Help me develop a seating depth test

[RmeJu]

I've done some initial load testing with charge weights, and found a very forgiving node (5 charge weights at .2 increments all very close to each other). FWIW, the groups were good at 10 thou jump, but in any event, I figured I'd just take the middle load and start playing around with seating depth to see if anything popped. I haven't messed with depth testing much before, and in doing some research, the way people test their depth seems to be all over the place.

Some people test in .001, .003, .005, .010, .020, or .030 increments... I'd personally be inclined to check in increments of 5, 10, or 20 thou, but I'm curious what works for you guys. I've also seen more openness to testing long jumps (.090-.150, or even more) that would've been scoffed at not too long ago. Again, I'm curious what works for you guys.

I'm thinking of testing in 5(ish) round groups (i.e., a one-round-per-depth Saterlee-style test doesn't really appeal to me), using a total of 25-50 rounds. Also, I only want to test more (not less) jump than .010.

Given that... help me develop a seating depth test:

- What increments should I test?
- Should I use more/less than 5 rounds per group?
- Any thoughts on where I should start testing at?
- Other considerations?

FWIW, bullets are Berger 184 F-Open shot in a 7mm RM.

Thanks for reading!

 

[straightshooter1]

I've done some initial load testing with charge weights, and found a very forgiving node (5 charge weights at .2 increments all very close to each other). FWIW, the groups were good at 10 thou jump, but in any event, I figured I'd just take the middle load and start playing around with seating depth to see if anything popped. I haven't messed with depth testing much before, and in doing some research, the way people test their depth seems to be all over the place.

Some people test in .001, .003, .005, .010, .020, or .030 increments... I'd personally be inclined to check in increments of 5, 10, or 20 thou, but I'm curious what works for you guys. I've also seen more openness to testing long jumps (.090-.150, or even more) that would've been scoffed at not too long ago. Again, I'm curious what works for you guys.

I'm thinking of testing in 5(ish) round groups (i.e., a one-round-per-depth Saterlee-style test doesn't really appeal to me), using a total of 25-50 rounds. Also, I only want to test more (not less) jump than .010.

Given that... help me develop a seating depth test:

- What increments should I test?
- Should I use more/less than 5 rounds per group?
- Any thoughts on where I should start testing at?
- Other considerations?

FWIW, bullets are Berger 184 F-Open shot in a 7mm RM.

Thanks for reading!

Assuming you want something that fits in your mag, then start at maximum COAL that'll fit. I guess your cartridge at .010 off the lands fits you mag???

If you're .010 off the lands, then moving back in .005 increments is as high as you really want to go so that you don't miss a node. I like to use .003 increments and fire a series of 3 rounds for each increment. I feel 3 round is best if one's reloading skill is producing very consistent cartridges, otherwise, 5 rounds can better help you see the the differences.

 

[Deleted member 10043]

You're over thinking it. You decide on what increments. And simple 5 round groups per depth is fine. Load development should be simple and quick. Too much bloated load development dogma out there. Based on margin of error .001 and .003 are in the lands and there is nothing wrong with that. Then .005, .015, and .02 should suffice. VLD bullets may need .025, .03...

As mentioned above if you shoot with a mag you may be limited on max COAL.

You say it is shooting good at .01 and there is good reason for that. Do your seating depth test then come back and post your results.

 

[clcustom1911]

I've done some initial load testing with charge weights, and found a very forgiving node (5 charge weights at .2 increments all very close to each other). FWIW, the groups were good at 10 thou jump, but in any event, I figured I'd just take the middle load and start playing around with seating depth to see if anything popped. I haven't messed with depth testing much before, and in doing some research, the way people test their depth seems to be all over the place.

Some people test in .001, .003, .005, .010, .020, or .030 increments... I'd personally be inclined to check in increments of 5, 10, or 20 thou, but I'm curious what works for you guys. I've also seen more openness to testing long jumps (.090-.150, or even more) that would've been scoffed at not too long ago. Again, I'm curious what works for you guys.

I'm thinking of testing in 5(ish) round groups (i.e., a one-round-per-depth Saterlee-style test doesn't really appeal to me), using a total of 25-50 rounds. Also, I only want to test more (not less) jump than .010.

