I've run out of steel stock for spacers but I have a ton of 6061 aluminum. If I made them snug to the Ti can ID and thick enough, could I use them for spacers?

Right now I'm thinking the spacer at the end of the stack, to make everything snug, so no more than 0.5" long. Probably 0.125" thick.

I might run a quick hoop stress hack on them, but I'd imagine the pressure would have dropped off substantially by the time the bullet is 5"+ from the end of the barrel.

Perhaps the different coefficients of thermal expansion would be the major issue?

Interesting question and I’ll subscribe for the pros to answer.

I’m about 50% on the subject but I do have experience in aluminum erosion. Ceramics can typically withstand the pressures of aluminum and last longer.

Fine for pistol and rimfire, and for low volume rifle cans.  But aluminum has a melting point less than half that of steel, and gets pretty squishy well below that at temperatures easily achieved with moderate rates of fire from rifles.   Combine that squishiness with the longitudinal compression forces of high velocity rifle rounds, it'll turn them into little bellow shaped things.

Thermal expansion, corrosion, and loss of strength at the elevated temperatures would be your biggest issues - that being said,  I'm not intimately familiar with magnitude of the pressures involved, so I can't really make a judgement call on the effect they might have on the performance of your can.

Thanks for all the comments. I hadn't considered the force that would cause the spacer to be "smashed" this making everything loose.

Looks like I'm going Ti then. Who's the go to for Ti spacers or spacer material?

techjunkie over on the form1.org forum sells spacers in various lengths for B-Tube, 1.259", D-Tube, 1.375", 1.5", 1.643" internal diameter tubes but can also do custom ID sizes for an increased price. Look for his thread in the Vendors subforum once you get signed up (if you are not already).

I've bought a few Ti spacers and a 9mm bore alignment rod from him with zero issues.