Just got back from a strange range experience with a 44 Vaquero..

[Virginian]

I went to the range to treat my cabin fever. Took along a Cimarron .44 Spl. and a Ruger Vaquero in 44 Mag., and a bunch of 200 gr. lead round nose Cowboy loads I loaded maybe 5 years ago. I need to practice a little anyway, so I can qualify on the indoor range with a .44, then I can shoot that or anything smaller, which covers everything I own.
Well, I have seen rifles that preferred certain loads, but this was a new deal for me. I couldn't put 5 of those loads on the same paper at 25 yards with the Ruger ! 15 shots later I was freaking out. Then I dragged out the Cimarron, and got maybe a 3" group without half trying. Back to the Ruger and shotgun city again. This Vaquero and it's mate have always been very accurate !
So I get out some 215 gr. semi wadcutters. Good groups, any variation is me. 240 gr. SWC, same deal. So I put on the Past gloves and drag out the Magnums. 220 gr. SJHP, good groups. Full house 240gr. SJHPs, and the best group of the day. Almost as small as my step son's eyes! I go back to the 200s, 3 on the target... out of 5.
So now I have a little hang tag on this gun. "With 200 gr. LRN, do not bother to aim."
Good thing the Cimarron seems to like them okay. I'd hate to have to pull about 400 bullets !

 

[Vern Humphrey]

Have you checked the bullet diameters? It sounds to me like they may be a bit undersized.

 

[Virginian]

Yep, checked the bullets.

I've been checking stuff since I got home. The 200 gr. bullets are the exact same size as the 240 gr. ones, and 0.001" larger than the 215 gr.
This Ruger barrel slugs exactly the same size as the other one, and both of them are less than 0.001" larger than the Cimarrons'. Cylinder throats all look good too.

 

[Vern Humphrey]

Have you tested them for hardness? I assume your loads are quite light, and the bullet may be too hard to "slug up."