95RK,
The thought had occured to me to get a wad to put under the bullet -- which I would do in a straight-walled cartridge ahead of using dacron. I just didn't think, for some reason....that you'd take to the idea.
Just in case your chamber is loose, try using a heavier brass case as well as what we've already discussed. That can have a significant impact, with Remington's usually being the heaviest, strongest of the cases from what I've seen. Winchesters are just too light for some uses. They don't give the same neck tension, nor do they resist expansion against ignition gases as well. Also, measure the flash hole in your brass, and de-burr the hole on the inside of the case. If the flash hole is less than .073 you may want to open it up to that size and then work up a load. You may also get more consistent ignition by going to a jacketed bullet.........really! It builds more pressure to assist with ignition when it first engages the rifling.
Here's one more idea: instead of criming the bullet in the location you are doing now, use a Lee "Factory Crimp Die" and seat the bullet deeper into the case and then crimp it. I'm not crazy about making a bullet jump further to engage the rifling.....but it might not be a problem in your rifle.
SS'
p.s. If all else fails, and it absolutely, positively has to work overnight: buy a .44 mag' and you'll have an easier cartridge to work with! :eek: