I think you will find that patching just up to the edge of your cylindrical section of your bullet and not beyond will perform most consistently.
Unless you are trimming the patch back after drying.

I would think that twisting the patch tail would be a decent method of patching these boat tails.

Interesting idea for sure.

Huvius, Bruce,
Thank you very much for the critique, I am trimming the paper after it dries - seems easier when time is of the essence.  Bruce, by all means be critical, no offense is taken.  When I have more time there are a few things I would like your opinion on.   If time and weather permit this week I hope to load and shoot these and see what the doppler shows.  I am experimenting with propellants that are new to me so the data should be interesting.
Greg

Finally, a day with temps in the 40's, had a window in work load and the wind went down- about dark.  I shot the diapered bullets I swaged and a few of similar weight and design grease grooved for comparison - each using the LabRadar.   I didn't have enough time (before dark) or ammo to get data for a solid conviction but the results were very interesting.   
First, because of a mention on this forum about the use of BH209 powder for larger cartridges this was the propellant I chose.  The cartridge is a 45-110, the rifle is an original Borchardt that got a new barrel.  Besides the low light issue, (overcast and darkness coming) I had to improvise and make a front sight that would fit the larger dovetail- just a straight post .060" wide.  The groups at 200 yards were all fairly uniform, about 3 minutes. 
All the loads were reasonably close and the SD for all three configurations averaged 12 fps.
The real interesting results:
- the grease grooved bullets had a BC - muzzle to 100 yds. calculated at .275, 100 to 200 yds. was .270.
-the cup base swaged PP had a BC of .286 consistent throughout.
-the boat tail, swaged PP had a BC muzzle to 100 yds. of .288 and from 100 to 200 yds. the BC calculated to be .317 –  All of these were averages but they were consistent.   This configuration will be my focus if I share anymore findings.  I plan to change the shape and length of the boat tail bottom punch to see what effect this has.   
The powder mfg. recommended a card over charge and in my samples, I had loads both ways with no change noticeable.  My alloy was pure lead in both swaged bullets (for ease of action) the GG was a 16:1.   I am working on a means of collecting the projectile with minimal distortion, Mann’s method of oiled sawdust is next, I’m thinking it would take considerable ballistics jell to catch this projectile, but it is an option.  Any suggestions/experience?
The density altitude at the time placed speed of sound at 1095 fps. so according to the recordings my load never went trans/sub-sonic.  MV for all three loadings averaged 1532 fps. and TV was 1200 fps.
In the next step of this collection, it will be interesting to see what these projectiles do at trans and sub sonic levels.  I doubt the radar will give clean data much beyond 200 – the SNR, or sound to noise ratio was becoming slightly erratic at 180 yds.  Opinions on reducing/changing the charge to have the bullet originate just above this barrier would be welcome.

"your best way to address higher b.c. is in the nose area,
look at elliptical or money noses for the least drag in the velocity ranges of b.p cartridges. that is transonic and subsonic.
lengthening the ogive will increase b.c.
however a nose longer than 1.5 calibres in a cast bullet will upset so that it will be 1.5 calibres or less on firing."

Bruce, 
I'm not in pursuit of extreme BC's,  I have dabbled in the elliptical and money noses, in fact there is a drawer full of these punches in my swaging die organizer.  I went down this avenue already, from small truncated to nose lengths congruent with Pinocchio.  In my experiments, most, not all became unstable  at 800+.  The heel and yaw showed up on paper screens consistently.  At 1000 many destabilized completely, giving the bumble bee effect I appropriately named. (they sound like it and you don't what flower they'll land on).  There is one bullet mold that I have matching your descriptions that is very consistent to 1500, it is a single groove 600 grain that Walt made me, but the reaction (recoil) isn't where I want to be in this particular rifle.  My round nose, about 1.1 caliber in length, and the ogive=4 nose diameter - gave more consistent results.   I have a testing area now that exceeds a mile, I plan to build frames for mats, but there is a distance to go yet.   
Greg

greg,
two things are required for a long range bullet.
one is that it can hold good verticle, which means consistent muzzle velocities and consistent b.c.
kenny wasserburger reports holding 1 moa vert at i mile with black powder and pp bullets.
the other is minimizing wind deflection as much as possible, simply done by using the highest b.c. possible, and maintaing good bullet stability.
the brits used antimonial alloy in their bullets, and the americans used alloys from 11:1 to 14:1.
in both cases this was done to maintain nose shape and length.
if the nose sets back and stays straight, a b.c. loss occurrs, but if it sets back off centre, that comes with introduced instability which comes with a lowering of b.c. as well due to yawing, or even full tipping of the bullet.
i have never shot past 1000 yds, but have found that a stability factor of 1.8 to 2.0 is optimum, due to wind shear effects, and possibly spin decay.
in the transonic zone, the money nose and the elliptical require similar comeups for the same muzzle velocities, while subsonic ellipticals have less drop than similar moneys.
velocity/trajectory figures suggest a b.c of around 0.5.
12:1 has less drop at 1000 yds by roughly 2 moa than 16:1, and similar figures comparing 16 and 20:1.
cast bullets cannot maintain a nose length of more than 1.5 calibres, so this is what we have to work with.
i have never had a bullet tumble, but some really long 40 cals have demonstrated  slightly elongated holes at 600 to 700 yds, going back to round holes after that.
the little step at the rear of your noses will move your centre of pressure forward, causing a greater overturning moment, and requiring a shorter bullet for the same twist than one with a smooth transition from the shank to the ogive.
good luck with your experiments. please keep us in touch.
keep safe,
bruce.

GT,
What is the length and Wt range of these current bullets?

AND What is the twist of the new barrel on that Borchardt?
It may be that you would do better for accuracy with a longer/heavier bullet  if it is say an 18 twist. That is the experience in the BPCR /BPTR game
beltfed/arnie

GT,
So, you are in the bullet length range for that 21.5" twist
though, I think you could go longer:  The 45 Gov't used a 22" twist and stabilized a 500 gr RN, 1.32" long even at long range.
I have had good accuracy out of my TD/22" twist with that 500 gr Govt bullet.
Not saying the shorter 1.1" /400gr bullets won't shoot well.
beltfed/arnie