Advantages to finding seating depth before charge weight?

[Ringostar]

Still reading, but if I had to do it today, id probably load 8ish rounds in .5gr increments from 57-61ish just to make sure pressure is safe, then pick a middle charge weight (58-59), and then run Bergers depth test. But im hoping I get a few more opinions before having to load this next batch.

This is a good plan for a cartridge without much info. What powder do you plan on testing with? Also what bullet?

 

[Fast14riot]

For me, shooting an Ackley chambering, I will do a seating depth test while fire forming. This will give me a good idea of where I need to be. Then, second firing is where I do my coarse pressure test and a ladder. Once I find a good rung on the ladder I will do a fine increment powder test. If needed, I will fine tune seating depth with final powder charge. Brass is now minimum 2x fired, some will be 3x. This is generally where I consider AI brass to be acceptably and fully formed.

 

[Metal God]

My understanding to why you find seating depth first is for when you go to adjusting seating depth you only go one direction . Meaning You find your max COAL ( touching or jammed ) in the lands and you start there with your charge testing . Once you find the charge you like/want you start adjusting seating depth back off the lands . The reason you do it in that order is "if" your charge is at max allowable pressure . Adjusting your seating depth off the lands "should" only reduce start pressures rather then increase them .

If you start .040 , .080 , .120 off the lands and you end up at max allowable pressure when charge weight testing . If you then start adjusting seating depth closer to the lands when you're already at max pressure way off the lands . You have a real chance of going dangerously over pressure the closer you adjust to the lands . So the theory is only adjust off the lands and never "too" the lands . Also if you only go one direction you will likely find what your looking for faster because there's a good chance adjusting one direction is going to be beneficial and the other direction of adjustment is likely going to do nothing to improve your load .

Oh and if you're using a long bullet that needs to fit in a mag . You clearly need to know your max COAL before you start to be sure your loaded round will fit in the mag .

 

[Kracken McGraw]

My understanding to why you find seating depth is for when you go to adjusting seating depth you only go one direction . Meaning You find your max COAL ( touching or jammed in the lands and you start there with your charge testing . Once you find the charge you like/want you start adjusting seating depth back off the lands . The reason you do it in that order is "if" you charge is max allowable pressure . Adjusting your seating depth off the lands "should only reduce start pressures rather then increase them .

If you start .040 , .080 , .120 off the lands and you end up at max allowable pressure when charge weight testing . If you start adjusting closer to the lands when you're already at max pressure . You have a real chance of going dangerously over pressure the closer you adjust to the lands . So the theory is only adjust off the lands and not "too" the lands . Also if you only go one direction you likely find what your looking for faster because there's a good chance only adjusting one direction is going to be beneficial so one direction of adjustment is likely going to do nothing to improve your load .

Oh and if you're using a long bullet that needs to fit in a mag . You clearly need to know your max COAL before you start .

That’s a great explanation!

 

[mike a]

I like NorCalMikies way best for straight up target shooting. Metal God has a good way also as long as when moving the bullet back you don't start compressing charges. Going in .120 is way deep. Mike

 

[Winny94]

This is a good plan for a cartridge without much info. What powder do you plan on testing with? Also what bullet?

H1000 and the 7mm 180gr VLD Hunting. I don't need sub .5moa accuracy. I'd be very happy w/ .5-.75 and a decent SD. It's a hunting round, not a match round.

 

[Ringostar]

For a target rifle, I like to take known good loads and back off slightly and test seating. Then slowly work up on powder at the preferred seating depth. Since it’s for hunting I assume that it needs to feed from a magazine. Compare bullet touch to lands measurement vs max magazine length. Make sure that you still have clearance at max mag length. I’m not saying this is perfect, but personally I wouldn’t want to shoot a jammed load in a hunting rifle. In you need to extract a loaded round, you could get a chamber and trigger full of powder. If you still have bullet clearance at max mag length. Then I would try a rough powder test at that length with this cartridge, since there won’t be book data for it. You should be able to find a charge weight where pressure starts to show issues. Back off from your max charge area and then start testing seating depth that feeds from your magazine. I’ve never tried the .040 change that Berger recommends. I would probably go .020 change for a rough test. When you find an area with promise, then test finer jumps in that area. Then do a finer charge test. It might sound like a lot of work, but when you decided to go with a wildcat round you didn’t plan on getting by easy. I actually like the info that I’ve read about this cartridge, good luck!

 

[Murray Brook]

Still reading, but if I had to do it today, id probably load 8ish rounds in .5gr increments from 57-61ish just to make sure pressure is safe, then pick a middle charge weight (58-59), and then run Bergers depth test. But im hoping I get a few more opinions before having to load this next batch.

This is just what I do, and it works for me. Don't be afraid to test as far as .120 off lands. My 7mm/08, which I thought was a .7 rifle became a .4 rifle when I decided to try the Berger depth test and found that .120 off was my best depth. JME

 

[dsculley]

I am using the 168 gr VLD's. The charge weight for my seating depth test is usually 5% below published max. The main consideration is I want a safe load, but one not too far from the range I expect to be using after load testing. You could drop back to 7% below max. The main thing is to know you are at a safe load for testing seating depth.