New to reloading and have question on seating bullet

[CarbonBonds]

Hello,

I have a question on seating a 95gr tipped Sierra matchking in a .243 win. In an unprimed brass I seated the bullet 0.020" off the lands: COL @ 2.675" to get the right length before loading up actual rounds to shoot. When I went to measure the length, the bullet itself was pushed deeper into the empty cartridge. Do I need more of a crimp to secure the bullet better? I sized and cleaned all of my brass prior to shooting this Christmas break.

Just the other day I loaded 105gr AMAX's and I had my test COL unprimed round for the .243 as well. The AMAX was rock solid and didn't move at all.

Happy New Year everyone!
CarbonBonds

 

[FearNoWind]

You will read lots of suggestions in forums such as this for using the method you've chosen to determine OAL. But there are two inherent problems with that method. One is what you've described, the other is that when you check length using that technique you sometimes force the bullet into the lands so that, when you remove it, the bullet hangs up just slightly and that creates in accurate results.

My recommendation is to uses this method:

Hornady Lock-N-Load Overall Length Ga Bolt Action

Coupled with these:

Hornady Lock-N-Load Bullet Comparator Basic Set 6 Inserts

and a properly selected Hornady Lock-N-Load Overall Length Gauge Modified Case in the caliber you're working with

http://www.midwayusa.com/product/128125/hornady-lock-n-load-overall-length-gauge-modified-case-243-winchester

and use the CBOL as your reference.

 

[ShtrRdy]

If the shorter COAL that you measured was with a different bullet, the length of the bullet may be to blame.

 

[FearNoWind]

If the shorter COAL that you measured was with a different bullet, the length of the bullet may be to blame.

Great point sir. Thanks for adding one more excellent reason for using the CBOL method.

 

[CarbonBonds]

Thanks for the advice. Went and purchased it and started the COL from scratch with the Lock-N-Load. Bullets are snug in the neck now and are shooting well for a starting point. Multiple groups at 0.56-.0.86" with five shot groups.

 

[kerrek]

FearNoWind,
Is it better to use the Hornady cartridge or one from your own gun(modified fire formed case)? Or doesn't it matter?

Ken

 

[WildRose]

FearNoWind,
Is it better to use the Hornady cartridge or one from your own gun(modified fire formed case)? Or doesn't it matter?

Ken

Where you can it's best to use something like the Hornady modified case OAL gauge.

https://www.midwayusa.com/product/6...gth-gauge-modified-case-300-winchester-magnum

It's cheaper to just save a round that's measured for the OAL and correct but it's not giving you perfect SAMMI dimensions for the whole case.

 

[FearNoWind]

FearNoWind,
Is it better to use the Hornady cartridge or one from your own gun(modified fire formed case)? Or doesn't it matter?

Ken

You're looking for COBL. Because you are measuring from the base to the ogive, unless the case shoulder interferes with the distance the case/bullet combination enters the chamber, there is no need to drill and tap a special case fired in your rifle to make the measurement. If you want to make sure of the shoulder tolerances you can always run the Hornady case through your sizing die to set back the shoulder and then use an expander mandrel or seat a bullet and then pull it to open up the neck for the loose fit bullet. You can make a case yourself if you want to drill out the primer recessand tap the hole but, IMO, it's' much easier to use the Hornady case.
Caveat - There may be a time when you can'f get hold of the case you need using Hornady's commercial products. In that situation, you'd be compelled to make one of your own. The drill size you would need is a .290 drill bit (letter "L") and a 5/16x30 tap. You can do it using a drill press but it's a bit tricky getting the alignment right so a lathe works much better. (That's why I said "IMO, it's' much easier to use the Hornady case.)