Hi guys, most of the common reloading manuals I have are of American origin. Our American friends tend to use longer barrelled (unmodified) hunting rifles compared to what we tend to use in the UK.
If you take 243 and 308 for example, the trend in the UK seems to lean towards 20 inch barrelled rifles. Most of the reloading manuals I have read have loads developed for the above calibres in barrels that are at least 2 inches longer and in many cases 4 to 6 inches longer!
Logically, if we assume we are getting the same velocity that our American based reloading manuals are telling us for a certain powder charge weight, we are probably significantly off the mark, With the actual velocity being significantly lower. Obviously the only real way of testing this out would to use a chronograph to measure the exact velocity of each load produced. In reality this is not a piece of equipment that the average reloader is likely to possess.
If we take the case of the 243 for example, it is my understanding that with a 20 inch barrel, some factory produced Ammunition struggles to make the UK legal minimum muzzle energy requirement of 1,700 foot pounds, that is the legal requirement for use on our larger species of deer.
I would be very interested to find out the average reduction in velocity in comparison to reduced barrel length for a given load, compared to the length of barrel that the load was developed in. For example, for a load developed in or fired from a 24inch barrel, what velocity reduction is likely from a 20 inch barrel?... 150 fps... 200 fps maybe?
I would be interested in your views on the above and it would be very interesting to hear from anyone who has actually carried out such a test.