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How far off the lands to seat bullets

11K views 5 replies 4 participants last post by  drymag 
#1 ·
I just received the Hornady OAL gauge and have measured the cartridge length from cartridge base to ogive on several bullets I reload. I've read many conflicting opinions of what the distance should be for maximum accuracy. Hornady says the ogive should be .020" - .040" off the lands. Some of the long distance shooters in my club load for .002" off the lands. So what distance do you guys that shoot for accuracy load off the lands?
 
#2 · (Edited)
Hi, there is no magic number regardless what anyone tells you.
The distance between the projectile and the lands can and will be different for every rifle - bullet /barrel combination.
However don't despair.
You simply start at the shortest amount of bullet jump , oh say .002 and test fire for accuracy.
Then load up a few more rounds at say .010. Was there any change in accuracy? Was it better or worst. If better, then add a few more thou. and do it all over again. Get the idea?

Now then to give you an idea in regards to my personal rifles.
Target 243 with shilen barrel .002
Target 7mm mag thompsom barrel .040
Target 270wsm hart barrel .510 (yea that's a little over a half inch . Commonly called free bore)

Target 22 rimfire jesop barrel -.01 yes the bullet is touching the lands. FOR 22 RIMFIRE ONLY
Never ,NEVER do this with center fire.

If it helps any, I always start with a bullet weight that the rifle seems to prefer over other bullet weights. ie. my 243 performs the best with 85gr bullets.
 
#3 ·
You have to also determine if this will be a hunting rifle, or a bench gun. If it's a hunting rifle, you will be loading the mag/box up + 1 in the chamber. Your rounds will need to fit in your mag/box below. If it's a bench gun where you load 1 round in to the chamber at a time, then who cares if they fit in the mag.

Some rifles like my M70 300wm limit me to how close I can be off the lands, and still fit in my mag. I pretty much have my loads where they just fit the box, and chamber reliably. I'm about .015" off the lands. On the other hand my Ruger M77 7mm RM has a short throat, and I can jam into the lands while still fitting down low in the box. I don't do this, but I am about .003" off the lands.

Just remember the closer you get to the lands, your pressures can/may/will go up. If you have a favorite pet load that's at or near max, and decide to move closer to the lands, watch for pressure signs.

Also with the Hornady OAL Tool, make sure you are just touching the lands, and not pushing the bullet into the lands thinking it's just touching. Then measure from ogive to head multiple times, and record your most consistent length.

There's a lot of work at the bench, and range to find that perfect load, but it sure is FUN!! :)
 
#4 ·
I was going to try that on my Mosin load but to get it near the lands required the bullet to be less than the diameter of the bullet in the case (close to 3/8th the diameter). On my sons ar, to get near the lands meant for the bullet to be longer than the mag and also came up short in the diameter department.
 
#5 ·
I have never loaded for a Mosin, but your right about the AR. I also load my .223 rounds to Mag length. There again, my AR's are only used for HD, SHTF, 3Gun comps, training classes, and range practice 5-100yrds max. If I can hit a 6" piece of steel at 100yrds in a match, I'm happy! :)
 
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