A 45-110 Dual diameter bullet design

[Kenny Wasserburger]

Based on Arnie’s DD PP Mould

As I have an over abundance of case capacity, and currently seat my patched to bore PP bullets about .420 in the case I have come up with this idea for a DD PP mould for the 45-110.

Increase the length of the larger diameter to .420 keep it .454
Use the same 3.5° leade

Increase the bullet length to 1.490 add that to the middle. Retain nose length.

Jim K and Arnie, I invite your thoughts and comments.

Kenny W.[attachment=0]3EEADD6D-D547-4055-BF07-4E9CD5EAA4E7.jpeg[/attachment]

[Don McDowell]

I'm thinking the base diameter at .450 might be a little better, based on what I've seen from the Brooks dd bullet I use, and some questionable things I saw shooting some of this newer design that came out .455 as they were sent to me by the owner of the mould.

[semtav]

I think you might be onto something Kenny.
Could be ideal for the 16 twists. Ive got a bull barrel coming soon id try that on if you get them to produce it.

I really like the.454 dia as that's what I shoot in my patched to groove loads.

That one pictured might be perfect for my 45 2.6 with the base modded to .454.

[Kenny Wasserburger]

Don,

Care to elaborate?


Brian, I was thinking, dangerous for me, when I came up with the idea of this bullet past few nights I have been playing with design and finally came up with what I proposed.
I would keep the minor diameter at .445 for the 25# 16 twist Dora.

Kenny

[Don McDowell]

Kenny the .450 base diameter dd I have shoots well in some rifles, particularly the heavy barrel 110, and the CPA 45-90. Haven't tried it yet in the 77. The Borchardt 110 likes it ok out to 900, but it goes to crap after that.The #1 45-70 hates them with a passion.
I haven't shot a lot of those new dd bullets, as I have a heck of a time getting the cases that haven't seen anything but .444 and .446 bullets wrapped in 55y, expanded enough to seat those bullets wrapped in same paper. Have to use the .458 M die and it's still pretty tight. Accuracy in what little I have shot hasn't shown enough to spend the money on a new mould. So I'm rather hesitant to get to many cases blown out that far. Could be a matter of working on powder charge, but then there's still the case expanding problem.
But in the end I'm thinking that the narrow base band as the bullet sits is probably about the limit before base finning starts to rear it's ugly head. Wider at that .453-455 diameter may exasperate it.
Where the .450 diameter lets the bullet length compress a tad, and the base finning isn't a problem as recovered bullets show minor rifling engraving just a bit above the transition.
You might want to call Jim and Dave and visit with them about it a bit.

[Distant Thunder]

Kenny,

When I design a 2-diameter bullet I make the minor diameter (the bore diameter) section to patch just a bit snug in my bore with my paper.

The 3.5* is not critical in my opinion and just a step seems to work as well for me.

The base diameter (groove diameter), which can easily be sized after patching, I like to make to be just snug in ANY freebore that is in the chamber. That freebore diameter would ideally be the same as the ID of a fireformed case or no more than .001" less than the case ID. In my .40-65 the freebore is .409" diameter and I patch to that diameter and the bullets are a nice snug fit in my fireformed cases when I use R-P brass for which the chamber was cut.

My thinking is that you want to limit the amount a bullet has to or can upset before entering the leade and being engraved by the rifling.

The length of the base diameter should however much you want the bullet to seat in the case plus the length of any freebore. So as an example (only) if you want your bullet .430" in the case and there is .050" freebore then the base would be .480" long plus the 3.5*. Then when chambered the 3.5* would sit tight against the leade of the rifling.

Bottom line is the patched bullet should not be excessively loose on any of the three diameters, the bore, the freebore and the case. Those are the diameters that serve to align the bullet with the barrel. The better the bullet fits those diameters the better the accuracy will be.

Also, Arnie's elliptical nose is a good design. The length of the nose is a key part of the design.

You should do your own math and not rely on my limited math skills.

I hope some of that helps. Feel free to ask any other questions you may have.

[Kenny Wasserburger]

Jim,

Again thanks that was exactly the type of information I was looking for.


Don, thanks for the input, I don’t seem to have any finning issues with my wad stack, so I am hopeful it’s wouldn’t be one here. The bullet is still under groove so will have to bump up, but much less than the nose section. The case fit I hadn’t thought of best to ball mic a few and see what the maximum size of bullet will fit in fired cases.


Kenny

[Don McDowell]

Looking forward to seeing what you come up with and how it works for you.

[Kenny Wasserburger]

Well I went and made some measurements.

OD of fire formed case is .4815 on this 25# rifle.

