Bedding the "H" Barrel SMLE

[Frederick303]

I would add a few things to check on an H bedded rifle that has a noticeable left or right hand shift in the group relative to a simple bore sighted expected zero:

1) Bolt lug fit. If one lug is not bearing or is just bearing by a small amount, the rifle will throw shots in the opposite direction. So if the left hand lug is not bearing enough, the front sight will have to pushed over to the left in the front sight base to compensate. The fix is to adjust the opposite bolt lug bearing until the group moves back in line with the bore sight zero. This step should not be done until the following defects are checked for:

2) Is the barrel mounted so that the bore line is true to the action body? If the threads or action body threads are not true or the rear of the chamber is not bearing on the full 300 degrees(less the extractor cut), then the barrel will shoot off of the expected zero. I have never seen a problem with this, but I have only looked at the rear chamber seat on 6 rifles, which is not a large sample size

3) Is the bolt head square relative to the bore line (i.e. a true 90 degrees relative to the center line of the bore)? If the bolt head is not square to the barrel bore line the rifle will throw rounds off of the bore sight zero.

4) Is the chamber concentric with the bore and action body? If the chamber is canted relative to either then the effect will be identical to having uneven bearing of the recoil lugs. I have seen some bad chambers that seem to be the result of over tightening the barrel to get correct vertical alignment.

Quickest way to check the last three issues is to look at the cases. If you put a fired case in a upside down die that is level and using a ball loaded caliper on a test surface, rotate the case in the die and see if the case head shows any run out, i.e. one part of the rim is higher than the other side by a few thousandths if it does one of the three issues above is a problem. If there is no run out or less than .001, then the chamber, action threads are not an issue. Note to check the run out in a test set up, use a new case as a zero gauge

If there is noticeable run-out do not despair, all is not lost. The first thing you should do is to apply the old Ed Horton trick of putting a small ring or spacer around the cases at the bottom to ensure when the action is close that the round of ammunition is held against the bolt face and true to the bore. Fire a few new cases and re-measure the case head run out. If the cases show no run-out then the problem is not the bolt head, it is with the chamber, or possibly the action body is bent.

All of the above assumes the barrel was correctly installed and indexed, and that the rear chamber of the barrel has a full 300 degrees of contact with the corresponding surface on the action body.

[Son]

Frederick, it's my understanding that if the cases show runout it just means they were not sitting in the centre of the chamber when fired.(relatively speaking, the chamber is much bigger than the case! They all are!) Then no runout after being fired with the o ring will not show if the chamber is concentric to the bore or not, just that the rear of the chamber that the o ring centred it on is concentric with the chamber.

Do a quick test. Pull a projectile out of a NEW round without stretching the neck, or better still, piece of commercial unfired brass. Drop the case in the chamber and see how much it rattles around in there!

Headspace (for a rimmed case) is the distance between the rear of the chamber and the face of the bolt head. For the bolt to close, that space has to be greater than the rim thickness of the case. The case will sit in the bottom of the available space because it is the bottom edge of the chamber that is lifting the case on the face of the bolt against the resistance of going up under the extractor claw as it is chambered.
When the primer is struck, the striker "nails" the case in the position it was sitting, and the expansion of the case wall out to the chamber is restricted on the bottom because of the striker holding it. Have a good look at the primer indent. Often you will see there is a tiny extruded ridge on one side that will be opposite to the side which the case wall expanded. This shows the rear of the case tried to rise on the bolt face to allow the even expansion of the case walls to centre the case. The striker indent will be slightly off centre, and the ridge will be toward the centre.
I will see if I can successfully photograph this and add it here.

I have written all the above purely from my own experiences and study of the subject. I'm not saying I haven't missed some other relevant possibilities, so I am very welcoming of discussion on anything here.

Brad.

[Frederick303]

Brad,

It is always a pleasure to correspond with you.

First off, yes your point is valid, but if the headspace is a bit tight then the case will not show as much run-out without the use of a o-ring. On one of my Fulton regulated rifles without any o-ring at all the case has no run-out when fired. As the case wall is blown out at the bottom, I concluded that headspace was a wee bit tight and is maintaining the case alignment with the throat. I have not done an exhaustive study on this. In general I think you are correct though on most cases showing some run-out without the o-ring. Poorly written on my part, the point is there may be miss alignments that can be detected by examination of the fired cases.

As far as the lug engagement, I have seen this effect and have corrected it on service grade rifles. For some reason the two worst offenders were both Savage rifles with poor left hand lug bearing. That should be checked

The real point I was attempting to get at is that is that many assume that if there is a problem such as was seen with this rifle you look at the wood work and stock bearings. I think, in general that is true when you are dealing with a SMLE with a service weight barrel that was factory assembled. But when you are dealing with match rifles assembled from parts, the trueness of the action threads, barrel threads, degree of barrel thread to action body thread engagement, chamber concentricity, bearing surface engagement between the barrel and action body and how square the bolt face is relative with the bore line of the barrel all have to be considered. All of these fits matter. In the case of an extreme group shift off to one side or another, one of these fits is incorrect.

[newcastle]

Don't think we're dealing with match rifles here. Even the heavy barrel SMLEs are still designed to hit minute of German as opposed to MoA and pretty much all of these are factory assembled and in original (or historical) configuration. No point having one if they're not.

[Frederick303]

Newcastle,

I have to disagree with you. No a heavy barrel SMLE will not go head to head against a M1903 at short range shooting "good" ball ammunition, but at long range correctly set up No 1 MK III might give the M1903 shooting ball ammuntion a run for its money at 800 through 1000 yards. Certainly in the 1930s, the target used by the SMLE in competition at long warge was smaller than that used by the M1903 rifle (36" v.s. 30").

