• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

Here is my tip on how to find ideal seating depth.

As many have said, "There is really nothing new in the world." The ideas for the method outlined above came from three sources. I interviewed all three for PS and got their ideas and assimilated them into one idea. These three were Tony Boyer, Joe Krupa, and Jack Neary (all three are Hall of Fame Members). Later, I was told by Eric Stecker (president of Berger) to not be afraid to jump VLD bullets quite a bit (as in .040 or more). I can usually find a good load without that much jump. Tony Boyer does not start at jam, but at "just touching" and always moves into the lands. He told me that he doesn't trust jumping with short range BR bullets. Gary Ocock told me that he has used the same method for many years....that is, he always shoots BT bullets and he normally jumps them by seating the bullets .030" off of jam and tunes with powder charge. So my method outlined above is a guide for those seeking a method for tuning. Sometimes I shorten the method by starting with bullets at .005 off jam because I have not had luck with bullets at jam. Also, I may shorten the process by using only two powder charges ... mild and hot. Good shooting...James

always funny to me to read these post. First thing i will say is whatever works for you.

this is a good method for the benchrest shooter. bet most that are disagreeing don't shoot consistent groups in the ones and twos.

with my bench guns i too start with a hard jam and work through load.development. then i back off .005 at a time. i have found secant ogive bullets like the VLD like the jam and the tangent ogive bullets like the MK are more forgiving about seating.depth and like a little jump. the new berger hybrids also like a little jump. now that is .005 off a hard jam so they still are probably touching. anyway after finding the magic seating depth i tweek my load a little.

for a hunting rifle where i need a mag length cartridge i use the berger test. quick and.dirty. fine tune afterwards. i found a seating depth for a 168 gr. VLD .130 off a hard jam one time. sounds crazy but it works.

http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
 
To find the ideal seating depth for a given powder and bullet a person needs to first find the jam for that bullet. Also, one needs to load at three different powder charges for each of the following seating depths. These should be a mild charge, a moderate one, and a hot load. These three loads are tested at different seating depths...starting at jam and then moving away from jam in .005 inch increments. (see picture below).

When one finds a 3-shot group that is in the same relative position with each powder charge (like those at .015 off), that is a great seating depth. After using this to find the best depth, one can tweak his best load by trying within the .005 inch window or within the .5 grain powder charge. Good shooting....James Mock
View attachment 1019593

I'm not an expert but I noticed every group shifts the point of impact. Is this as important s group size?
 
tag

as has been mentioned, trying to load to the 'touch point' would seem to be, well, a little too touchy. we strive for conditions where the rate of change is minimized, and i can easily visualize a 'keep out zone' there and +/- a couple thou.
 
Last edited:
Does a load lose it's tunability with seating depth changes if your making a huge jump just to get to the lands with a light bullet ? I'm basically at mag length just to keep enough bullet seated so the case holds it.
The gunsmith who built my first two custom guns once told me that he thought that nodes would sometimes repeat at about 30 thousandths intervals.
Some years later , a friend left a well built 308 with me as it shot factory loads well , and I suspected I could really get it to shoot.
I started 10 off the lands as it was clip fed and a hunting gun so I did not want it jammed. Found an excellent load, but too long for the clip.
Backed it out to 40 off and it went right back to shooting excellent groups and it allowed the bullets to feed through the magazine.
Not nearly enough evidence to prove the point, but the load may come back into tune as you back off the lands.
 

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Forum statistics

Threads
165,759
Messages
2,202,207
Members
79,089
Latest member
babysteel45
Back
Top