What comes first, correct OAL or charge weight?

[RedRyder]

First off, OAL for me is an incorrect term. I don't measure from case head to bullet tip. I measure case head to ogive.

Having said that, I have stopped trying to count how many variables that have to be overcome to develop an accurate load.

Bullet type, bullet weight, primer type, powder type, powder charge weight, OAL, type of brass, whether I'm wearing a plaid shirt or a solid color shirt...you get the picture.

So, I've been trying to develop a load for a 264 Win Mag for a LONG time. Yeah, I've researched the internet and read a lot of opinions. And to tell the truth, there are two bullets that shoot REALLY and I mean REALLY well out of that rifle. I mean exceptionally REALLY well. Even by my standards. But those two bullets are 140 SierraMKs and Amaxs. Not really what I want to use for hunting. Yes, I know, some guys say they're perfectly fine for hunting others say they're poor for hunting.

What I'm trying to shoot though are 140 Accubonds. Loaded up 6 batches of 3 rounds each - one batch was .10; one batch was .20 and the third .30 off the lands. I won't mention the powder because then I'll get a bunch of replies about why it's the wrong/right powder. And believe me, I made repeateded measurements to determine correct head to ogive length. Results were mixed but I'll leave it at that for now.

The point I'm trying to get to is where do you start? Do you try diffferent charge weights? Do you pick a charge weight and monkey around with the OAL? Or, do you determine OAL and then experiment with charge weights? I know that the scientific method would be to change only one variable at a time. But which variable to start with? - OAL or charge weight?

I've got a nosebleed just thinking about it.

 

[Rover31]

I do charge weight and then length. Couple of rifles I have are started at mag length which seem to usually stay there. Other rifles (fclass) then I play with length.
Unfortunately to add to your stress, neck tension is something I find very important.

 

[Kadams1563]

Seat them twenty thousands off the lands then find your charge weight. Once you are getting good numbers with velocity, SD, and ES then go back and run seating deoth changes to see what it does.

 

[Deleted member 113831]

I posted this over on another thread in the Reloading Depot. It is what I do, you might give it a try and see what you think:

Load 2 rounds each at your maximum acceptable over all length in .2 grain intervals starting 2 grains below max....record velocities for each pair. Use the recorded velocity along with other traditional pressure signs to determine max charge for your rifle.

Once max charge is determined, back off 2% and adjust seating depth deeper in .005" increments to adjust barrel timing until groups tighten up.

Once a promising OAL is found, fine tune load weight up and down .2 grains to see if there is a difference.

You are done.

 

[RedRyder]

Oh yeah, I forgot about neck tension. I'm aware of it but man...I don't even want to go there. I think neck tension would be very important. I just don't have the correct tools to measure and deal with it.

The problem with 264s is that they're susceptible to pressure spikes, it's like in their nature. Kind of like bears like to eat sheep. OAL is particularly important because, of course, you seat that bullet out too long and you're going to contribute to the spikiness.

264 Win Mags and pressure spikes are how I like to flirt with disaster. And remember kids, always wear safety glasses around firearms.

Thanks for your comments.

 

[Deleted member 113831]

you seat that bullet out too long and you're going to contribute to the spikiness.

That is why I didn't mention a specific distance or length. It is simply the length YOU have determined, for whatever reason, to be maximum.

 

[RedRyder]

Ok. Thanks