Accuracy Asymptote

rimfiremac

rimfiremac

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Are there any standards out there commonly used to find out what OAL a given rifle likes?

From my perspective, you can approach best accuracy using the powder charge as the free variable, while OAL is fixed; or, fix the powder charge and vary OAL to find the same, however if I understand correctly, seating to the lands may cause pressure increases, which I would imagine you would not want if operating near max already.

What approach do you use to dial in both powder charge and OAL?
 
From what I have heard, accuracy can be increased by giving the bullet a little jump, as in being 1/10 or 2/10s off the lands. I suppose its subjective for each rifle though
 
I usually start my load develop with bullets seated at the lands. I find the best powder load and then tune with seating depth.

Generally speaking though, a BT bullet (such as the Sierra MK) likes a jump and the VLD's (Berger for instance) like to be jammed. I know Berger says otherwise but testing around here has resulted in jammed Berger bullets and Jumped Sierra's.

The above is for F-Class or Target shooting.
If loading for a hunting gun or repeater then jamming the bullets probably isn't a good idea or not feasible due to mag box length anyway.
 
Gotcha... next up... what do you do to figure out what OAL seats the slug at the lands? I've tried seating a bullet excessively long on an empty, non resized case, and then chambering it, but it comes out looking like it went in. No dice on setting OAL by using the lands to 'seat' the bullet to the right depth.
Ideas?
 
What bullets are you using to check you oal?? The method you used should work, however, I put a bit of squeeze on the empty case to ensure the case mouth has a bit of grip when the lands push it back. You should repeat this process at least 10 times to get a consistant reading. If this process doesn't work I can only guess that you have a lot of freebore in your barrel. Or the barrel is old and showing excessive wear.

There is an excellent artical on Bergers website on how to determine the best oal for "thier" bullets, but it will work for any im sure.

Hornady makes an OAL guage that is designed for this. Very easy to use.
 
I'm running 140 gr Hornady's in a Brno 270- it may have an excessive amount of freebore- at least it surprised the heck out of me when the cartridge came out looking the same as it went in, and it went in looking something like a 6.5 swede in proportion. Will try again...
 
I use the method suggested in the Nosler manuals, which is pretty much as you described, but you left out the part about blackening the bullet with a felt marker. Colouring the bullet allows you to see where it contacts the lands or if it doesn't, and how far it was pushed into the neck or if it wasn't. The bullet sometimes moves when you extract the case and you use the marks on the shank to reseat it to the lenght it was in your chamber. Along the lines of what Barks said, if you are using a very short bullet and have a very long throat it may not contact the lands. Try using a longer bullet and repeat the test to see what happens. Good luck.
 
I set up the die with a "standard round" constructed by seating a bullet in the rifle, hard to the lands. Once the seating stem touches the bullet with the ram in the up position, I take the standard out, and screw the stem down a half turn. That works out to about 15 thou off the lands.
 
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