COAL help

[yzm19]

does it matter if you are + or - like .03 on your loads? i am going to load some .308 and was wondering if i need to be "spot on"??

 

[AJ Peacock]

The closer the better. .03" is a LOT.

.003" is almost tolerable, if your not close to the lands. I try to keep mine within .001" base to ogive lengths.

Are you having problems getting your reloads to the same length?

How are you measuring the length? Base to tip or Base to ogive?

The best way is to measure base to ogive, as then your keeping the bearing surface a consistent distance from your throat.


AJ

 

[MagnumManiac]

does it matter if you are + or - like .03 on your loads? i am going to load some .308 and was wondering if i need to be "spot on"??

If you're referring to SAAMI length, then no. SAAMI listed COL's are a guide only for the shortest chamber, and do not have to be followed to the letter.
An easy way to determine the COL for YOUR rifle is to cut a slot in the neck of a dummy round, seat the bullet long, and chamber in the rifle. This will show you where the origin of the rifling is with THAT bullet. This measurement will change with different bullets.

I always set my handloads either for the maximum magazine length, or for single shot target rifles, to the length that the rifle likes.
This may be shorter than SAAMI or longer, depending on the above restrictions/usage.
Each bullet profile has a different ogive length, which dictates how far into the lands it will seat and the COL will need to be adjusted for this, normally a length just shy of the lands is preferred, but this cannot always be had. So, if a magazine rifle, seat 3 bullets that are .010"-.015" short of magazine length, then 3 at .020", and so on at .005" increments, until you find the 'sweet spot' with THAT bullet, this may/will change with each bullet profile you use.
Hope this helps you out.
MM.

 

[yzm19]

well i i ment .003 not .03
how do you measure from the ogive? so do you guys measure every single load to get it just perfect?

 

[AJ Peacock]

well i i ment .003 not .03
how do you measure from the ogive? so do you guys measure every single load to get it just perfect?

The way I do it is as follows.

1) find out the longest I can seat a bullet without touching the lands. (several methods to do this, ask if you can't find it using search)
2) seat it deeper an appropriate amount for the type of bullet I'm loading (typically between .005" and .030")
3) use a consistent motion to seat each bullet. I usually measure every round just to make sure nothing has moved. I seat the bullet and measure while my RCBS chargemaster is weighing the next dose of powder.


There are a couple good ways to measure base to ogive, you can get a tool that attaches to your calipers that is made by hornady (they call it a bullet comparator), check this link Hornady it is down a little.

The other way is to buy a little hex nut that has different size holes in it. Like this one from sinclair Bullet Comparators - Sinclair Bullet Comparator #1

I have both and like the Hornady tool the best.

Just go to Sinclairintl.com and search on bullet comparator to see the options.

AJ

 

[yzm19]

aj what +/- tolerance do you use for your coal? i have been trying to stay .002 +/-.
i have been measuring my rounds wile the chargemaster works too.
thanks for the links ill look at trying the ogive measuring method.

 

[AJ Peacock]

aj what +/- tolerance do you use for your coal? i have been trying to stay .002 +/-.
i have been measuring my rounds wile the chargemaster works too.
thanks for the links ill look at trying the ogive measuring method.

With really good bullets (Sierra Match Kings), Mine are usually nearly perfect. Trying to measure base to tip is a complete crap shoot, as the tips are never close enough to really know where you are at.

AJ