MacD37
Good to hear a positiv feedback on the conversion of the TIKKA for 450NE.
Of course I wouldn't screw up my lovely 9.3x74r, I did plan to change my 12/70 change barrel set to the 450NE 3 1/4, and to reproduce the regulation mechanism because this would be cheaper than to build it fixed and regulate.

The professionals all said, that the power of the 450 will stretch the system after a few rounds, because it is to soft to withstand the energy released.
And then it will be off the face and this can't be repaired then...

What I don't understand is, wy will the action take a 30/06 pressure and not withstand the much lower pressure of a 450NE?
Where is the most critcal point on the action, where the power of the released energy is stressing the material of the action?

The figures for the capacity of the caliber are messured in different ways (as I have been told by more experianced people who understand gunsmithing), this is done around the chaimbers and ?sometimes on the face of the action.
So what does it mean then to have 3500bar for 30/06 and 2700bar for 450NE 3 1/4? Can it be assumed that an action that takes 3500bar will withstand 2700bar of a more powerfull round? If this is true, and this really got me worried, than someone could build a 577NE or even a 600NE in the TIKKA 512S without a problem because the CIP pressures for those are 2200bar only?

Franz

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Franz A. Holzer

Franz@Holzer.com

Franz, You understand this is just my opinion, but I don't think you have anything to worry about. Actually the 30-06 will have more rearward thrust than the 450 NE, the reason being the very long, streight, case of the 450NE grips the chamber walls much better than the 30-06 case. The more the taper of the cartridge the more rearward thrust, assumeing the same pressure. The lower pressures of any of the NE rounds up to 450 bore put far less stress on the chamber walls, than any of the standard bottelneck rounds like the 30-06, and even less rearward thrust. P.O. Ackley did quite a bit of experimenting with the shape of cases, and their relationship to rearward thrust. He found that the closer to parallel
the walls, and the longer the cases are, the less the rearward thrust. That fact, coupled with the lower pressures, IMO, gives you the edge with this conversion. Ackley got his findings with a Mod 94 lever action rifle chambered for his 30-30 Ackley Improved round. The action had the locking lugs removed, and increasingly heavier loads were fired till it failed. This rifle was held up by sand bags, and the only thing holding the rifle closed was it's own weight resting on the lever. When the rifle failed, it failed through the sides of the chambers, and the action was never blown open. The barrel was blown apart at the chamber walls, and never opened the action, indicateing the commonly thought rearward thrust worry was not justified. I would, however, use a set of 12 ga barrels for the conversion, to get the extra barrel meat in the chamber walls, and make sure the headspace is absolutely MINIMUM. Loose headspace allows the case to slam rearward, stretching the case.

The coming off face is more a result of poor care of the rifle, allowing the surfaces to ware, because of grit, and friction, than it is because of high pressure. A person I know had one of the old VALMET 412s that was made way back before they were available with rifle barrels. It doesn't have the lug on the bottom of the mono-blok like yours, and it was re-barreled to 45-70, back in 1972, and the last time I saw it, about 1995 it was still tight. Admittedly he did not shoot anything but factory ammo in it. The Valmet 412K (early 1980s) the double rifle barrels were chambered for 243 Win, 308, 30-06, 375 Win, and 9.3X74R. I know of several that have been rechambered from 375 Win, to 375 JDJ without a problem. I have one of the older Valmet 412, 12 ga, and I have been thinking of re-barreling it to 41 Rem mag with 18" barrels to carry when I'm back packing in the mountains, and trout fishing in Alaska. Being light , and carried on a sling would be nice to carry while fishing. Could be wrong but I simply don't think you will have a problem with the 450 NE.

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..Mac >>>===(x)===>
also DUGABOY1
DUGABOY DESIGNS
Collector/trader of fine double rifles, and African wildlife art

[This message has been edited by MacD37 (edited 01-29-2002).]