no4 mk2 Lee enfield 1953starts to string shots vertically in an un-controlled manner.

So Im happily shooting away shots 1 to 9 (within 1 ~ 1.5 moa) fine then shot 10 goes 3moa high and 3moa to the right....11 and 12 shoot 2~3moa low but on line for wind. Next 12 shots vary from 2 or 3 moa high to 2 or 3 moa low. Strip gun, cant see anything. Fire about 7 more and 4 to 5moa vertical throws, no pattern I can see just random....strip gun again cant see any fault...no cracks in wood or receiver...

Any ideas?

Such a sudden change suggests a failure of some sort but I cant see anything to indicate that.

Is the main (front) trigger guard screw still tight?

Check that the front hand-guard hasn't slipped forwards and is binding on the foresight block

Is the butt stock bolt done up tight?

What ammo were you using if it is any year of POF Mk. VII ammo then you did well to keep it like that if your reloading what is the powder weight, projectile type & weight, primer, type of powder, cases, do you crimp but I would ensure all is tight has it been HS'ed how long have you had the rifle etc pics of the weapon and the groups at 100 would be grand then the gurus or wise pelican will advise as they see fit.

Things just do not go south without a good reason :dunno:

Just speaking in MoA's means nothing in itself. It's all relative to the range. If you give us the RANGE/distance you are shooting at and the amount you are off in inches (or metric) you'll get the probably answer

Like Peter said we really need to know the range if you are at 900yds then your rounds are 27" high and 27" to the right ?

On the other hand, if you're shooting on a 25 metre range...............
And what ammo are you using. The backsight is only truly relevant if you are using .303" Mk7 NATO ball

Yes to the first 2, I have to check that the butt stock is OK, it was, but that was before it went "funny" on me..

The foresight block was binding, I dremmeled it clear, but Im still having 4~5MOA vertical random strings at 300m

---------- Post added at 10:33 AM ---------- Previous post was at 10:30 AM ----------

Hi Ammo is my own reloads, ADI2208, 174gr flat base FMJ, 1943 brass cases, Fed 210 primers. The first 9x shots went well, shot 10, 11 and 12 went AWOL as did teh next 12 and the next 7 so I gave up. Before that Id shot 24x at 500metres no problems.

NB, actually 12 x 1943 cases and 12 x S&B cases as Im testing to see how long the S&B last.

---------- Post added at 10:37 AM ---------- Previous post was at 10:33 AM ----------

AJParker type "5c" rear sight through a Parker Hale FS22 front sight and ring. Its set to 320yds for a 300m range. Its not the sight's setting its the fact it has up until now shot very well, better than me, so I can waterline at 300m and 500m give or take my error on the wind. Now on a constant wind day it "waterlines" vertically by 4~5MOA in a random manner. So Im doing 4 or 5 1/2MOA clicks up or down the target centre in no disernable manner.

---------- Post added at 10:45 AM ---------- Previous post was at 10:37 AM ----------

Id have to check the NRA target size for 300m (I cant find any reference off hand). But basically its gone from me getting it inside the x and 5 ring to shooting +/- 2~3MOA at 300m (or 500m) vertically in a random manner. So I could drop the sights 2MOA and then it would shoot 3 or 4 MOA high.

Hi, Yes I know, Ive had it 6 or so months and fired < 100 rounds. I load my own ammo, its 38grains of ADI 2208 (Varget) in a 1943 case with a Fed210 primer and a flat abse 174gr FMJ from Barnaul. I fired maybe 30 rounds with this load before it suddenly went "funny" on me.

I have stripped it twice now, cant see anything amiss, though I need to check the butt screw is tight as someone suggested.

It wouldnt happen to be all S&B cased rounds that went 'AWOL' would it ?

No, both....I even tried 6 full sized, "fresh 1943" rounds I'd made up myslef and they stringed vertically 4~5MOA as well. So I can see no link to an ammo problem.

Given shot 1 to 9 was fine and then shot 10+ was significantly awful in the vertical only that suggests some sort of failure to me. Several ppl have said "bedding issues" but I cant see anything explaining that like a crack or material degradation.