I have an Interarms Mark X 458 Win mag. I was told that this rifle is on the weak side and should not be loaded to the upper end of .458 specs.
Does anyone know of any inherent weakness?

Snowtigger: I am not aware of any weaknesses associated with the Mark X and the action is I presume one of the Czech made 98's. They have been used for a lot of different high intensity cartridges.

The only problem with the 458 that I am aware of has to do with the loads sometimes creating high pressures if they are subjected to high temperatures as they did in Africa on occasion or if left exposed to direct summer sunshine. I understand factory ammunition may no longer be loaded to their original published levels as a result.

You might get more information on this matter at the Accurate Reloading web site where a lot of big bore enthusiasts hang out.

I've never heard any reports to that effect regarding the Mark X .458's. They are Zastava actions, and very tough and well made in my experience.

I've worked with two .458's in the past of the same make and model, and both were well made actions. However, I will say that the bedding of the action to the stock in both rifles demanded help. One rifle had a cracked stock due to firing repeatedly with poor inletting/bedding. Perhaps this is what was referred to as being on the weak side? It is true that they need attention in this regard, but the actions themselves are well made and up to the task.

Hope this helps.

God bless,

I've got one too. Basically, these are a commercial '98 Mauser action. Not sure why anyone would call it 'weak;' they've been used for plenty of cartridges in that pressure range with the magnum case head size. It inherits all of the '98 features, for both good and bad. About the only complaint I could really make with mine is that it has a trigger safety instead of the 3-position safety on the bolt shroud. Why anyone would drop one of the most desireable features on the '98 is beyond me....

Surprisingly accurate. 400gr. Speers over a case full of Varget (abou 74 grains) are good for about 2150fps; plenty for the hogs we have around here :)

Mine's pretty light; I've quit loading higher long before the rifle said 'uncle!' Shot one round of factory ammo so far (standing). May try again now that the recoil pad has been replaced with a Decelerator - the original one ('Whitworth') was hard as a rock.

Gonna try some cast bullets but the throat is very long, so we'll see how that goes.

Warne rings/bases with a Leupold 1.5x5 scope, pushed as far forward as it will go to avoid forehead re-arranging :D

Mine's a Yugo receiver. Agree with Marshall that the stocks could be made a little stronger, but I'm not going to jump-shoot elephants with it, either.

Man, that was fast. Ididn't even have time to get up from the computer.
I thought the guy was blowing smoke, but i wanted to be sure.
Marshall is right about bedding, less than 200 rounds and there is a chip in the stock right at the point where the rear tang meets the stock. It looks like the action is moving to the rear, hey,that's toward me!!
The "bedding" looks like they threw some Bondo in the stock and slapped the action in.
Thanks to everyone who responded.
BTW Marshall, I am going to try some of those 525 gr bullets in this rifle, any suggestions? Roger

snowtigger: As well as a proper glass bedding job using one of the steel re-inforced compounds, that rifle needs to be equipped with two steel cross bolts. One butting against the recoil lug and one through the web behind the magazine. If the rifle has a second recoil lug under the barrel that should also be glassed. Although I like Mauser actions generally, the size and location of their recoil lug is a design fault IMO. Even the bulk of military rifles in much lighter chamberings had a single steel cross bolt which adds a great deal of strength by keeping the wood under compression and preventing set back.

You should provide about .030 behind the rear tang to prevent further chipping and/or splitting.

And, with regards to my first post I probably should have said Yugo rather than Czech although I keep thinking they may have been made with both markings. Not sure.

My .458 has the recoil block on the barrel, which someone glassed in, and at least one stock cross-bolt. If it splits I'll get a Bell & Carlson, but I think the stock is tougher than I am at this point.

BC.... it think that Interarms got actions wherever they could, wouldn't surprise me if some were Czech or from anywhere else, for that matter.

Mike G;
That may have been a lapse of memory on my part. Something in the back of my mind associates Mark X's with both Yugoslavia and Czechoslovakia but I could well be wrong,

I've built several custom rifles for people on Mark X's but that was long enough ago that the markings are vague in my memory. Call it "ol' man's syndrome."

Overall the actions were good but not quite as smooth as some Mausers. Required a bit of polishing in the rails and sides to bring them up to good standards.

Guys,
The Zastava/MarkX does have rumours being circulated that it's somehow weak or flawed or something. Back many moons ago on the AR forum it was discussed with a poster in Europe stating that the action was not one to be choosen for custom work due to some weakness and supposed testing and a blown action or something. In my mind it was just Blah blah blah. Mind you some 375H&Hs that came to Australia did seem to be built on standard length actions but opened out at the front rather than the rear, which is generally thought of as a no-no. I just sold a Zastava 458WM that was a great rifle. It also split its stock, a Ramline, but the problem was 8mm diameter screws in 10mm diameter holes! Replaced it with a Butler Creek and had no more problems. Another rumour mentioned in light of the Zastava's is "fast" barrels. My 458WM came with a 24" barrel which I lopped and gained 30fps! It also always chronographed faster with its 22" barrel than identical loads fired in a CZ550 with 25" barrel. One rifle doesn't prove anything but it was a point of interest.
Cheers...
Con