Loads with Lead vs Jacketed

[Guy B. Meredith]

I have not seen any comment on why max loads for lead are lower than jacketed.

I know it requires more to move the jacketed bullet, but it would seem that pressure behind the jacketed bullet would also be higher than a lead bullet for a given amount of powder.

If so, then it would seem that more powder could be used behind lead.

What gives?

[DAVID NANCARROW]

Lead builds more pressure than jacketed bullets because it obturates the bore more efficiently.

[Contender]

Guy,

If you are referring to the listings in say a Lyman manual or load data using factory made swaged lead bullets, that has less to do with pressure to the extent it has more to do with leading and the bullet stripping in the bore.

Hardness variables in lead alloy bullets actually allow for a wide range of pressures and loading levels.

You have the hardest lead alloys that can be made to move out as fast as the top loads with jacketed bullets.

The softer the alloy the lower the pressures it can take upon firing as a rule of thumb. The bullet may lead the bore, deform to the point of raising pressures like a plug or actually strip in the rifling when it is kicked in the rear by a higher pressure loading.

In rifle loadings you have two schools of thought, some use faster pistol powders for the lighter/slower velocity loadings and you have others that use the medium to slower burning powders for heavier/faster loadings with more gradual pressure curves. An easier "push" if you will. This will result in giving the cast bullet a chance to engage the rifling easier without stripping.

The use of gas checks, better bullet lube and using a harder alloy sized properly to the gun, can result in a lower pressure loading behind a cast bullet with performance alongside the jacketed counterparts.

As a matter of fact, in say a handgun, hard cast gas checked bullets in equal weights as jacketed can result in lower pressures and faster velocities with similar loads.

With lead you have a bit of a balancing act between bullet hardness, pressure, lube strength and sizing going on. This can be controlled by the handloader/caster to his advantage. Something not possible with jacketed.

Cast bullet hardness can result in a rise of pressures for the particular loading but there are usually other variables at work too.

This can get to be a very involved, vast subject rife with theory and argument but I've just touched on some salient points here for now.


FWIW

[Guy B. Meredith]

Thanks for the comments, gentlemen. I am using West Coast Bullet copper plated bullets. Copper plated bullets seem to fall somewhere between lead and jacketed and West Coast supposedly has heavy plating so they may fall closer to jacketed.

Anyway, trying to go from load table to acuality and chrono/pressure indications is not straight forward. I find that I am using much heavier loads than lead and sometimes even jacketed to get the same velocity. I do not have ejection problems or primer deformation that would indicate danerously high pressures, but it is worrisome to be loading in the larger amounts of powder--and it costs more.

I do understand that my components affect the overall figures as well. I've loaded thousands of safe effective rounds, but that has always been pretty much a load copied from others. Now I want to move into new territory and don't necessarily feel I have all the information I need for that.

[Mike Irwin]

David,

That's not always a true statement.

Sometimes yes, chamber pressures are higher with lead, sometimes no, they're not.

I really don't think a small amount of blowby is going to have that much of an effect on chamber pressure.


Contender is absolutely correct, though. If the lead is hard enough, it can certainly be fired at the same velocities as jacketed bullets.

At some point, though, you're going to reach the point where no matter how hard the lead is, you simply can't drive it any faster without the bullet stripping through the rifling.

When that happens, leading is immediate and SEVERE.

[renaissance7697]

I believe "David" nailed the "WHY" succinctly.

I have found that for my purposes;
DECREASING a given load for Jacketed Bullets,
by six (6) percent,
gives me comparable perfromance when useing a
Hard Cast LEAD bullet
of the same weight.

This rule of thumb works for me:
using CLAYS CLAYS
and judging performance by
the way it reliably functions a
semi auto action, and performs downrange

ie:
The minimum load for
reliable function and reasonable accuracy
in a given weapon.

(I've GOT to get a Chrono!... One of these days.....)

[C.R.Sam]

Choice of lube can make a HUGE difference in whether or not a cast bullet is going to lead a bore.

Sam

[Bill Adair]

Something I've wondered about, is the bearing surface of the bullets? Doesn't that effect velocity, all other factors being equal?

Some lead bullets have one or more crimp grooves and lube grooves, and only driving bands bearing against the bore, while other lead bullets have nearly the entire length in contact.

Plated bullets generally have more bearing surface than bullets with grooves, so there may be some effect there.

