Cast vs copper jacket same weight

[357reloading]

If a cast and copper jacket bullet are same weight seems to me the copper jacket would be faster because more powder can be used.

Correct me if i am wrong.

[Bwana]

Its comparing apples to oranges. However, in a pure sense, you a "can" drive any given weight cast boolit faster than any same weight jacketed bullet. This has to do with the different resistance of the material to being pushed down the bore.

[Lefty SRH]

Copper has more drag on the bore.

[a1albert]

In the barrel or out? I would think that once it leaves the barrel the copper bullet would out run the lead boolit do to higher bullet BC. The lube gruve area on the lead boolit would create some drag I would think.

Albert

[runfiverun]

if you use the same load the lead will be faster.

[Larry Gibson]

if you use the same load the lead will be faster.

+1, correct answer.

However, there are other factors that make cast bullets not conducive to the velocities with the same accuracy as jacketed bullets are capable of in many cartridges, particularly bottle necked rifle cartridges. Dare I mention why;).........:groner:

Larry Gibson

[Texantothecore]

The jacketed bullet has a lower ballistic coefficient than the lead bullet and the lead bullet will outrun the jacketed one. Jacketed bullets also require more powder due their high degree of hardness from the copper jacket. It simply requires more pressure to push the copper into the rifling than it does for the lead.

Jacketed does not shoot well at all with reduced loads as the accuracy will suddenly fall off as you get to a lower pressure that is not sufficient to spread the bullet in the barrel.

[mpmarty]

Correct me if i am wrong.

OK you are mistaken.

[Cherokee]

I have CB handgun loads that are faster and more accurate than jacketed of the same weight, then I have some CB loads that are less accurate than jacketed. Depends on the gun and the load in my experience. YMMV

[miestro_jerry]

I don't care about about comparing the two for speed. I use jacket bullets in all of my gas operated rifles, cast shoots in everything else I own, except my Ultra Mags. Cast bullets seem to break up when they are flying at 3,200 fps and faster.

Jacketed bullets work well in most rifles, except I have some "surplus" rifles that the bores are well worn, perfect for slightly oversized CBs.

I get better cast hunting bullets from my Ranch Dog molds when I use them in my Marlin Leverguns.

So comparisons of speed between the two does not give me any useful data, when deer hunting, does it matter which bullet gets there first?

Jerry

[44magLeo]

In my Lyman 49th, 44 mag with 245 gr cast uses 20.6 grs of 2400 for 1248 fps.
240 gr JSP with 20.5 grs 2400, 1154 fps.
45 ACP 230 gr FMJ 5.8 grs 231 849 fps, 225 cast 5.8 grs 231 902 fps
This shows that comparing loads cast jacketed that at the same powder charge, the cast boolit is faster.
This is from the resitance of the rifling engaging the boolit. It takes more to engage the jacketed than the cast. Less resistance = more velocity.
Look in most books that have both cast and jacketed in it and you will find the same comparisons.
In handguns you can often use more powder, the less resistance of the boolit means less pressure, so you can boost the powder to bring the pressure back up.
Leo

[Wolfer]

In my RNV 45 with the lee 452-255 RF 8.8 gr Unique got me right at 1000 fps. This was the velocity I was looking for so I filed my front sight to POA. On a whim I decided to try some Nosler 250 HP and it took 10 gr to get to the same speed which also hit at the top of the front sight.
The cast load was shootable without ear plugs ( while hunting anyway ) but the j- load was considerably louder.

[Larry Gibson]

Texantothecore

Don't you mean "friction" coefficient instead of "ballistic coefficient"?

Larry Gibson

[stubshaft]

I think he means obturation Larry.

[runfiverun]

i wasn't going any further than the correct answer.

[Bret4207]

In the barrel or out? I would think that once it leaves the barrel the copper bullet would out run the lead boolit do to higher bullet BC. The lube gruve area on the lead boolit would create some drag I would think.

Albert

If you can get some of the older Handloader mags or their compilations you'll find articles discussing this. In short, when talking handgun boolits, with similar profiles, you'd have to get waaaaaay out there to see any discernible difference. In a rifle the difference is often more apparent because they tend to have more streamlined forms. But comparing say a 311041 and standard 30-170RN started at the same speed you still aren't going to see a difference until you get way out there, well beyond the usable range for a 30-30 At 350-400 plus yards, yes you will start to see a difference, especially in vertical dispersion.

Of course if you are talking a 22-250 then we're in a whole 'nuther field. But depending on form the cast designs lube grooves aren't going to play a significant role until you get way out there,and even then it depends on how much lube is still in the grooves.

The problem is too many people try and compare something like a Sierra 30-168MK and a Lyman 311440- apples and Spam. You'll find far more difference at extended ranges due to the Cast boolits FB profile and long range jacketed designs boat tail.

[fatelvis]

I always thought the combo of filling the bore more completely for a better "seal" against the powder's gasses, and a lower "coefficient of friction", the cast bullet moves quicker. Is there more to it?

[MtGun44]

Lead alloys are used as bearing metal in engine bearings because they have a very
low coefficent of friction on steel with a lubricant. Same in your barrel with a good
lube. Lower friction gives higher velocity with the same load, like Larry and RunFive
said.

Bill

[303Guy]

I have first hand experience with copper jacket bore resistance. I tried a full case of Trail Boss in my hornet under a 55gr bullet. It stopped halfway down the bore and took some force to push it back out. The same weight cast boolit is about sonic.

[MikeS]

The jacketed bullet has a lower ballistic coefficient than the lead bullet

I don't think you can say that as a generality. If the boolits have the exact same shape, than the ballistic coefficient will be the same if shot to the same velocities.

[HangFireW8]

I always thought the combo of filling the bore more completely for a better "seal" against the powder's gasses, and a lower "coefficient of friction", the cast bullet moves quicker. Is there more to it?

There's more to it. Sometimes an easily obturating boolit will not allow enough pressure to build to allow for complete combustion. That means that sometimes (not always) hard, tough to start boolits (or bullets) will have greater velocity. That sometimes usually involves slower burning and/or heavily retardant coated powders.

Interior ballistics is a complex system and sometimes changing even one variable doesn't lead to linear (that is, predictable) results.

-HF

[HangFireW8]

I don't think you can say that as a generality. If the boolits have the exact same shape, than the ballistic coefficient will be the same if shot to the same velocities.

Unless the cast boolit has a different sectional density than the jacketed...