250-41-FN (Bob’s Boat Tail) -18- GB283

I measured my Hatsan .25 cal barrel on the AT-44 Long this morning, as best I could without removing it from the gun…. Here is what I found….

Muzzle – pushed a .257 cal bullet in 1/2″ and pulled it back out…. 0.249″ land (or smaller)…. 0.255″ groove….
Breech – I chambered a .250 cal BBT by closing the bolt, and then pushed it back out…. no marks at all…. none…. and no resistance to chambering….
Twist – 17.5″

With these measurements being nearly identical to those for a LW barrel, and Hatsan supplying both…. I suspect they copied LW’s stated dimensions of 0.248″ land and 0.254″ groove with a 17.7″ twist…. Those measurements would be within my measurement tolerances….

If you are ordering either the 41 gr. or 51 gr. BBT from NOE for a Hatsan, I would suggest the 41 gr. in the larger size (0.255″/0.253″)…. If you want to try the 51 gr., you should be aware that since it has a recommended twist of 16″, if you push it too close to Mach 1, you may have a stability problem in the Hatsan barrels…. However, the Stability Factor works out to the recommended SF = 1.5 at 800 fps for the 51 gr in a 17.5″ twist…. so you will likely be fine at any velocity you could likely reach in a Hatsan, even a fully modded BT-65….

Bob

Updated.

List updated.

I want a 2 cavity in .255/.253 thank you

Me too….253/255.

You can order a Lyman style HP pin in one cavity in this mould, for $35 extra…. Having it done later would be MUCH more expensive, and I don’t even know if NOE would do it…. but you can get it done through others (for about $100)…. I am getting a 2-cavity mould with one HP pin….

Bob

List updated.

Al notified.