Is newly designed bullet better than original?

[Naphtali]

This query is to solicit advice/opinions whether the bullet design we've created in software will be an improvement over the similar design we've rendered into a mold and bullets for our Marlin 45-70s.

My shooting partner created a mold design that is nearly identical to Beartooth's 425-grain Piledriver Jr. 45-70 bullet. We had Mountain Molds cut a mold. We have been testing it for accuracy with IMR 3031. So far, from a Marlin 1895, customized (including 16.5-inch barrel and Grizzly's adjustable aperture receiver sight) by Grizzly Custom Guns in Columbia Falls, Montana, 100-yard accuracy is 3-to-3.5 inches. We anticipate improvement to, perhaps 2.75-to-3 inches. We think our limiting factor has become the sights.

Here are thumbnails showing the bullet and its Mountain Molds specifications.

http://s1d4.turboimagehost.com/t/2084475_45-70_Bullets__dimensions.jpg (http://www.turboimagehost.com/p/2084475/45-70_Bullets__dimensions.jpg.html) http://s1d4.turboimagehost.com/t/2095685_Bobs_425-gr_LFN_GC.jpg (http://www.turboimagehost.com/p/2095685/Bobs_425-gr_LFN_GC.jpg.html)


As we were evaluating the bullet, we wondered whether we could improve it without significantly deviating from basic design goals. While the bullet shown previously was designed to function in Ballard-rifled Marlin 1895s without need for gunsmithing bullet's feeding, were we willing to have Grizzly adjust feeding, if needed, could a bullet be designed that was more accurate, and, perhaps, size & lube more easily in Ballisti-Cast and Star push-through sizers?

Here are specifications for what we are considering.

http://s1d4.turboimagehost.com/t/2198728_Improved_Piledriver_Jr.jpg (http://www.turboimagehost.com/p/2198728/Improved_Piledriver_Jr.jpg.html)

Differences between the two 425-grain bullets are:
1. Front bearing band is significantly larger on second design. We think this will enhance accuracy. We are concerned that the chamber-leade of Marlin 45-70s may be too short to chamber the bulleted cartridge without gunsmithing, but we don't know.

2. Bearing surface beneath crimp grove does not change, but bearing bands are significantly wider. Will fewer but wider bands improve accuracy compared with narrower but more bands?

3. Lube grooves have become one large groove, with a small lube groove just in front of gas check in both designs. This small rear groove is a quirk of my partner. He strongly believes it helps in all cases. This lube groove arrangement should be more convenient for the sizers I mentioned earlier. Our concern is that there might be poor distribution of lubricant (LBT Blue Commercial), that leading would occur at upper level velocities.

[Bret4207]

Can't offer any advice, but that Lazer-cast is a hunk of crap! Did it come out of the box that way?

[BABore]

The first thing I noticed, and question, is the full diameter top band on both boolits. How does it chamber and engrave? The reason I ask is that Marlin 45-70's typically have a very short throat. Usually you can only get away with a 0.060 top band. These boolit designs are what I would typically do for the 450 Marlin. The second thing kind of ties in with the first one, sized diameter. I see your sizing these to 0.459. Have you done a throat cast and looked at maximum allowable boolit diameter in the case. Most Marlin chambers are quite generous. All that I have checked will safely allow a 0.462+ diameter boolit to be used. What I'm thinking that may be happening (based on a similar situation) is that you likely have the nose jammed into the throat & rifling pretty good. The boolit's base on the otherhand, has the potential to yaw as the case expands due to the small boolit diameter. Picture standing up a dowel in a press fit hole and then hitting it with a hammer, without supporting it between your thumb and forefinger. Only a perfect hit will drive it straight.

As far as the band configuration and accuracy, I will refer you to my web site's Rifle design page. I have two 458 caliber boolits called out as the 462-420 GC TBR I and 462-420 GC TBR II. The TBR I is loosely based off of the JB Young "Crater Lite" which I believe is from a BallistiCast mold. Before I started making molds I had Mnt. Molds cut an exact copy of it and only changed the bore ride nose diameter. The "Crater Lite" has a 0.449-0.450 diameter nose and didn't really touch anything. I went with 0.4515. I also specified the as cast diameter to be 0.462. It fit and shot pretty decent. Upon designing and cutting my own mold, I decided to do a tapered BR nose so it would engrave more easily acrossed a more broad spectrum of gun. I kept the driving band configuration the same as the original. While turning the cherry I got the wild hair to make a duplicate with different driving bands. Wanted to see if there was any accuracu differences. I later accuracy tested both designs, side-by-side, in both a 450 Marlin and 45-70 Marlin lever guns. In all cases using 3 powders and 2 different lubes, the TBR II (with more, smaller bands) always shot better. Usually from 1/4 to 1/2 inch better.

A few things I have observed in loading and shooting HV 450 and 45-70 loads. IMR 3031 is an outstanding powder for this. H322 and Benchmark are as well. If a particular gun does not like H322, it will likely not appreciate Benchmark. I then try IMR 3031. It seems to be one or the other. They all have very similar burn rates, but the harmonics of H322/Benchmark are different than 3031. In all cases, the use of Federal 210M match primers will improve accuracy and reduce velocity variation. How hard a boolit engraves can sometimes make a difference. Sometimes a particular boolit likes a little running room. Barrel harmonics and Marlin forend fit is a real wildcard with HV loads. Controlling recoil from shot to shot is difficult at best. How the forend is supported makes a big difference and can change with powders and even lubes. An hand held forend, from the bench, seems the most forgiving, but it has to be consistent from shot to shot. I always have a buddy watch the gun's recoil while spotting shots. Many times he can spot a flyer, based on the muzzle rise, before he even looks through the scope.

