John the 2 on the right weigh 345 grains, the far right on was made for me by Paul Jones both are bore riding, but will fit in bore .
Kidd here's what I did with the 38 gloveless bullet. Take a cast billet and run it between 2 bastard files then size it putting lube in the grooves you just made. Weigh your bullet then weigh the groove less I'll bet it is carrying more lube.

John you know Harlans chicken bullet is for a 12 twist, I don't know how it works in a 14 twist. My P-J bullet is 1.475 long ,nose measures .3495 to .3497 and seats .380 in case with all lube grooves covered. It is 10 twist and uses 2.080 brass, bullets are tight hand fitted. It's the one on the right in picture.I shoot it in a 26 inch barreled Browning BPCR

I had a good exchange with Tom (bullet/chamber design software developer).    It started out as a discussion on what is meant when we say “filling the throat” but as a byproduct he offered his version of a bullet that fit my chamber.  He’d seen mine so knew something about what I was looking for.    His bullet decreases the number of driving bands and lube grooves, pushes them back towards the base so as all but one lube groove is inside the neck and makes the front driving band taper to fit the 3* leade.    Also -- a little difficult to see at a glance but there is about .075 of bore riding diameter in front of the driving band.

I like it about as well as anything I’ve drawn but would enjoy hearing from you Frank and Hiwall, Beltfed too if you have any opinion on which may be preferable between the two.    I guess the limitation is a loss of flexibility in seating depth… at least cheating it forward.    

As for myself, I do like a longer base band.  And I might decrease the grease groove depth per previous discussion/recommendation.  I like the way he accomplished what Frank accomplished with the increase in the first two driving band diameters. 


This is what Tom wrote specifically about the drawing:
“…. I like to have a grease groove right at the chamber mouth so that, when the bullet initially expands from the Black Powder detonation and inertia is hindering forward movement, the lube in the forward groove will be forced into the gap between the case mouth and start of the freebore. (if lube is in there, then no lead can be extruded into the space and cause the little lead rings that sometimes form).
 
The front band is constructed with a 3 degree taper that matches the leade angle into the rifling and the top and bottom diameters are 0.0005”  less than leade diameters the same as the 0.0005”  clearance of the bore ride diameter.
Respectfully,
Tom Myers
(218) 472_3226
Precision Ballistics and Load Records
The Precision Software Store”

A note on the reduction of driving bands and grease grooves:  When I ran a mini-groove design by Steve Brooks earlier this year his comment was that they sometimes have more difficulty falling from the mold.   I don’t have any mini-groove so can’t speak to that but it sounds plausible.   Any comment on that point?  Steve was also an advocate of a longer base band.   

Thanks for taking the time to have a look – and comment if you have any thoughts either way.  btw... I learned how to do multiple pictures

First of all , I agree with Frank, groove dia 0.330 for 0.0150 depth. 
Then, Why seat the bullet 1/2 inch into the case. ===lost powder capacity.
I would go thusly, starting with the base
1. base band, 0.359"
2nd from base, 0.359"
3rd from base, use the 3 degree taper here .357  to 0.349
4th, 5th 0.349, 0.3485
"base of nose at 0.348.
Now you can seat the bullet only about 0.2" or so in the FF case, and use more powder.
While the bullet is 2/3 to 3/4 of its bearing surface effectively breech seated for excellent concentricity to the bore.
beltfed/arnie

I think Arnie has the right idea but you would probably have to wipe between shots, blow tubing you might need a little more lube.

Thank you Highwall 55,
Indeed, go to wiping with minigroove bullets.
beltfed/arnie

John, you probably know my thoughts. I'm with Arnie. The idea of faux breech seating and with that added powder capacity just seems to make a sense. The janitor of this forum has more experience than me however so follow whatever path they suggest over my thoughts.

Hi Tom,  Glad to see you here.   You can help keep me honest:-)

That concern was my recollection too but I wasn't sure if I'd expressed it here or elsewhere.   I know I've pinged you before with the question related to the Snover capacity and lube groove volume in other well-thought-of 40-65 options.    

As for this effort, I tend to throw my rope around so many options that I then have trouble making a final decision.    In this case I think I like the fit of your drawing best but this morning was trying to visualize how I could combine features, (short bore riding section on the nose along with a good fit to the leade angle, and still have the capability to sneak the bullet forward if more velocity were needed.   

Regarding the potential need for that, stability factor is a 2, so that implies my stability at 1267fps velocity is ok.    But having only shot the 250 gr bullet in this chamber with 40gr of OE, I've wondered what velocity I'd actually get with another 25-30gr of bullet weight?  In other words, the velocity I keyed in may not be the velocity I got with the neck filled and similar compression as my apples to oranges comparison.