Shallow based Minies

[gjkershul]

I was rereading the 1985 Dixie catalog and and came across their ad for a Parker-Hale Minie mold-apparently imported from Engalnd.
In the ad, they said that shallow based minies shot better in rifle musket type arms. I have been experimenting with an enfield carbine this Spring and just got the Lyman Parker Hale bullet sized and shooting. I have been shooting the Lee traditional and modern minie and can't tell any any difference between the three. Has anyone on the list had outstanding results with the Lyman Parker-Hale Minie?

 

[paulvallandigham]

The reason shallow, hollow based minies shoot better in some guns is that the " skirt " formed at the bottom edge of the bullet is thicker, and less prone to break off, or chip away when the skirt expands to fill the grooves, then the deeper HOllow bases, which, of necessity, tend to have thinner skirts. To get the angle needed on the plug that creates the hollow base, so that the plug releases easily from the casting, the ogive is a bit wide, and thins the skirt. Deep hollow bases have not been shown to perform any better than shallow hollow based conicals.

Now, remember that rifles made to shoot hollow based conicals tend to have much more shallow grooves(.002-.004") than those made to shoot the PRB, or flat based conical. If you use any hollow based minie or conical in a gun with grooves that are .012-014" deep, you are going to have blow-by problems, unless you use a OP wad, or base wad to protect the skirt, and help seal gases. Also, the accuracy of these conicals can often be affected by the comparative width of the lands and grooves in a barrel. A barrel with wide lands, and deep, narrow grooves, may be fine for shooting PRB, but it should not be expected to shoot hollow based conicals well, regardless of the ROT.

 

[ResearchPress]

they said that shallow based minies shot better in rifle musket type arms.

Perhaps a little pedantic, but the term 'rifle musket' needs clarification.

The Pattern 1853 Rifle Musket (commonly referred to as the three-band Enfield) has a 39" barrel with 1 in 78 rifling. Later versions and some repros. have progressive depth rifling. That employed on originals was 0.015 deep at the breech diminishing to 0.005 at the muzzle.

The various short rifles (commonly referred to as the two-band Enfields) have a 33" barrel with 1 in 48 twist rifling. Progressive depth rifling employed on originals was 0.013 deep at the breech diminishing to 0.005 at the muzzle. The Pattern 1861 Artillery Carbine with its 24" barrel had similar rifling.

As a starting point the deeper based bullets are commonly used with the slower twist rifle. Shallow based bullets may not stabilise with the 1 in 78 rifling, but can provide improved accuracy when used in the short rifle with the faster twist rifling.

Note that Parker-Hale made some P.53s with 1 in 48 rifling for export to the US and the skirmisher market. These are not however reproductions of any Pattern (service issue) arm.

David

 

[gjkershul]

Thank you for the information gentlemen.