They are not MOA guns, but 2 to 2.5 MOA guns with full power loads, which is not bad. Most shooters will find with the light weigth and low comb they are hard pressed to shoot the rifles up to their potential in matches, at least that is my personnel experince. With reduced loads one might even do a bit better, though I cannot say I have ever pursued that angle.

As far as setting up H barrel SMLE rifles, in the late 1990s you could still buy Lithgow heavy barrels, new in the wrap. I bought three of them and still have one new, in the plastic wrap. Most of the heavy barrels guns in existance are privately set up examples for target shooting. Until the last 10 years they were not that uncommon in AUS and NZ, I personnelly imported quite a number at what woudl be seen even back then at low prices.

[Demo]

There's still plenty of heavy barrels around in Australia and I've come across quite a few still sealed and wrapped just in the last 6 months. You just have to pay big money to get them in most cases.

[Bruce_in_Oz]

THE problems with the extant "H" barrels, and I have a couple of "new in the wrap" example, are several:

They were made for Mk7 ball and Mk7 ball only.

The rifling on the one I have "unbagged" is interesting: Lands are incredibly shiny, grooves show toolmarks typical of cut-rifled military barrels.

There is a slight "belling" in the last inch or so at the muzzle, possibly caused by over-zealous lapping (after ball-burnishing???). Pushing a lubricated soft lead slug through the barrel reveals slight variations in resistance. This slug (cast bullet), was sized to .312" and did not appear to be deforming to the full depth of the rifling grooves, as there were no striations visible that should have been picked up given the visible marks in the grooves.

There being five grooves, the usual internal measuring tools are of limited use. I might have to go mad (and into debt) and get a set of star gauges ground.

Thus, unless you have a good stash of Mk7 type projectiles, the chances of your bullets completely sealing the bore (and grooves) is fairly slim.

There are folk out there in bench-rest and exotica land who are experimenting with "bore-riding" projectiles machined solid from bronze alloys. Good luck to them, I say.

What would be nice is to have someone with more toys than me to fire some Mk7 ammo through a SMLE and into a (water??) trap that would catch the bullets with minimal distortion. Then measure them. Could be interesting. Then do the same with some .311 Sierra Match King or similar (even Mk8Z ) boat-tails: I'd reckon there might be a diameter difference at the tail end.

And about that little filler in the nose of the Mk7 bullet:

It is there to keep the weight down and thus the muzzle velocity up to what the engineers and ballisticians wanted. Replace it with pure lead and the tables go out the window. Change the ogive to a slinky VLD shape and not only do the tables go wonky, such a pointy bullet (but flat-based) would probably have "issues" with retention in the magazine and subsequent feeding therefrom. Make the jacket thicker and the bullets cost more, are harder to make in bulk and are more resistant to deformation by the rifling. Alloy the lead with something much lighter and several things happen:

You increase the hardness of the core and thus reduce its ability to expand and deform into the (mil-spec) rifling.
This centre of mass will shift and this will impact on precession behaviour down-range.

None of the above would be real problems if you were running a national ordnance system and were quite happy to modify all the rifles in the system to accommodate such ammo "improvements. After all, that is exactly what happened with the transition from Mk6 to Mk7 ammo just pre WW1. However, I suspect that even the best heeled collectors on this site don't have THAT many rifles nor would they consider such a plan for their historical artifacts.

[Lithgow 41]

I have found with the H barrel (as i got an unissued and unfired one; still in the grease) the bedding style that I have come across in trial and error, plus also discussing it with Lithgow and the armoury sector, is having the knoxs form touching and the nose cap also touching (around 4-6 pound of pressure on the barrel) with nothing else being in the way.
nose cap is also not drilled out.

manages to shoots 3"-4" groups at 200 yards, with 150 grain .310 projectiles all day, from both a cold barrel to a hot barrel with no issue, and no float with barrel warming up, so im pretty happy with it.
but like all SMLE shooters will agree with, is; find what works for your barrel, what works with one doesnt always mean it will work with all of them.

[martins8589]

I believe that there were a number of H barrels that were sold late from the factory that were actually seconds. Still greased in the wrap but stored for years as they were out of spec. I had a new H barrel and it was on the maximum of tolerance and had very rough cutter marks. Looked like the apprentice had made it. Would not fire SMK174BT and needed MKVII projectiles to shoot. On the other hand I have a MLE shortened range rifle with a H barrel and it is so tight it shoots 7.62mm projectiles fine.

[Son]

I have found with the H barrel (as i got an unissued and unfired one; still in the grease) the bedding style that I have come across in trial and error, plus also discussing it with Lithgow and the armoury sector, is having the knoxs form touching and the nose cap also touching (around 4-6 pound of pressure on the barrel) with nothing else being in the way.
nose cap is also not drilled out.

manages to shoots 3"-4" groups at 200 yards, with 150 grain .310 projectiles all day, from both a cold barrel to a hot barrel with no issue, and no float with barrel warming up, so im pretty happy with it.
but like all SMLE shooters will agree with, is; find what works for your barrel, what works with one doesnt always mean it will work with all of them.

There in lies the issue.... If you are using anything other than MkVII ball, all bets are off. Almost a century of trial and error and close scientific study (as close as technology permitted at the time anyway) around nodes and anti nodes of the H barrel was solely for the benefit of service ammunition.
You should be able to get those sort of figures from almost any decent H barrel bedded in almost any way imaginable simply through load development. Being able to say the POI does not change from cold to warm is a good achievement... but my favourite old sporter with fully floating barrel does that too, only with milsurp ammunition and achieves the same accuracy.

Here is what "old faithfull" looks like currently.... (it was always a D&T'd sporter and used to be .25cal... no collectable rifles were harmed in the creation of this beast. For those with weak stomachs, look away now)

Attachment 67917