessary, or even desirable in most situations. So long as the bullets are seated straight, with as little runout as possible, the advantages of loading close to the lands are largely over-stated. This said, be certain that the seating depth you choose does not cram the bullet into the lands. Stay at least .020" or so off the lands for these excercises." 

Now my hand loading experience is limited, but all the .224" bullets I have developed loads for in the past, have ended up grouping their best when seated .002" into the lands of my particular rifle.  Anything off the lands is at best disappointing.  Would the panel suggest following Mr Newberry's advice of seating .020" off, or would they start by seating into the lands if that's where the barrel likes them?

 

 

[Andrew]

I agree with the man's statement about seating depth. I load to recommended OAL for all loads.... the same way manufacturers load their match ammunition. ~Andrew

[Catch-22]

OCW isn't about seating depth or accuracy, it's only concerned with showing you which group of powder charges provide little variance in POI on the target. 

Once you know which charges give you the best shot to shot consistency, then by all means play with seating depth to fine tune the load for best accuracy.

I think Dan's point about not jamming into the lands is to remove the possibility of developing high pressures. It could be dangerous for one but it can also scew the results - you're not gonna get consistency if your bullets are jammed and produce varing degrees of pressure.

[RobertH]

Thanks Catch, and understood, but how can I ascertain shot to shot consistency if my barrel is spraying them everywhere at .020" off? A three shot group seems a bit hit or miss, perhaps 5 shots may be more representative. I will try it though on Sunday and see how I get on. Perhaps a rifled hosepipe may be a better option....!

[Catch-22]

The point is to look for the groups that are consistent.

If they're scatter gun then the chargeweight is not within the OCW. If however you see a couple of groups that all seem fairly consistent to each other (e.g. very similar POI) then pick the middle of that group (that's your OCW) and fine tune it further (e.g. seating depth, neck tension etc).

If all your results are truly that bad, consider your shooting technique firstly (as you should get at least 2-3 groups that appear similar) or secondly then accept your rifle may not like your particular load combination. Go back to the drawing board, change 1 variable at a time and try again. In this scenario I'd change things in the following order;

1. Up the powder charge only if you're sure you've not already got to within maximum

2. Change of primer

3. Change of bullet head

4. Change of powder

HTH

[RobertH]

Thanks again for your input Catch, (not sure if HTH is an amusing acronym or your initials?)

When I first started reloading I went down the route of minimum charge weight working up in increments of .2 gr or .3 gr, observing group size and overpressure signs on the way. Find the tightest group and then work on seating depth to fine tune. I arrived at loads which I was more than happy with from both a velocity and accuracy standpoint.  

I was using CFE 223 and H4895 but these have been withdrawn on H&S grounds, so I find Viht N133 seems pretty well recommended for 60 gr projectiles. I have fiddled with loads for 40, 50, 53, 55 and 60 gr V-max's, 50 gr Varmint grenades, 69 gr Sierra HPBT's and 75 gr A-max's which wouldn't shoot out my 1:9" barrel despite some internet users claiming success. Everything bar the A-Max shoot extremely well using the " traditional" method when they're in the lands. 

Having since found the OCW method I would like to give it a go, and was simply trying to remove any variables by starting where my barrel likes its bullets, but I see it makes perfect sense to start with a blank canvas as it were, so will conduct the exercise on those grounds.

As a matter of interest, I've arrived at 8 load increments; 22,2, 22.6 and 23.0 as fouler and sighters, then 3 rounds each of 23.5, 23.7, 24.0 24.3 and 24.6. I'll load all these at .020" and see how I get on.