Dyer Multi-Caliber Rifle

I received a request from a collector trying to find information on the Dyer International Caliber Rifle. I have been unable to find anything myself, but the fellow did have a pair of technical drawings that he shared with me, and the rifle they depict is certainly something different.

The drawings are dated December 1943, and signed by one H. Dyer – about whom I know nothing beyond his rank of Lieutenant in the Royal Engineers. The rifle he envisioned was a magazine-fed, bolt action one with the ability to chamber and fire virtually any cartridge from 6.5mm up to 15mm. This was to be accomplished by constructing the barrel from 20 individual staves or strips with truncated pyramidal cross sections. When pressed tightly together, these staves would form a 6.5mm bore, thus establishing the minimum caliber that could be used. To use a larger projectile, the clamps holding the staves would be be loosened such that the central bore they formed would be .30, or .32, or .35, or whatever diameter was desired.

Dyer International Caliber Rifle bore
Dyer International Caliber Rifle bore

The chamber was formed using a slightly different method, since it would need to accommodate varying shoulder placement and dimensions as well as diameters. Instead of having staves the full length of the barrel, the chamber area used very short ones like fingers – just a few millimeters long each. This would allow the chamber area to conform to each different cartridge case shape.

Dyer International Caliber Rifle chamber
Dyer International Caliber Rifle chamber

Now, there are a number of apparent problems with this design (although I do have to salute Dyer’s creativity). For example, I do not see what would prevent gases from entering the space between the staves and venting mostly around the bullet when shooting anything larger that 6.5mm. There is an expanding sleeve drawn around the outside of the staves to trap the gases within the bore, but that would not keep them from venting forward around the bullet.

I would also question the use of a partially-supported case head (the bolt would have to be no larger than the smallest case that was to be used, so that the extractor could hook the rim of any cartridge) and the strength of the mechanism used to support the chamber fingers. The magazine would also be a challenge to design, unless one was supposed to use a different magazine for each family of cartridges.

I do like the inclusion in the buttstock of a pair of gauges to allow the shooter to ensure that the cartridge being used had neither too small a bullet nor too large a case to fit the mechanism.

Not surprisingly (given the British 1943 drawings), the bolt, furniture, sights, magazine, and trigger appear to be heavily influenced by the No4 Enfield rifle design.

If anyone knows anything about this design (especially if the technical problems were ever overcome to the extent that a prototype was made), I would love to hear it! You can see the full drawings here (click to enlarge them):

Dyer multi-caliber rifle blueprints
Multi-caliber barrel and chamber details
Dyer multi-caliber rifle blueprints
Overall rifle design