No.1 MkV vertical stringing

Finished running all the engine parts in my area AGAIN, so time for another question:
My No,1 MkV strings shots up and down in a very pronounced way, with the low velocity rounds shooting high and high velocity rounds low. IIRC a 200fps variation resulted in about a 12 inch change, way more than would be useful for long range compensation of trajectories.
Bedding and stocking up seem OK (I'm really more familiar w/ tweaking No. 4's than SMLE's) and the rifle is gripped on the fore stock while shooting from the bench rather than using sandbags. No other MkV's with which to compare it so just wondering what's up. Isolated quirk or some oddity w/ this variant?

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Originally Posted by jmoore

Finished running all the engine parts in my area AGAIN, so time for another question:
My No,1 MkV strings shots up and down in a very pronounced way, with the low velocity rounds shooting high and high velocity rounds low. IIRC a 200fps variation resulted in about a 12 inch change, way more than would be useful for long range compensation of trajectories.
Bedding and stocking up seem OK (I'm really more familiar w/ tweaking No. 4's than SMLE's) and the rifle is gripped on the fore stock while shooting from the bench rather than using sandbags. No other MkV's with which to compare it so just wondering what's up. Isolated quirk or some oddity w/ this variant?

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The following is a list of faults which would tend to give inaccurate
shooting. These points should be checked before attempting to Zero


1. Badly fttting Stock Fore-end,
2. Loose Butt.
3. Loose Screws. (Particularly front trigger guard screw)
4. Loose or damaged Blade Foresight
5. Loose Block Band Foresight.
6. Badly fitting Bolt. It should bear evenly with Bolt closed and no 'slop'
7. Condition Of Barrel for wear, bends, bulges or cordwear.
8. Loose Backsight.
9. Trigger to Sear to Bolt interfaces

jmoore,

Am on a quest for info regarding No1 MkV as i am restoring a sported No1 Mk V, would suggest contact Peter Laidler, or the boys at EFD, if the fore end is similar to SMLE would say it could be, fore end stud and spring, nose cap interference with barrel, check inner barrel band, only other thing you say the rifle is gripped at the forestock is this by hand or benchrest?

The 200fps variation is most if not all your problem with the vertical stringing.

The FIRST thing you need to identify with a 'stringing' problem is whether the string is high or low or straddling the point of aim. If it's high, then without doubt it's the front trigger guard screw. I say that a bit glibly because it's not a hard and fast rule!. If it's straddling the POA, then it's the ammo. Once again, I say this carefully...., same as above. But if it's below the POA then it's the fit of the fore-end because as it's whipping it does something magic to the tail end of the bullet and distorts its true flight path. I think the magic thing it does it just tip it or something like that. Ballistics wasn't my thing but the harmonics/vibration was the bit I took a bit of interest in. I'm reading this from Shrivenham notes I made ages ago. BUT, the above, below or straddling the POA is very relevant.

We used SLR's with various problems set into them for this, such as very elongated handguard screw hole, loose gas blocks and I think, stripped threaded foresights.

It was always much more apparent on old No4's though............

That's a bit of food for thought JMoore. Interesting querie, let us know your findings

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Originally Posted by Peter Laidler

We used SLR's with various problems set into them for this, such as very elongated handguard screw hole, loose gas blocks and I think, stripped threaded foresights.

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Interesting method.
On re reading Hatcher's Notebook I found that he'd also used this sort of method for training machinegunners. He'd introduce a bent part or out of headspace barrel to induce jams and other problems so the trainees would have to use their heads to get the gun back in action quickly.

Enfield Purists, please do not read this.

JMoore, remove the fore-end stud and spring, make sure the barrel is not binding in the hole at the front of the nosecap, and try again. I only got sense out of mine when I did that AND removed the nosecap and handguard. Looks horrible, but groups better. I know I must be missing some important fact, but I just don't have the time to work it out.

In other words, strip everything off until you have a free-floating barrel, try it out, and then put the bits back one by one, noting what effect they have.