[JSnover]

3. Lube grooves have become one large groove, with a small lube groove just in front of gas check in both designs. This small rear groove is a quirk of my partner. He strongly believes it helps in all cases. This lube groove arrangement should be more convenient for the sizers I mentioned earlier. Our concern is that there might be poor distribution of lubricant (LBT Blue Commercial), that leading would occur at upper level velocities.[/QUOTE]

I dunno, but check the designs at biglube.com for some ideas on boolits using one or two large grooves

http://www.biglube.com/BulletSampler.aspx?ItemID=e4baa9fe-9ebd-4537-a842-1662597954ce

[MtGun44]

Sights are not limiting you to 3.5" at 100 yds unless it is the particular shooter's eyes
that don't work well with open sights. I can reliably get 2" or better with the stock
Guide Gun sights from the bench with my best handload in .45-70. That said, I find
an aperture (peep) sight much faster and easier to use, so most of my lever guns have
been switched to receiver mounted aperture sights which have the added benefit of
a longer sight radius.

Bill

[Naphtali]

The new design's forward bearing surface may force 1895s' chambers-leade to be altered. We're not sure, and won't be until/unless we create the mold and load it. The existing bullet feeds more easily and reliably than any other 45-70 bullet we have loaded.

Since we also expect better accuracy from original bullet, we intend to continue to experiment with powders and charges. Our 3031 initial load is:
46.0 grains IMR 3031; WW case; WLR primer; OAL 2.53 inches.

We will be shooting next:
41.0 grains IMR 4198; WW case; WLR primer; OAL 2.53 inches.
***
BABore: You've furnished much to investigate. Throat cast shows .459-.460 inch is correct bullet diameter in the test rifle. I'll verify my two 1895s and three barrels to see what's what.

[crabo]

http://castboolits.gunloads.com/showthread.php?t=61562

Have you looked at this boolit? It's been tested to work in the lever guns with no gunsmithing. I think I would have a problem having a mold built that I had to modify every gun that I wanted to shoot that boolit in. Then what if I decided I didn't like the boolit after modifications? Did that make more problems for me?

Could be that I don't really understand what you are trying to do here.

[Naphtali]

Could be that I don't really understand what you are trying to do here.Our present bullet requires no gunsmithing. We're considering a, perhaps, more accurate variation that is easier to run through Star and Ballisti-Cast push-through sizers than our multiple lube groove bullet. And you're right. We may be spitting into the wind. To get the benefits described, gunsmithing for feeding is no big deal. Smithing need not be done on large numbers of 1895s; we have three. We are acquiring no more.

Hope this clarifies things.

[GabbyM]

well that's just great.

Clicked on the bullet chart in post #1 and got a trojan block message from my anti virus software. That's the second time in two days I've had a trojan attack after clicking on a photo server link in this forum. It's not always free you know. Not dumping any blame on the posters as I know they have no control over ad content of free sites and are a victim. Just wish to warn members they should run their anti virus software if they've clicked on that. argh.

This also could be a targeted attack upon my computer from the wonderful shiny scum in the wonderful nation of India which I'm having a true knock down with. Odd they get mad at you after they steal your credit card number then you recover fraudulent charges back from them. As if I owe them my money. Any of you who may have an account with E*Trade. My financial advise is to close your account. As with any other banking accounts serviced in India. Not trying to trash the nation of India. After all I live in the state of Illinois, home of Chicago. Just like Chicago India has people that would rather rob you than work for a living. But when E*Trade wrote me that my legal complaint was denied since the accused refunded my money I didn't feel justice was being done. Of course that email came from India and the same room which sold my credit card number. Not saying convert to gold but keep your money closer to home.

Sorry for being off topic but I get stirred up when attacked in any fashion.

[Naphtali]

well that's just great.

Clicked on the bullet chart in post #1 and got a trojan block message from my anti virus software. . . .

Sorry for being off topic but I get stirred up when attacked in any fashion.Hmmm. I just opened all three thumbnails blandly and uneventfully. Sorry you're having problems, but I cannot replicate them.

[Bret4207]

Some programs give false alerts with some files. I frequent one tractor site that always gives me an alert but there are no problems with the site- the problem in in my settings. To me it's not worth changing.

[GabbyM]

I'm probably to paranoid. Maybe if I wrap my monitor in aluminum foil it would help.
I just now clicked on the image again and received no warnings.

[Naphtali]

. . . Since we also expect better accuracy from original bullet, we intend to continue to experiment with powders and charges. Our 3031 initial load is:
46.0 grains IMR 3031; WW case; WLR primer; OAL 2.53 inches.

We will be shooting next:
41.0 grains IMR 4198; WW case; WLR primer; OAL 2.53 inches. . . . We've tested several 4198 loads. This powder [approximately] doubles group sizes at 50 and 100 yards from those obtained with our 3031 starting load. We're going back to 3031 and futz with charge. If groups tend to tighten as charge increases, after hunting season, we'll mount the same telescopic sight on each M1895 to determine the original bullet's consistent overall accuracy. Bob has heat treated 50 bullets at 450 degrees. Hardness before sizing-lubing is 28. We expect a drop to the middle 20s? Will this improve accuracy? We'll see.