Ross Mk II*** with Aluminium Military Style Butt Plate

This thread has been cross-posted to the Ross Rifle Forum.

I disassembled a recently acquired sported Mk II*** to clean it up and do some minor maintenance. I was surprised to find something I had not seen before - a cast aluminium or aluminium alloy military style butt plate. The rifle had been varnished while assembled and the aluminium color had been masked by a layer of yellowed varnish.

Some general information
The stock has been cut for the Ross Mk III rear sight, so the rifle would presumably have been initially manufactured as a Mk II 4* and subsequently converted to a 3*. The bbl is original length with nice rifling, the stock has been cut just ahead of the mid band and the band set back about 2". The right face of the butt has, as usual, been scrubbed and the rifle still has both sections of top wood. A commercial sight has been installed on the still-present rear sight base. There are "DP" stamps in small 1/16"font on both the bbl and bolt and the bolt has a 4-digit number stamped on the underside of the root of the bolt handle. There are no US military markings on the underside of the pistol grip - which has no noticeable sign of being altered. The butt plate, the door and the spring are identical in all respects to a normal steel butt plate with the exception that the plate is aluminium. There is what I assume to be a mould number cast into the inside surface. Since the butt has not been altered and the plate is a perfect fit, I have no reason to believe the plate is anything other than original to the rifle. The plate has obviously seen extensive use. I can post pics of the overall rifle, but don't think it would contribute anything to the subject.

My research indicates aluminium came into widespread use in the 1890's so, theoretically, the plate could be contemporary to the rifle. The plate does not look like the product of a back-yard foundry and, to me, the presence of the cast in place (mould?) number would indicate industrial or possibly large scale production. A secondary question is likely why would someone go to the trouble of casting a plate in aluminium when one is so easily forged/stamped in steel.

I would very much appreciate your input. Has anyone else come across an aluminium butt plate on a military Ross? What are your thoughts?

Pics have been posted. Hopefully, they will show up eventually.
The steel plate is off a commercial Mk II**, so has a serial number. Same plate as military Mk II's
https://www.milsurps.com/images/impo.../352p6ia-1.jpg
https://www.milsurps.com/images/impo...4/rlxh7a-1.jpg
https://www.milsurps.com/images/impo...4/ic1kx2-1.jpg
https://www.milsurps.com/images/impo.../14oc4dv-1.jpg
https://www.milsurps.com/images/impo...4/nya7fm-1.jpg
https://www.milsurps.com/images/impo...4/rkv6es-1.jpg
https://www.milsurps.com/images/impo.../15xs2kj-1.jpg
https://www.milsurps.com/images/impo.../2i7sjmr-1.jpg
https://www.milsurps.com/images/impo...4/mt8eiq-1.jpg

Never say never, but never seen before AFAIK. There doesn't look to be any sign that the butt trap door has been slid back and forth much, which would suggest it hasn't been on the rifle that long, particularly when you remember that the aluminum should wear much more easily than steel in that situation. There were plenty of foundries and very talented foundrymen in the Maritimes in days gone by and I wouldn't be surprised if this was a little private venture by some foundryman, either for the hell of it, to save a few ounces, or to sell to others for the same purpose.

Excellent point WRT wear due to trap movement and I certainly agree with the comment regarding foundries and Foundrymen. The pattern number, if it is that, would support the notion that it was likely foundry produced. It is interesting others have not been encountered. The rifle is a generic, albeit quite well done, sported service rifle that has not been otherwise customized. I would not expect to find a one-off custom made component such a rifle, but that could well be the case.