I have 3 Ruger only loads that I shoot through my Blackhawk. 300 grain JSP with 22 grains of powder which creates around 30,000 pressure. 325 grain cast lead with 21 grains powder which creates a little over 20,000 pressure. a 357 cast lead with 19 grains powder which also creates a little over 20,000 pressure. The recoil actually felt less on the 357 grain bullet than the others. All loads are with H110. Is the pressure increase in the 300 grain because of the copper jacket?
Do jacketed bullets create more pressure?
- Thread starter AL45
- Start date
Jacketed bullets will as a rule cause more friction in the barrel then lead will and this will raise the pressure.
You don't list the velocities of your loads.
The 300 gr jacketed is probably traveling much faster than the lead bullets because it is jacketed and will take much more pressure than lead.
But, Lead bullets won't take the pressure that a jacketed bullet will take so by nature the jacket bullets can be loaded to the rounds fullest capability. Again, that may be why the pressure is 10k higher on the jacketed round for the loads you listed.
The hardness of the lead will dictate how fast you can send lead out the barrel. Most ammo manufactures will use softer lead in their lead loads so they are usually much slower than the jacketed loads of the same weight.
Buffalo Bore uses hard cast in the their loads so they can raise their velocities a lot higher. I've never used them so I don't know how well they work as far as leading your barrel.
I hope that made sense
You don't list the velocities of your loads.
The 300 gr jacketed is probably traveling much faster than the lead bullets because it is jacketed and will take much more pressure than lead.
But, Lead bullets won't take the pressure that a jacketed bullet will take so by nature the jacket bullets can be loaded to the rounds fullest capability. Again, that may be why the pressure is 10k higher on the jacketed round for the loads you listed.
The hardness of the lead will dictate how fast you can send lead out the barrel. Most ammo manufactures will use softer lead in their lead loads so they are usually much slower than the jacketed loads of the same weight.
Buffalo Bore uses hard cast in the their loads so they can raise their velocities a lot higher. I've never used them so I don't know how well they work as far as leading your barrel.
I hope that made sense
Do jacketed bullets create more pressure?
Maybe, maybe not.
Looking at some 44 Mag load data from Ramshot we can see that with True Blue Powder, the 240gr Jacketed bullet used more powder and developed less pressure that the Lead bullet.
Using Ramshot data for Enforcer we see the Jacketed bullet used less powder and generated more pressure than the Lead bullet.
So, with just these two examples the answer is "Maybe, Maybe not"
Maybe, maybe not.
Looking at some 44 Mag load data from Ramshot we can see that with True Blue Powder, the 240gr Jacketed bullet used more powder and developed less pressure that the Lead bullet.
Code:
240 NOSLER JSP 11.9 1,188[B] 13.2 [/B]1,320 [B]34,200[/B] 1.595
240 (L) LC SWC 11.5 1,152 [B]12.8[/B] 1,259 [B]35,764[/B] 1.610Using Ramshot data for Enforcer we see the Jacketed bullet used less powder and generated more pressure than the Lead bullet.
Code:
300 HDY XTP 16.2 1,170 [B]18.0 [/B]1,300 [B]35,500[/B] 1.580
300 (L) CP WFNGC 16.7 1,225 [B]18.5 [/B]1,361 [B]32,750[/B] 1.590So, with just these two examples the answer is "Maybe, Maybe not"
A lot is going to depend on the exact diameter of the jacketed and lead bullets, and the hardness of the lead in each. And there may be some unexpected things like softer bullets "riveting" in the forcing cone and raising pressure higher than the same (very stout) load with harder bullets.
So, there is not simple "take it to the bank" rule about what bullet will create higher pressure in all guns with all loads.
SL1
So, there is not simple "take it to the bank" rule about what bullet will create higher pressure in all guns with all loads.
SL1
"pressure" usually refers to Maximum Average Pressure (MAP) and is usually measured close to the case mouth. But once the bullet has moved any distance pressure drops quickly, so "friction" isn't really an issue with MAP. If the bullet is harder to engrave into the rifling then pressure might be higher.
MAP is the average of the peak pressure of some number of rounds fired, and the goal is to get a statistically valid sample of where the peak pressure is running. And hopefully the peak pressure, with margin for reloader boo-boo, etc., is well below the yield strength of the steel in the receiver.
So my point in all this babbling is that whether hard cast or jacketed, the pressure peak usually occurs before the bullet has barely moved, making the bullet material less of an issue.
MAP is the average of the peak pressure of some number of rounds fired, and the goal is to get a statistically valid sample of where the peak pressure is running. And hopefully the peak pressure, with margin for reloader boo-boo, etc., is well below the yield strength of the steel in the receiver.
So my point in all this babbling is that whether hard cast or jacketed, the pressure peak usually occurs before the bullet has barely moved, making the bullet material less of an issue.
