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Forcing cone extention


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Guest stevo

If the chambers are lengthened the gun would be 'out of proof' and therefore require re-proofing, the gunsmith would be unlikely to do the work unless submission for proof was included in the job.

Spot on.

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Provided the gun is sound and you're not overly anxious to keep it that way, there's no reason why you should not use 67 mm cartridges. Many Eley offerings and some Hull just as two examples have cartridges which are crimp closures and specified for 2 & 1/2" (65mm) chambers but are 67mm. However, TDS above is perfectly correct.

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All forcing cones are not created equal, some can be quite a steady angle into the main bore, but others can be quite a suden angle not that far off a step.

If you look at say a AYA no4 mine as a quite long steady cone, but i remember i had a manufrance ideal a long time ago it had steep cones, and was 65mm chambers, if you put longer hulls in it did not just run up the tater a little it bunched up quite bad and i dare say could have cause problems.

Accuratly measuring the chamber length and comparing it to a fired hull from a recognised factory loading might reveal some loads that could work safely in your gun just as it is right now with no modification.

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Guest cookoff013

65 / 67 mm is 2.5"

Both sizes have the minimum siza chamber of 65.1 mm.

 

If you want to check it out, the cip have it listed as so.

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Most 2 1/2" chambers are actually about 2 5/8" (67mm is a whisker over 2 5/8"), but being a 'cone' means there isn't a sharp edge. I have several 2 1/2" proof guns and have always received advice from gunmakers that 67mm and 67.5mm cases are safe and suitable provided load restrictions are met (i.e. usually maximum 1 1/8 oz.) Rarely, you do hear about seeing the end of the crimp 'nipped off' - and if this was to happen, I would seek expert advice from a gunmaker, but I have never had it happen. 70 mm is of course NOT suitable despite what a few forums and websites (mainly in the USA) may say.

I would agree that the Hull Comp X and Imperial game are very good cartridges and use those in my older guns.

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