30x6.5 RPM Wildcat Thoughts

[264MHC]

I've thought pretty hard about doing the same thing. Make sure you have a 3.7+ Mag box if you're gonna use heavy bullets 200+. 300 PRC is 2.28 to the neck/shoulder junction. 30-6.5 RPM would be 2.25ish with a straight neck up. Would have a nice .330ish neck with minimal taper and 35 degree shoulder. Should be a little faster than 300 wsm but not much. Brass is still less than most good magnum brass at $1.50 apiece but it's Hornady so not sure how good it is.

 

[MattT]

I've thought pretty hard about doing the same thing. Make sure you have a 3.7+ Mag box if you're gonna use heavy bullets 200+. 300 PRC is 2.28 to the neck/shoulder junction. 30-6.5 RPM would be 2.25ish with a straight neck up. Would have a nice .330ish neck with minimal taper and 35 degree shoulder. Should be a little faster than 300 wsm but not much. Brass is still less than most good magnum brass at $1.50 apiece but it's Hornady so not sure how good it is.

You may have brought up the big issue with my current plan, my current bottom metal take AICS long action mags, not CIP. So that might be a limiting factor if I need 3.7+.

 

[264MHC]

I think standard AICS take 3.65" coal so may not be too far off depending on the bullet

 

[nicholasjohn]

Yeah, my back of envelope math, not knowing how cartridge design will influence velocity or how necking it up will influence capacity has it maybe a little faster than a .300 WSM? I'm sure someone else will have better estimates.

The 30-06 Ackley runs really close with the 300 WSM, and a 30 RPM case would be a bit bigger around for its full length. I'll bet you would pick up an additional 100-125 fps over either the 30-06 AI or the 300 WSM if you use the 6.5 RPM case. I also think that the 300 Sherman would be a ballistic twin, but case forming would be somewhat less involved with your new idea - provided you can handily acquire the cases. I'm really interested in seeing how this works out for you, since I have thought of necking this one up myself. I was thinking that a 7mm on that case would be equally interesting. For me to jump in there would depend on brass availability.

 

[Mram10us]

The 30-06 Ackley runs really close with the 300 WSM, and a 30 RPM case would be a bit bigger around for its full length. I'll bet you would pick up an additional 100-125 fps over either the 30-06 AI or the 300 WSM if you use the 6.5 RPM case. I also think that the 300 Sherman would be a ballistic twin, but case forming would be somewhat less involved with your new idea - provided you can handily acquire the cases. I'm really interested in seeing how this works out for you, since I have thought of necking this one up myself. I was thinking that a 7mm on that case would be equally interesting. For me to jump in there would depend on brass availability.

The 300 wsm is 200+ FPS faster than the 30-06ai, in my experience. Where are you getting your numbers?

 

[nicholasjohn]

The 300 wsm is 200+ FPS faster than the 30-06ai, in my experience. Where are you getting your numbers?

I got velocities of 3050 fps with the 180-grain Swift A-Frame in a 26" barrel, and when the same barrel was cut back to 24", velocity was 2950. Isn't that about what a 300 WSM gets for velocities ?

 

[MattT]

I think standard AICS take 3.65" coal so may not be too far off depending on the bullet

Interesting, I'll have to seek out some advice on what COAL would be on some 210 Berger VLD's or something that size in this wildcat. I assumed the .30 cal bullets wouldn't be significantly longer than the 6.5's.

 

[Mram10us]

I got velocities of 3050 fps with the 180-grain Swift A-Frame in a 26" barrel, and when the same barrel was cut back to 24", velocity was 2950. Isn't that about what a 300 WSM gets for velocities ?

I'm surprised the 30-06ai is that fast. I have only looked at the 210s.

 

[nicholasjohn]

I'm surprised the 30-06ai is that fast. I have only looked at the 210s.