Gray Ghost
New member
Don't lead bullets expand more than jacketed and therefore create a tighter seal in the bore? I would think that lead bullets potentially create more pressure than jacketed.
Hammerhead
New member
Yeah, they seal better, but I think they still have less resistance in the bore, so I'm not sure.
There's no maybe about it. It takes more force to engrave copper than lead.
I don't know if saying jacketed bullets create more pressure is the right way to phrase it, but they certainly require more pressure to move through the bore.
The rifling has to dig into the bullet, and it takes more pressure to do that to a copper jacket than it does to even the hardest cast lead slug.
You never hear of anyone "slugging the bore" with a copper slug, its always lead, and soft lead at that. Why? Because with a good rod and a patient hammer, you can drive a soft lead slug through a barrel, "by hand". I know you can do it with copper, but its a lot more difficult (effort intensive).
you can drive a stuck jacketed bullet out of a barrel, but its not easy. Comparatively speaking, driving out a stuck lead bullet is easier.
one way to test which bullet "creates" more pressure, if you have a means to measure pressure (I don't), choose a load that won't stick the bullet in the barrel - obviously- and then load everything exactly the same, except for lead vs. jacketed bullet and measure the pressure. That should tell you something.
I don't know if saying jacketed bullets create more pressure is the right way to phrase it, but they certainly require more pressure to move through the bore.
The rifling has to dig into the bullet, and it takes more pressure to do that to a copper jacket than it does to even the hardest cast lead slug.
You never hear of anyone "slugging the bore" with a copper slug, its always lead, and soft lead at that. Why? Because with a good rod and a patient hammer, you can drive a soft lead slug through a barrel, "by hand". I know you can do it with copper, but its a lot more difficult (effort intensive).
you can drive a stuck jacketed bullet out of a barrel, but its not easy. Comparatively speaking, driving out a stuck lead bullet is easier.
one way to test which bullet "creates" more pressure, if you have a means to measure pressure (I don't), choose a load that won't stick the bullet in the barrel - obviously- and then load everything exactly the same, except for lead vs. jacketed bullet and measure the pressure. That should tell you something.
It takes more force to move a jacketed bullet down the barrel. As 44 AMP stated, it's literally "engraving."
That's why I shake my head when I hear/read about what seems to be conventional wisdom to use lead loading data for plated bullets. Stuck bullets in the bore are no fun. And using low-end lead data for plated bullets will do just that.
That's why I shake my head when I hear/read about what seems to be conventional wisdom to use lead loading data for plated bullets. Stuck bullets in the bore are no fun. And using low-end lead data for plated bullets will do just that.
Pressure or Force to physically move the bullet through the bore is different than "Chamber Pressure", I think.
If you look at load data that has both lead and jacketed bullets you will see that often times the lead bullet generated more "Chamber" pressure the same same weight Jacketed bullet.
http://data.hodgdon.com/cartridge_load.asp
http://www.ramshot.com/wp-content/uploads/2010/09/WP_LoadSpec_1-23-14.pdf
Now if the OP was talking about the amount of force/pressure to physically push a bullet through a bore then, "yes" more force required for jacketed vs Lead. If the OP was talking about "Chamber" pressure then according to Pressure Tested Load data then the answer is "Yes' for this load and "No" for that load, in other words "Maybe.
One theory why Jacketed bullets produce less "Chamber" pressure is "obturation".
A properly sized lead bullet seals off the bore and traps the gasses behind the bullet. A harder jacketed bullet does not seal the bore as well or as completely and gasses can escape past the bullet thus reducing "Chamber" pressure.
Brian Pfleuger
Moderator Emeritus
Looking at different load data is comparing apples to oranges. All else being equal, as in load up a bunch of rounds using identical brass, primers, powder charge and changing only the bullet between lead and jacketed of the same weight, and seating the bullets so that powder space is identical, the jacketed bullets will result in higher pressure.
Here's an example from QuickLoad, using .357sig, since I had it loaded already.
9.0gr Power Pistol, both bullets seated for a usable case capacity of 12.5gr
124gr Hornady XTP, seated at 1.140, pressure 44,000psi
124gr LRN, OAL 1.070, 40,000psi
The lead has a "start pressure", which is the pressure required to engrave the bullet into the rifling, of 1160psi. The XTP is 2176.
Here's an example from QuickLoad, using .357sig, since I had it loaded already.
9.0gr Power Pistol, both bullets seated for a usable case capacity of 12.5gr
124gr Hornady XTP, seated at 1.140, pressure 44,000psi
124gr LRN, OAL 1.070, 40,000psi
The lead has a "start pressure", which is the pressure required to engrave the bullet into the rifling, of 1160psi. The XTP is 2176.
