Bullet weight for 9.3x72R

[wkvcooper]

How heavy a bullet will a 9.3x72R stabilize? The Lyman 366408 mold weighs about 250 gr. I have 2 drillings in this caliber and both have a twist of 1-19. That seems a little slow for 250 grs. The little information I can find on the 9.3x72R has most of the bullets at about 200 gr. Both guns shoot 2.5” at 50 yards, but open up to 12” at 100 yards. Might be open sights and my eyes.
The 38-55 has a twist of 1-18 and Lyman list loads up to 300gr

[JohnH]

How heavy a bullet will a 9.3x72R stabilize? The Lyman 366408 mold weighs about 250 gr. I have 2 drillings in this caliber and both have a twist of 1-19. That seems a little slow for 250 grs. The little information I can find on the 9.3x72R has most of the bullets at about 200 gr. Both guns shoot 2.5” at 50 yards, but open up to 12” at 100 yards. Might be open sights and my eyes.
The 38-55 has a twist of 1-18 and Lyman list loads up to 300gr

My 1-18 twist 38-55 stabilized the Lyman 265 grainer (375449) just fine

[wkvcooper]

Thank you for info. It could be my eyes. They are 63 yrs old.

[JohnH]

I wasn't thinking too clearly yesterday. Somehow I missed that you are shooting drillings. Are they SxS? If so, one problem that exists with them is barrel regulation. I'm no expert on the subject, but do know that SxS are quite sensitive to load variations, so part of the question becomes how close to standard velocities are your loads, and simply having a similar or matching velocity may not be enough as the weight of ejecta (read burning powder and expanding gas) have an effect on barrel whip which will definately wreak havoc on regulation.

If they are SxS drillings, my next question would be are you shooting both barrels in your group or only one. 50 yards seems a close range for sight regulation, but when one considers that such guns were likely intended as dangerous or heavy game guns, sight regulation at 50 yards is not nessicarily unreasonable, even though perhaps unlikely. In that even, assuming SxS, it is quite possible the right barrel is shooting left of POA at 100 and the feft shooting to the right, with an exaggerated group size being the result. This senario would not be my first supposition. Assuming SxS, I think the problem most likely relates to barel/load regulation. If SxS is correct, try shooting one barrel untill satisfactory groups are attained, then add in the variable of the second barrel.

What velocity are you shooting? All this may relate to speed of a plain base boolit.

[wkvcooper]

They are not SS. They have 1 rifile barrel under 2 shotgun barrels.

[wkvcooper]

velosity is about 1400 ft/sec

[wkvcooper]

I tried again and the 100 yard groups were OK. The bullets were stable. It was all the shooter.

[Old Ironsights]

My Drilling (16x16/9.3x72R) shoots a 200gr cast bullet with suprising accuracy for a 100y/o gun with lousy (almot non-existent) sights.

In my gun, a 250 would be WAAAY to long/heavy.

But with a 200 I drilled a Coke Bottle at 50yds right at the POA. I'd have no problems using it as a sub-100yd deer gun.

My load is (iirc) 18gr 2400 over a commerial cast 200. I ordeed a mold from Mountian Moulds, but haven't had the opportunity to shoot any of those yet because I'm having the hammer sears adjusted and the barrels re-regulated/choked.

Here is the page I ordered the bullet from: http://www.huntingtons.com/bullets_leadcast.html

[wkvcooper]

I have been doing better with the 250 gr bullets at 100 yards. It may be my eyes and the minimial sights. I do really well at 50 yds. I have just loaded some 220 gr bullets from a NEI mold that I will try tomarrow. Thanks for the info on the 200 gr bullets and the 2400 load. The only load I have been using is 30 gr of 3031.