Still cant make this LBT fly

[charger 1]

The hottest we can get this fella going is 1760fps out of a 45/70 22" barrel hornady GC . Been all over the powder burn rate chart. It just wont hold accuracy at decent speed. Any one getting accuracy and speed outta this 459 350 M LBT?
http://i7.photobucket.com/albums/y259/Chargerdive/HPIM0772.jpg

[Bass Ackward]

Charger,

Thanks for the picture. It appears that one must have been cut for a lever. Got a reduced nose on it? That takes drive strength away from an already light design. Just guessing, it looks like you lost 30% of the drive area and converted it to unsupported nose weight.

So what that means is that you will either need a harder bullet than normal, taller rifling to grab what is there, the slowest twist rate possible to stabilize that particular bullet, .... or you will need to lower the velocity expectations of it. And it will always be more finicky. You may have to accept the level that you have obtained as a maximum level. We all reach one.

I maintain that the highest velocity potential from any bore diameter comes from the lightest bullet that can maintain a bearing length of 2 times the bore diameter. That can occur as light as 155 grains in a 30 caliber just to give you perspective, but comes into better proportions at 160 grains. The lightest I have been able to get it in a 45 caliber with an olgival style bullet is 420 grains. If you cut back on bearing length, you lower the contact with the rifling placing more stress on what is already a soft bullet no matter how hard the lead is. And .... you reduce the high velocity capability of a bullet.

But there is a balance and always exceptions. And I am not trying to say that a light bullet can't be shot accurately. But statistically, you really have to have something going for you in paragraph two to reach higher levels. Poor bullet designs that were made to fit everything with the least amount of problems is the reason that cast has the reputation of 1100-1800 fps accuracy depending on bore diameter.

What twist rate are you running with this?

[charger 1]

I would tend to agree with you. I shoot the LBT 350 WFN which contacts close to %70,rifling cuts into 1/3 of ogive even and it dont struggle with 2150 fps worm holes. Buddy was so impressed with it that he ordered the above bullet mold from LBT thinking he was getting same.For the fps this things gonna end up flying at theres no sense even having a GC on for the ride if you ask me. These are in marlins 95's to boot. You know the ballard deep cut rifling. Well thats correct except the word deep

[Pepe Ray]

Charger 1
The pic of your boolet appears to me to show ROUNDED edges. Is this true?
If so , you've lost some of your boolet somewhere. Could this be connected to your problem?
Pepe Ray

[charger 1]

Charger 1
The pic of your boolet appears to me to show ROUNDED edges. Is this true?
If so , you've lost some of your boolet somewhere. Could this be connected to your problem?
Pepe Ray


No without thinkin I just picked one of the very first ones to photo to give an idea. Everything we've been sending downrange has been crisp edges

[KCSO]

Good Grief! only 1750? That should turn a bear into red mist and a whimper.

It's hard to say what the problem is without the alloy and lube. For hunting I would guess that you are shooting w/w? Also what is the twist of the rifle? A lot of newer 45-70's are 1-18 and don't do real well with the lighter slugs. In a 1-22 you should be good to go to at least 1800. Also what kind of groups are yo getting now and what do you want? If the gun is going inot 2" now and you want 1" Well??? The next thing would be the leade. I have seen 45-70's with anything from no leade to a long tapering leade. Have you done a chamber cast? My 1886 wants a bullet snugged right to the rifling and has almost no leade and my Sharps won't shoot unless the bullet is back some. The Sharps is a Uberti and has a tapering leade and a 1-18 twist and just doesn't like the lighter bullets, a 330 Gould will only hold into 2 1/2" at 100 and the 450 will shoot into an inch. Also I know this is heresy but try sizing the bullet to 457. For some reason my 1886 shoots better with the smaller bullet even though the bore is 457 and 459 SHOULD be the right size.

[charger 1]

I think the 95 marlins are 1-18..The mix is ww's +2 tin. . The accuracy is super but only at 1750. I would think with a GC in tow 2000 would be the min.. If its not why have the GC?We use lyman super moly lube on pretty much everything we cast. I think as Bass said the design(which is not ours,but LBT's) has to little contact on the shallow marlin rifling

[45 2.1]

What diameter?

[charger 1]

What diameter?

We've tried em from 458-4605 in increments of .0005

[45 2.1]

We've tried em from 458-4605 in increments of .0005

Your 1895 will take a 0.462" boolit easily. Get them at or above Lyman #2 hardness and try bigger.

[44man]

I just hate to say it again and again and again---accuracy is more important then speed! I would be very happy with that load if I hit what I aimed at.
The boolit is short and needs the gas check for drive area. A 1 in 18 twist really needs a much heavier and longer boolit. Of course the velocity will be less but the thump at the other end is still worth it. Put the chrony in a drawer! Meat in the pot is better.

[KCSO]

I thought Marlin's were a 1-22 twist, but I haven't measured one in a long while. I will have to agree with 44man that if you are shooting good at 1750 you won't need 2000 to kill a ???. If the twist is really 1-18 you are perhaps going to have to step up to a heavier bullet. I know that the Marlin will push a 405 to 1900 with good accuracy, if you can stand it.

[Finn45]

If this is .45 Marlin rifle with original barrel, then it's 1-20". Have been so quite a long time.

[charger 1]

Doug,
I think you are probably right, as the 350 gr is the shortest I make in the M bullet, because the bearing is so short. In my mind I'm selling it for low recoil purposes, not power, yet I can see how many customers would want to make their 45-70 into a Swift if possible, and I can't spell out the bullet requirements unless I know the customers desires. An LFN at 300 gr has considerably higher accuracy potential at high velocity, and at 350 gr, it is hard to do anything wrong so far as pouring powder behind it in a 45-70. One factor that is absolutely mandatory for high pressure loads in this and all the straight wall ctgs is that the bullet be large enough to expand the case out to a close chamber fit, say not more than about .002 smaller than the chamber. This keeps the bullet from tipping.

If you are sizing your bullets, try just locking the checks on and finger lubing. It that picks up a couple three thousandths diameter and they chamber smoothly, velocities should be able to be boosted without losing accuracy. Another trick, lay two narrow strips of heavy duty aluminum foil between the blocks, one at each end. This will fatten the bullets .002, and let you know if larger bullets will solve the problem. Understand. Bullets with STRONG bearing can straighten themselves a little if started at a slight angle. The short M bullet you have can't tolerate it when pressures get too high, but it it's impossible to lean while being driven from case mouth into the rifling, they will fly straight at much higher velocity.

Let me know what you learn in this respect and perhaps I can throw you some more solutions.
Veral