One of Gitano's threads gave me this idea and I also remember Drinksgins talking about doing something similar.
 
History:
Gitanos question about which caliber and why from.323-.375 was answered by me in favor of big for want of getting elk down faster with a big hole.
 
Purpose:
Getting elk is something I really want to do but also can not afford a new rifle right now. I own two 45-70 so why not throw a .458 chunk of lead I figures.
 
Problem:
Rain bow trajectory
Best by the tables I see for a cast bullet is a hunting zero hold range of 150 yards, I want to push that out to 300.
I have a rolling block Argentine and a falling block sharps replica out of Italy.
 
Idea:
Use my existing molds of 405 flat point or 340 falt point to make a hollow point by drilling out the centers.  Get more velocity, shoot further flatter.
 
Or buy jacketed factory soft flat points and drill them for hollow point and get even more velocity.
 
Questions for the general info return.
1. Which action will let me use the highest pressure in pursuit of velocity?
2. What would be the max diameter and depth I can hollow a bullet before it comes apart under shooting?
Which rifle action will withstand the most pressure thus produce the most velocity.
 
Possible solutions:
Shoot what I can and let the others along take the areas out side my euipment comfort zone.

I don't have answers to most of your questions Al, but I have some ideas.
 
First, I don't think you're gonna gain too much in range by hollow-pointing your existing bullets. Of course, if you hollow them out sufficiently to lower their weight by half say, the increase in velocity potential would be significant. And I assume that was the basis of the question "How hollow can I go?" I don't have any specific numbers, but considering the slow twist of .45-70s and the low MVs, I'd say you could hog out "quite a lot". However... BC is the "real deal" for extending range. Increased velocity helps, but at the cost of significant increase in recoil for mediocre increases in range.
 
Have you looked at the Lee .458-500-3R mold. http://www.leeprecision.com/cgi/catalog/browse.cgi?1204492287.64=/html/catalog/bullmol2.html With a BC of .443, it's the best aerodynamic bullet I know of for the .458 caliber, including a whole arm-load of jacketed bullets. If you can get that one to shoot straight, it's gonna give you the flattest trajectory. The only cast bullets I have gotten to shoot from my H&R 1870 Buffalo Classic in .45-70 are the Oregon Trail Silver bullets in 405 -grain. They shoot very, very well in my rifle.
 
I have no idea which action is most appropriate for what you have in mind. Others will have to help you there. However, I can give you some trajectory numbers for the Lee .459-500-3r.
 
In a 26" barrel, QuickLoad says you could use 49.4 grains of Accurate 2495 to generate 1775 f/s at the muzzle with a chamber pressure of 35,000 PSI with the Lee bullet. That would be a muzzle energy of about 3500 ft-lbs, 100 ft-lbs less than my .338 Win Mag with 210s. Sighted in for a 12" target (plus-and-minus 6" from Line-of-Sight and open sights 0.75" above the centerline of the bore), the zero range would be 200 yds, it would be 6" high at 100 and 22" low at 300 and carrying just over 2007 ft-lbs. You could stay 'on hair' out to 275 for sure, and probably 300 depending on your confidence in being able to put the bullet where you wanted it to go.
 
Reducing the weight of the bullet to 400 grains would reduce the BC by an amount I am unable to calculate exactly, so I will make an educated guess that it would drop to .410. (You'll hafta try these out to determine their exact trajectory anyway regardless of what is done to the bullet.) At this weight and BC, and keeping everything else the same, QuickLoad says you can get 1930 f/s at the muzzle with a little over 3300 ft-lbs of energy. It'll be 6" high at 100, and 16" low at 300 while retaining 1900 ft-lbs.
 
Personally, I would experiment with drilling out the base ("Minie-ing") as well as the nose (HP-ing). I think one coould "Minie" the bullet and get 100 grains out of it. Also, I have made my 459-500-3Rs with gas-check heels. The base could be drilled out with a relatively small diameter bit, and the hole covered with a gas-check. Heck, you might even get down to 350-grains. Who knows?
 
Paul
 
OOPS! Barrel lengths are 26" not 24.

Thanks Paul
 
For the record I have been going over my notes and have a load with 3031 that boasts a 1/2" group at 100 yards. I know too that I have had this rifle grouping well at 200. The nearest load I can cross reference in the spear book gives
BC .27 340gr fp cast 1700 fps muzzle
7.5" @ 100, 0 @ 200, -29.5" @ 300.
Energy Muzzle 2,182.8, 100 1608.2, 200 1193.4, 300 928.2
 
Which give me peace to 225 or 250 with work.
 
Spear lists their 458 at 400 gr with a BC of .214 and my books do not get to that BC you mention in tables at less than 2000 fps muzzle.
 
Taking it out of the back may be a good idea on cast and I will explore that. I will look to picking one of the molds you mention as .443 BC would do a lot.

Id have to say that as someone contemplating building a single shot 45-70 or 45-90 the complete lack of pointy lighter bullets (300gr to 350gr) is a somewhat discouraging factor.
Certainly, the bulk of 45-70s are Marlins and Winchesters but H&R and Ruger have been building moden single shots for years and companies like Pedersoli have also been building replica Sharps rifles, all of which would benefit from SMPs, SPs or SPBTs, cast or jacketted depending on the application.
Paul's suggestion of hollowing the base and then gas checking it seems cool, although your still limited to lower velocities because leading would become a problem.