Case wall thickness avg .0125 total of .025

.4815-.025=.4565 patched large diameter. My paper adds .005 so .4565-.005=.04515 base diameter of bullet.

My actual bullet in case and I went checked my notes, was changed a few years back to .350 in the case. My Shiloh chamber has about .050 of freebore. If we add .350+.050 we get .400 total major diameter length. The .445 diameter nose is what I currently use for my PP bullet in the 25# Dora Rifle.


Jim, you’re probably better at the math stuff than I am.. look through my numbers, and see if I am missing anything.

Bruce feel free to chime in also. And I look forward to Arnie’s comments.



Kenny Wasserburger

[Distant Thunder]

Kenny,

Asking me to double check your math shows a lot of trust, but this is simple enough stuff that I think I can handle it and your numbers hold up when run through my calculator. You should be good. Just don't ask me to add 10 numbers together and give you a total! That seems to be too difficult for my old brain!

The only really critical dimension here is the .445" which you have a history with so that should be good. The base diameter can be sized if needed so that gives a bit more room for error there. The length of the base band you could adjust your seating + or - a bit to suit the fit to your chamber so your number there is good. Your bullet OAL is good, well within the what a 16-twist will stabilize well especially at your higher velocity.

Should be a winner!

[semtav]

.4815-.025=.4565 patched large diameter. My paper adds .005 so .4565-.005=.04515 base diameter of bullet.
Kenny Wasserburger

Did some measuring when I got home tonight.

With my current 45-110 the as fired shells accept a .459 GG bullet or a Patched to .459 Bullet smoothly and snugly .
I also use a patch that adds that adds .005 to the dia.
May explain why the .454 bullet works so well in my 45-110, it has a slightly larger chamber.

I don't have my Shiloh 45 2 7/8 yet, but I would reckon the measurements will be the same as yours.

Possibly why Don says a .455 major Dia DD bullet wasn't working as well.

I'm wondering if .452 major dia may be the way to go with the Shilohs based on your measurements
I won't know how well or if my .454 bullet will work in the Shiloh until it arrives.

[Kenny Wasserburger]

Brian,

After I measured up everything that made partial sense why Don said the .455 major wasn’t working well.

I am betting that your 110 chamber is like mine.

I am hoping that the .452 is the way to go, may help other Shiloh 45-110 PP shooters in the future.

Kenny Wasserburger

[gunlaker]

It'll be interesting to hear how that bullet works for you Kenny. I've had similar thoughts, just no place to shoot until spring . I expect it'll seal the bore just a little quicker than a bore diameter bullet. The one thing that makes me wonder about the dual diameter bullets is sizing them. I have always had the most consistent results when sizing the bore diameter bullets down to a consistent size after patching. I don't know how to get that done on the bore riding section of a dual diameter bullet.

Brian, the Shiloh chamber is probably pretty close, but in my 14lb bull barrel .45-2-7/8" I can't slip fit anything bigger than a .458" bullet. That's with Norma brass. My other .45 cal Shiloh rifles will all slip fit a 0.459" bullet, but I use Starline in those.

Chris.

[Distant Thunder]

Chris,

It is possible but complicated to size a 2-diameter bullet and probably best just to avoid having to do so. The die would be somewhat similar to a sizing die for any bottleneck case except there would have to be an ejector rod out the top of the die to push the sized bullet out. I made one for some grease groove bullets that had a nose diameter that was just a bit too large. It works pretty well but it's slower than a push through die. I would think it would be very costly to have such a custom die built! It is best to have the mold cut to the exact size that once patched is a slightly snug fit in the bore. The 2-diameters and good fitting brass should work together to center the bullet up well.

I size my patched .45 caliber bore diameter bullets for my tight chambered Hepburn and they shoot very well me. I also size just the base of my 2-diameter bullets for my .40-65 and that is just to get a good consistent fit in that rifles very long freebore. The freebore in that rifle is long enough that it is really doing most of the centering and the fit is therefore important. The accuracy from those bullets in my .40-65 is the best I've been able to achieve in any BPCR with any type of bullet.

I have also been sizing just the base of the 2-diameter bullet BACO made for my .44-77 but I don't have enough rounds down range to say too much about that bullet yet.

[semtav]

Brian, the Shiloh chamber is probably pretty close, but in my 14lb bull barrel .45-2-7/8" I can't slip fit anything bigger than a .458" bullet. That's with Norma brass. My other .45 cal Shiloh rifles will all slip fit a 0.459" bullet, but I use Starline in those.

Chris.

My measurements may be askew, but measuring the total thickness of the brass at the neck, I come up with Starline being .002" thinner and ww brass another .001 thinner than Norma Brass.

That may be the reason for the .455 dimension on BACO's bullet. A lot evidently hinges on the brass used.