6BR “Boyer Method” Help Needed

[GSPV]

Curious,
I chose .01 jump based on Erik Cortana’s recommendation to start at jam minus .020. I didn’t want to start that far away because I know this gun will shoot 105 Bergers quite well at .01 jump.

I don’t know if it’s the case here, but many people define “jam” as how far a lubed bullet can be pushed into the lands. They basically lube up a bullet, seat it long and chamber it. Where it ends up is “full jam” or just “jam”. They then use this as their “index measurement” and base all seating depth measurements relative to it. All of their measurements are then “X thousandths off of jam”.

Others find the point where a bullet is just touching the lands. Often using 0000 steel wool and a magnifying glass. Their measurements may then be “X thousandths jump” or “Y thousandths jammed”.

I know people that use either one or the other successfully.

The issue is when the two get mixed up.

Again, not saying that’s the case here. Just bringing it up to head off confusion.

 

[Ccrider]

I am using a Stoney point tool pushing the bullet as far into the lands as it will go and calling that “jammed”. So this is passed just touching the lands. I don’t think that it matters much as long as you have a base point and adjust your load off of that. When I become more proficient, and have more time, I will try the stripped bolt method.

 

[kenacp]

Cc- I highly recommend the stripped bolt method. It will find the exact spot of "touch". Just make sure that your sized brass has no drag when you close the bolt on the case., then proceed to seat your bullets.
Kenny

 

[#40Fan]

It doesn't really matter what method you use. As long as the measurement you get is what you base the rest of your measurements off of.

Hornady tool says 2.000" to CBTO.

Stripped bolt says 2.010" to CBTO.

Your gun shoots best with a 1.980" CBTO using the Hornady measurement as your gauge.

Your gun shoots best with a 1.990" CBTO using the stripped bolt method as your gauge.

They are both right!

 

[Evan]

Can you explain what you are seeing that made you choose .025?

I wanted to go back and discuss this a little more in detail. I see three groups of equal size and shape, impacting at the same 8 o'clock position without much variance, despite 110fps difference and mid-teens ES.

Here's what I don't know. Does this typically hold out to 300 or 600 yards, or is a new tune often needed?

 

[Ccrider]

I wanted to go back and discuss this a little more in detail. I see three groups of equal size and shape, impacting at the same 8 o'clock position without much variance, despite 110fps difference and mid-teens ES.

Here's what I don't know. Does this typically hold out to 300 or 600 yards, or is a new tune often needed?

I have not had a chance to shoot the load at 300 or 600.

 

[Tim Singleton]

A little more powder might help get that dab of vertical out
.5 grain or so

Course the next day it may not be there anyway

 

[Ccrider]

• I emptied the heavy sand from the ears on my rear bag and will replace it with playground sand. If that does not help I will step the charge up and see what happens. I never saw pressure signs but did not exceed 32gr.