I'm looking a trying to reproduce 408 Cheytac ballistics in something more affordable using a Ruger No. 1 action. Now the No. 1 is really strong but limited in the diameter of the cartridges it can handle, especially if one is going to run them at 60,000 psi. Some we have to go longer. The previous post mentioned the 500/416. Does anyone know the case volume? How does it compare to the Cheytac?

The next step would be to use the 450 Nitro No. 2 or the 475 Nitro No. 2, both of which have the 3-1/2" case. Now we're getting more exotic since this would be a true wildcat.

fyi I emailed Ed Hubel a while back about his 450 Express, and apparently there are no plans to produce the brass. That would have also been a good starting point.

Something based on the 50-140 Sharps might also work, but would seem to offer no advantage over the 500/416.

Question-all of the above (except for the Hubel) are cases designed to operate at double gun pressures. Does anyone know if there's anything in the case design that would cause a problem at high pressures?

Someone else MUST have already looked into this.

(Note-there's some good info in this old thread

Why not go to 375 where there are higher BC bullets?

I don't think the 500/416 NE has enough volume to match the CheyTac or even close. It has a strong taper from rim to shoulder. But if you blew out the case or necked the 500 NE to 416 with no other change you could get closer. But probably no better than the 416 Weatherby.

The limiting factor will be the design of the particular brand of brass. The CheyTac has a VERY thick web to withstand the full-house pressures and any rimmed brass has to meet that criteria too; not just case volume.

I know the action will accept the 577 Nitro case so why not the original 408 CheyTac? If you don't want a 408 bullet, there is the 505/416 Gibbs which is a close fraternal twin to the 408. Jamison 505 Gibbs brass has a strong enough web; he uses the same web for both cartriges last I checked. And I happen to have a 505/416 reamer, funny enough.

One factor is how big you can go in case diameter without pushing your luck. The Ruger only has 1" threads, so whem you get to the big cases the barrel walls start to get pretty thin. I have seen Lazzeroni Warbirds on a No. 1 and that's a .580 case running at 60,000 psi plus. Now how much bigger than that can you go? I don't know. What kind of safety factor is there with this setup? Again, I don't know, and I don't think anyone else does either. The guns work, but there aren't a lot of them. I've been looking into this for a while and no one seems to know what additional strength you get from the receiver. The 505 case I think quite a bit bigger (.635?), so you are in uncharted waters. I've seen 505 No. 1's and even bigger, but these are all running at much lower pressures.

Too bad, because I'd love to just use the Cheytac as is.

Update: Horneber says their brass is good to 60K psi. So we're moving in the right direction.

Next step is to check case volume. If I can't get enough powder in the case there's no point proceeding. I need to get to roughly 408 Cheytac volumes, in other words, significantly more volume than a 416 Weatherby. I have Weatherby cases. Does anyone know the case volume of any of the following?

408 Cheytac
475 No. 2 Nitro
450 No. 2 Nitro

If no one has the Cheytac size the 505 Gibbs volume would be helpful.

Thanks!

Go to www.ammoguide.com and use their free Cartridge Creator. Change the given dimensions to what you need, capture and print the screen with the easy and simple-to-use Howie's Funware screenshot capturing tool. Then you can calculate the volume with a bit of a tolerance for the webbing at the base of the case. You might even find specifics about the cases you have in the list of 700-plus cartridges they have on file there...

ammoguide.com lists the 408 CheyTac as having an estimated volume of 150 grains of water. They give 162 grains for the 505 Gibbs...

Cartridges of the World list the 505 Gibbs head diameter as .635" and a length of 2.83". To get a rimmed case of comparable capacity you have to go to the 3.25/3.5 cases of the 476 and 475 No 2; or all the way up the the 577 based cases that are even larger than the 505 Gibbs. None of these cases is designed for high pressures, all were double gun cartridges designed for low pressures for easy extraction in the hot African sun. Perhaps Horneber cases can go to 60,000 psi, but due to the large diameter of the cases will the Ruger barrel have enough strength to hold 60,000 psi? I know Ross Seyfried didn't like the .586" head diameter Rigby 416 case in the Remington 700 because the barrel thread was only 1 1/16"; you are talking about a larger case in a smaller barrel.

I checkd ammoguide, here is what I found (case capacity in grs of water)

505 Gibbs : 162 grs
408 Cheytac: 150 grs
475 No. 2 Nitro: 152 grs

1. For one, it looks like the Cheytac cases are significantly thicker than the Gibbs.

2. The Nitro case does have the capacity. And since it will be a wildcat already we can blow out the case a little and move the shoulder forward for more room. Since its rimmed fireforming is fairly simple.

3. McDermott: That is the $64 question. The No. 1 has very good case support, so I think running at 55K - 60K is OK as long as the brass will take it, which they say it will. As far as the size, that's the gray area. I think for years no one would build 416 Rigby/378 Wbys on the No. 1, then Ruger surprised everyone and released the 416 Rigby. Of course the 416 specs are not in that pressure range, but they had to know people would load them up, and people have build Lazzeronis and big Weatherbys on No. 1's without a problem (At least I haven't heard of one - has anyone?). What kind of safety factor would there be? I don't know. How will a really long column of Reloader 25 or some other slow burning powder behave? Again, I don't know, and having 130 grs of powder let go 6 inches from your face will not be pleasant if things go wrong.

Anyway, the investigation continues.