Given that... help me develop a seating depth test:

- What increments should I test?
- Should I use more/less than 5 rounds per group?
- Any thoughts on where I should start testing at?
- Other considerations?

FWIW, bullets are Berger 184 F-Open shot in a 7mm RM.

Thanks for reading!

Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

VLD bullets are designed with a secant ogive. This ogive shape allows bullets to be more efficient in flight (retain more velocity = less drop and wind deflection). While this result is desirable for many rifle shooters the secant ogive on the VLD bullets produces another result in many rifle.

bergerbullets.com

Youre welcome. It worked for me.

 

[Dthomas3523]

For PRS, you’ve got a lot of room for error. So if you just want to do .005 or .010 increments, find a large seating node that’s stays within .5 moa or so, and then just load on the long side of the node for the life of the barrel (not changing anything at all)......that’s perfectly fine.

If you want to get into the weeds and squeeze out everything you can from the barrel, you’ll need to keep tabs on it. Here is one method, though there are a few other ways as well.

 

[Dthomas3523]

I’d personally do .003 increments.

If the first two shots aren’t touching, I wouldn’t waste the 3rd or the other 3 if doing 5 shot groups.

Similar to tuner setup. Take 2 shots, if not touching, move on.

If the first two touch, I’d either fire the third, or I’d move to the next depth and fire the first two there. Since looking for a seating node, you want it to be good on a few different depths. So, it would be something like this:

.023 don’t touch
.026 don’t touch
.029 touch 2
.032 don’t touch
.035 touch
.038 touch
.041 touch
.043 don’t touch
.046 touch
.049 touch
.053 don’t touch

That’s 22 rounds instead of 55 rounds. I’d then go back to the .035-.041 and shoot the other 3 rounds for groups to verify.

Obviously this relies on you breaking good shots. If you know you didn’t break a good shot on say .026, then shoot another 2 shot group and really focus on breaking good shots. If it doesn’t touch again, keep moving.

 

[phlegethon]

Read this and all will be clear: https://precisionrifleblog.com/2020/04/28/bullet-jump-research-and-load-development-tips/

 

[Deleted member 10043]

Read this and all will be clear: https://precisionrifleblog.com/2020/04/28/bullet-jump-research-and-load-development-tips/

"What if instead of looking for the one exact bullet jump that provides 100% optimal precision and having to constantly adjust the seating depth as the lands of the barrel erodes, we instead looked for the bullet jump that is very forgiving AND still provided good precision over a wider range of jumps?"

 

[Diesel65]

I have a two part OCW spreadsheet that makes nice neat calculations thats printable. Got it from somewhere but cant remember where. I can try to email it to you, wont attach files here for some reason

 

[Joshcrz]

100-200 or further out for seating depth testing???

 

[Doom]

Since you found a charge weight node you also have a gross seating node from that test. You can refine that depth by going on either side by several thousandth. The recommended .+/-0.003 increments should work and a max of +/-0.006 should give you a good feel. I have not used the system Dthomas suggested, but I think his system has merit.

 

[Joshcrz]

Since you found a charge weight node you also have a gross seating node from that test. You can refine that depth by going on either side by several thousandth. The recommended .+/-0.003 increments should work and a max of +/-0.006 should give you a good feel. I have not used the system Dthomas suggested, but I think his system has merit.

My mistake.. I didn’t clarify.. was speaking about testing distances. 100-200 yards or beyond. Just interested in what some are doing?

 

[straightshooter1]

My mistake.. I didn’t clarify.. was speaking about testing distances. 100-200 yards or beyond. Just interested in what some are doing?

I like to do most of it at 100 yrds in order to minimizes environmental factors. Then when I've got it pretty tuned there, I'll move out to distance (300 or 600 or 1000) and fine tune some more when there's virtually no wind to speak of.

 

[Doom]

I like to do most of it at 100 yrds in order to minimizes environmental factors. Then when I've got it pretty tuned there, I'll move out to distance (300 or 600 or 1000) and fine tune some more when there's virtually no wind to speak of.

That’s it.