The Firing Line Forums - View Single Post - 30-06 jacketed vs. cast loads, why are they so dfferent

redrider · September 13, 2002, 10:48 AM

I have a Lyman 41'st Ed. book. (1957) In it the loads listed for Unique powder for a 30-06 (happen to have some laying around, not first choice of powder) are as follows:

110 jacketed: 15g.-1960fps. ; 19.8g.- 2320fps
110 cast gas check: 9g.- 1400fps. ; no max listed

125g. jacketed: 14.5g.- 1750fps. ; 19g.- 2200fps.
120g. cast gas check: none listed

150g. jacketed: 14g.- 1640fps. ; 19.5g.-2050fps.
150g. cast gas check: 10g.-1500fps ; no max listed

180g. jacketed: 13g.-1430fps. ; 18.4g.-1840fps.
180g. cast gas check: 19.3g.-1785fps. ; no max listed

no pressures listed

I am confused! I understand a gas check is so that the butt of the cast bullet doesn't melt under firing heat. What I'm not sure about is the differences between shooting cast vs. jacketed in a rifle. (30-06) I would think that since a jacketed bullet has more bearing surface and is harder than lead, it would be harder to push down the barrel, and lead is soft so it would go down the barrel more easily. I think that a jacketed bullet would have to be 'mashed' down the barrel, but a cast lead bullet is soft so it would conform to the lands and grooves easier. Is this wrong?

Some questions: Why is the 110g. cast load half of the jacketed max load? Why is there no 120g. cast load? Why is there no max listed for 150g. cast? The 180g. load seems to have the least difference between the cast and jacketed. Why do handgunners use cast bullets alot? Why, why and why?
How do the pressures differ? Why are the cast loads so much less than the jacketed loads?

I have been messing around with light plinking loads, then after reading these recipes I realized that I could make the 06 like a 30-30, which is much nicer to my shoulder for long sessions at the range. Last session I loaded up some M1-a 110g. jacketed bullets over 14g. of Unique. It was a real nice plinking load, soft and pretty accurate, three holes touching, the other two holes were close, at 50yds. Maybe 3/4 to 1 inch, didn't measure it. Fairly accurate at 100 yds as well.

Please enlighten a thouroughly cofused reloader.

September 13, 2002, 10:48 AM	#1
redrider Member Join Date: June 18, 2002 Location: seattle, washington Posts: 67	30-06 jacketed vs. cast loads, why are they so dfferent I have a Lyman 41'st Ed. book. (1957) In it the loads listed for Unique powder for a 30-06 (happen to have some laying around, not first choice of powder) are as follows: 110 jacketed: 15g.-1960fps. ; 19.8g.- 2320fps 110 cast gas check: 9g.- 1400fps. ; no max listed 125g. jacketed: 14.5g.- 1750fps. ; 19g.- 2200fps. 120g. cast gas check: none listed 150g. jacketed: 14g.- 1640fps. ; 19.5g.-2050fps. 150g. cast gas check: 10g.-1500fps ; no max listed 180g. jacketed: 13g.-1430fps. ; 18.4g.-1840fps. 180g. cast gas check: 19.3g.-1785fps. ; no max listed no pressures listed I am confused! I understand a gas check is so that the butt of the cast bullet doesn't melt under firing heat. What I'm not sure about is the differences between shooting cast vs. jacketed in a rifle. (30-06) I would think that since a jacketed bullet has more bearing surface and is harder than lead, it would be harder to push down the barrel, and lead is soft so it would go down the barrel more easily. I think that a jacketed bullet would have to be 'mashed' down the barrel, but a cast lead bullet is soft so it would conform to the lands and grooves easier. Is this wrong? Some questions: Why is the 110g. cast load half of the jacketed max load? Why is there no 120g. cast load? Why is there no max listed for 150g. cast? The 180g. load seems to have the least difference between the cast and jacketed. Why do handgunners use cast bullets alot? Why, why and why? How do the pressures differ? Why are the cast loads so much less than the jacketed loads? I have been messing around with light plinking loads, then after reading these recipes I realized that I could make the 06 like a 30-30, which is much nicer to my shoulder for long sessions at the range. Last session I loaded up some M1-a 110g. jacketed bullets over 14g. of Unique. It was a real nice plinking load, soft and pretty accurate, three holes touching, the other two holes were close, at 50yds. Maybe 3/4 to 1 inch, didn't measure it. Fairly accurate at 100 yds as well. Please enlighten a thouroughly cofused reloader.