Struggling with Seating Depth Precision - 300 PRC - Monometals

[btuley]

could your powder be compressed? I've seen that cause inconsistent depths and they can grow longer over night.

I don't think the load is compressed, but possibly. These measurements are right after seating, rather than in the morning.

 

[cajun]

You can measure your bullets with the same comparator you use for oal. Measure the box and see how much variance there is. But I can tell you .006 variance in seating depth will not turn a 1/2" load into a 1.6" load.

 

[Aggie1999]

I've had problems like this with new brass before as well. Everything smoothed right out after first firing. Might give it a go with fired brass and see what happens.

 

[Mike D Texas]

What is your process for setting your final neck diameter?

Its most likely you have more seating tension than you think, or are you loading compressed loads?

I have several sets of Whidden dies and have been pleased with them. I have most recently however gone to a Wilson in-line die and arbor press for seating bullets and seen consistency tighten up a noticeable amount.

Do you have a ball micrometer and pin gauges?

 

[btuley]

Thanks everyone.

I took out the 35 rounds of Barnes 208 with 74 grains of H4831SC that I had prepped for the Elk that didn't who his face this fall. I measured the CBTO and grouped them into 4 groups based on length. They were around 0.01 jump so I had room to set them all back towards 0.02. I used four different settings on my seating die with the assumption that the original group differences were driven by bullet variations from where the seater stem presses to the ogive.

The result is that for this group my extreme spread decreased from 0.0075 to 0.0035. Still not quite what I would hope, but significant evidence that much of my error is driven by the bullet variation.

I plan to get out to a range I can shoot from prone and test these for groups.

Thanks to this conversation I feel good about keeping the stock jaws on the Forster press. I may still need to work with a different seater die. I think I'll also use the expander ball as I size the rest of my unfired brass.

I've got some 176 grain A-tip and just receives some different powders, H1000 and Retumbo, to try some different combinations for better groups, but as I work through those combinations I want to be nailing my seating depth. We'll see if the A-Tips seat more consistently, fingers crossed

 

[btuley]

What is your process for setting your final neck diameter?

Its most likely you have more seating tension than you think, or are you loading compressed loads?

I have several sets of Whidden dies and have been pleased with them. I have most recently however gone to a Wilson in-line die and arbor press for seating bullets and seen consistency tighten up a noticeable amount.

Do you have a ball micrometer and pin gauges?

Mike,

I do not have a ball micrometer. My tension setting for this group was just neck sizing due to new brass.

Not compressed loads.

What are your thoughts?

 

[orkan]

Seating depth inconsistency comes from brass inconsistency. Watch a bunch of content on my youtube channel and you'll learn more than you can imagine about brass consistency. That, combined with a good bullet seating die/press... will solve the problem of bullet seating depth consistency.


-----------
Follow on Instagram
Subscribe on YouTube
Amazon Affiliate

 

[Jesse09]

I guess I've always been fat, dumb and happy; my standard seating practice is always to adjust the seater for a longer initial bullet seat, then checking the ogive before readjusting the seater, and repeating as many times as it takes to get it right, just like Dmagna replied, above.

 

[btuley]

I guess I've always been fat, dumb and happy; my standard seating practice is always to adjust the seater for a longer initial bullet seat, then checking the ogive before readjusting the seater, and repeating as many times as it takes to get it right, just like Dmagna replied, above.

That is what I did, but once I got to the right spot, and made more than one bullet at that setting, the product is a wide variation.

 

[btuley]

You can measure your bullets with the same comparator you use for oal. Measure the box and see how much variance there is. But I can tell you .006 variance in seating depth will not turn a 1/2" load into a 1.6" load.

Yes, I'm going to work through other powders and charges and test some more, but as I do, I want to get the seating depth nailed.

How are you suggesting I measure the CBTO with my existing tool? It is a Hornaday COAL tool so it has a guage on just one side to measure the ogive on either the front or the rear, but nothing to measure from the seating stem contact to the ogive...

Hmmm. Thinking about it, I could measure base to Ogive and hand hold the stem on the bullet and measure bullet plus stem on bullet... Arduous and potentially error prone with the hand holding the bullet and the stem together... Could give me an idea if some variation exists though.... Is that what you are suggesting?

 

[Jesse09]

Maybe I should have made it clearer; after EACH round is properly seated, I dial back on the seater and repeat. I absolutely can't trust that the next round will seat at the same ogive as the one before it. That's just the price I pay to get it done.

 

[pointy sticks]

This may be a dumb question, but is this your first time using Whidden micrometer die? Do you have it set up correctly?

 

[pointy sticks]

Is the little lock nut on top of the dial tightened down properly? it can wander a little if not. especially if you're trying to do seating depth testing and your turning it a lot it won't track properly. Otherwise I agree the brass is prob the culprit.

 

[cajun]

Yes, I'm going to work through other powders and charges and test some more, but as I do, I want to get the seating depth nailed.

How are you suggesting I measure the CBTO with my existing tool? It is a Hornaday COAL tool so it has a guage on just one side to measure the ogive on either the front or the rear, but nothing to measure from the seating stem contact to the ogive...

Hmmm. Thinking about it, I could measure base to Ogive and hand hold the stem on the bullet and measure bullet plus stem on bullet... Arduous and potentially error prone with the hand holding the bullet and the stem together... Could give me an idea if some variation exists though.... Is that what you are suggesting?

Your over thinking this. Just use the hornady tool and use the bto measurement.