Why do bullets of the same weight and design but different

construction (ie lead, plated, jacketed) have different load data?

 

How come lead typically requires less powder, plated a little more,

and jacketed the most? I have not found much info on this.

 

Looking for some insight. Thanks.

Lead is softest and easiest to force into the rifling and out of the barrel. Plated is a bit harder and jacketed is the hardest so you need more pressure to get them out.

Lead deforms easily and creates a better seal earlier. Which means higher pressures with the same amount of powder. Jacketed doesn't deform as much and causes a more leaky seal, so less pressure for the same amount of powder. Plated is somewhere in between depending on alloy, manufacturing method, thickness of the plating, etc. Rainier I load like lead and bump it up if the velocity isn't there and it doesn't show pressure signs. For Berrys regular flavor I'll split the difference between lead and jacketed and work form there. For berry's double struck I load like jacketed, as well as for extreme and bulletworks. The caveat to that being I'll chack FMJ vs JHP loads for that weight in the data. JHP tends ot be longer. If they reduce for JHP, I use the JHP data as it means the powder is more sensitive regarding case volume, and that may also apply with regard to the mroe ductile bullet hitting the rifling after the freebore.

These guys basically just covered it all. Just to add one thing for the plated vs FMJ in terms of jacket, plated is not as "durable" and tends to sheer off at higher velocities which is why it is loaded lower, the better/thicker the plating the more it can take.

Not to mention that design is never really the same. The bullet profile is different from manufacturer to manufacturer and that changes how much of bullet body contacts the rifling and the length of the bullet, even at the same weight. Lets say you have a JHP at 230gr from two different manufacturers, and one punches a deeper cavity then the other. Weight being the same and diameter being the same that means that length or profile can not be the same. If the length is not the same but you sit them in the case for the same overall length that means one will have less room in the case then the other leading to different pressures.

Great info guys thanks.

Also, if you push lead too fast it turns into a giant mess. The better the jacket, the higher the velocity you can achieve.

Ken

There's a bit of disinformation here. Not dangerous mind you but not totally accurate.

 

If you take a lead bullet and a jacketed one of the same profile and weight you will find you need less powder for the lead bullet to achieve the same velocity as the jacketed. This is because the lead bullet (if sized properly) seals better but it also has a lower coefficient of friction in the bore. While the lead bullet is sealing better its also getting pushed down the bore easier. You drive the lead bullet at the same velocity as the jacketed with lower pressure.

 

Although you probably have to shoot a gazillion rounds of jacketed bullets to wear out a bore you'll never wear out a bore with lead bullets. They're just too soft to do so.

 

If you use the same lead and jacketed bullets and the same powder charge the lead bullet will be faster. This is due to the lower coefficient of friction. In this case the lead bullet generates less pressure. Higher velocity does not always mean higher pressure. By the same token high pressure doesn't always mean high velocity if it peaks early. That's why for high velocity loads in say a 357 or 44 magnum you use a slower burning powder and not Bullseye.

 

If you are trying to achieve the maximum velocity at a safe pressure a lead bullet with a gas check is the way to go (I'll get into gas checks next).

 

Leading in a bore can be caused by improper sizing (too large or too small) or too soft an alloy but more often than not is cause by too high a pressure not too high a velocity. The higher pressure deforms the base of the bullet and you get leading. You can solve this two ways. One is to go to a harder alloy. The other is to use a gas check on the base of the bullet. The gas check protects the base of the bullet, prevents it from deforming, and prevents leading. The thin coating on the base of a plated bullet works the same way to a lesser degree.

 

I know a guy who shoots lead bullets in his 1903 Springfield and Garands. He casts his own from a controlled alloy. He pushes these lead bullets to nearly 2000 fps until he has leading issues. When he puts a gas check on the same bullet he takes it to about 2600 fps with no leading as the gas check protects the base. He can push them a little faster but his accuracy is better at his 2600 fps charge.

 

There are a few reasons gas checks are not used as much as they were once was. One is the extra step and expense when you cast your own. Another is if you buy gas checked bullets they cost about as much as jacketed. The biggest reason is probably the bullet weights, styles, and designs available and relative low cost have taken a lot of people away from casting high velocity lead bullets.

 

 

 

 

There's a bit of disinformation here. Not dangerous mind you but not totally accurate.

 

Such as?

If you take a lead bullet and a jacketed one of the same profile and weight you will find you need less powder for the lead bullet to achieve the same velocity as the jacketed. This is because the lead bullet (if sized properly) seals better but it also has a lower coefficient of friction in the bore. While the lead bullet is sealing better its also getting pushed down the bore easier. You drive the lead bullet at the same velocity as the jacketed with lower pressure.

....

 

If you use the same lead and jacketed bullets and the same powder charge the lead bullet will be faster. This is due to the lower coefficient of friction. In this case the lead bullet generates less pressure. Higher velocity does not always mean higher pressure. By the same token high pressure doesn't always mean high velocity if it peaks early. That's why for high velocity loads in say a 357 or 44 magnum you use a slower burning powder and not Bullseye.