Bill

[DAVID NANCARROW]

Excellent point, Bill. The bearing surface is going to have a direct effect on pressure and velocity, as well as the bullet material itself, all else being equal.

[doctor j]

GBM, FWIW here are some jacketed vs plated results from an experiment I tried last weekend from a 5" 1991A1 in 45ACP

5.8 gr W231, CCI300 Lg Pistol Primer, S&B brass, 1.268" - 1.271" overall length, Lee Factory Crimp 3/4 turn after initial contact.

West Coast 230gr RN (plated), average velocity = 837 fps
Remington 230gr RN jacketed, average velocity = 806 fps

18 rounds each. Alternated strings of each type. Fired 10 fouling shots of jacketed ammo before starting the test.

[Bill Adair]

David,

Thanks.

Looking at my chrono data spreadsheet, I realize that I've never made a direct comparison with lead, plated, and jacketed bullets, using otherwise identical powder charges and components.

Might be an interesting experiment to load the three types of bullets with identical loads, and see just how much velocity varies?

My spreadsheet indicates that with similar loads, I had about a 70 fps loss with plated bullets over lead.

Bill

[DAVID NANCARROW]

I have always heard that copper wears the barrel, and lead pressures the barrel, all else being equal. I got myself some pretty hot loads one time using gold dot bullets in my 45 by using copper jacketed powder data. It's my understanding that Speer uses a lead alloy so soft that its nearly pure, and then copper plates the slug. Apparently what happens is the slug deforms on ignition like a swaged lead slug but has the friction of copper, so the pressures went really high. I won't use any reloading data but speer when reloading for these, and I also use gold dot data for generic plated bullets as well, with pretty good results on average.

[ryucasta]

You'll also get different performance characteristics with moly coated lead bullets like bear creek.

[ryucasta]

Bill,

If your really serious about working up a load and take all those variables that you mentioned into account I would suggest you get a copy of QuickLOAD Internal Ballistics software. It will save you a lot of experimentation time.

Heres the website

http://www.neconos.com/

[labgrade]

& I'd suggest that y'all start off with the 10% reduced load for anything that you'll be "experimenting" with & work up to safe pressures In Your Gun. Period. (except for all the "disclaimer" powders, such as H110, etc. - YMMV here)

All listed data is based upon a standard set of variables determined in a "platform gun" as established by that (specific) testing (all components = powder, bullet, powder, primer, brass, & shooter; i.e. "test barrel" or whatever, & even if a "dedicated platform," it still varies - & at times, quite a bit).

True answer/s = ... it varies.

You must establish what is safe in your shooting platform. &, as a big benny, what is actually accurate - & that is the defining requirement, no?

Too many of us want to "push the envelope" without knowing what it is that goes into internal ballistics. It can be a real recipe for disaster.

Worse case = you get to make a post about a damaged.blown up shooter, & even worse than that = you get to post pix of how damaged is your body parts ....

Reloading is a science, AND an art. Heavy on that last.

What works very well indeed in mine, may well likely blow yours up! & with catestrophic results.

THE only way to determioe "what's THE BEST LOAD! in any firearm is to start with the recommended starting load & work up to acceptable limits.

Hopefully, during that process, you will find a combination that will allow you to shoot at your best accuracy. If not, you get to play with all the other variables to come up with your own very special load - till there's a component change ....

End result in all shooting = if you put the proper bullet in the proper place, what you shoot at will experience what end result you wish. (whether it be hunting, or target shooting - take care of the aforementioned & you will be happy. making that happen in your gun is a matter of careful attention to detail & how you compile your components to acheive that end)

There is no magic load! Nothing "shoots best" in any other shooter/platform.

Take the time to work it up to determine what's safe & accurate (in that order) in your own shooter.

Probably a good idea for one of us to just do a quick 'n dirty primer that just states these facts .... everything else is just gravy.

[Bill Adair]

Dave,

Good info, and it reinforces the importance of using the exact components, when working near load manual maximums.

Ryucasta,

Thanks for the link. My chronograph has built in ballistic software that gives me similar data, but without the chart. It's good enough for what I do, which is informal paper punching.

Labgrade,

Very good advice, thanks.

Almost all of my handloads are below published maximums, and I generally follow reloading manual recommendations very closely. When I do work near maximums, I pay attention and work up as you recommend.

Bill

[WESHOOT2]

Don't forget to mike the bullet diameter...........