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Are you sure the "152mm" hasn't been rounded down to the nearest whole figure from the actual metric equivalent of 152.4mm (6"), a common practice?Quote:
Originally Posted by Sunray
Are you both saying that a 155mm shell needs 2.6mm/3mm clearance between it an the barrel? It seems a lot of clearance. Yes there are the drive bands but don't forget about the gaps in the rifling to fill/seal.Quote:
Originally Posted by browningautorifle
I am quite sure once they have rammed the projectile home either by pole or in Naval craft a hydraulic rammer and they set the charges off the bands will obturate quite well as they are in the lede of the rifling not the rifling proper if they tried that lark of no lede it would probably burst the barrel due to a huge pressure spike trying to force the projectile to start the engraving process by the rifling.
Besides the clearances we are talking about is only 1.3mm each side a minuscule amount considering the size of the projectile the driving bands will easily take that slack up when it obturates, same as our rifles but on a bigger grander scale. anyway besides there is always blow-by in every weapon except maybe an air rifle where it would be counter productive for velocity.
The weight of 75lbs empty fits with certain types 155's having @25lb of H.E in them
No, I said it sure looks like the 155mm I had. A boat tailed projectile with that drive band and ogive...whether it is or not remains to be seen.Quote:
Originally Posted by Flying10uk
Does someone not have a shell that is known to be 155mm that can be accurately measured with vernier callipers or a micrometer, please?
I think those use charge bags and don't have a casing. Imagine manhandling an already 100 lb projectile with a case and charges...all measuring a meter in length...trying to hand ram. Here's a link so you can better see. https://aw.my.com/en/forum/showthrea...rtillery/page5Quote:
Originally Posted by Flying10uk
Or do you mean the projectile?
I don't have any big calibre projectiles but have definately measured some BIG bores of anti-tank guns, 3", 76mm, 81mm, 3", 2":, 51mm 20 pounder, (learned on 25 pounder) 105mm and 120mm ordnance and in reality, as told by several here who have/might have actually done the same bore gauging with the old rods and vernier plates or electronic I/C's, the bore size is not relative to the actual designation. Yep....., quarters of EFC life and all that palava............
Depends if you quote to the nearest whole figure when you list the metric or imperial conversion, not everybody does, and if you do to how many decimal places you quote the conversion to.Quote:
Originally Posted by Peter Laidler
F-10...... Been there, done it, measured and calibrated plenty of them........ Mortars and tanks mostly
PL.,.......Been there, done it, with regard to imperial measurement, to metric conversion and vice versa, being doing it for years and years and years. Seen errors occur when people take it upon themselves to round up or down the figures in the conversion, without telling anyone. The classic example is when U.S. technical/engineering drawings come to the U.K., they tend to be dimensioned imperially, or the last example I saw was, a few years ago. As the U.K. tends to work to metric sizes mostly nowadays, in industry, you sometimes see people doing their own, unofficial metric, version of the drawing. You have to watch how the metric figure has been expressed to be sure that it hasn't been rounded up or down, either to a whole figure, or just to one decimal place, when accuracy demands that the figure should have been expressed to two decimal places.
I think the point here is the Army or Ordenence section will call it 155mm not 154.94" imagine a FOP calling in "20 rounds H.E 154.94mm, Fire for effect." 155mm rolls of the tongue allot better besides rounding up & down has been with us for eons and unless some Arty types can conclusively identify the projectile we could go on for ever and a day trying to surmise this one out.
Allot of the stuff used is heavilly stencilled denoting it designation they would never put unidentified ordnence out to the troops which could lead to a calamity surely!
Found this on Wiki; which I think pretty much settles it I'm out........................
The M107 155mm projectile was the standard 155mm high explosive (HE) projectile for ... (12.7 lb); Length (excluding fuze): 605.3 mm (23.83064 inches); Body diameter: 154.71 mm (6.09027 inches); Driving band diameter: 157.98 mm (6.219666 inches);
O P's measurememnts they took match this bang on I would say at 6" and 23.75" base to tip (minus fuze) I took it to the nth degree with decimal places so there would be no quibiling about "Well its not quite.........!" God forbid that the body diameter is under 155mm and driving bands take it to over 155mm in diameter.................................:yikes: