Marlin Firearms Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
1,270 Posts
Discussion Starter · #1 ·
why is cast loading much slower and lower in velocity rather than the jacketed? i gather the fact that leading from too much velocity is posible but what about pressure? what kind of pressure can cast bullets actually take? if velocity is the main reason for low preasure then is it ok to load say a 190 grain bullet in the 7.62x39 at 40,000psi for a maximim volocity below the leading threshold? maybe even 250's in 30-30 an neer max preassure for a velocity below the typical leading velocity?
 

·
Premium Member
Joined
·
1,167 Posts
luvalever said:
why is cast loading much slower and lower in velocity rather than the jacketed? i gather the fact that leading from too much velocity is posible but what about pressure? what kind of pressure can cast bullets actually take? if velocity is the main reason for low preasure then is it ok to load say a 190 grain bullet in the 7.62x39 at 40,000psi for a maximim volocity below the leading threshold? maybe even 250's in 30-30 an neer max preassure for a velocity below the typical leading velocity?
I'm not sure what you mean. I load cast bullet in most cartridges to full velocity, that is, .444's up to 2300 fps, .30-30's to 2200 fps, ,35 Rem to 2150 fps, .358 Win to 2500 fps and I've never had a problem with leading or hunting accuracy at those levels. I load 150 gr Saecos (actually 160 gr) to 2200 fps in the 7.62x39 with excellent accuracy and deadly killing power on medium game. I'm going to try some 170's later in the spring. You can adjust for the pressure range you're in by varying your alloy hardness and load even faster than I do. There's a few little tricks to it but nothing special or magic.
 

·
El Kabong
Joined
·
8,333 Posts
With the right fit, and properly hardened and gas check boolit, you can send them spheres to the wall.
Ive moved Ranch Dogs lever 30 cal boolit over 2600fps, with no leading. Using White's 2500+ lube
Out of a beater 1948 Mauser.
 

·
Super Moderator
Joined
·
5,573 Posts
Very often it's because of two things:

Faster powders are used in many cast bullet loads, necessitating lower velocities, and,
Accuracy is often better with lead bullets at lower speeds, depending upon the rifle, barrel twist rate and bullet fit and hardness.

Too much pressure with a relatively soft bullet intended to expand on game can be a problem indeed. Any severe deformation under the stresses of high pressure firing can distort it to some degree and make a somewhat less accurate load. Obturation of a bullet is not always a good thing. It can also unbalance the bullet. But the whole obturation thing is problematic, and often doesn't occur even though calculations say it should be happening. If a soft bullet isn't shooting, harden it up and see what happens.

I have no great difficulty duplicating factory load speeds with quite sufficient accuracy for hunting, but usually lower speeds mean better accuracy for me. It's the much safer way to bet. The question is whether the accuracy difference means anything.

Shooting a 30-30, 35 Remington etc. with cast bullets at no loss of velocity compared to factory loads and only a relatively insignificant accuracy loss compared to lower velocity cast loads is so commonly done that Marlin shooters regard it as a rather mundane task.

I shoot a 225-230 grain (depending upon lead source and lubricant used) gascheck bullet out of relatively soft 12 BHN wheelweights at 2050 fps out of my 35 Remington with a number of different powders. Accuracy is better slower or with a harder bullet, but the rifle shoots very well enough as is. The idea with the straight wheelweights is to allow a fairly rapid expansion for deer hunting. If I was black bear hunting over bait the bullet would be better at 16 to 27.

And my SKS likes cast bullets just fine, too so your idea for the 7.62 is a good one. Lee makes a good 160 for it and it does well at just under 2000 fps in my gun. The 7.62X39 makes a good cast bullet cartridge and is plenty good enough for deer. It will shoot the cast loads as well as any jacketed. Filing a small meplat on the 160 Lee makes it a bit better.

Leading really isn't the problem with lead bullets that it is made out to be. A velocities common to the levergun rounds any halfway decent lubricant (50-50, etc.) will hold leading at bay with a gascheck bullet very easily. I don't clean my cast bullet shooting levers very much because they don't need it very much.
 

·
Registered
Joined
·
1,270 Posts
Discussion Starter · #5 ·
wow guys very enlightneing and spot on answer for my question thank you thank you...but another thing, can load data be substituted between jacketed and cast or what is the reduction percentage or rule for working up loads and deciding for powders and burn rates?
 

·
Premium Member
Joined
·
5,222 Posts
you're usually pretty safe. I'll say that I shoot plenty of 243 and 3006. You don't usually use them up to their velocity potentials or you will et some accuracy and potential leading issues.
 

·
El Kabong
Joined
·
8,333 Posts
luvalever said:
can load data be substituted between jacketed and cast or what is the reduction percentage or rule for working up loads and deciding for powders and burn rates?
I use cast loading data from cast books. Most loads are way below the jacketed amounts.
The 45-70 is one exception. Where some jacketed loads are lighter than their cast counterparts.
 

·
Super Moderator
Joined
·
5,573 Posts
Swapping data successfully depends upon the caliber.

If, for example, you think you're gonna successfully substitute a 180 grain cast bullet for a 180 grain jacketed bullet in '06 at 2800 fps and also expect good accuracy, well, then, good luck to you.

Won't happen.

The lower pressure calibers are usually more successful at such things. As in also shooting well, which is always important.
 

·
Registered
Joined
·
1,270 Posts
Discussion Starter · #9 ·
thanx much fellas.
 

·
Administrator
Joined
·
23,793 Posts
To your original question as to why it is low pressure and lower velocity.


30-30 165 gn cast, 6gns of Unique = over 1000 loads per pound of fun.
 

·
Registered
Joined
·
1,537 Posts
Another point to consider is if the lead bullet data is for a cast or a swaged bullet. I know Hornady lead bullet data is for their swaged products, is is most likely the Speer data. Cast bullets are much harder than swaged and can withstand a higher speed, generally. Of course there's much more to leading than bullet hardness, but that's a topic for another post.
GH1 :)
 
1 - 12 of 12 Posts
Top