Earthshattering Revelation (I KNOW someone has had to have thought of this.)

[Hamish]

Talking about nose pour moulds with madsenshooter started me on this so blame him, not me!

Why is it not possible to mould a hollow base boolit, in any dimension wanted, that would eliminate the problem of gas cutting, when pushing a boolit to the speeds that dictate moving from a plain base to installing gas checks?

Realizing that there are physical limits to how small you could go before you are talking about a hollow point pin the size of a large needle and the wall of the boolit being so thin that????

Is this train of thought only dragging boolit discussion all the way back to the Minie' period? Just a dead end unless you are talking about single digit bhn and big 'ol BP rifle boolits??

Rich @(:^]#>::

[Rocky Raab]

The problem with hollow-base bullets is that they can and often do distort or even break at the instant they leave the muzzle. That doesn't do wonders for accuracy.

[lwknight]

There is probably a treid and proven reason that HB bullets are not used for higher velocities.

[HangFireW8]

Sharpe covered this back in 1937. The skirt of the HB is fragile and comes off in the cylinder gap or muzzle or sometimes just partway down the barrel at higher pressures or velocities. They work best in mild low velocity loads like 38 special or big black powder rifles. They can be quite accurate in slow 38's but for muzzleloaders not as accurate as a close fitting plain base boolit. The real advantage for ML is faster loading only.

[303Guy]

It seems that many folks use a hollow (or cupped) base design for paper patching. The idea is the twisted tail nub fits into the hollow. Paper patched loads are not low pressure. Fairly soft alloy is generally used.

[btroj]

A very slightly cupped base might be able to handle higher pressure but how deep? A large hollow base like that required for certain upset to fill the barrel will also allow some chance of excessive base enlargement upon leaving the muzzle.
A bullet MAY work in these cases if loaded to a very specific pressure and velocity. An example would be the hollow base bullets used in some factory lead 45 colt ammo. Very low pressure, very set parameters.
I am not interested in a bullet that is so limited in use. I would rather have a "normal" design that fits my gun so I can load to a wide range of pressures/velocities.

Brad

[MtGun44]

HB is a real workable solution for severe cylinder throat and barrel dimensional mismatch
that has been fairly common with older .45 Colt caliber SAAs. Both Rem and Win low power
lead boolit loads have HB boolits, and I am sure it is to help them deal with this common
problem.

Unfortunately, reports are that they blow out badly if you load them very hot.

Bill

[missionary5155]

Good afternoon
+1 on the above plus HB boolits are still used for serious undersized bolits in fat chambers and bores... such as the 41 Colt.
Mike in Peru

[olafhardt]

Suppose we used a harder alloy?

[btroj]

Harder will only go so far in helping. Too much pressure can still low them apart. Worse thing is that the harder the alloy the more pressure you need to get them to upset to fill the bore.
The real problem is that a hollow base has a very small window of pressures in which it will expand enough to fill the bore yet not blow open on exiting the muzzle. Keep in that window and all is good.
Notice that pretty much all hollow base bullets are designed for low pressure work? There is a reason for this.

[Cap'n Morgan]

It is an interesting idea and I've been thinking along the same lines myself. If you look at the geometry of even a slightly cupped base, it has a larger area than a flat base and should expand/obturate more easily, but whether it would be an improvement over a plain base boolit with a perfect fit, I cannot say.

On a similar note, all the 22LR bullets I've examined have been a hollow base heel design. If you watch this absolutely amazing (and mesmerizing) video, at 6:30 you'll see 22LR bullets in flight, where all traces of the heel is ironed out.

http://www.youtube.com/watch?v=QfDoQwIAaXg

One of these days I'm gonna make a mold for my Swedish Remington. The bore/land measurements are .516/.484. Squeezing a solid boolit down .032 seems like a lot, and this makes a HB design very tempting. I will probably use a fairly deep HB cavity profile since this is a low pressure round, but it will be easy to change the design along the way if necessary.

[mdi]

I remember seeing a drawing of a bullet base, prolly from late 1860s, that used an insert, similar to the inserts used in the noses today's hunting bullets. Would it work with modern metals and technologly?

[Hamish]

?? A conical base bullet ?? http://www.youtube.com/watch?v=QfDoQwIAaXg

[Cap'n Morgan]

?? A conical base bullet ?? http://www.youtube.com/watch?v=QfDoQwIAaXg

Since it's a German made video, the conical base bullet is probably an RWS or a Brennecke TIG bullet.

[leadman]

did you notice the cupped bases on some of the pistol bullets? I had some Remington 9mm bullets that had a cupped base.

[geargnasher]

Onandaga did some impressive stuff with a .500 S&W magnum NEF and minies, his secret to success was using BPI Original compacting shot buffer as a filler.

Gear