Is Too much up pressure possible?

[jonh172]

Hi all, I need some advice.

I recently made a target rifle out of a sporterised No4 and performed a centre bedding job on it.

The rifle shoots 1.5” 5 shot groups consistently with 2013 mk8z ammo.

I’m curious though, when I bedded the barrel for the up pressure I didn’t use any specific number of pounds of up pressure. I merely shimmed it until I felt there was a good amount of pressure then bedded it.

I’ve had a few groups string vertically when the barrel was getting hot but I was also experimenting with different ammo.

The second link shows a target that had 3 pretty much touching then 4 and 5 strung vertical in order.

Just curious if anyone knows if there’s such thing as too mich up pressure and what the adverse effect would be if so.

Thanks!

Jon

Link to some pictures

https://imgur.com/a/cWxPM7Z
https://imgur.com/a/tsnj1Io

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Alan de Enfield]

The UK military didn't centre bed the Enfield's, but using the 'correct bedding' :

TESTING THE STOCKING-UP

30. The accuracy of the rifle when fired will to a large extent depend upon the freedom of the self-aligning barrel within the fore-end and handguards. To ensure this freedom, each fore-end is individually fitted to its barrel and body, and then stamped with the serial number of the rifle.

31. With correct stocking-up, and providing the barrel is straight, the muzzle end of the barrel should be free to move vertically upwards from the fore-end, and to have slight lateral movement, but no downward movement on to the fore-end. The stocking-up may be tested as follows:--

(a) Ensure that the rifle is correctly assembled, that all screws are tight and that the serial number of the fore-end agrees with the barrel and body numbers.

(b) Grasp the fore-end and handguard near the muzzle with both hands, with the thumbs on the underside of the barrel. Press the muzzle end of the barrel vertically upward away from the fore-end; there should be definite movement of the barrel. The pressure to move the barrel, if measured, should be from 3 lb. to 7 lb.

(c) Change the position of the grip and test in a similar manner for slight lateral movement on both sides.

(d) Repeat, with the thumbs positioned on top of the barrel; there should be no downwards movement of the barrel.

Note:--Should it be found that there is no vertical upward or slight lateral movement of the muzzle-end of the barrel, the fore-end and handguards must be removed and re-fitted as described in paras. 52-55.

[Bruce_in_Oz]

A couple of "issues" here;

The original No4 bedding was done to tune the rifle to Cordite-fueled Mk Vll ball, not Mk8z

Is the barrel a standard, unmodified No4 barrel?

Is the "new" fore-end an original, a Kosher repro or "unknown"?

Range shooters do some very odd and sometimes dangerous things to these rifle, in a wild pursuit of more "possibles". Sometimes it's bit like; "Another wafer, Mr. Creosote?"

IF you have a MINT, original military barrel and exclusively use your pallet of Mk8z, you can do your own thing, but it might take a fair few rounds, a bit of barrel life and a lot of fiddling with woodwork to get the desired result. Or, you might chance on the magic formula tomorrow.

Has the new fore-end been correctly seated on the draws and on the barrel reinforce / Knox form?

Every time you remove the fore-end and "do something" to it,and then refit it, your "zero" WILL shift, whilst the groups may get smaller, or not. If the timber is not totally stable, evil things will happen to your grouping AND MPI every time the weather changes: hot, cold, wet, dry. If you also keep fiddling with the ammo as the seasons and conditions change, it will get untidy.

That is why all the original fore-end timber was selected for straightness of grain and grain cross section, the "rough" blank, that had been curing for several years, was cut to a "flitch' which was a slightly over-length chunk, not a lot bigger in cross section than the desired finish shape, stored in a climate-controlled place for a a few more months, to stabilize and only THEN, fed into the machinery to cut away any bits that did not look like a fore-end.

Some of these time-frames were "abbreviated" in WW2, but as far as I know, no steps were omitted entirely. This, and the "interesting" challenges posed by conditions in the event of Nuclear, Biological and Chemical warfare drove the shift to moulded, synthetic furniture on small arms. Steam cleaning a timber-stocked No4, or any wood-bearing small arm, for that matter, does interesting things to the furniture. "Chassis" systems, like the Accuracy International AW, etc. are a further step away from timber furniture.

[jonh172]

Do picture links work?

Here’s the rifle specs.

