What attributes of HBWC are really important?

I enjoy playing around and working up ammo that works better. Better than what is another discussion. I'm wondering why we only see HBWC's in 32 and 38. Maybe a few in 45 revolvers but that would really be like seeing a unicorn. I get that the feeding in autos might be a challenge to work out. Which attributes of the HBWC make the most difference in their accuracy?
Soft lead and the obturation of the skirt make some sense until you consider that we don't worry about that much obturation with other bullet shapes.
With such soft lead being used for these bullets, why is external concentricity so critical? They are being custom fit to the barrel upon ignition.
Does the hollow base shift the center of balance while making a long-for-weight bullet and make them more accurate?
Does the concentricity of the hollow cavity create issues? If so, why not eliminate that variable and use a solid base? If not, why are some so much better than others?
I'm sure there are other variables to consider. Why are just a few brands of "store bought" HBWC's considered capable of outstanding performance while others stink?

Lyman used to have molds for a button nose .45 ACP wadcutter in 185 grains and 200 grains.  Bullet # 452389 and bullet # 454309.  Not sure if you can still find them.  One of our bullet makers here used to make them, but he passed a way and I don't know who got all his equipment.

What attributes of HBWC are really important?

Cutting "X"'s! Sorry couldn't resist!

Also swaged lead that is sized to the barrel to mitigate leading!

Smiles,

All I can tell you is I spent a LOT of time trying to get a 38 button nose wadcutter  H&G 050  to shoot as well as a HBWC.  I could not do it.   I tried everything. 

David

All excellent questions djhoran.  I don't have any of the answers but it's been a goal of mine lately to search for them.  My first step was just to duplicate what has already been a proven projectile, the H&N .315 HBWC or .314 in its current production.  I'm in the process of making swaging dies to make them since they are practically unavailable. 

To your question about the hollow base function I suspect it has just as much to do with shifting the projectile center of gravity as with obturation.  At least that's been my experience with airgun pellets.  It's possible the thinner skirt on the H&N as opposed to the thicker skirt on less than accurate projectiles plays a part in better obturation.  I hope to find out with different base punch designs.

I'm sure lead hardness has a role to play.  I plan to start with a lead alloy having a BHN of around 8, which is again consistent with the H&N.  Working up from there is hard on swaging so that might be the maximum hardness but it will be interesting to see what happens with something softer.

Lube grooves, lubes and coatings is another area that might affect performance.  Again, I'll start with the type of grooves and coatings that H&N uses and work around that.  I just received some .314 HBWCs from Bear Creek Supply.  These are moly coated without any grooves or knurling.  Another forum member has tested these and didn't have any success with them without reswaging. 

Just a hunch but I think the biggest factor in bullet performance has to do with maintaining concentricity and consistency in diameter.  And of course the best diameter for the barrel being used.  The Speer .314 HBWCs were horrible in this area with diameters ranging from .3115 to .314 and concentricity equally disappointing.  Some have found much better performance, almost equal to the H&N after reswaging.

There are 45 HBWC available from Bear Creek Supply.  I use them in revolvers.  But they do make a 185 gr. SWC HB that should work in a 1911.  I haven't tried it in my 1911s, but in my revolvers it groups as well as anything else.  It makes a decent 50 yard load with 4.0 N310.

https://www.bearcreeksupplybullets.com/45swc185

I shot some of thos Bear Creek 185 HBSWC in a revolver.  They shot ok ... this was with iron sights 

I just tested the Bear Creek .314 HBWCs for hardness and they came out with a BHN of around 11, which is the hardest I've found among swaged 32 or 38 HBWCs.

It would make sense that moving the CG forward, just like with darts and arrows, would be good for accuracy, except JHPs move the CG towards the base and they are the standard for pistol accuracy.
I have no idea about what makes an accurate HBWC, other than Remington knew what was needed and Speer and Hornady have no idea.
Some things that help a HBWC to be accurate are:
1) don't swage it down. The Remington HBWC is the most accurate I have ever found, but if the 0.360" skirt was swaged down during seating, it lost some accuracy.
2) following 1) above, minimal sizing of the case. For a M52 with S&W barrel, I found unsized cased gave the best accuracy. For revolvers and M52s with custom barrels, sizing with a Lee .38 FCD with crimp guts removed was more accurate than FL sizing

No matter the type or style of a bullet, the quality or "perfection" of the base is very important to accuracy.  The base is the last thing that touches the barrel.  If there are imperfections there, they can lead to a little gas blow-by as the bullet departs the muzzle.  And that's enough to affect things at 50yds; at 25yds not so much.

Dr.Don wrote:No matter the type or style of a bullet, the quality or "perfection" of the base is very important to accuracy.  The base is the last thing that touches the barrel.  If there are imperfections there, they can lead to a little gas blow-by as the bullet departs the muzzle.  And that's enough to affect things at 50yds; at 25yds not so much.

Are you thinking gas checks or 1/4 jacketed bullets?

One of the reasons a HBWC works is it can crush down in the barrel without producing fins on the base .  The head can bulge forward or not move at all since there is a thinner rim surrounding the point. 

It's the big reason for M52 requiring hbwc ; solids have to crush too far in a .355 groove and the poisson effect makes the head and base bulge, not to mention the extruded fins that mess up accuracy 

I have been playing with a Lyman DEWC that casts smaller and sizing it to .356.  That one works much better than the h&g50 which casts at .358 or larger.

Oh the rabbit holes we go down   148 grain hbwc and 2.9 grains of bullseye shoot ok in my 5'' model 27 but that gun really shoots well with a stiff load of w296 and a 146 grain Speer half jacketed HP swc (no longer made) unfortunately that load is no fun too shoot and anybody next to me at the range gives me the stink eye.  I do find it interesting that there is a lot of talk about loads that are ok for 25 yards but not for 50 yards.  I would think that if the load is an X ring or smaller load at 25 yards it would be at least a 10 ring load at 50 yards.  For me it is not that critical because if it is not a 10 at 25 yards it is because the jerk pulling the trigger caused the shot to be in the white rings.

Ha-Ha! Stink-eye! 
I remember shooting next to jr Farley in the Reeves match one year.

I'm ready to make some noise! He said. Shot something equivalent to coal dust that with the wind sprinkled me with soot, sand, and voluminous plumes of smoke. Had to shoot between his puffs!