Given the discussion so far, I thought you might be interested in something I knocked together in 1/35 scale a couple of years ago...
Magach 5 Avenger
Following the Yom Kippur War the IDF’s holdings of M48s and M60s were dramatically reduced (500 and something down to 200 and something). OTL the US resupplied with M48A5s and more M60s. In this TL, however, some of the M60s supplied were M60A2s. Whilst the IDF had no intention of fielding the M60A2's gun/missile system they were desperate for AFVs. The A2 turrets were removed and replaced with either salvaged M60 105mm gun turrets or the new twin 120mm breach loading mortar turret (another story/project). Having suffered such great losses of its MBT force to Egyptian AT missile teams, the IDF were keen to come up with/prove the concept of a tank escort support vehicle. A deal was struck with the US for the IDF to acquire a limited number of GAU-8s to be retrofitted into the discarded M60A2 narrow profile turrets. With the barrel group sticking out front, the length and width of the turret was about right - although some modification was required to accommodate the large ammunition drums. The turrets, which were entirely unmanned, were then fitted onto older M48 hulls (same sized turret ring) with the 3-man crew (Commander, Gunner and Driver) being positioned within the hull. The end result was not, and was never intended to be, a MBT. The Magach 5 Avenger proved to be highly capable in its escort/urban role and, although never produced in large numbers, proved to be extremely popular with both AFV crews and infantry alike.
Factual detail:
- The A-10 routinely carries 1150 rounds of 30mm ammunition for its GAU-8 Avenger cannon. The GAU-8 was designed to have 2 rates of fire - slow 2100rpm and fast 4200rpm. In operation the gun now has a fixed rate of fire of 3900rpm. However, I would suggest that in a ground vehicle mount the slower rate of fire would more than suffice. Thus at 2100rpm you fire 35 rounds every second. This gives you approximately 32 x 1-second bursts from 1150 rounds.
- This compares favourably to a modern SPAAG such as the Gepard, which carries only 320 rounds per gun but also only fires each gun at a cyclic rate of 550rpm. In other words, 9 rounds per gun per second for a total of approximately 36 x 1-second bursts.
- In order to prevent possible ingestion of spent cases into its engines, the A-10 keeps hold of its fired empty cases in the rear drum immediately behind the ammunition feed drum (All of this is part of the overall 5.93m length of the gun system).
- There is no ingestion problem on a ground vehicle and so no need to retain the spent 30mm cases, thus the second drum could be used to hold more ammunition, effectively doubling its capacity to 2300 rounds. This would give approximately 64 x 1-second bursts from one complete ammunition load. The bonus, of course, is that each 1-second burst fires 35 rounds down range as opposed to the Gepard which fires 18 rounds per second from its 2 barrels.
- The GAU-8 operates a linkless round system with the rounds effectively pushed along the feed rails by the ammunition drum, which is designed like a giant corkscrew. Whilst this storage and feed system could be replaced with something less linear there is, I believe, scope for some sort of gun elevation system, which would only move the front part of the gun without adversely affecting the flexible feeds. In the A-10 mount this mid section appears to be taken up with what I assume are hydraulic and/or electric motors to spin the barrel group and power the ammunition drums. Without the limitation of aircraft space and weight constraints, I am sure that the above mentioned elevation system could be worked out.
- The empty cases are ejected from a armoured port on the right-hand side of the turret. The process of reloading the ammunition drums is facilitated through an access panel on the rear of the turret which allows a reload feed belt to be attached.
The model, which represents the 2nd Vehicle, 2nd Platoon of the 2nd Magach 5 Avenger Company, is made from parts of a Tamiya M48 Sgt York, a Tamiya M60A2 and a fair bit of scratch build/bits from the spares box.