Patrick

jmore get some ammo that has the same velocity or is very close first. As a reloader i know that the different combinations possible will and do have huge effects on groups. Projectile weight the same as well. When the ammo is right then get into the other suggestions.

Sorry I wasn't clear as to the ammo situation. I was combining several tests all at once during one range session. Most of the velocity variances were due to using five different types of 174gr ammo. But even within those types a 25fps change showed up on the 100 yard target.
Primary test was to see what ammo the rifle liked best. Secondary considerations included checking the regulation of the rear sight and function. Chronographing the loads was just a happy accident as there usually isn't time to fiddle w/ it. (AFK for a couple of hours here toget some WORK done -happy, happy whilst it lasts!)

Alan, regarding your points:
1. Fore end Seems OK, nothing obviously warped or loose including the draws.
2. Butt tight!
3. Screws tight!
4. Front sight tight and edges square.
5. Front sight block altogether snuggly w/ barrel.
6. Faces of locking surfaces bear evenly.
7. Pretty dang nice bore (I've a Hawkeye borescope 'cuz I'm too curious for my own good!).
8. Its not as good as a No.4 but nothing that would account for Very repeatable results.
9. Hmmmm, can't rule it out, but nothing noticably different from the usual SMLE.

Mr. Duke, my bench shooting technique could be described as firing from a luxury foxhole. That is, lean forward, pull rifle hard to shoulder, rest offhand on sandbags whilst firmly gripping forestock,and brace torso against "wall", all whilst seated (unless I'm at Ft. Benning). With an accurate iron sighted rifle its no drama to shoot 1 1/2 MOA, unless I really screw up. Sub-MOA shooting needs a bit more elaborate set-up.

Bindi, I've run the same multi-ammo/velocity tests on many other .303's without this extreme result! Hence the headscratching.

Mr. Laidler, the loads producing the "bog standard" 2440fps velocity shot very low. To zero required setting the rear to the 500yd setting IIRC. Lowest velocity rounds shot just a tad low. Stupid thing is, rounds that recorded the same velocity would be about touching on target!

Mr. Chadwick, when I take back to the range I'll give your suggestions a whirl. The inner barrel band placement seems futher rearward than a MkIII and definitely more than earlier Mk's so Harmonics came to mind early on!

Thanks all! The mystery shall remain unresolved a bit longer, I guess. Sorry for the huge post...

Concerning shooting 1 to 1 1/2 MOA, thats w/ rifles known to shoot 1/2 MOA or better from a "machine" rest. That is I add about 1 MOA inaccuracy to whatwver rifle I'm shooting from my "luxury foxhole".

I will throw another curly one in the mix, boat tails v flat base. Some rifles dont like BTs. Keep having fun

Am intrested to see, how further forward the inner barrel band is set, as i have only half the forestock of an original ,but even this compared with an mk111 is different, any photos etc would be appreciated.

I took the night off so mebbe I'll remember to find the MkV and measure it. Its hard to think of stuff after being up 23 hours straight. Ain't able to stay up days at a time anymore!

Bindi, it likes boat tails fine, unlike quite a few others I've shot.

The front trigger guard screw is tight but is there a chance that it's a bit too long and is bottoming out in the threads before the receiver and forend are in tight contact? Could the screw bushing be too long?

Seen that drama before, Steve, but think that's been checked. Overrun right now, but it'll be checked again. Can't promise quick feedback.

Mr. Duke, here's an example of "don't believe anything you see on the internet". The inner band location is NOT different than the SMLE Mk III. That jmoore fellow doesn't know what he's talkiing about!

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Originally Posted by Steve H. in N.Y.

The front trigger guard screw is tight but is there a chance that it's a bit too long and is bottoming out in the threads before the receiver and forend are in tight contact? Could the screw bushing be too long?

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More likely the collar is too long. The wood has probably shrunk, or the collar was replaced with one that did not fit properly.

Thanks Jmoore, some pics would be nice.

See the ongoing pic dramas in the Remington-Lee thread. I'm telling y'all my computer-fu is weak, and if work picks up I'll be back to lurking! But meantime I'll see ....