Saw a crazy rifle today "243 RUM"

[300 RUM]

I talked to a guy today I mention I had a 300 Ultra and he grinned and said "take a look at this"

He showed me a Rem 700 action with a 28" fluted bull barrel and a crazy tactical stock. Fully adjustable length of pull and cheek piece. There was not much of a forearm it was about a 11/4" round like a pipe and you could see 90% of the barrel. Just the last inch or so as it entered the reciever was covered. The only marking were on the barrel ".243 Phoenix"

This was obviously a custom built gun, the guy said he got it in a 10 gun trade. This guy was a few cards short of a full deck. He had 3 50 caliber rifles, at least 8-10 bushmasters, several H&K MP3 and every other tactical rifle you could imagine.

He didnt have any loaded ammo for it but had a box or so of brass that said 300RUM on the cases. Then he had a box of bullets. These things were the longest bullet I had ever seen. I would have to guess they were like a 130-140 grain .243 diameter. he offered to sell everything to me for $800.00

I would imagine by the looks of it its was several thousands of dollars to build this thing. If I had the cash I thing it would be one hell of toy to play with.

Just curious if anyone had heard of such a wildcat cartridge.

[Rocky Raab]

I've never seen one.

If it's a full-sized 300 RUM case necked down to 6mm, and if he had a box of fired cases, the barrel may already be burned out.

The idea is to launch an extremely long bullet (with incredible sectional density and ballistic coefficient numbers) as fast as possible. Supposedly, that adds up to very high retained velocity and energy at extremely long range - and hypotehtically less wind drift, too.

The theory sounds good, but...

Bullets like that require an extremely fast rifling twist (perhaps as fast as one turn in six inches!) and that causes extremely high pressures. So they can't burn all the powder the case holds, anyway. And they can't get the velocity they wanted. And they burn out the throats in 100 shots or so.

And then they sell the gun. Hint, hint.

[Lone Star]

Bill Davis did a test for American Rifleman in March 1991 with the .244 H&H Magnum. This was a full-length H&H case firing a 100 grain bullet at an advertised 3500 fps. After 300 rounds fired, the throat had extended 0.150" and chamber pressures increased with the same loads. It required charge reductions of 10% or more to keep the pressures at acceptable levels, and velocities were reduced by 150-200 fps. The throat was so rough that it was damaging the bullets enough that occasionally they would break up in flight. This experiment was performed with two different barrels, with identical results.

Since the RUM case holds considerably more powder than the H&H case does, I'd assume the issues would be even more extreme. Run away as fast as you can....

[Evan03]

or cut a fe inches of the chamber end have the barrel re reamed to whatever 6mm you like rethreaded and go from there.

there can always be second life to a used barrel.