 

Hmm .. really?. I'm using the the data from Hodgdon's website here

 

for .357

 

125gr Lead using 6.8gr of Universal results in 1401fps at 34200 CUP

125gr XTP using 7.1gr of Universal resutls in 1394gps at 34900 CUP

 

5% more powder resulting in 1.4% more pressure. The lead load is higher pressure

 

for 9mm

 

115gr LRN 4.3gr Titegroup 1151fps 30500 CUP

115gr GDHP 4.5gr Titegroup 1135fps 29500 CUP

 

The GDHP uses MORE powder for less pressure.

 

In both those cases the jacketed round is also a hollow point so all other things being equal (they are not exactly equal, OAL is a tiny bit different) they would be deeper in the case taking up more volume and increasing pressure.

 

I'm really curious to know what source you have for lead being more slippery as I have a really hard time finguring out how a soft metal moving under pressure over rifled barrels would put up LESS resistance then copper.

 

 

Although you probably have to shoot a gazillion rounds of jacketed bullets to wear out a bore you'll never wear out a bore with lead bullets. They're just too soft to do so.

 

Hmm. Depending on a the bullet and barrel gazillion is a large number. Jacketed ammo wore out the barrel in my CZ in about 50000rd to the point that accuracy suffered. You can wear out steel with human skin eventually so lead will wear out barrels too, just a lot slower, but certainly not never.

Also, if you push lead too fast it turns into a giant mess. The better the jacket, the higher the velocity you can achieve.

Ken

 

More isnt always better. Most bullets are meant for a relatively limited velocity range..too little, it doesnt expand, too much, it's unstable..or in the case of Rifle bullets, the jacket can fail...dont ask me how I know that

You are not gonna get the velocity to reach ot 600 yards with a 308 with lead. I dont care how you load it. It will turn into a mess.

With pistols it may be different but with rifles your gonna have problems.

Ken

+1 to griz

More isnt always better. Most bullets are meant for a relatively limited velocity range..too little, it doesnt expand, too much, it's unstable..or in the case of Rifle bullets, the jacket can fail...dont ask me how I know that

 

Back in the 80's I tried handloading some light bullets in my 6mm for woodchucks. At 100 yds., I couldn't find any holes in my target. I put a target frame out at 50 yds. and tried again. What I discovered was that if I pushed the old 70 gr. Hornady SP (sold at that time, now discontinued) at 3,600fps in my 1x9 twist barrel, it would disintegrate and hit the target at 50 yds. with an 8' pattern of copper and lead. Spin frangible rifle bullets too fast and they will disintegrate. (I see they have lighter bullets now in that caliber but bullet technology has come a long way in thirty years.)

Back in the 80's I tried handloading some light bullets in my 6mm for woodchucks. At 100 yds., I couldn't find any holes in my target. I put a target frame out at 50 yds. and tried again. What I discovered was that if I pushed the old 70 gr. Hornady SP (sold at that time, now discontinued) at 3,600fps in my 1x9 twist barrel, it would disintegrate and hit the target at 50 yds. with an 8' pattern of copper and lead. Spin frangible rifle bullets too fast and they will disintegrate. (I see they have lighter bullets now in that caliber but bullet technology has come a long way in thirty years.)

I was pushing Sierra 22gr HPBTM so fast that they were literally detonating on the fur of woodchucks Made a hell of a mess but also not lethal had to anchor them. I also burned out the bbl of my old Rem 788 in under 100 rounds.

I was pushing Sierra 22gr HPBTM so fast that they were literally detonating on the fur of woodchucks Made a hell of a mess but also not lethal had to anchor them. I also burned out the bbl of my old Rem 788 in under 100 rounds.

The 788, though understated, was a great little rifle.

 

I have noticed new bullets in .243 diameter as light as 55 grains with published reloading velocities exceeding 4,000 fps. Haven't tried them yet, but that is fast for a 6mm. I suspect the light bullets are more geared to 6mm Dasher, 6mm BR and the like. I am happy with the accuracy I get out of the 80 HP's by Rem. & 85 Gr. BTHP Sierra's.

The 788, though understated, was a great little rifle.

 

I have noticed new bullets in .243 diameter as light as 55 grains with published reloading velocities exceeding 4,000 fps. Haven't tried them yet, but that is fast for a 6mm. I suspect the light bullets are more geared to 6mm Dasher, 6mm BR and the like. I am happy with the accuracy I get out of the 80 HP's by Rem. & 85 Gr. BTHP Sierra's.

 

I loved that thing.re-barreled it and gave it to a buddy for Christmas one year

I loved that thing.re-barreled it and gave it to a buddy for Christmas one year

I run into them every now and then on the used racks upstate and they command good prices, especially in the oddball calibers. They have a cult following.