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Bullets flat vs cupped base
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Author:  someone1980 [ Thu Mar 29, 2007 7:50 am ]
Post subject:  Bullets flat vs cupped base
I wonder if there is a reason why one would want a pistol bullet with a cupped base vs a flat base?
Author:  Selurcspi [ Thu Mar 29, 2007 8:01 am ]
Post subject:  Re: Bullets flat vs cupped base
someone1980 wrote:
I wonder if there is a reason why one would want a pistol bullet with a cupped base vs a flat base?


When bullets were made of soft lead and manufacturing tolerances were high, the skirt of a hollow based bullet would consistently create a gas seal and engage the rifling.
Another reason found by PPC shooters is that you can have a longer bearing surface to engage the rifling to provide consistent rotation at low MV with lighter bullets.
Webley of course came up with the idea that if you use a double hollowed bullet, you gain the afore mentioned advantages and this massive hollow point mushrooming effect. This bullet was dubbed the “Man stopper” for obvious reasons.
:D :D :D :D :D :D :D :D :D :D
Author:  Pinnacle [ Thu Mar 29, 2007 8:27 am ]
Post subject: 
There is nearly nothing more potentially ferocious than a .38 DEWC loaded BACKWARDS

Hollow base bullets are nice - they make a good gas seal - they are cheaper to manufacture

Flat base bullets are just fine as long as there is a slight taper to the jacket to ease loading and not to collapse cases.

Flat base bullets are normally (sometimes) a feature of a JHP but is not always the case. Sometimes there is exposed lead at the base - but not always.

Hornady - Sierra - Nosler use a flat base (copper base enclosed) on their pistol JHP's (winchester offers some with an exposed lead base - RA9TA)

They can handle a lot higher velocity without leading the bbl - or deforming.

Cupped bullets are fine and are a feature of lead - and sometimes FMJ's exposed lead at the base - this exposed cupped area does not necessarily make for a better gas seal - but I suppose that there is a chance of it... Anyhow....
Author:  mmcnx2 [ Thu Mar 29, 2007 9:22 am ]
Post subject:  Just a thought
I assume your talking about either lead or exposed base bullets. Both can have concave surfaces.

One thing to consider with these is your leading in the barrel will be higher than with jacketed bullets that have closed base.

Just food for thought.
Author:  someone1980 [ Thu Mar 29, 2007 12:39 pm ]
Post subject:  Re: Just a thought
mmcnx2 wrote:
One thing to consider with these is your leading in the barrel will be higher than with jacketed bullets that have closed base.


Closed base is where there is copper over the base also?
Author:  mmcnx2 [ Mon Apr 02, 2007 1:40 pm ]
Post subject:  Yup
Yes, a closed base has copper on the bottom of the bullet, there are a nmber of companis that make Jacked hollow points this way but finding a fully jacket bullet with the base covered can be a littel harder.

If forved to choose I'd take the JHP with a closed base over a FMJ with a exposed lead base. Just due to the leading.
Author:  mobocracy [ Mon Apr 02, 2007 2:29 pm ]
Post subject:  Re: Yup
mmcnx2 wrote:
Yes, a closed base has copper on the bottom of the bullet, there are a nmber of companis that make Jacked hollow points this way but finding a fully jacket bullet with the base covered can be a littel harder.

If forved to choose I'd take the JHP with a closed base over a FMJ with a exposed lead base. Just due to the leading.


All of the JHPs I've seen have the base jacketed. This is true of JSPs I've used with revolvers.

I always assumed it was because they were created with the same technique used for FMJs, but the die used for forming them formed the hollowpoint rather than the exposed base.
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