Reloading Swiss Black special

[Varmits nitemare]

Just picked up a SBS , 1:10 twist , I have been a benchrest / highpower rifle shooter for years , noticed that the 55grn FMJ ammo has bout .120 of freebore till they contact rifling ( bullet to rifling contact ) most guns shoot the best with .005/,020 of freebore , I removed the factory bullets and replaced with 55grn sierra hp/bt and by changing the bullet seating depth i can get the .005/.020 , I have ordered some 60/62 grn berger / sierra bullets to try , I think this weight is better suited for the 1:10 twist , I am waitng to get my burris one piece scope mount , before shooting , to see what type of acc i can get from this gun , the mag will accept the longer bullet oal so i should be able to get the freebore distance that will be better . just wonder if anyone has developed a very accurate load for this type of gun and done some load testing , and what type of powder have you guys found works with the semi auto action . Thx for taking the time to read and reply .

 

[beltfed]

Are you planning on using the ammo in any other rifles using 223 and if so, will they need to be mag fed?

If yes to either of those two questions, I'd stick to 2.260" oal as a maximum.
If not, you can take advantage of the longer length the mags on the Sigs will allow.