Home Forums Hunting & Shooting Custom Rifles & Wildcats Wildcatting the 7mm Rem Mag

Swampland thanks. It was the 7mm LRM I was thinking of.....

Your wildcats off the Norma cases have a solid jump over the LRM in capacity I think(?).


You don't see too much about those Norma cases which is unfortunate,as they seem to be real great cartridges.

I admit I do not know much about them myself.

Now I understand the velocities with the 7mm.....impressive! Also interesting the Rem 700 can be modified to chamber them.

perhaps the comparison pic below will help explain the capacity difference between the 375 Ruger based wildcats vs the 338 Norma Mag wildcats, The ability to attain 338 Lapua Mag and 338 Edge capacity and still run effortlessly in 5 round detachable mags with high bc bullets like the 265 gr Cutting Edge MTH with .800 bc, 275 gr MTH with .820 bc and the Berger OTM with .822 bc is highly desirable to me,

most here on the Campfire are stuck in the rut with factory rifles in belted mags and 308 Win based cartridges and have blinders on to stare straight ahead, if you look around some, there has been a ton of activity on the 338 Norma case and all of is positive

Bob,
These LRH's look like they are based, roughly, on Rigby/Lapua brass which is .589\.588 body diameter.

The RUM's have a body diameter of .550 but are rebated so the head is .532.

Since the H2O capacity is about 110 then they are a short version of an Ultra Mag.

If those velocities are coming from 26" barrels, then I'll bet the pressures are much higher than SAAMI maximums. The 7mm LRH is moving a 195 bullet about 200 fps faster than a 7 RUM will move a 175 using Nosler's loads. I doubt if there is any laboratory tested pressure data.

Also, chambering them in M700's exceeds that action's design limits for barrel shank wall thickness. Sooner or later the combination of high pressures and inadequate shank thicknesss will result in failure of some sort. Read Dan Lilja's and Jim Borden's papers on that issue. Both are mechanical engineers so should be listened to.

Pretty good reasons to stick with your Mashburn.

Bob,
Since the 338 Edge is based on a RUM case it can be used in a M700. It is within the hoop strength design limits of that action.

Also, using a M700 means there has been an extractor conversion likely a Sako or M16.

Would necking down 7RM brass in a FL .270 Weatherby and .257 Weatherby die and fireforming qualify as wildcatting?

Are the "Pro" or "Long Range Hunter" lines proprietary?
Who makes them?
Is formed brass available?

I still see usefulness in H&H based belted mags as hunting rounds. Some remain really great cartridges, and I think there are a couple of minor advantages to the belt with few of the theoretical disadvantages actually applying to real life. But I also like some of the more modern cases. What advantage do these wildcats have over the .28 Nosler? I was playing with a Nosler Thursday and getting great velocity, reasonable recoil and 1/2" accuracy with the top load I shot and it's a factory round, which appeals to me for numerous reasons.

It's been awhile since I have played with 7mm Mag, and I think I forgot how anemic 7mm load data can be. I'm shooting a Remington and a Sako. My current experimentation revolves around 160s and numerous powders. The Sako gets a few more FPS than the Remington, but top published load data gets each to upper end 7x57 / 7-08 velocities over an Oehler.

The PRO and LRH wildcats are my designs and I own the original reamers,

"formed brass" ? it's a DIY wildcat cartridge thing ...... brass is easily made from the parent 338 Norma or 300 Norma Mag cases by simply MOM banging in the chamber or firing a bullet jammed into rifling with a med pressure load, if a shooter reloads ammo he can fireform , simple as that

Lapua brand 423 Dakota and 338 Lapua Mag brass requires case forming dies to make cases for these wildcats, well worth doing because the super strong Lapua brass will last 10-15 firings,

In answer to your earlier comments all I can say is you have made a bunch of assumptions without knowing any of the facts....... there is a lot more to it and my short answer is ........ just stay with a 308 Winchester and a 375 H&H with 20" barrels and leave the expirementation to those who are capable


not everybody climbs the tallest peaks and dives in the deepest seas, some people travel the world just to see it's wonders while others cower in fear in a box of their own making ..............

Boy you got that right...the short action boys twist themselves into knots and will argue for pages whether their latest short action creation and some wonder powder will get another 100 fps. ,if they stand on it hard enough. And of course, there's no pressure

If they'd buy a rifle with an action a half inch longer, they could chamber it for a cartridge that will easily get that 100 fps and more.

But if you show up here with some 7mm or 30 caliber cartridge design with real legs (belted or non),they'll also twist themselves into knots and use up 40 pages telling you how much it sucks..... and why.....even if they've never used it.

I've even read on here there's no reason for the 7mm Rem Mag....because we have the 308 Winchester.

Hilarious.

Keep working those wildcats Swamplord. Even if I don't follow your lead (I'm happy with what I have), I'm still interested.

I am shooting 11 gr more than max per Hodgdon 140 gr H4350 7mmRM.
At 13 gr more than max, I see the threshold of extractor groove growth, a repeatable precursor predictor of loose primer pockets.

I have used that load in factory 7mmRM rifles and in rifles that I reamed the chamber and cut the threads.