All during the 1970s one of the favorite subjects of the gun writers was about the design of the 300 WM's case. They didn't like the short neck saying that it didn't grip the bullet enough or that the neck being so short made the bullet protude into the case to much thus taking up powder space.

The same was said about the 7MM Rem. Mag.

Some time in the late 1970s or early 80s both Bob Hagle and John Wooters [maybe others also]wrote articles about if you had magazine space you could have the barrel throated out deeper, seat the bullet out longer and gain back the powder space, burn more powder and also gain velocity.

At that time I had a Model 700 Rem in 7MM and read these articles with great interest. I had a gun smith in Casper throat out the 7mm and it would burn 3 more grains of the old surplus 4831. I did not know if I gained the desired velocity because I didn't have a chronograph but it didn't matter because I wanted a 300.

I sent the rifle along with an empty case with a 180 grain Partition seated. The base of the bullet came to the juncture of the neck and the shoulder of the case. The bullet did not extend into the powder space. The COL was 3.6 inches verses standard 3.340 inches. I instructed the gunsmith to throat the barrel so that said round could be chambered with approximately 10 thousands clearance. He installed a 26 inch Douglas barrel chambered to my instructions.

When I recieved the rifle back and started testing it it was clear that it needed lots of powder. I started at 74 grains of 7828 and slowly worked up 80 grains and just stopped. It could possibly take another grain of powder but I figured that 80 was enough.

At these levels the rifle produces a velocity of 3152 FPS and around 1 to 1 1/4 inch three shot groups.

I can't say what pressures are but I get good case life with some cases being loaded around 20 times.

For me this rifle is a long range hunting machine. Just today I had it out for my daily walk, saw a small white rock that needed killing. I flopped down in the prone position and got it. After the shot the rock was lasered at 326 yards. This rifle shoots flat!

Regards, Keith

Great to hear keith!

You can get more velocity than you are now, unless your rifle has characteristics that preclude it.

I have a factory Browning A-Bolt .300 with a 26" barrel that fires a 180 gr Accubond with 74.5 grains of H-4831sc at 3150...no special throating.

Before that, I had a Remington 700 with a short 22" barrel with a factory chamber that my load for it chrono'd at around 3200 with the 180. That was with IMR 4831; a little faster.

You have good taste in calibers!

quote:

Just today I had it out for my daily walk, saw a small white rock that needed killing. I flopped down in the prone position and got it. After the shot the rock was lasered at 326 yards. This rifle shoots flat!

That's great, I'm jealous! I have to move to Wyoming someday. If I did that here, my next walk would be in an excercise yard. BTW, I've decided to start reloading .300 win since I just bought another one and to date I've been reloading handgun loads only.

I drank the WSM Kool-aid for three or four seasons, could never get the groups I've always gotten with my old Springfield A3 rechambered to 300 Win Mag. My CZ 3 in 300wsm is going down the road and will hunt my lifetime bighorn sheep this Sept with my old Springfield. This 300wm is one of three bug-hole rifles I own. One is a Husqvarna 30-06, another is a FN mauser I bought as a barreled action at a gunshow for the action, decided to try out the 30-06 barrel before unscrewing it for something else...BUG-HOLE!! (in a cheap core-light stock). These three rifles are all once in a lifetime guns.. I'm pretty luckey to own 'em.. Les

Why not just build a .308 Norma?? Or, 30-338??If anyone still chambers factory rifles for one or the other, get one of those. Solve all your problems at once.

I'd much rather have a svelte 22" 7-08 spitting 162's at 2700fps,as my LR Hammer,over a 26" 300Winny launching 180NPT's at 3150fps.

At 500yds the 7-08 arrives with 90fps more speed,19 lbs less "energy" and 1.6MOA less wind drift.

I'll greedily take the reduced recoil,less vertical ES,less wind drift and far handier/lighter parcel...if only every time.

It gets pretty ugly downrange from there,if only obviously.

Interesting. I have a .300 Win Mag with a barrel chambered by E.R. Shaw. I went looking for the rifling with a decent amount of bullet left in the neck, using longer and longer bullets, and my recollection is that I didn't get there until I tried the Sierra MatchKing 220gr HPBT. The 190 HPBT would touch the rifling, but there wasn't much bullet left in the neck. Surely a standard reamer wouldn't cut an extra-long neck? Or did I fall victim to the extra-long taper of the bullet?

I think the Navy uses the Mk248 Mod 0 .300 Win Mag load with a Sierra MatchKing 220gr HPBT at 2850 fps, at least 75 fps faster than any reloading manual that I have (I have 5) will permit. The Sierra manual tops out at 2750 fps.

On the other hand, the IMR slow-burning stick powders are pretty darn bulky, and probably significantly faster in some applications than the slowest ball powders like WC 872. When you are totally full of 5010, there would be room for more grains (weight) of 872.

Maybe, just maybe, it would be possible to stay under the pressure limit and achieve the Navy's ballistics, with a maximum load of WC 872. Those of us who have a chronograph but no pressure barrel will be left wondering.....

I'd much rather launch the 155 Scenar and it's .505BC at 3400fps+. They are much more predictable on Critters,than SMK's.

I'd go 208A-Max before the 190,220 or 240SMK.

'22 is your Huckleberry.