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MR1

303 From 405 Win

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I was looking at my Lyman manual and compared 405 Win brass to 303 and decided to get some Hornady 405 and made up some 303s. I have 2 with generous chambers, and I think these will work to give good fitting brass.

 

mr1

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just a thought....could"nt you just fire form 303 brass to fit your chamber....

That's what the salesman at the gun shop suggested. The 303 brass and ammo you buy doesn't measure what the loading manuals say it should, ie .455 at the base, it is closer to .450, the Hornady 405 Win is closer to .457. I think the 303 British gets a bad rap on headspace and rear lockup, when I believe the large chamber is the culprit. The case swells at the junction of sidewall and the solid head and the size die sizes it back and they seperate quickly, looks just like an excessive headspace problem. Heck they didn't care how long the cases lasted once was enough.

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That's what the salesman at the gun shop suggested. The 303 brass and ammo you buy doesn't measure what the loading manuals say it should, ie .455 at the base, it is closer to .450, the Hornady 405 Win is closer to .457. I think the 303 British gets a bad rap on headspace and rear lockup, when I believe the large chamber is the culprit. The case swells at the junction of sidewall and the solid head and the size die sizes it back and they seperate quickly, looks just like an excessive headspace problem. Heck they didn't care how long the cases lasted once was enough.

 

 

Cheaper and easier to fireform 303 cases. Then [neck size] only when reloading. This leaves the case fitting the chamber as is and does not create the overwork hardened brass that causes seperations.

 

 

Yes, not quite as pretty with the bulge at the web but I only care how they shoot.

 

JM2c

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Been there done that, how much 303 shooting/reloading experience do you guys have? Or are we just repeating what we have read on the internet. I have used neck sizers and Lee collet dies and still have seperation after 1 reload, so if I can get 2 or 3 reloads I will be happy.

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Headspace on a .303 is an entirely different animal then rimless rounds. Has nothing to do with the shape or size of the cast itself, all that matters is the space between the bolt face and groove at the mouth of the chamber where the rim sits.

 

I have 7 LE's so neck sizing is really not practical I just keep the loads down towards starting weights and ease off on the sizer die a couple of thousands. Lee Enfield chambers were not cut to SAAMI specs so there is no sense in over working the brass.

 

I have some really nice once fired HXP brass I can send you if you want to try them out. They seem to out last commercial brass.

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An update, I have worked out the forming process and I have test fired 10 or so rounds, not bad for 2 years. Rounded up 375 H&H die and shortened it to start the necking down, then into 35 Rem with a locking ring to raise it up some, a 8x57 trim die to neck more and cut extra length off and 303FL then trim & chamfer, then on to neck turning. It has test fired fine, I have found PRIVI brass that measures better than US stuff, I had some HXP that was the same size as US stuff, but found 50 primed HXP cases that were about .455" that I'll try out. I like the thicker rim on the 405 brass, can make up for sloppy headspace.

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