243 oal question

[profman]

using factory loads in 100 gr 243 bullets, i get 1.5 inch groups at 100 yards. using imr4350 powder and speer 100 gr spbt bullets, i am getting the same grouping. rifle is remington 700 and not shot a lot so throat should be ok.

in trying to get the oal of my reloads, i used a fired cartridge and a bullet in the case and loaded the empty round into the rifle and ejected it and measured the length. did this with two separate cases.

the bullets were pressed into the cartridge shell and didnt come close to the cannelure. here are the measurements of the ejected cartridges.

oal 2.65
case length 2.054
the bullet needs to be seated 0.0638 - 0.0640 deeper to reach the cannelure.

even if a crimp is not used, it seems that the bullet would have to be seated really far out to get close to the lands using the 100 gr bullet. doesnt seem to be a lot of bullet left in the neck to hold it, even tho it is less than max oal. would seem impossible to do with lighter bullets which are even shorter.

how can the bullet be seated closed to the lands if the bullet is seated properly to crimp on the cannelure?

advice or recommendations would be appreciated.

thanks.

 

[rcmodel]

It can't.

Lawyers have made excess leade or free-bore very common on a lot of factory chambers anymore in an effort to reduce pressure.

Some are so deep there is no way to "load to the Leade".

A good rule of thumb is either seat to the cannelure and fogadaboutit.
Or seat at least one bullet dia deep for proper case neck tension.

I feel consistent "bullet start pull" from proper case neck tension will do more for accuracy then seating to the rifling when you can't.

Excessively shallow bullet seating in the case and resulting reduced bullet start pull will hurt accuracy.

rc

 

[interlock]

+ 1 to what rc says. i had a ruger m77 mk2 in 243 win. i loaded it with hornady 2450 to about a couple of thous off the rifling. the cannulure groove seemed far to far out. the rifle shot pretty well but following an incident with my .30-06 when i had seated the bullet into the lands - where it subsequently got caught - and subsequently spewed a load of powder out and ended my hunting trip, i shortenned everything down. the 243 went down to the groove.... there was no difference in the groups.

i have a remmy model 7. when i load to best accuracy the rounds won't fit in the magazine. i won't be hand loading whilst hunting so i have wieghed off a little accuracy for reliability.

 

[243winxb]

The bullets base can be at the neck shoulder junction and still shoot fine. On a boatail, use the full diameter of the bullet.

 

[steve4102]

The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of
the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.

 

[NCsmitty]

+1 on the other poster's suggestions.

You need to load so that the ammo cycles through the magazine. It's not necessary to crimp unless you want to, or if the neck tension on the bullet is not up to the norm.
I try to load to .020 off the lands, if the rifle/bullet combo allows it.



NCsmitty