I just wanted to tell the forum members how lucky I was too see the 550 mag RNS and its creators this weekend. I went to my Father in-laws for fathers� day in Yuma and was able to sneak away from the wife and family to see Neal Shirley�s (RNS) 550 mag RNS being built by Mike Scherz. What a treat, both are pure gentleman, and gave time to listen to all my rants and answer my questions. The gun though not finished, is well on its way. Mike showed me a magazine feeding of 700 grain Bridger flat nose solids without a fuss. With Mikes proprietary barrel contour you can see and feel how the rifle really balances out.



The cartridge is a real eye opener, and one can see how ideal this diameter truly is as far as the .50 and over club goes. I got to look at bullets from 600 grains to 800 grains loaded on dummies, and when compared next to a 458 lott it is plain embarrassing. As some of you know, I am not a stranger to large bore rifles, and I really think the 550 has some merits for those who want an optimal big bore(if you can call it that) over .50 caliber. The rifle can be managed a little better than a 600 OK or a 585 NT and I have no doubt it will penetrate better.



The shorter 2.65� 550 Express is probably the best big bore story developing. I do not think its going to have any problems hitting 2150, and will be able to fit in a standard action. This bruiser will moe down anything in its path. The 550 is at diameter where loading heavy cast bullets are going to add some serious flexibility to hunting anything from moose down. Now all we need is a rimmed 550 for a double.



I want to thank Neal and Mike for spending the time with me, it was a pleasure and I cant wait for the test fire.

smallfry,

That's great news. I haven't called and bugged Mike in a while so it is good to hear an update. I am definitely looking forward to Mike getting Neals rifle up and running and fine tuned...as mine will be one of those built shortly thereafter

I think this round is very cool and I love the variety of bullet weights available (and soon to be other styles and brands) as well as the apparent ease of converting a CZ to this cartridge. I have decided to sell my 600OK barrel, dies and brass and concentrate on the 550.

John

Has the shorter 550 Express been registered as a sporting cartrige yet?

Smallfry, the 550 beats the bigger guns in spades for convenience, but what makes you think it will outpenetrate them?

Karl.

They have higher sectional density in the similar weight bullets.

What Harry said.

the 577 has an sd of .313, and it's known as THE penetration round with a 750gr at 2050. The 550 express will have a 700gr at 2100 (within 50 ft/lbsof energy, but that doesnt MATTER) with an sd of .330, and a slightly lower crosssectional density.

In effect, the bullet will be slightly narrower, and somewhat longer, resulting in a deeper penetration, at the same speed.

Neal and I's goal on the express was to match the 577 NE in power, while fitting in a standard sized action, AND to ahve high SD bullets. The 650, which *I* consider to be a minimum for this, has an sd of .309.

jeffe

My point is that the bigger cases of the 585/600's will get higher velocities with the same SD bullet.

A moot point for most people's recoil limits and the goals above of course.



Karl.

The 550 has very good momentum density... obviously attributed to its smaller area than the 585 and 600. Aside from that... Matt and I have tested his 577 and 500, along with various 458s 416s and 375s and from that I have a "hunch?" the 550 will do pretty well. Any cartridge is going benefit in penetration from having flat point solids it would be great to see a side by side comparison of the 585, 550 magnum, and 600 OK, but getting optimal performance out solids is not as easy as some think and I am not sure anyone has even toyed with flats in 585 and the 600.

Yes except that in a DG rifle most people select the highest SD bullet for caliber they can shoot well so "same SD higher velocity" is not the best comparison. You can get higher SD bullets in the 550 than either the 600 or 585.

I just spoke with Hawk, Bauska, and CH4D

Hawk, bullets are done!! If you want crimping groove, it'll be a couple weeks. Since Bauska, below, I don't mind

Bauska
Button not in yet, expecting ~July 4th

CH4d
Dies are at the heat treaters... 2 to 6 weeks (range, no date given).. 550 express

My status...

I have taken a parker hale cast bottom and I am trying to make a floorplate and release. for 15 bucks, what can you expect? My floorplate will be perchbellied.

I will have to proably make a ramp extention on the mag... don't ask, I don't have it figured out yet...

Jeffe

Well thats just what is needed as it can be built in a light enough rifle that it can be packed all day long in 120 degree heat, then you can creep in the bush and fire it bent over double threw a hole in the bush and it will no doubt kill both the shooter and the elephant and break all the limbs above the barrel and scatter wood for half a mile for locals, who will all shout with joy!! enjoy!