quote:

Originally posted by dirklawyer:
I have a 458 Lott with Granite mountain action and Danny Pederson cut rifle barrel 21 inches long and I get 2250 with factory Hornady and with reloads of R-15 74 grains I get 2200 fps with 500 grain bullets. These velocities are recorded on an Oeler chrono with screens set on four feet, thus the chrono is giving accurate readings.

Don't you mean 84 grains of RL-15? Typo? If not, then you got something very atypical going on there.

quote:

The standard CZ .458 WinMag with its long box will deliver more velocity with the 500 grain TSX than a .458 Lott in a Winchester M70 can do with the same bullet. It is a very long bullet with 5 cannelures to pick from. Similarly, the .458 Lott in a CZ box makes the .458 Express 3-Inch a no-need.

What is the maximum overall length with a M70 magazine? Is there a way to lengthen a M70 mag to solve this problem with the TSX's or would a shorter throat fix it? I would like to rechamber a LH M70 Classic in 7 or 300 Mag and was curious how the longer TSX's would fit.

.375 H&H boxes, 3.59" for pre-64 M70 and 3.62" for a Classic M70, IIRC. Really not a problem with the Lott.

Not recommended to lengthen the M70 box to Rigby length (3.75"), as this would weaken an M70.

A CZ 550 Magnum has 3.80" at least, maybe 3.84", IIRC, off the top of me head.

All of these points are good. As to the lott being more versitile because more powders will allow it to cachieve the 2150-2300 f/s range.So what! You only need ONE powder that gives you your desired velocity. I dont know anyone that hunts dangerous game that says HEY! I have 6 different rounds here and each will deliver xxxx f/s with yyyy bullet and are loaded with a variety of powders and primers. Am I not special???? Each different round would print to a different point of impact isn't that great. The simple fact is that I have 4 458 Win mags and one Lott. I can achieve 2150-2200 f/s from all of them with a 500 gr bullet. Faster with 480 and 450 gr. bullets. In my 22" barrelled rifle the groups tend to be a bit better at 2150 than 2200. Most of the loads I make for my short barrel Winchester lightly compress the powder in the case. Art Alpin likes only compressed charges for his dangerous game rounds.That will prevent bullet setback and can be a major problem for the Lott. If I load the Lott to the same velocity, the powder charge is not compressed therefore the bullet can set back after each firing. That is a major detractor.

My philosophy on speed is similar to the British. Big bullet going slow. If a 500gr bullet in a 470 NE was more than ample for the biggest game, why should we take that same bullet and try to drive it 200 f/s faster? I think it is just because we have the philosophy that if 2150 is good 2300 has to be better.I dont go for that and never will. I have chronographed many of the original Kynoch loads in my rifles (300 & 375 H&H, 404 Jeffery, 450 #2 and a 500 NE) None of them came within 100 f/s of their target velocity. I had originally thought that it was because some of the rounds were over 20 years old, however, after a lot of reading, I am sure that the over optimistic estimates were due to proofing in 30" barrels not the 24-28 " barrels found on most rifles. Even so, the rounds at reduced velocity were great killers of dangerous game. So the moral of the story is if the original calibers that were used to hunt dangerous game for 50 years ++, and they were not even delivering the stated ballistics but were so effective, why are we killing/kidding ourselves by making stuff go faster???

lb404,

In Graeme Wright's "Shooting The British Double Rifle" he writes of his findings that in general, the rifles shoot 75-100fps slower than the "advertised velocities" of the various rounds, just as you point out. This result is acheived using either old Kynoch ammo or modern loads developed to shoot to regulation.

There were some exceptions, two being the 450/400 NE 3 1/4" and the 450 NE 3 1/4", as I recall.

JPK

Both used 26" and 28" proof barrels respectively. I also believe that they were done with hotter powder (cordite) and more pressure than proper powders of today. All in all, I think it is we are better off today in loading consistant ammo for the British rounds. I also think that we must load to the pressure curve of the cordite rounds and not necessarily to the same speed. This is what we have learned to do with Moly coated bullets. One needs to develope the same pressure with moly vs. non-moly bullets to achieve the proper speed which means more powder.

The first batch of handloads I built for my CZ-550 .458 Lott were over 2300 fps. I had referenced multiple manuals to build that load but even though I started low the load was still hot.
That was with 78grs H335 and Hornady 500gr IB.
FYI the Hornady manual estimated 2050 fps MV with this load.

I reduced loads because I knew this MV was too high. I find 75 grs H335 gets 2200 fps and 76 grs gets 2250 (in my rifle).

My rifle was a .458WM that I had reamed to the Lott cartridge and I guess the chamber is just a bit "tight".

Thank God for Chronographs.

lb404,

As I mentioned in the "Loading for a Modren Double" thread on double rifles, loading to the same pressure cordite produced in the NE rounds will result in higher velocities than most rifles actually produced with cordite and result in possible regulation issues in vintage doubles. Not an issue with a modern rifle regulated to the cartridge's spec pressure with the modern powders. Since curves were not provided in Greame Wright's book, I'm talking about peak pressure, btw.

Again, this is what I would do if I ordered a 450/400. But I don't think I would do it with the 375 Flanged, since the velocity difference between a 375H&H and 375FLM is only 75fps on the Kynoch website, both using 28" barrels, and either version has enough velocity, imo.

Nice pair of rifles to have coming. I'd scope the 375H&H - ideally with claw mounts, but they are expensive - and have the grooves for the Talleys put into the 450/400.

I though of having Butch make me a 375FlMag, but decided that I'm happy with my 375H&H bolt and my DR as a combo.

JPK

Butch mills Talley bases into his quater ribs so they fit flush and clean. I had both done with his scope mounting system. I have been saving a pair of bran new 1.5x4.5 Swarovski `1" tube scopes with 4A reticles for this project. They are lighter than the 30mm and have beautiful eye releif. It should make a nice and impressive as well as useful pair. I would really like to have a 450 #2 in his classic but I really think that the pair I have will do most anything I really need done.