I don't know if whether or not this is typical, just that this is how fast the 30-06 AI is with that bullet in my rifle. The powder I was using was H-4350, and the 180-grain A-Frame bullets were moly-coated. ( That was all the rage at the time.) I haven't tried any other bullets or powders, since that combination shoots exceptionally well, and is a great killer on animals. It's also not anybody's favorite long-range bullet, but out to the 400 yards or so that I've shot animals with it, it has worked phenomenally well for me. The A-Frames have always expanded well enough, even on smallish deer & antelope, and held together beautifully on everything bigger. They don't make really big holes - just big enough. Exit wounds are typically nickel-sized, whether I hit big bones or not. Actually, I've never had an animal take another step after receiving one of these bullets.

I wish I could tell you more, Sir, but that is the full extent of my experience with the cartridge. I found a good load without much shooting, and shot a ton of animals with it. Since this is a long range shooting forum, I wish that I had something to tell you about the kind of bullets you would be more interested in - like the 210's you mentioned. I just don't know, because I haven't tried them. I don't even know if the 10" twist in my barrel would stabilize those. I suspect maybe not. I also can't even hazard a guess at what velocity to expect from this cartridge with that bullet weight. Somebody on this forum probably has the answers for you, though - ask around. See ya.


Nick

 

[Mram10us]

I don't know if whether or not this is typical, just that this is how fast the 30-06 AI is with that bullet in my rifle. The powder I was using was H-4350, and the 180-grain A-Frame bullets were moly-coated. ( That was all the rage at the time.) I haven't tried any other bullets or powders, since that combination shoots exceptionally well, and is a great killer on animals. It's also not anybody's favorite long-range bullet, but out to the 400 yards or so that I've shot animals with it, it has worked phenomenally well for me. The A-Frames have always expanded well enough, even on smallish deer & antelope, and held together beautifully on everything bigger. They don't make really big holes - just big enough. Exit wounds are typically nickel-sized, whether I hit big bones or not. Actually, I've never had an animal take another step after receiving one of these bullets.

I wish I could tell you more, Sir, but that is the full extent of my experience with the cartridge. I found a good load without much shooting, and shot a ton of animals with it. Since this is a long range shooting forum, I wish that I had something to tell you about the kind of bullets you would be more interested in - like the 210's you mentioned. I just don't know, because I haven't tried them. I don't even know if the 10" twist in my barrel would stabilize those. I suspect maybe not. I also can't even hazard a guess at what velocity to expect from this cartridge with that bullet weight. Somebody on this forum probably has the answers for you, though - ask around. See ya.


Nick

Can't argue your experience so I guess I better build one

 

[nicholasjohn]

Can't argue your experience so I guess I better build one

A couple of considerations for you : If it's important to you to be able to shoot factory ammo, or if you want the fire-forming process to be very simple, make sure you set up your 30-06 AI chamber to headspace properly on un-altered factory brass. A slight "crush fit" is important. When I first got mine years ago, its headspace was too long. I had to do the neck-up/neck-down process, and leave a secondary shoulder on the brass for safe head-spacing. This wasn't a huge deal, but it definitely wasn't safe to shoot with factory loads - some didn't even go bang. I had the barrel set back and corrected the issue, so now it's OK.

That said, the brass forming process isn't such a big deal if you don't mind spending the time to do it. When I was still employed, there was a lot of stuff I had to do to stay current in my profession, so it was an issue then. Now that I'm retired, and don't have to spend my off-hours doing job-related homework, it wouldn't be an issue for me at all. If I was going to have another one built today, I would lean toward the 300 Sherman - and do all the case-forming chores with 270 or 280 brass, instead of using 30-06 brass to make the Ackley Improved brass. As long as you're going to do the extra work, may as well have the extra performance - that's why you want an AI anyway. The Sherman should give you an extra 100+ fps boost over the 30-06 AI - maybe more. The neck length on the Sherman is plenty long enough; the neck on the 30-06 AI is really longer than necessary - and I like long-necked cartridges. If you're a big fan of Lapua brass, keep in mind that they don't make it in 270 or 280. I've been using Norma brass anyway, so that's not a thing for me.

The other thing that was a little out-of-spec on my 30-06 AI was the throat. The guy set it up with a Weatherby-style free-bore, and that may be why mine gets the velocity it does. I don't really know, because I have never had another one to compare it to. I thought you ought to know that before you jump in with both feet. I'd hate to see you get disappointed and find out that the performance improvement wasn't enough to make it worth the work. Good luck.