-Barrel is a mint 2 groove LB’43 cut just ahead of the front sight.
-crown cleaned up with 11degree crowning tool and followed with a 45.
-Stock has been bedded for tight fit in the draws and up against the front face of the socket.
-buttstock has been fit tight with a gap all the way around at the shoulder.
-bolt lugs were lapped for even contact and bolt head chosen for min 0.64” headspace.
-bolt head does not over turn on the body, it fits to just the slightest overturn.
-barrel bedded per “centre bedding” technique.
-Knox and reinforce bedding set up for contact along the bottom only.
-trigger tuned to a creep free 5.5lb let off. (First stage is 3.5lbs)
-scope mount is a TO-1 torqued to 30”lbs and red thread locker used.
-weaver scope rings
-Redfield 3-9

[muffett.2008]

If in doubt, remove the forewood, fit the trigger guard and spacer and test fire without the timber.
You will need to support at the magazine, but will effectively remove any possible timber bearing effects.

[jonh172]

If in doubt, remove the forewood, fit the trigger guard and spacer and test fire without the timber.
You will need to support at the magazine, but will effectively remove any possible timber bearing effects.

That’s interesting I’ve never heard of that!
I’ll give it a go!

[mrclark303]

A couple of "issues" here;

The original No4 bedding was done to tune the rifle to Cordite-fueled Mk Vll ball, not Mk8z

Is the barrel a standard, unmodified No4 barrel?

Is the "new" fore-end an original, a Kosher repro or "unknown"?

Range shooters do some very odd and sometimes dangerous things to these rifle, in a wild pursuit of more "possibles". Sometimes it's bit like; "Another wafer, Mr. Creosote?"

IF you have a MINT, original military barrel and exclusively use your pallet of Mk8z, you can do your own thing, but it might take a fair few rounds, a bit of barrel life and a lot of fiddling with woodwork to get the desired result. Or, you might chance on the magic formula tomorrow.

Has the new fore-end been correctly seated on the draws and on the barrel reinforce / Knox form?

Every time you remove the fore-end and "do something" to it,and then refit it, your "zero" WILL shift, whilst the groups may get smaller, or not. If the timber is not totally stable, evil things will happen to your grouping AND MPI every time the weather changes: hot, cold, wet, dry. If you also keep fiddling with the ammo as the seasons and conditions change, it will get untidy.

That is why all the original fore-end timber was selected for straightness of grain and grain cross section, the "rough" blank, that had been curing for several years, was cut to a "flitch' which was a slightly over-length chunk, not a lot bigger in cross section than the desired finish shape, stored in a climate-controlled place for a a few more months, to stabilize and only THEN, fed into the machinery to cut away any bits that did not look like a fore-end.

Some of these time-frames were "abbreviated" in WW2, but as far as I know, no steps were omitted entirely. This, and the "interesting" challenges posed by conditions in the event of Nuclear, Biological and Chemical warfare drove the shift to moulded, synthetic furniture on small arms. Steam cleaning a timber-stocked No4, or any wood-bearing small arm, for that matter, does interesting things to the furniture. "Chassis" systems, like the Accuracy International AW, etc. are a further step away from timber furniture.

"Some of these time-frames were "abbreviated" in WW2"

Post war too, it seems quite a few NOS forends twist along their length.

I've replaced a few twisted examples for friends over the years and had to replace my example when it cracked laterally along the barrel ledge, on closer inspection it was splitting along a fault in the grain of the wood.

I know these have been stored for 50/60 years, (who knows under what conditions), but I would assume a bad cut from the blank and lack of drying time, would cause twisting?

[Bruce_in_Oz]

"I've replaced a few twisted examples for friends over the years and had to replace my example when it cracked laterally along the barrel ledge, on closer inspection it was splitting along a fault in the grain of the wood.

I know these have been stored for 50/60 years, (who knows under what conditions), but I would assume a bad cut from the blank and lack of drying time, would cause twisting? "

Good point.

I suspect that the "care-factor" also plummeted somewhat as the introduction of the L1A1 or variants thereof, drew nearer. I certainly saw that happen later when our L1A1s were about to be replaced by the "Tupperware" F88 (Steyy AUG).

[Patrick Chadwick]

If in doubt, remove the forewood, fit the trigger guard and spacer and test fire without the timber.

I did that with my No1MkV. The results were awful!

It seems to me that the SMLE barrel is so whippy that it really needs the complete fore-end assembly to calm it down. Maybe there would have been a magical load where the bullet progress down the barrel harmonized with the vibrations, but it was much simpler just to reassemble it as Enfield intended!

[Bruce_in_Oz]

That "magical load" as the classic Mk Vll ball ammo.

They developed the round using heavy mechanical test rigs with ultra-stiff barrels then tuned the rifle mechanics to deliver those tricky bullets with consistent accuracy. The method certainly got results!

Sadly, there is not much real, Cordite fueled Mk Vll ammo left out there. EVERYTHING else will produce a different set of forces / vibrations on the barrel, etc.. Thus, different trajectory, MPI and grouping.