Awf,
The lead deposited toward the end of the barrel does indicate a lube problem. If you're currently getting the lube applied right (despite your troubles with the lubrisizer) you'll need to try one of three things.
1. Change to another lubricant. A lot of shooters have found that the softer, stickier lubes do a bit better job under adverse conditions. This doesn't mean to change from an 50% Alox 2138F/50% beeswax type lubricant. There are beeswaxes and there are beeswaxes. Some of the lubricants use refined beeswax, some use unrefined beeswax. Generally, the unrefined product is stickier.
2. Your alloy is marginal for this application, IMO. You might want to try hardening this if you haven't done so, or simply switching to something harder, like linotype.
3. You might critically examine your barrel. A borescope is nice, but you can tell an awful lot by simply pushing a tight fitting patch through a clean bore. Does the patch move easily once it has started? Are there any rough or unevem feeling places in the bore? Using a magnifying glass, does the surface of the patch look roughed up once it has emerged from the bore? Lastly are you sure that you've gotten all of the lead removed from the bore. The slightest bit is an invitation to major leading at the next shooting session.
Lastly, sometimes the crude expedient of another mould does work out. One of my favorites for troublesome 30 calibre rifles is the old Lyman # 311467, an obsolete, but not difficult to find item. 180 grains, lots of lube grooves. You start with lube in all the grooves, then start decreasing the number of grooves filled. When you stop finding lube on the muzzle of your rifle you know that you've reached the minimum amount. If the amount is just a bit more than the bullet that has been giving you trouble then a harder alloy will likely fix the problem. If the amount needed is greatly more than available with a troublesome bullet then the issue probably isn't primarily lube related.
regards,
Bob