284win help

[pointy sticks]

I am building my daughter a hunting rifle in 284win. Running lapua brass. Getting ready to order a barrel from carbon six. Looking for advice on proper amount of free bore for 140-168 class bullets. My max coal is just under 3.25in. I have zero 7mm bullets to get any measurements from I only have 6mm and 30cal. I would be willing to buy singles from someone who has a good selection of 140-168s to get my own measurements and to send them a dummy round or 2. I have attached the reamer print they have on hand. I would have to rent one if I wanted something different.

 

[pointy sticks]

Anyone have any experience with this cartridge?

 

[Taylorbok]

I set mine up to shoot the 180's I went with .225 FB.
I have some 166 a-tips I can measure for you tonight.

 

[pointy sticks]

Can you get to the lands with the 166s? And if so what is your cbto and coal? If you have that info for the 180s that might help as well. Also do you have the reamer print for your chamber?

 

[pointy sticks]

The print above shows .233 seems a bit long but I actually don't know. This is the other option I found. Shows .152fb.

 

[Taylorbok]

I haven't shot or loaded any of the 166's yet. Based on my measurements I'd still be able to reach the lands no problem. If I was setting up a reamer specific for those bullets I'd go for a .190-.200 FB. My reamer is an 284 Win-improved. I can share the print if you like.

 

[pointy sticks]

So maybe go with the .152 reamer then have it throated after I get some measurements? Ya sharing your print would be nice. I haven't chambered it yet so I could go imp

 

[Taylorbok]

I just realized you have a pretty short COAL restriction I should have seated one and measured that for you. I can do that later today if you like.
IIRC my COAL with the 180's is like 3.30" ish so you should be able to do 3.25 with 166 ish bullets.

I am shooting the 180's at 2850 ish out of a 26" barrel. If 7 PRC was a thing when I started this build I would have looked really hard at that. If you want to do improved you need to have custom dies made. I went the route of ordering a resize reamer and having my smith cut a set of Newlon die blanks for me.
Here is the print

 

[pointy sticks]

Ya a coal measurement would be awesome! I am a little limited but I am building this for my daughter so I was only going to run 150 to 160s I thought I would be ok.

 

[pointy sticks]

Looks like the reamer they have in house has a .010 shorter fb than yours. If your coal measurements of the 160s are under 3.25 with the bearing surface above the neck shoulder junction. Unless the throat angle is different and that changes things. I will prob just go with that one. That would make my life easier then trying to hunt one down to rent.
@Taylorbok

 

[Taylorbok]

With boat tail seated at the junction you are about 3.210 with these 166 A-tips. Personally I'd use the short reamer and have it throated separately.

 

[pointy sticks]

.

 

[pointy sticks]

Do you know what the measurement is coal or cbto for the 166 at the lands in your chamber?

 

[Taylorbok]

In my chamber with the a-tips just touching the lands coal is 3.250 exactly.