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Looking up different load data from one source to the next I would totally agree, but with data from the same powder distributor with the same testing medium and maybe the same lot of powder, not so much.
If Ramshot lists more powder with less pressure using jacketed then with lead, then the lead bullet created More chamber pressure than the jacketed bullet under identical conditions. At the same time looking at the same data you will find jacketed bullets generating more pressure than same weight lead bullets.
If actual pressure tested data is to be believed and followed than the answer to the OP's question is still, "Maybe".
If Ramshot lists more powder with less pressure using jacketed then with lead, then the lead bullet created More chamber pressure than the jacketed bullet under identical conditions. At the same time looking at the same data you will find jacketed bullets generating more pressure than same weight lead bullets.
If actual pressure tested data is to be believed and followed than the answer to the OP's question is still, "Maybe".
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Brian Pfleuger
Moderator Emeritus
Because you DON'T know that the conditions are identical.
Unless you know the length of each bullet and the powder burn space at ignition, you can NOT assume that the conditions are exactly identical. In fact, they almost certainly AREN'T identical.
I can use the same, exact bullet and the same, exact powder charge and change the pressure by 10's of thousands of PSI just by seating it 0.015 shorter, so switching between bullets without knowing the exact conditions is really no comparison at all.
Unless you know the length of each bullet and the powder burn space at ignition, you can NOT assume that the conditions are exactly identical. In fact, they almost certainly AREN'T identical.
I can use the same, exact bullet and the same, exact powder charge and change the pressure by 10's of thousands of PSI just by seating it 0.015 shorter, so switching between bullets without knowing the exact conditions is really no comparison at all.
Brian Pfleuger
Moderator Emeritus
"Hard and fast"? Well, there might be exceptions but it's a virtual guarantee that a jacketed bullet creates higher chamber pressure under identical conditions because it DOES take more pressure to engrave copper than it does to engrave lead.
That pressure only has one source, chamber pressure, so if the engraving force is higher, the chamber pressure will always be higher.
It might be 1,000psi with in one example, 3,000 in another and 5,000 in another but I doubt you'd find many (if any at all) where the lead would be higher. If you did, it would literally be the exception that proves the rule.
That pressure only has one source, chamber pressure, so if the engraving force is higher, the chamber pressure will always be higher.
It might be 1,000psi with in one example, 3,000 in another and 5,000 in another but I doubt you'd find many (if any at all) where the lead would be higher. If you did, it would literally be the exception that proves the rule.
Brian Pfleuger
Moderator Emeritus
Dude! They're not identical situations! We just went over this! I can adjust the seating depth in a .357 mag by 0.045 and go from 30,000 psi to 70,000psi. A change of 0.015 can change it well over 10,000psi. That's with the exact same bullet and no other changes.
The seating depth dictates initial burn space which dictates pressure FAR more than any other single factor.
Data being listed with different bullets doesn't tell you ANYTHING unless you know the OAL, bullet lengths and therefore seating depth. There's also no guarantee that data listed in the same book or even section of data was all done at the same time, with the same components, with the same powder lots, brass, primers or even the same test equipment, guns or barrels.
There is NO QUESTION that, all else being equal, a jacketed bullet requires more pressure to engrave than a lead bullet. That pressure can ONLY come from the chamber pressure. You might be able to make adjustments in OAL that CHANGE the conditions but under identical conditions the lead bullet will create less pressure in virtually all (if not all) cases.
There are weird, abnormal conditions that change the math. A really hard lead alloy, a soft plated bullet that's not truly "jacketed", IIRC some lead bullet can have trouble in a revolvers forcing cone and raise pressures but those are particular EXCEPTIONS.
The rule is that you will have higher pressure with a jacketed bullet than a lead bullet under otherwise identical circumstances.
The seating depth dictates initial burn space which dictates pressure FAR more than any other single factor.
Data being listed with different bullets doesn't tell you ANYTHING unless you know the OAL, bullet lengths and therefore seating depth. There's also no guarantee that data listed in the same book or even section of data was all done at the same time, with the same components, with the same powder lots, brass, primers or even the same test equipment, guns or barrels.
There is NO QUESTION that, all else being equal, a jacketed bullet requires more pressure to engrave than a lead bullet. That pressure can ONLY come from the chamber pressure. You might be able to make adjustments in OAL that CHANGE the conditions but under identical conditions the lead bullet will create less pressure in virtually all (if not all) cases.
There are weird, abnormal conditions that change the math. A really hard lead alloy, a soft plated bullet that's not truly "jacketed", IIRC some lead bullet can have trouble in a revolvers forcing cone and raise pressures but those are particular EXCEPTIONS.
The rule is that you will have higher pressure with a jacketed bullet than a lead bullet under otherwise identical circumstances.