Well I bought one of those molds Paul and will start experimenting with making a hollow base projectile as light as possible. Plus see what kind of shooting I can get out of standard.
 
I think 1600 fps muzzle is going to be the hottest I will want out of her though. Would you mind running out a balistic chart on 500, 400, 300 gr weights for me at that velocity and 1800 at 300 gr.

Al,
 
Without changing the BC, and using the same MV, the trajectory for each weight will not differ. In other words, trajectory is a function of BC and MV only. Unless you change the MV (or BC) for each weight, the trajectory won't differ.
 
I was scroungin' around today and found my BC calculator and tried it on the Lee 459-500-3R. I came up with the same BC as Lee said it has. That was really good news, because the calculator is a bit complicated. What I'll do is recalulate the BC for this bullet with the different weights. It'll be close enough to give you 'go/no-go' information.
 
I'll post the trajectories for the 500 at 1600 and 1800 fps. When I get new BC calulated I'll see how those effect trajectory.
 
Finally, tell me what powder you're planning on using and I'll estimate MVs for the differnt weights relative to the pressure generated by the 500 at 1600.
 
Paul

Here ya go...
 
Interesting results... Even with the BC changed, the trajectories remain the same because of weight, but delivered energy drops with weight. Anyway, here are the tables.
 
I'll post the results of increasing the MVs with decreasing weight and BC in the next post.
 
Paul

Now this is a bit more interesting....
 
I kept the chamber pressure for each of these examples the same as for the unmodified 500-grainer, but let the MV rise to meet that pressure, then recalulated the trajectories with the new MV AND BC. No need for the 500, 'cause that's the same as above, and no need for the 300 @ 1800 because that IS above. So here are the trajectories for the 400 and 300 at MVs produced from chamber pressures identical to the chamber pressure generated to get the 500 to 1600 fps.
 
So pick your poison.... Give up terminal energy for trajectory, or keep energy and 'lob 'em in'. :cry:
 
Ain't no free lunches.
 
Paul

Thanks Paul I am printing all of these off to add to my "book". Most likely powder will be IMR 3031, that is what has worked best for me in the past. Since I have a lot of time to play with this I also have some 4895 and will take suggestions.
 
Being an incurable sulphur sniffer I will also be using some 2F and maybe duplex that for burn just to see what develops.

Just out of interest, what max MV would you put on cast bullets, even the gas checked ones?
This technique could turn bullets that were formerly boat anchors into rocket ships and in a strong action the temptation would be to push them hard.
What no one would want however would be extensive leading in the rifling from too high an MV.

Other cast bullet shooters here are more experienced than I am in this area, but since most of the cast bullet shooting I have done has lead to what I consider substantial leading, I'll reference that.
 
First, I got very, very serious leading at 1300 f/s in the .50 ALaskan. I attribute that mostly to newly cut rifling. Gas-checked, I get no leading at 1800. Better still, I get no leading with jacketed bullets.
 
I was unable to keep from getting what I would call "considerable" leading in my .45-70 with all of my un-gas-checked cast bullets, all in the MV range from high teens to low 20s, except Oregon Trail Silver Bullets (un-gas-checked). Which also shot the best precision-wise. They leave the muzzle around 1800 f/s
 
I didn't get any noticeable leading in my K-31 or the 8x56R Steyr at 2400 f/s with gas-checked bullets. Also couldn't hit the broad side of a barn from the inside compared to jacketed.
 
In conclusion, I have decided that bore leading (and I'm quite sure it applies to 'coppering' too) is largely a function of the age/condition of the barrel and the alloy and lube used.
 
First, if the barrel is well broken-in, and in good condition, I think leading will be least. In new/rough barrels, gas-checks help immensely, but do not eliminate leading.
 
Second the alloy appears to have some small bearing on the matter in my limited experience. The Silver Bullets are surprizing -comparitively - in how 'clean' they run.
 
Third, more lube is better, but it can only help so much. It made almost no differnce in the .50 and the .45-70.
 
Finally, in the .45-70 Gov't, I think you're gonna have a tough time getting even the 300 over 2500 MV, and if you do, it's gonna be unpleasant to shoot with ME's in the 4,000 ft-lb range. From what I read, 2500 is about the top of the 'no leading zone'.
 
I've read a great deal of voodoo about the alchemy of alloys and lubes, and frankly don't buy 99% of it for even one heartbeat. It's just a matter of mechanics. That said, there are clearly some alloys that work better than others. But it isn't magic - it's mechanics.
 
Others with more experience are welcome to amplify or 'correct' my comments.
 
Paul

Quote from: kombi1976;75342Just out of interest, what max MV would you put on cast bullets, even the gas checked ones?......
 
What no one would want however would be extensive leading in the rifling from too high an MV.

Kombi
I vvill an$vver your que$tion by $tating I have alvvay had the be$t accuracy out of my falling block at beteen 1600 and 1800 fp$, no matter the bullet type or propellant. Tho$e $peed ju$t do not have leading problem$.

Thanks for 2 excellent answers, especially the really comprehensive one from you, Paul.
For the record, if I build my Martini into a 458 cal it'll be a 45-90.
That's why I wondered if the higher MVs would be a problem.