I have chronographed variability in muzzle velocity within some IVI lots of +/- 120 fps with 175 grain Ball (FMJBT - full metal jacket boat tail) Mk8Z ammunition . That is a severe velocity spread (or standard deviation) and indicates possible issues with Quality Control at Industries Valcartier Inc. Having said that these were older lots from the early 1990’s. The good news is that IVI is now owned by General Dynamics Canada whom has significantly increased ammunition quality since then .The way this works is as follows. Only caveat is that you keep an open mind . This might not be the answer you’re expecting.
Fast bullets exit the barrel sooner than slower bullets. There is normally some degree of standard deviation in cartridge formulation (powder charge, crimp strength, primer quality, etc) .
The relationship is as such: "The longer it takes for a bullet to exit the muzzle the higher the point of impact will be at shorter distances". “Why" ? you ask... As the slower bullet proceeds down the barrel the muzzle continues to rise due to recoil and barrel harmonics. This actually starts at the rear bolt lugs, through the action and continues on through the barrel. The No4 rifle is especially subject to this internal ballistics phenomenon – where-as the No1Mk3 SMLE is less prone to it because the forestock and nose cap play a limiting factor in barrel rise (where it doesn't in the No4Mk1).
Remember the No4 require 5 to 7 lbs of downwards foretip pressure for a few reasons, partially as a result of this and for shooting with bayonette attached.At short distances this translates why we can expect bigger group sizes when using poor quality ammunition. Slower bullets impact high and faster bullets impact low (vertical relationship not horizontal).
There is an exception though and this occurs at longer ranges.... Starting at about 500m the slower and faster bullets start to impact at the same point. Groups start to get smaller at long distance in relation to the shorter distances to target. Mind blowing stuff eh!
So in summary - YES the lee enfield is more accurate at long ranges when shooting low quality ammunition. It`s all in the ammunition! This phenomenon would not come into play if you had ready access to match grade ammunition.
Now do me a favour, call a Ranger buddy, get some ammo, targets and a shooting record book from your Patrol Commander. Go to the Range and HAVE SOME FUN!
Can mark 1 No 3 rifle handle hot loads? Can the bolt hand the pressure and not blow up in face? Can I use magum power loads? I have a .3o3 British Made in India.Fun to shoot mark 7 and mark 8 ammo.
ReplyDeleteLong delay on this one Anonymous, sorry for that; but overloading a Lee is not a good idea. The action is quite "elastic" (rear lockers always are, even tough ones like the Schultz and Larsens), and your brass will be under undue stress. Hogdon BLC-2 is excellent powder for the .303, as it gives much lower pressures for given ballistics than most other powders. For instance, it is easy to get over 2700fps with 150gr bullets with pressures 3000 lbs/squ in less than the rated working pressure for the Lee action.
ReplyDeleteIn general though, don't "hot load" a Lee Enfield. It probably won't "let go" unless you get really insane with charges, but it wont shoot worth a damn if you over load it. Stick to the loading manuals, and preferably get a chronograph, and use it. It can tell you a lot about rate of pressure escalation for each unit of powder charge increase. A chronograph can, in fact, save your butt (to put it bluntly!). :-)