Handgun nose shape

[Brad]

A couple of recent threads have touched on handgun bullet nose shape and how it comes into play at longer ranges. By longer ranges I mean more than 50 yards, out to at least 200.
Looking at a truncated cone nose how much can we get away from the "standard" shape we see? Most I have measured have around a 20° angle from the bearing surface.
How much flatter can we go? Changing to 30° lets us have longer bearing surface for the same size meplat.
How much does meplat come into play? Does a smaller meplat let us use a steeper nose angle?
At what point of steeper nose do we essentially have a wadcutters and accuracy goes south before 100 yards?

Lots of questions here. If I was made of money I would have Tom make a series of moulds that differed only in nose angle and see what happened. Sadly, I'm not made of money.

 

[gman]

Take one for the team Brad!

 

[gman]

How many molds would you be talking about? Could get single cavities. Maybe split it up.

 

[Brad]

Take one for the team Brad!

One what? Divorce?

This would be a very interesting study. Figure on 500 for moulds to start along with a bunch of powder, primers, and brass.

 

[gman]

I'm going to try the Accurate 43-265D in my SBH's to see how that bullet works in those guns. Looking over my two SRH's it looks like my brass goes right up to the throat. Waiting to see your results with that bullet design.

 

[Rick]

I wanted a sharper nose on the mold you just ordered but you wimped out. I also wanted you to radius the meplat, not the entire nose, keep the truncated cone and radius just the meplat. As long as there is enough nose angle for the air come off the bullet out away from the bullet and not have the nose act like a parachute I think your good. What angle would that be for best long range? Dunno, Brad needs more molds BUT some respected shooters, Glen, Veral have suggested a meplat of up to 65% & more of bullet diameter for decent 100 yard accuracy. For strictly target shooting and not hunting I wouldn't use nearly that much meplat.
.

 

[Rick]

Are you sure about that? I've never owned an SRH but from everything I've heard and read they have both long chambers and long throats. The long throat is a wonderful thing and the long chamber can be fixed with proper brass made to fit.

 

[Brad]

Do what I did, make a pound cast.
Fill a case with lead, put a soft bullet sticking way out into the throat. With case in cylinder and case head on a hard surface use a throats size steel rod and hammer to get lead to flow into the throat.

Look right ahead of case mouth. See the straight section? That is .053" that the bullet has to jump. Make brass longer and that is another .053" in the throat.
Notice too the taper above that straight section. That is .1" the bullet jumps from case mouth to enter the actual throat.
Think about it, you need a .153" front band at full diameter in front of the crimp groove to REACH the entrance to the actual throats and you still have ZERO bullet supported by the throat.
This was a real eye opener to me.

 

[Ian]

Fiver made an excellent point in the other thread about staying supersonic for the distance you shoot. A look at the BC and ballistics tables of various bullets at range can be enlightening.

 

[gman]

Your right. All I did was a quick check. I'll use your method and see what I get. I haven't had the chance to shoot the one I just picked up.

 

[Brad]

Fiver made an excellent point in the other thread about staying supersonic for the distance you shoot. A look at the BC and ballistics tables of various bullets at range can be enlightening.

Staying transonic is an interesting idea but it is practical? The silhouette guys shoot amazing 200 meter groups with revolvers and I bet those bullets are going transonic at some point.
Rick, got some real world velocity numbers and BC's?

 

[KHornet]

An interesting thread, and will follow it along. However not being a distance handgun shooter, for me it will be information only.

Paul

 

[RBHarter]

One cartridge , 3-5 platforms could be unintentionally valuable .

 

[Ian]

.44 Magnum SWCs go subsonic somewhere between 100 and 200 yards, pretty much no stopping that unless the Supermag can push muzzle velocity a lot higher. I can only guess that short, stubby, flat-nosed bullets don't buffet about as much as longer, lighter, smaller-caliber bullets do when they suck back through the pressure wave. The differences between supersonic and subsonic flight, and the respective differences in design of all things meant to fly is a Ph, D. all it's own and I barely have a 2nd-grade education in aeronautics.

 

[fiver]

I think this is a case of a lot of small things adding up to help out the cause.
I have looked at the shadow grams of as many bullets in flight as I could find over the years.
just looking at secondary waves off stuff like the lube groove edges and the crimp groove shows a lot more drag and areas creating secondary waves than I'd like to see.

a small radius on the meplat edge would help the bullet become a lot slipperier than you would think.
this would allow the air pressure on the nose to bend back further over the bullet lowering the resistance by a good 10%.
something like the radius on the H&G 68's nose would be pretty darn good.
combine that with a RNFP style nose base where it goes right into a flat [hidden] drive band before a small crimp groove and your getting into a pretty good shape for longer range stuff.

 

[Rick]

Exterior ballistics is a science unto itself. I don't think I ever ran into going subsonic with revolver but was only shooting 200 meters. With a muzzle velocity of 1550 fps with the 357 and a decent BC for a revolver bullet (RCBS 180 Silhouette at about 188 gr) it wouldn't be subsonic at 200. A fact of exterior ballistics is that light bullets which carry little momentum loose speed much quicker than heavier bullets that have momentum to keep them truckin along. Even when i was shooting the RCBS 35 200 if they were going subsonic by 200 meters I never had an issue. That bullet cast about 212 gr and most likely never went subsonic. Possible this could be an issue shooting 300 and beyond, I never did so can't really speak to that.
.

 

[Rick]

a small radius on the meplat edge would help the bullet become a lot slipperier than you would think.
this would allow the air pressure on the nose to bend back further over the bullet lowering the resistance by a good 10%.

True enough but some people just won't listen.
.

 

[RicinYakima]

The drop from super- to trans- to sub-sonic accuracy is also a matter of bullet mass. When I was able to shoot the Trapdoor at 300 yards, and other guys at long range, fine very little effect with 500 and 550 grain bullets. Mine only start out at 1240 and are at 950 at 300 yards. Not from the ballistic table but shooting over chronographs (well protected with steel plate) shows the charts are calculations in that range. I have been told that cast bullets change form and length depending upon composition when fired, so the charts are mostly calculations.

 

[Bret4207]

Isn't twist going to come into play at some point when you make those long slippery noses? Obviously chamber length is going to be a factor, but in a SS it's not as big a deal. I wonder if any of the common handgun twists from years back when shorter, squater and lighter designs are a bit slow for longer, heavier designs?

 

[Brad]

I have no idea if handgun barrel twists have changed over the years Bret. Might do some online searching on that. I do know that Linebaugh frequently mentions using a slow twist barrel on his revolvers and they certainly aren't made for light bullets.

External ballistics is a complex subject and way over my head. Biggest issue we have is that almost everything I can find regarding the topic involves long, skinny rifle bullets at long ranges. Not nearly the same as out fat, stubby handgun bullets. How does SD and BC affect transonic accuracy? Don't know

A mould might be a bit cheaper if I had Tom cut 4 different cavities in a single block.