Effect of hot barrel on POI

Gents,
I would like some advice regarding my No1MkIII*
Last week I used it for a competition at 200 metres. The first 5 practice shot's were on target, the next 10 shots were good (for me) scoring 79/100, but slightly lower than the practice group. However the second series of 10 had a noticeably lower impact position,(dropping into the white zone) while remaining a reasonable group size, it was only worth 64 points.
There was approximately 5 minutes between each series (5 then 10 then 10) and the shots fired within 3 minutes.
Could this vertical drop of POI be caused by the barrel heating up? If so, is there a remedy?
The rifle has a new barrel (old stock) with about 200 rounds through it. The wood is well fitted and the nose cap pad spring is new.
What do you guys think!
Thanks, Shaun

Shaun,

If you look at the 1931 armour notes or Jim Sweets little handbooks, the conventional bedding notes for the No 1 MKIII is covered in detail in both volumes. Either would provide a good guide for inspection of the rifles forend fitting.

Some years ago, when speaking to a Australian Armourer trained in the 1950s, he said that if the bedding was all correct but the rifle had a tendency to move the point of aim as the barrel heated up, there were 4 possible reasons:

1) The front trigger guard spacer was not the correct length, either too long or two short was an issue. He said the most likelihood was the spacer was too short and a slightly longer one could be tried., the basic reason was as the bearing under the barrel warmed up the tension on the barrel reinforce would cause the barrel to have too much up pressure under the reinforce and the point of aim would shift vertically (I think he said low but would have to check my notes).

He specifically said that in adjustment of the rifle that the tool used to adjust the length of the spacer for the front triggergaurd screw, that small variations in length would sometimes be required depending on the wood, though that might be due to the fact he was in Australian and the moisture content of the rifles might be drastically different on south Australia or Queensland. I think that is whey the forends were supposed to be soaked in linseed oil, to offset this.

2) The tension of the middle band was not correct. This was very unlikely, but could be if the two wood bearing surfaces on either side of the inner band were not at the correct level. I have heard competitors that adjusted the spring tension on this inner band, though myself I do not know exactly what the procedure was or how they troubleshot this.

3) The wood is relatively new and when it heats up there is a stiction condition created between the wood and barrel, that creates a different barrel movement profile shot to shot and as such the POI can move, though the likely effect is more of a scatter gun approach. The best fix for this is powdered graphite between the barrel and the bedding points where it bears.

4) A small number of barrels that were straightened in production tend to bend when they heat up and there not much can do with these.

The above was referenced in regards to rifles used in "Roberts" competitions, that is rapid fire matches where competitors start at the long line and run down form ~600 yards down to 200 yards, stopping to shoot a number of rounds at each yard line.

With ammunition that had the normal variations in velocity the No 1 MKIII will string shots vertically at 100 to 200 Meters (so called compensation). so if you are firing small groups of 3 shots, you could have the appearance POI shifts at the shorts, but it is really just the fact the rifle does tend to string vertically.

Thank you very much for your input Frederick. I will print your notes and inspect the rifle this weekend; check to see if anything has loosened off.
When I bought the rifle, it looked good, but was awful on the range. (trigger pull off, rear sight moving under recoil, worn muzzle, 6" groups at 50 metres!)

I've done a lot of work to get it to shoot well, however I had not really shot that many rounds in a short time frame, so had not seen this problem before.
The rifle is originally 1929 BSA, wood is replacement but of original manufacture. Over the last 2 years since getting this rifle; I have checked and adjusted the fit to ensure the barrel is in the middle and it has a snug fit on the recoil pads. I had to make brass shims to equalize the contact here.
There is no contact between the fore end and the barrel except under the knox form.
The barrel does contact the nose cap at about 11 and 1 o'clock. The up pressure pad spring is new.
Should the barrel touch the nose cap on the upper edge?

A couple of quick questions.... Is it a standard or heavy barrel?
Do you use a sling when shooting?

Like Son, I was going to advise a few pointers such as using a stable rest and the best of the bunch is a sandbag, using the same point of aim each time.
I have always been one to blame the user first and not a proven rifle, and explore several techniques that can produce good grouping, especially if as you say you have a new barrel fitted correctly.

