New build throating

[frostop]

I have made up my mind to convert an existing short action Ruger from 338 Jamison to 270 WSM and I think I want to make it a single shooter. From what I have read here it is my understanding that for best powder capacity and performance to seat the bullet so that it only occupies the neck?
Doesn't extend below the neck much if at all? Than have the barrel throated accordingly?

Thank u for any replies

Gary

 

[AZShooter]

I have seen handloaders fret over the OAL of a case on many forums. IMO there is little velocity to gain with an OAL so long that you have to single load. Regardless of where you seat the bullet you can get accurate results without placing the bullet in that ideal locatin where the boattail /bearing surface junction is even with the shoulder/body junction of the case.

If you have the cases on hand you could try an experiment. It would be easier to do with some fired cases or with some that have had the necks expanded enough to slide a bullet in place without neck resistance. I use an K and N expand iron the tool that is used before using their neck turning tool.

There are plenty of powders that would have 100% load density. Figure out what OAL would fit and feed from magazine and fill case with powder so bullet sits at that height. Do same with bullet seated out for max OAL for single shot.

Divide the larger charge weight into the smaller one for a percentage. Subtract that value from 1. Then divide that value by four to see the velocity gain you will get by seating the bullet to a longer OAL.

Example lets say you can get 65 grs of powder in the shorter OAL and 68 grs for the single shot mode. This is about where the 270 WSM ends up. This comes out to be .956. Subtract from 1 minus .956 = .044 Divide .044 by 4 (see John Barsness's article on this fact) = .011 or a 1.1 percent increase in velocity!

I seriously doubt you will get more than a 2 % gain in velocity for the inconvenience of going to a single shot.

 

[frostop]

Thank you azshooter for the reply! In your opinion is there any disadvantage to having the bullet seat below that line into the powder besides reduced powder charge, accuracy etc??

Gary

 

[AZShooter]

I don't think there is an accuracy issue with a bullet seated deeper in the case. Many factory cartridges do exactly that. The 300 win mag is an example with quite a bit of the bullet inside the case.

I put together a very accurate load for my friend's 300 WSM using the 230 gr berger hybrid. It had to fit a 2.8" mag restriction. Velocity is 2735 fps. This is the most extreme example of a deeply seated bullet I have ever fired. It feeds and shoots just fine.

 

[TOM H]

I have made up my mind to convert an existing short action Ruger from 338 Jamison to 270 WSM and I think I want to make it a single shooter. From what I have read here it is my understanding that for best powder capacity and performance to seat the bullet so that it only occupies the neck?
Doesn't extend below the neck much if at all? Than have the barrel throated accordingly?

Thank u for any replies

Gary

Since you converting over to single shoot I'd seat the bullets out and take advantage of not loading compressed load and having neck more on the bearing surface.

You should make up some dummy rd with bullet you want to shoot and that give you idea of the difference going 2.800" and seating further out.

I'm not much into compressed loads and I have mine custom throated and it's not worth getting into battle over which is best.

Well good luck