The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Gents,

Did some shooting today with my No4 Mk2, firing PPU 174gnr heads over 40gnrs of N140.
Throughout my windage was bang on but I had some trouble with elevation.
At 100m range with sights set to 200m the point of impact was 6 inches below point of aim. Group size 2.5inch.
At 300m range with sights set to 300m the point of impact was 12.5 inches below point of aim. Group size 10inch.
To get point of aim and point of impact to correlate at 300m I had to set my sights to 500m

Is my zero out or are my hand loads too;
Slow, spending longer in the air and falling a greater distance relative to the target.
Fast, spending less time in the barrel thus leaving the muzzle at a lower angle as it recoils.

It's because you are using heads in stead of bullets
I'm sure heads are where sailors $hit

If you were using bullets and getting that results I would say you need to zero the rifle with the correct size foresight blade.

How does your poi/poa compare with factory ammo?.Sounds like a variation caused by different bullet weight,powder type and powder load.
The range marks on your rear sight will be calibrated for the standard military load.

My Dragunov scopes are zeroed using standard Russian 150gr milsurp, if I use 174gr or 180gr Commercial ammo (S&B, Prvi etc) my poi/poa changes elevation-wise.

Enfield rifles have removable foresight blades and there are replacement blades of differing sizes to allow the rifle to zero for the ammunition.

Regarding the range scale on the rear sight, this assumes that any ammunition is following the same trajectory as military spec 303.

I found the standard 174 grain SMK a bit slippery in comparison to the original MkVII ball and I ended up with a perfect 600 yard elevation but with everything else slightly out. Then I found some 175 grain Spitzer with cannelure that were a tenner/100 and shot well with N140 and POA and sight graduation, sadly I am down to my last 200 and the old chap that sold them is long since gone.

This from milsurps
With all the talk about key-holing, boat tail bullets, MKVII and MkVIII ammunition I thought I'd do a little investigation into the 'new' (recently made) Kynamco MkVII ammunition.
http://www.kynochammunition.co.uk/index-2.html

Powder charge = 39.3 grns
Case = S&B
Bullet = 174 gr R.O
Primer = Boxer
Velocity (Muzzle) 2489 ft/sec
Velocity (at 100 mts) 2406 ft/sec
Energy (Muzzle) 2400 ft/lbs
Energy (at 100mts) 2238 ft/lbs

Bullet length = 1.286"
Bullet diameter 0.311"
Case rim thickness = 0.058" - 0.060"

Not a boat-tail bullet (with the 0.311 being at the base)

Don't alter your reloads, those are great groups ! Get file and adjust the foresight to suit . It can be done at the range.

PS, Making the foresight shorter raises the POI

Best replace the fore sight with a shorter one and keep the current one for when a new load is developed, best not to file when there is no need to.

dromia wrote:Best replace the fore sight with a shorter one and keep the current one for when a new load is developed, best not to file when there is no need to.

Trouble with that is that it's likely to mess up his windage.


He might as well just buy another blade for later and not install it till needed. The cost is the same :)