Erratic grouping

[Brian Dick]

The Remington UMC as Ridolpho suggested, is the closest commercial equivalent to Mk.7z and very good. I think Cold Zero uses it too with great results. I had some Winchester "white box" made on contract in 1981 that was Mk.7z spec but you can't find it anymore. I wish Winchester would produce it again. I'm seeing a few problems in rifles sent here caused by the S&B and PPU Mk.8 spec stuff. Usually inconsistent primers but no fault of the rifle's. I understand guys who don't reload having to shoot what they can find. I just had a local fellow bring me a recently imported 1936 Ishapore Mk.III for service that's been through Indian rebuild but has sound woodwork and is matching. It passes the .074 no-go gauge and is in spec with the run gauges but the barrel swallowed the .310 erosion gauge in the throat/leade well past the 1/4" mark so he'll be needing some flat base projectiles for sure!

[jr57]

Ok thanks all for the replies.

Peter, I have done as instructed but with commercial ammo.

At 25 yards my shooting friends group was 1" low and 1" right of centre with no flyers.

I then shot a group of 5 with exactly the same result, no flyers.

I then shot a further 8 and again exactly same result, no flyers.

All groups were 1".

[RobD]

Dear jr57,
Now, I am no expert, but here is my 5p worth:
Poor ammo tends to give vertical errors. Bedding errors also typically string vertically, rather than horizontally, as the barrel heats up.
Approx 39-40 grains of Vit N140 plus any 174 grain projectile should give excellent results at 100yds and beyond.

The fact that your shots are horizontally off POA suggests something else is at work.
Maybe your scope/mount arrangement is wobbling horizontally?
I know nothing about the internals of scopes, but it is conceivable that, if the rig is solid, then the internals could also be loose.
Suggestion: Why not eliminate the scope/mount and see what the rifle/ammo combination does: i.e, If you shoot through iron sights at 100yds, do you get the same flyers?

[Peter Laidler]

Rob, you've totally lost me............ And presumably JR too by now! Surely he HAS eliminated the problem by using commercially made ammo as we can see from the groups detailed in thread 12! All he has to do now is to zero his rifle to suit. The 'accuracy' of a rifle is nothing to do with the tele sight.

[RobD]

Sorry, Peter, I missed his reply No.12 while I was musing over the causes of horizontal flyers... a Sauvignon Blanc moment...

Yup, if the rifle groups, only needs to zero it. If it still sends horizontal flyers intermittently I reckon either he is flinching or his scope/mount is wobbly.

[Robert303]

JR57. Now that you have tried commercial ammunition. Do as suggested and take it out to 100m. If all OK there then you have problem with inconsistent handloads. I had this a few years ago when I could not get consistent neck tension. I solved the problem by cleaning all my dies and resetting them and by adding a crimp die. If at all possible beg, borrow, steal a chronograph as that is the only real way to test your homeloads. Not sure which part of Scotland you are i but if near Edinburgh hopefully you can make it to the Scottish Historic Rifle Championships on Sep 21st at Castelaw. (See Vintage Arms Scotland website for details)

[jr57]

Gents, thanks for your assistance.

[Peter Laidler]

Brian in thread 11 makes a good point about eroded leeds. The gauge he mentions was used to test or measure the wear at the leed but seemed to fall into dis-use for rifles during the 60's or so but remained in use for Brens until the end (the Vickers had its own.....) But some used to swear by this gauge over all others as with it, you would see the wear for gas to pass the projectile and cause the projectile to become unstable even before it really started its way up the bore. Even more unstable with the boat tailed Mk8 stuff.

The moral here is that everyone should keep a small stock of standard military Mk7 ammo just for test/calibration purposes. Like finding a No32 telescope. Get some now while you can still get it resonably cheap and available.

[musketjon]

What diameter bullets are you using? Also, have you slugged the barrel to see what diameter bullets you NEED to use?
Jon

[Robert303]

Peter at No 18. Thanks for the explanation of the .310 guage. As to the Mark VII ammo. Does anyone know of a source in the U.K.? If so please pm me!