Lead vs. Jacketed: Why a huge difference?

[Boomer686]

I don't have any experience loading lead (non-jacketed) bullets. I did notice that there is a large discrepancy in the size of the charge for similar weight bullets with the only difference being bare lead or jacketed. Why? What is it about the lead bullets? Do they react different to the expanding gas? I realize you need a gas check over a certain velocity (700 / 800 fps maybe???) But you would figure that a similar projectile eg a LRN 230gr .45 would have a similar charge to a FMJ RN 230gr .45 round.
Anyone????

Regards,

 

[joe-nwt]

Because lead offers less friction in the barrel, it takes less powder to achieve the same velocity.

 

[Boomer686]

Never thought of that.... I guess that's why I came to the pro's for help!
Is that the only / main reason ?



Regards,

 

[joe-nwt]

Never thought of that.... I guess that's why I came to the pro's for help!
Is that the only / main reason ?



Regards,

I'm only a pro if you pay me.

The only reason I was ever told. Maybe someone else will offer something else.....

 

[Cerdan]

I'm becoming a regular thread hijacker, but as always, my question's related...

I noted some considerable difference in data between FMJ and copper-jacketed bullets of the same weight. Would barrel friction account for those differences as well?

 

[joe-nwt]

I'm becoming a regular thread hijacker, but as always, my question's related...

I noted some considerable difference in data between FMJ and copper-jacketed bullets of the same weight. Would barrel friction account for those differences as well?

The jacketing material and the bearing surface of the bullet both affect friction and therefore load data.

 

[blacksmithden]

I thought that firing a lead bullet under full tilt loads caused the rifling to rip off the outer bit......rather than getting a good bite and spin on the bullet. ????? Hey, I'm no expert......just very opinionated

 

[ben hunchak]

Rifling can have that effect on cast bullets if a number of things are present....a) abnormally fast twist b)bullet too small for bore c)bullet to soft for velocity.....cast bullets have been driven to 3000fps. without being stripped by the rifling or showing poor accuracy. Some rifles that i have tested showed problems at any speeds above 1200fps., at microgroove Marlin .444 and a Win.94 in 25/35 with a 1-8" twist.

 

[Boomer686]

Thanks for the help Guys!

Regards,

 

[John Y Cannuck]

You will also note a tendency in cast loads to steer away from the slower powders, use the fast ones, particularly with non-gas check loads, or 'plain base'. This is to get the lead bullet to Bump up to the bore size and seal the bore efficiently.
It can make a huge difference depending on the hardness of the lead, in both bore leading, and accuracy.

 

[machinistbutler]

some styles of bullets,of the same weight,are designed to perform at a certain velocity a certain way.Some bullets may be down loaded in the manuals so they maintain performance as intended.