.303 British handloads in ruger #1

[hammie]

I just received my Ruger #1, factory chambered for .303 British, and I couldn't help wondering if you could bump up the performance a bit by using .308 winchester loading data as a guideline. From the data I could find, the .303 Brit has about 3 grains of water more case capacity than the .308 win, i.e. both cartridges are virtually identical in capacity. The rifle is capable of handling chamber pressures in the .308 class, and in the ruger, the entire cartridge is supported by the barrel and breechblock. I'm not necessarily planning on doing this, but I don't think this question has ever been asked because few if any commercial rifles have ever been made that were capable of handling higher pressures than standard for the .303 Brit.

 

[Slamfire]

303 loads have been limited by the relatively weak SMLE or No 4 actions. Those rear locking actions stretch so much that 303 cases develop case head separations in just a few reloads.

I don't see any reason why you cannot load the 303 in a Ruger #1 to higher pressure levels. That action is much stiffer than a Lee Enfield. In part due to this, the case will be better supported. The weak link in all actions is the cartridge case. In my opinion, actions are "strong" or "weak" based on how well they support the cartridge case.

Use a chronograph, monitor pressure signs, stop when extraction gets sticky or you get leaky primers.

 

[Clark]

I have thought about building a 303 Brit Ruger #1.
The brass and the action are good for more pressure than the primer.
So the primer piercing is probably going to be the limit.
Hard extraction or flowing into the extractor mis fit are also possible.

The biggest problem is the variation of the rim thickness of the different brands of brass. It can vary from .057" to .064" in my collection, and who knows what your rifle was headspaced at.
I would get one big batch of brass and process it.
I would fire form the brass with moly grease on the cases, 8 gr any pistol powder, and cover the powder with cream of wheat and no bullet.
Then I would neck size with a Lee Collet die, and let the head spacing be on the shoulder.
If the cases ever grew too much, bump the should back .001".

 

[hammie]

Thanks for all the insight.
Mr. Clark: I wasn't clear in my post. You don't have to build one. Ruger is now factory chambering the 1-A for .303 British. I hadn't realized that the rim thicknesses varied so much. I'm shooting commercial remington cases, and so maybe the rims will be more uniform. I've done the fireforming thing. A friend gave me a bunch of 30-40 krag brass for free. I fireformed it the way you said, with a wax plug in the neck. It worked but was sure messy as heck.

 

[Clark]

Per SAAMI drawings, 303B cartridge rims can be from .054" to .064".
Per SAAMI drawings, 303B chamber rims can be from .064" to .071".

Per SAAMI drawings, 30-40K cartridge rims can be from .054" to .064".
Per SAAMI drawings, 30-40K chamber rims can be from .064" to .071".

I would want to get the shoulder fit perfect to stop the forward movement when the firing pin tried to push it forward.
That would be either using a neck die or partial neck size with a full length die.

 

[wncchester]

"I couldn't help wondering if you could bump up the performance a bit by using .308 winchester loading data as a guideline."

Well, you can certainly bump up from common military pressures and you could use .308 data but it would be virtually meaningless.

Why not just use your rifle and creep up with the normal powders until you see some sort of high pressure signs. Then back the he77 off 2 or 3 grains!

 

[hammie]

Mr. wncchester:
Reading pressure signs has always been an arcane, mystical, reading-of-the-bones type thing for me. By the time I am really sure of high pressures, I seem to be frighteningly past safety margins. Flattened primers don't necesarily mean anything, and by the time you reach sticky extraction, you're past where you should be. Not to belabor it, but since the case capacities are essentially the same, why not use .308 win published data for the same bullet weights and work up to .308 maximums? A chronograph could tell you if you are beyond reasonable velocites for the particular bullet/powder combination. The #1 rifle is capable of .308 win chamber pressures and the case is fully supported.

 

[Clark]

If you still need recipes, you should stick with the right recipes.