LANDS, JUMP, POWDER. Which comes first chicken or the EGG!!!

[Jim Buck]

Gentlemen,

I have been working on loads based on powder type and bullet type. I have finally figured out the best way to find the Lands. I have found gret loads with standard bullet depth based on what manufacturer calls for and powder types. It seems like now that I have this it is a waste of time and lead to go back and do the bullet seating.

Question: Should I just jump the bullet .020 and keep working, or get the right powder bullet combo and then figure seating depth?

 

[jbarnwell]

First, I always find a bullet and powder combination that work for my rifle, as these seem to have the greatest impact on reaching your final results. Then I check other factors, such as seating depth, primer type and case type to see if I can improve on the original load. If I am satisfied with the original I don't mess with it anymore! At that point I may look for other combinations.

This is just my two cents on your question. The above has worked for me for many years.

Good Luck

Jarvis

 

[kyreloader]

In a hunting rifle, I load to maximum magazine length or 10 thous off the lands and work on the powder charge that works best. I then shoot groups seating deeper by 5 thousandths until I reach "the" seating depth. For Berger bullets hunting bullets, I seat them the way they recommend on their website. Here is a link, read the April 2009 posting on this page.
http://02b0516.netsolhost.com/blog1/?paged=2

In a target rifle, I start 10 thous into the lands and then find the powder charge that works. I then work into the lands by 5 thousandths until 20 thous into the lands. I also seat deeper by 5 thousands until about 20 thous off the lands. Usually 1 or 2 of the seating depths really shines.

 

[Shynloco]

Jim,
I'm not sure I can answer your question about the chicken and egg dilemma. But I can tell you what I discovered by doing much the same as you have. I started testing various powders and a specific manufacturer's bullets using the recommended meaurements by the bullet manufacturer. I then measured the "jump" in this particular rifle which was a Ruger M77V 22-250 and came up with .080. I then started seating bullets (ten rd groups) in groups of .010 closer to the lands until I got into the lands.
Found something interesting when I got to the range. I shot two five shot groups for each measurement depth setting @100 yds. From .070 to .050, there was no remarkable improvement in the size of the groups over the recommended setting. And after any closer setting, there was a drop off in the accuracy and the groups got bigger. What that told us is that this particular rifle LIKES a jump of .080. And after talking to a few Gunsmiths and ballistics guru's, I learned your "particular" rifle will tell if it likes the jump or if your accuracy can be improved by setting you bullet closer to the lands or even into the lands. Keep one thing in mind...and thats if you get into the lands, you will also drive up the chamber pressure so be careful.
Different rifles (this time a Savage Model 12 .223 VLP DVM & a Ruger M77V .308), same exercise....the closer I set the bullet, the better the accuracy and the best came when I set the bullet into the lands (on the .223).
Moral of this longwinded story, despite the conventional wisdom of setting the bullet closer or into the lands, there is always the exception to the rule. Guess you'll just have to keep at until you find out which works best in your rifle.
Good luck and have fun in your hunt.

 

[pgg]

jim Buck I have some great notes on this on my loading bench when I get back to the house I will get those to you. Good question PG

 

[allenn]

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1713419#Post1713419

 

[coyoteklr]

i'll tell you one thing is that different bullets like different jumps......
case in point barnes tsx and ttsx.... and different calibers may make a difference....
barnes triple shock like a min. of .060 and can go as high as .125 and barnes triple shock also really like speed to be accurate ........they don't like to be coddled... so it may take some experimenting..
some bullets don't care if you jump them .010 or .050 but others do........

 

[serial # 001]

In my .223 Svage I fired five five round groups at 100 yards of several loads. This test proved beyond a doubt the this rifle prefered .015" off the rifling. Each is an individual.