243 winchester - magazine chamber or optimum performance chamber.

358Scout

358Scout

Regular
Rating - 100%
72   0   0
Location
Saskatoon
WOW! Have you ever gone into a project and become totally flustered by all the recommendations. I'm at that point now. My new 243 Winchester build seems to have got out of control. My intentions were to use Berger bullets and maybe switch to Sierra ( 107gr and 105 gr) As you may have read, my gunsmith needs a loaded cartridge ( COAL ) to complete the chambering.
The Sierra is no problem. I contacted Berger for the COAL for a 243 Winchester using the 105gr VLD. THis is what I got back - in short............

The COAL we furnish is a SAAMI spec of 2.710. But this is not good for you. For this bullet to realize its maximum performance it should be seated so the junction of the boat tail and body of the bullet does not pass the junction of the neck and shoulder. This will be to long for normal magazine use as it will be to long. You have a decision to make, if you want a magazine chamber or optimum performance chamber...........

Well I did some measuring. The boat tail is .071" long. The neck on my Lapua's are .220. This gives me next to no brass to hold the bullet maybe .150 inches.

The twist is a 1 - 8" - should I forget the Berger and stick to Sierra?

Since Gaillard rifled the barrel for the Berger 105gr VLD am I going to have a problem with other bullets like the Sierra or Lapua.

WHAT TO DO?
 
If the junction of the boattail and the body of the bullet is seated no deeper than the junction of the neck and the shoulder, you will have .220" of neck holding the bullet.
 
OOPs your right - I read it wrong. Thank you .

Still - I loaded one Berger and a Sierra - that's an awful long cartridge.

Any suggestions or comments on switching to different bullets once its been chambered?
 
I have a Remington 700 and follower in place. Now that I'm looking at it, I guess it doesn't matter how long the bullet is set forward as its going to be primarily a single shot.
 
Sierra's shouldn't be a problem, they are the least sensitive to seating depths and shoot very well with some jump into the lands.
 
There is no rifling particular to a brand of bullet, the twist makes a difference. 1:8 in a 243 will stabilize everything. I have found Lapuas to be a finicky bullet and they prefer a tight bore. Some guys have no trouble making them work extremely well, but I have not had luck with them

I have loaded up a 243 case (2F, lapua brass) and used 3 bullets. They were seated for optimal shoulder/boat-tail seating. Here are the measurements...

107 Sierra COAL = 2.829" Case case base to Ogive measurement: 2.150

Berger 105 VLD COAL = 2.831 CBTO = 2.097

Lapua 105 COAL = 2.858 CBTO = 2.238"

Hope this helps
 
Although not ideal, Berger VLD's shoot just fine when the boattail is below the neck shoulder junction. So if the mag length is 2.85", it will be fucntional.

Now if you really want to be sneaky, why not build a 6XC? unless you are planning on a +26" barrel, the XC will keep up with most 243 loadings, feed from the mag no problem even when the 115's are used.

More to add to the mix.

Jerry
 
Thanks guys. Mysticplayer - I think I will stick with my 243 Winchester for now. Nearly peeeeeed my pants - my barrel arrived in the mail today. Time to put all together. Just downloaded the loading pages from Sierra's manual on the 243 Winchester. It claims the C.A.O.L for a 107gr HPBT Match in Lapua brass is 2.850. I think I'll stick with that for now.
By tomorrow I may even change it to "Obtundeds" loaded COAL of 2.829"

Since I dont have my action at home - any one know where on the web a person can find the maximum COAL for a Remington 700 SA. For the life of me, I cant find anything on it...
 
You must log in or register to reply here.
Back
Top Bottom