MLKeith, I haven't tried anything above 250 gr with T7 so you might be right. I do have some 300 gr shockwaves that a buddy gave me to try, so might have to do a little testing to see if that changes anything. I suspect the bore fit is a good explanation as well. I know a couple of guys who couldn't use the SST sabot and had to switch to TC sabot due to sizing.

The windex trick works really well for getting out grim I find. Other use windwasher fluid in lieu of windex. I saturate my patch with a spray bottle then ring it out so excess isn't pushed to breech, I place the patch over the bore and push it down into the bore with the jag vs rapping the jag. Using short strokes gradually lengthening and then finish with a couple of dry patchs. If you have excess build up a second wet patch may be required.

Never heard about the adding of vinegar, it is a good cleaner. Be interested to hear your or others results on the vinegar? My mom use it with water to wash windows claiming it is much easier and leaves no streaks to traditional glass cleaners.

MLing is a finky business as many will attest, the only way is T&E and then stick to what works.

Best of luck!