The Winchester .307 is capable of higher velocities, but there aren't a bunch of them out there.
True, same with the 308ME. 307 Win brass is a tough find and expensive, or a duty to make. A levergun chambered in 307 Win is going to cost you $1K to $2.5K. This is more about using a firearm that you already have. I bought the Rossi Rio Grande NIB for $300 shipped to my FFL. Bought two, one was sent to JES to be rebored-rechambered to 38-55 Win.
Ranch Dog have you worked with the strain gauge on the AI version?
Yes, I have. On my Marlin 336A, I did a bunch of testing. The were no surprises running it between 40K & 45K. I ran two like rifle together, one in 30-30 and one in AI. On another forum, I was explaining the use of Go, No-Go, and Field gauges with a leveraction, but you can see the strain gauge on this Rossi. I ended up tearing it off, but these things have a life limit, and it was exceeded. Little buggers are about $35 each.
What you do notice, and this goes back to the bolt trust stuff of a bottlenecked vs. tapered/straight walled case, is that the AI functions as a knife through butter. The tapered/straight walled case of the parent cartridge becomes tough to extract the more pressure you apply to it. Of course, the other side of this is without the extraction indications; it is easier to get it trouble as you push it harder. Among the POA fans that say the improvement can handle more pressure because of less pressure being placed on the bolt and locking bolt; I've seen a couple of levergun KABOOMs, and I've never seen a bolt or locking bolt fail, it is the barrel that departs the receiver. Pressure is pressure on the weakest part, and that is where the threads have been cut in both barrel and receiver.
The gain in the 30-30 AI besides the shape and it's effect on pressure, is approximately 1.4-grains of H20. The utility of the AI is in getting to the SAAMI pressure limits of the parent cartridge (42K PSI). Typically, with the 30-30 you are compressing the charge to get near that pressure. If you are reloading with a cast bullet, the powder compression & lube on the bullet is making it tough to seat and crimp unless you are combining the step. Forget using a Factory Crimp Die. Plus, you are driving pressure up with the compression, but velocity is no longer responding linearly. The AI lets you run both pressure and velocity up without exceeding 100% of the usable case capacity. RangerPoint Precision
, in Cypress, has a lot of good information about their RRP3030AX
and the 3030AI
. I tried to contact them about the work on my Rossi Rio Grande as my sister lives in Cypress and said she would drop the rifle off but they never got back to me. The RPP states that they charge $100 for the AI work, but it said that three years ago. If it is still that, it is a deal because renting the reamer, with +/- pilots, the gauges, and a T-Handle is going to cost you $97 with insurance and postage both ways.
I designed a cast bullet for a fellow that did the RPPAX and then had them rebore-rechamber the rifle to 35 caliber so he had a 35RPPAX.