Anyhow, once in a while, a juicy tidbit of information comes my way, and its too priceless not to share here on this forum, which as Pillar recently said on the "Herding cats...Bears" Video Thread, of really, really good people who care.
So for the background story, I have been working on a custom handload to get a 1942 Savage made #4 Mark 1* on target at 1538 yards using a 205 grain cast bullet from Buff Arms sized in the end, at .314. They also offer a .312 bullet, seated long, and I was going to use that seated very long, but at the last moment, I have 3 sources, including our own Jeremy Reed, tell me he remembered his Savage slugging out at .314. I seat the bullets out as long as I can by the camming into the rifling, then back off 2-3 thou for cast lead bullets. No crimp. Single shot only intended. Pressure matched to bullet hardness using Blue Dot and a bullet at 15-18 Bhn which is the best that Buff Arms could give me at the time I called, and slowing the bullet to 1600 fps if I can. Reason for that, is that when they go transonic, and subsonic, they completely go haywire. Lower velocity is actually better in this case. My best friend Tym made a "once in a lifetime" shot with his LE Mark 1 using factory military ammo on the FoBD target years ago. The following year, we could not detect where the bullet was even hitting, it went so far askey going transonic and subsonic.
OK, that's a lot of information to absorb at one time. Just wanted to bring you guys up to speed of what I have been working on lately and will test over Spring Break as Jeremy knows. So, the "age old" dilemma has been that there are those who think the 2 groove rifling on the Savage-made rifles is substandard and those who (especially the Canadians) who think their Long Branch rifles shoot better. So the comments from my learned friends below:
I got really lucky when I found this rifle at a local gun show. I hope to make it shoot the best it can be. It was made in 1942, unissued and has the vernier rear sight. For super long range shooting at this velocity, it will probably need a modified or extension of the rear sight. Might know a guy who can do that named Randy. Custom bullet mold to probably follow but that will take a long time in the current Covid economy.Bill just called.
The two-groove is ideal for cast bullets, far superior to any other rifling design. That was an accident of wartime expediency, but it is a fact.
Carefully slug the bore and then carefully measure the slug, or send it to your mould maker and have them build the mould to create a nose-rider section that fits the bore and then size the shank 1/1000" or so bigger than the groove and you will have a shooter. One way to do this is to make the bore-riding section taper about 2/1000" along the length and then adjust seating depth to drive the bullets hard into the rifling upon loading. With some cases, you can do that and not create a situation where the bullet gets left in the bore if you have to pull a chambered round -- neck tension is your friend.
Cast bullets are an art but it is one that can be learned and the payoff is worth the effort.
Also, Bill notes that with a hard enough cast bullet, in the two-groove barrel accuracy past 1900 fps is entirely feasible.
Finally, he also notes that others in the know have found that the two-groove barrel will shoot with acceptable accuracy significantly longer (shot count wise) than the four-groove barrels will.