Someone left a stack of Alliant Reloader’s Guides at our range so I took one. For various cartridges, the data included one load for each one of the appropriate Alliant powders and Speer bullet weights, using Federal or CCI primers, since ATK owns all four companies. It didn’t say whether the loads were maximum or what.

For 180 grain bullets, three loads for the .300 Weatherby ranged from 2990 to 3109 fps, averaging 3058 fps.

Five .300 Winchester 180 grain loads ranged from 3050 to 3110 fps, averaging 3070 fps.

There was one .300 H&H load, 2996 fps. Three .300 WSM loads averaged 3006 fps.

In other words, they claim no difference between the .300 Weatherby and the Winchester and only a 50 fps or so advantage for the Weatherby over the H&H or WSM.

Can that really be true? No difference between .300 WBY and .300 Win? Besides, when I worked up loads for my .300 Weatherby both Hornady and Sierra handbooks showed 3200 fps with H4831.

...............Chances are you may have answered your own question. ""It didn't say whether the loads were maximum or not."" .....Imo, ya gotta go by averages using several rifles of each before you can narrow things down. You have slower barrels and faster barrels. You have various other ballistic factors as well including different bullet brands, no two rifles are alike and all that jazz.

I will say that given the same 180 grain bullet brands, using the same identical powders, firing from the same barrel lengths, and using all max loads, the 300 Wby will on average have the higher velocities coming from any group of rifles tested....

Weatherby always out runs the competition. One of nature's laws.

There was a time when Weatherby brass was soft. What was the date on that reload document? 338 Win Mag equaled or bettered 340 Weatherby. Same with the 300’s.

Look in other (new) manuals you’ll find that the Weatherby loads better the Winchester’s.

It's dated 2013. When I worked up a 180 grain load a few years ago, the Sierra and Hornady manuals both listed 3200 fps maximum for rhe.300 Wby.

The .300 Wby has got to be faster than the .300 Winchester at equal pressures for simple law of physics reasons--case capacity.

Another The manual says 73 grains of RL7 with a 300 grain bullet in the .458 Winchester a compessed load but 74 grains with a 400 grain bullet isn't.

I think the manual is junk. Some of their powders are very good.

I’ve loaded for both the Win and Wby for many years. Given equal barrel lengths and pressures the Wby typically runs about 75 FPS faster in my guns. I’ve also found they each do best with different powders so choose accordingly.

Exactly..

Yeah, when you get a ,300 Winchester to giddyup to 3,350+ fps with a 168 TTSX come wake me up,,..

That reminds me, I need to play around with some 175LRX in my wby...

Old manuals in general are not as good as the newer ones. If you want to make a magnum out of your old war horse look at early Speer manuals (kidding).

However, my old Lyman manuals are about worn out as I refer to them all the time for cast bullet loads.

I’d guess that Alliant had not updated their data since the soft brass of years before.

That soft brass issue caused me to look down on Weatherby at the time and I bought a 300 Win Mag. Now I have two 300 Weatherby’s.

Old manuals are good for some things, such as finding some data on obsolete cartridges and cast bullet loads, but many early manuals were developed without the use of modern testing equipment.

But even using new manuals a reloader has to be careful, first using the same components - brass, bullets, primers. But some powder lots differ a bit. Then there’s differences in chambers and bores.

Besides Gun Gack and Gun Gack II I have several manuals and when starting out with a new for me cartridge I’ll look at several and perhaps old issues of Handloader magazines.

You often see advice on working up loads in your rifle with your components, good advice. I think the advice I’ve seen from a sage in this forum is to measure velocity and not to exceed velocity seen in trusted sources. Velocity, I believe is proportional to pressure as measured by the old crusher method and the measuring of the expansion of the base of the fired cartridge method. That’s about as good as a shooter can do without expensive equipment, in my opinion.

Case capacity, not the SAAMI drawing, is what defines the combustion chamber.

It's not apples to apples to compare max loads in Winchester .300 Win brass to max loads in Remington .300 Roy brass.

I thought about that, too. But I dialed in a RL 26 load that really tightened the groups up at 3,306 fps average MV with the 168 TTSX so I hesitate to mess with success. It’s about 20 fps slower than the MagPro load, but a fuzz more consistent. I don’t shoot extreme range so the 168 will do. Happy Trails

Indy,

You might want to check Alliant's latest data, instead of relying on 7-year-old stuff. My experience with Alliant over that period is they often didn't try every powder in a certain load combination, resulting in a lack of overall perspective on cartridge potential.

The highest velocity with 180 Speer Hot-Cors in their latest goes like this
.300 H&H--2996 (26" barrel)
.300 Win.--3089 (24" barrel)
.300 Wby.--3147 (24" barrel)

When I still had my .300 Wby. Mk.V, my go-to load was using RL 22 and a Barnes 165 gr. TSX bullet, at a chronoed MV of 3390 fps. An elk-killing machine, for sure.

One of our hunting group was always tooting his horn about his .300 Win being just as fast as the Roy. One year I dragged my chronograph along and the results silenced his guff about his Win Mag, which is a great elk cartridge anyway.

The loading data is rubbish.
A chronograph will prove it.

One does not buy a .300 magnum for mild loads. For the amount if times it gets used on game, it offers a lot more that most reloading manuals indicate.
Expect a 180grainer to deliver around 3100-3150fps even in 24" barrels and a .300 Weatherby another 100fps more.
The value of the Winchester is a more common tendency for a very decent level of accuracy and also be a top velocities with H 3350 without going to the slower powders which can shorted barrel life if that is a concern. The extra volume of the Weatherby case will need those slower powders to gain that additional velocity as well as the longer barrel.

Both cartridges are great if you have a good barrel and can handle the blast and recoil though I think blast is a greater factor for the user.

Most people forget a loading manual is not a Bible, that is why you look at a few different sources of information then go shoot through a chronograph, every rifle is different and don't like the same load as another of the same caliber.
I did that today, I shot 3 rifles through my chronograph, a 270 Winchester that shot 200fps faster than the manual said at 2gr under max, a Rem 7Mag that I had loaded 2gr over max that was still more than 100fps slower than the manual said and a 300WM that shot to with in 20fps of what the manual said.
The only absolute with loading is that BS1917Kchunter Fhuqking knows everything (if only in his own mind)

You are only making yourself looks stupid with your remarks. Ive proven you to be a dipschidt at least 3 times today. Boy you're butt hurt aren't you? Fist with your stupid azzed Leupold you said you'd sell for $150.00 because you thought the op was crazy for thinking he could get $250 out of his. I sold the same exact type of scope, you so foolishly offered for $150.00 here, for $325.00 on ebay. Your own actions only make you look stupid as schidt... Keep shooting those 270 loads that are 200fps over book max, maybe you will learn something.. Ha ha.. You might want to consider using your reloading press as a boatanchor, because you don't know much about it...

BS Kchunter, The only thing you have proven is your high post count translates into being a gasbag without much in the way of useful knowledge.