AR2201
(.275 member)
19/09/05 01:36 AM
Re: Backthrust on actions

500 Nitro

Shotguns are made on the same actions so
why doesn't it or wouldn't it apply to them as well ?

Funnily enough that is what drew my attention to it as someone (somewhere) was discussing building a DR on a shotgun chasis and had calculated (somehow) that the action could take the backthrust from the 450 BPE but not the NE cartridge.

My curiousity was piqued, I will have to find the original thread again to see if I can ask them what they were on about.

I know there is a 500 Nitro built on a Ruger U/O action on the market, it would be useful to assess if something built for a 12ga really would cope with a 500 Nitro.

Just a sec.

Nothing surprising here, 12ga SAAMI 11,500CUP this would be equivalent to a 500 Nitro at 21,335CUP or BPE levels. My you beaut program only cuts in with loads at 30,000, tepid stuff.

12ga are basically operating at BP pressures so the actions rating for a 12ga does not in and of itself indicate it as suitable for NE.

Even assuming it takes the SAAMI for the hottest steel shot 3.5" shells at 14,000CUP that converts to ~26,000CUP or trapdoor springfield levels.

500 Nitro in a trapdoor springfield, ah hem ... I think I will let someone else do that.

NB. this says nothing about the Ruger action's suitability, it is only commenting on the minimum strength action necessary to fire a 12ga shell at SAAMI intensity.

Though it does mesh with what the other bloke was on about, making a set of 450BPE barrels to go with his shotgun. Useful enough, a 350gn 0.458 slug at 2,150fps (there have been 45-70 sleeves available for 12ga for donkeys), but, I think the bloke was on a "see if I can do this" trajectory, good on him, I completely understand.

While you are at it, do you think different actions
and thrid bites have an affec on this calculable force ?

The force itself is a function of the cartridge so no. But, on how that force translates itself through the action, most definitely.

It is notable that dolls heads, cross bolts and other esoterica have been produced. There was a clear perception of need, whether there was a need is a very different question. Their merit, would depend entirely on the quality of production, because, unless the fit is such that each load bearing surface takes its share of the stress simultaneously, then one will bear the brunt and the others will be in effect useless.

My bet is these things were sales gimmicks. The Hyundai add where the snake oiled yobbo shuts the door, which gives a satisfyingly "solid" sound on shutting , and then says "solid" while looking into the camera springs to mind. What does the bloody door noise matter really?

What does a crossbolt matter? if things have gone so pear shaped that the massive main load bearers have given way what is a pissy crossbolt going to do for you?

It is interesting to check the load bearing surfaces to see what is actually doing anything. I had a crap shottie with a crossbolt that did precisely nothing, it didn't even touch the sides of its hole, shotgun worked fine.

Have any of yours got crossbolts? take a look and see if they are under load.

I would be very interested to see a Lancaster wrist breaking back lock action, apparently they were easy to open but a bastard to close, so struggled for popularity. Our unlamented snake oiled yobbo was clearly unable to work a pitch with that one.

AR2201
Those who can make us believe absurdities can make us commit atrocities




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