Home Forums Hunting & Shooting Ask The Gunwriters Ask John Barsness Questions About "The .300 Weatherby"

Thanks, makes sense as usual.

John, did you work on any loads with IMR 7828? I have no problem matching factory ballistics with published data in both of my 300s.

Two questions:

1. Although I haven't chronographed them, Wby factory loads print higher on the target at 200 yards than does the same bullet handloaded by me with the maximum H4831 load in the Sierra or Hornady handbook. Is there any reason one shouldn't load the .300 Wby to higher pressures in order to duplicate factory velocity? After all, there is all that hype about the long freebore, the strength of the MkV action, etc.

2. Back in the early 1960s, Weatherby used to publish load data for IMR4350, since apparently H4831 was not yet available. I notice that this data is considerably hotter than maximum loads the handbooks publish now. Why?

MagMarc,

I didn't try 7828 in this rifle, mostly because people have been asking for data for newer powders. I have used 7828 in the past and it worked well. In fact I believe at one time (maybe 10-15 years ago) that was the factory powder, at least with 180's.

Indy,

1) As far as I know it is still a country free enough to allow anybody to load what they want to. But in general somewhat slowwr powders than H4831 will produce good velocities with heavier bullets.

2) In the early 1960's a LOT of data was hotter, mostly because of the relatively primitive pressure-test methods common then. IMR4350 has also changed a little, but the big deal is better presure data.

Thanks John!

What are the best powders for use with 26" barrels and 150, 165, 180 (especially) and 200 grain bullets? Are they the ones mentioned in your article?

Also, do you have any idea why the Norma manual should list a maximum charge for 180 grain bullets which was so much more than the safe maximum in your Vanguard? Is it possible that a MkV has more freebore than a Vanguard, allowing more powder without excess pressure? Were you using Weatherby cases? (I've found that Remington cases weigh about 20 grains more than Norma cases in this caliber, with less volume, obviously.)

In many years of testing various barrel lengths, I have found that the same powders that are good in one barrel length are also the best in others, at least in velocity.

I don't know if the powders I tried are "the best." The main point was to try newer powders and see what happened. These often are an improvement, though often in not in mere velocity, the basic standard of most handloaders. So I loked over the loading manuals and tested what looked good.

I was indeed using Weatherby cases, and the Vanguard apparently (I checked with a bore-scope) has the same freebore as the Mark V. I have no idea why Norma data was so warm in my rifle, but it is another excellent example of why it's smart to start low. I might have used a different bullet than the Norma data, in fact I am almost certain that I did, which might be part of it.

Hi John,

Great to see your column and I'm happy to read your writing!

You've probably answered this 100x already (I just don't know where ;)):

1. How much of a velocity advantage does the 300 Wea. have over the 300 Win mag. given equal barrel lengths and pressures? I have a guesstimate of about 100fps, but I value your opinion more since I have no first hand experience with the 300 Wea.

1.b. To your knowledge, does this velocity advantage change with bullet weights. If so, how much of a difference have you observed?

2. What minimum barrel length would continue to give the 300 Wea. a velocity advantage over the 300 win mag and still be practical? For example, if I already have a 300 win mag with a 24.5" barrel, if I rechamber it to 300 Wea. and keep said 24.5" barrel, what velocity gain might I expect with diff. bullet weights vs. added muzzle blast, noise, recoil? (I'm not recoil sensitive), etc.

Thank so much for taking the time to answer question.

Muledeer,I've been thinking of rechambering a 30-06 ruger#1 to a 300 weatherby and was wondering if there are any forseeable problems I might or my gunsmith might encounter?

The only thing that's deterring me is the weatherby freebore.This was an accurate 30-06 and would like to maintain that level of accuracy.
How much does the freebore affect accuracy

Keep up the awesome work JB,I really enjoy your writings

I can easily match Wby 180gr factory ballistics (caveat: with no "apparent" signs of pressure) with, of all things Remington Nickel brass, 180gr TSXs and 80.1gr of RL22. And I can hit 3300 with 84gr of IMR 7828 and Norma Brass. The former is my go to round from hot to cold weather. jorge

Sorry not to get back to the latest questions sooner, but was gone huntin'.

Canadian Lefty, according to my calculations with case capacity, the .300 Weatherby should indeed get about 3.5% more muzzle velocity than the .300 Winchester, in equal barrel lengths at the same pressures. This means that if we can get 3100 out of the .300 Winchester in a 24" barrel, we can get around 3208 out of the .300 Weatherby in a .24" barrel.

Note that this does not mean with the same powder, but whatever powder gives top velocity in each case. Also, it wouldn't quite the same if the standard throating was changed in either round. For instance, you can get a little more out of a .300 Winchester in a longer magazine rifle, with a chamber throat longer than standard. But it still will never match a .300 Weatherby, everything else being equal.

This is also an approximate number, but you will be able to get about a 3.5% increase with any bullet weight.

SawDoctor,

The feasibility of rechambering would depend a little on barrel contour. It might not be truly practical in a #1A with it's light barrel, but would be no problem in a 1B.

In my experience freebore doesn't affect accuracy if the freebore is "tight," meaning just enough to allow a .308" bullet. We have three Weatherby rifles in the house, chambered for the .240, .257 and .300 Weatherby Magnums, and all are VERY accurate. So it would depend mostly on the reamer your gunsmith uses.

Thanks John for answering my question! I appreciate it and it makes my decision easier.

I thought you might be out hunting Hopefully, it was fun?!

Best regards,
CL

Thanks for asking. I got one of the best mule deer of my life, and the hunt was very interesting as well, with fine people. And the buck was fat as pig, which means great eating as well!

John
Are all of your Weatherby rifles Vangards?
What state did you hunt and will you post some photos the Mule Deer?
Thanks
Phil
Sorry JB, I was in to much of a rush.

Awesome!! I'm very happy for you! Hard to beat a super eating and trophy animal along with good people.

Congratulations!

labsandelk,

No, one of the Weatherbys my wife and I shoot is an Ultra Lightweight in .240 Wby. Magnum. It is very accurate, by the way, with a good trigger right out of the box.

I got the mule deer buck in Wyoming, but sorry, I won't post photos. If I did, then I'd be posting photos all the time on the Campfire!

Canadian Lefty,

Thanks! Sometimes we all get lucky....

I ran some factory 300 Weatherby ammo over the chronograph recently. Rifle is a pre64 M70 300H&H rechambered to 300 Weatherby,original 26" barrel.Very accurate rifle....the Federal 180 Nosler SB and the 180 Nosler Partition average about 3150.

The Weatherby factory 165 Nosler BT did 3413.I think this is a bit high,and suspect it is loaded pretty hot.

With these velocities,and the accuracy these loads give, I have not even bothered to handload for this rifle.

In watching a couple of friends develop handloads for their 300 RUM's I would say it is generally a faster cartridge than the Roy,but who cares. It also kicks more (to me),and if you can't get it done with a 180 gr bullet at 3150,stay home....Roy got it right in the 1940's(grin).