Bin a bad boy, Colt Cobra target.

[brutus51]

Just returned from my first range trip with the new Cobra, gun shot like a dream the action is buttery smooth.
First I shot 50 rounds of Remington 38 specials, followed by 2 dozen Federal magnums. Since I didn't experience any problems I switched to my handloads. These were Missouri bullet company 158gr. semi-wadcutters loaded in magnum cases with 5.3gr. of universal clays.
Bullets would not seat all the way down in the cylinder. Cylinder length is 1.560 same as my Python, Dan Wesson is 1.634.
Bullets seat fine in both my DW and the Python. Got it home and started taking measurements, turns out the chambers are bored short.
SWC bullets are hitting the throats preventing them from seating all the way down. All other bullets, with a rounded ogive, seem to work fine.
The 50 rounds of my Hornady XTP reloads worked just fine, so I'm not sure if I have a complaint or not.

 

[GooseGestapo]

Those short throats go a long way to explain the excellent accuracy most are reporting.
That’s a good thing.
Try some match grade flush seated wadcutters.

 

[Master Blaster]

Seat them deeper, you do not need to leave an 1/16" of the bullet shoulder/ edge above the case to ensure feeding

 

[brutus51]

Forgive me if I'm wrong but I believe the problem is long throats, short chambers.
Problem is all my favorite target loads are based on a 158gr. semi-wadcutter roll crimped in the crimp groove, not real crazy about reinventing the wheel for this revolver. In other words I now need to re-load cartridges at two different length's to accommodate one pistol.
Using the shorter loading in my Python or DW would result in a longer bullet jump for them. This is a dilemma I never expected.