bullet seating and COAL

[popeye4]

Get one of these

Redding Instant Indicator/Comparator: http://www.redding-reloading.com/pages/instantind.html
RCBS Precision Mic: https://shop.rcbs.com/WebConnect/Mai...0&beginIndex=0
Hornady (old Stoney Point) Bullet Comparator: https://www.hornady.com/shop/?ps_ses...ac1a8d6e16635b
Hornady OAL gauges: https://www.hornady.com/shop/?ps_ses...a34eaef6e83165
Sinclair gauges of various types: http://www.sinclairintl.com/prod_det...eadspace-Tools

Here's an article by Rick Jamison on the Redding tool: http://www.redding-reloading.com/pages/rickjamison.html

If you want to get really anal about this, you can establish what the headspace is set at on your brass (as that determines exactly where the cartridge sits in the chamber) and seat your bullet based on your case headspace datum line to bullet ogive distance. For instance, if you aren't consistent in setting headspace when resizing brass (say, you have a variation of 0.005"), that will directly translate into a similar variation if you are seating your bullet based on case base to bullet ogive. Maybe it matters......

[swerv512]

Seat a bullet long in a resized case. Stuff it into your chamber using your thumb. If you need to use a thumbnail or a tool to get the cartridge back out, the bullet's touching the rifling--seat deeper by 0.005" and try again. When the cartridge falls out of the chamber from gravity alone, you're clear of the rifling, but still very close. Measure you COAL. Now you can adjust the jump for that type of bullet by adjusting COAL by the same amount (I would actually put the dummy cartridge aside so that you don't have to do this every time you go back to that same bullet).

This is the simplest, cheapest and by far the most repeatable way to measure where the lands are that I know of.

Adjusting jump is a lot easier & quicker with either a micrometer seating die or a bullet comparitor that goes on your caliper. The longer way around is:

1. set the die for zero jump (either by doing the above or using the dummy you saved from last time) and make a cartridge to match. Measure COAL and decide what you want for jump (say 0.020")
2. Use your bullet puller to move the bullet out farther than your desired jump (that original COAL + 0.020" or longer)
3. Move the seating plug up
4. Now you can adjust the seating plug down till you get the COAL that gives you the jump you want.

I tried this method but my bullet falls out with gravity no matter the length of the cartridge...

[30Cal]

I tried this method but my bullet falls out with gravity no matter the length of the cartridge...

Depending on the bullet and the barrel, you might not be able to seat near the lands. I'm assuming it's a factory barrel--they typically set a very long leade to accomodate whatever ammo you might use without causing pressure issues.

I'd recommend picking bullets with a good reputation for not being picky about jump. The traditional Sierra match bullets are good in that respect.

[ocabj]

I'd recommend picking bullets with a good reputation for not being picky about jump. The traditional Sierra match bullets are good in that respect.

Just follow 30cal's advice. Lots of people still use Sierra Match Kings and don't worry about chasing lands. The traditional BTHP design is very jump tolerant.

Granted, I've found VLDs to be jump tolerant, at least in the .223 AR SR platform.

Plus, trying to fine tune bullet seating depth is one of the last things you should be worrying about in load development (just stay within the safe range, i.e. don't jam into the lands some insane distance). If you have a load that has severe issues if you don't seat the bullet just right with respects to jump, then you should probably try something new (different powder charge, primer, brass, or bullet altogether), unless you are confident in your handloading skills (ability to chase lands effectively). If you get a good component combination, it should shoot great regardless of the jump to the lands (within reason, or course).

[swerv512]

thanks 30cal and ocabj.
i thought i was just screwing the measurement up. it a rem700 .308. i hear they are known for this...