30Three,

Too answer your Q, yes, the barrel should contact the muzzle cap at 10 & 2 position, and if you push a loaded round into the muzzle, you should be able to spring the barrel down away from the contact.
I am jot sure if this is also correct for a Heavy barrel, but is for the standard barrel.
I look forward to seeing you get this problem rectified. :-)

Thank you Gent's for your replies.
The barrel is standard type.
I was shooting from the prone position and using the standard sling around my left arm.
Occasionally I use a sand bag under the front for testing ammunition etc. But as the competitions are all shot without extra support, I prefer to practice as per competition rules.
Normally I use my No4 Mk1/2 for these competitions; but wanted to try the No1 as I had got it grouping well. However I had not shot the same quantity of shots in that time frame. Unfortunately I did not have the opportunity to photograph the targets; but the overall group size was similar, but just lower down the target. I am satisfied that my aim was regular. If I do pull a shot it tends to be lateral deviation as opposed to vertical.
I'll have to work out how to upload photos, so when I inspect the rifle I can post pic's of anything odd.
Cheers.

30Three,
From what you say, there appears to be very little to worry about as you describe the group has crept down the target but the MPI is still there, and the shots are all together.

IMHO that charateristic could be down to most probably the barrel as it heated up, as you mention numerous rounds in a strict competition timeframe. They do strange things from time to time and I am sure there are those more qualified than I to reply on the science of why that happens with certain metals used in barrels.
In short soldier on, but see what the rifle does next time out of a competition using a sandbag and replicate the rate of fire. If it creeps then its a charateristic of your barrel.

Thank you Gil.
If I can repeat symptoms then I can probably find the correct adjustment to counteract it; i.e. add a click or two after the first 10 round set.
This rifle has been a bit of a project for me since buying it . It's been lot's of little improvements to get it right. Fitting the fore end was probably the biggest improvement. Here are photos of before and after sorting out the fit of the recoil pads and general wood fit.

Attachment 72223Attachment 72224

These were shot from a sand bag at 50m, so you can see how bad it was!!

Sandbags the answer out of any Competition then, looking at that right hand target, and a tight sling positioned on the back of the arm when in a competition and tighten everything up, your grip, your hold and the butt back deep into the shoulder, that will really help!!

My groups tend to widen when the barrel heats up. But so does my ability to concentrate. And my eyesight diminishes too :bitch:

I asked the questions yesterday for good reason.... now I have a little time and am at home, I can expand on my thoughts

Using the sling can and will string your groups vertically if you cannot use the exact same tension every time. Even the service shooting pam says not to use the sling

Attachment 72226


The foreend is supposed to contact the barrel at the Nock's form, for an inch either side of the inner band and for at least four inches back from the muzzle. Take a look at an undisturbed factory fitted foreend on a No1 MkIII*

Attachment 72227

The inner band does nothing if the foreend is fitted properly. It and the barrel centering stud under the muzzle along with the two tiny lugs in the muzzle hole of the nosecap are there to help control the accuracy if the foreend bedding fails (foreend warping) and nothing else. You should be able to shoot a No1 with only the foreend fitted with the trigger guard, no inner band, no barrel centering stud, no nopsecap, no handguards and shoot the same POI as the complete rifle does.

If you can, try the same shooting program off a sandbag without the sling and see what happens. It is not unusual for a little vertical stringing from cold to hot, but I am suggesting any more than three inches from the first shot to the tenth shot means you may have a problem. I have several No1 rifles that don't vary more than about 2" no matter how hot they are. Trouble is, there can be a lot of work t5o achieve this, and even then there is now way of being sure it will ever improve... they can be that fickle! :surrender:

Another not mentioned one if you have just fired a string say 10 rounds in 5 minutes then you may get the next string not long after of say 10 x 1 shot 2 second exposures then as a finale a 10 shot in 1 minute the only break being the time it takes to score and patch the targets Oh and waiting for the Mausers.

We then induce a heat haze from the wood as believe me when we shoot in 40 degree heat and crank out the rounds the heat from the wood rising up certainly affects what you see 3-4-500m away, slight variations in head hold with the No.1 sighting if the blade is not exactly level with the top of the rear sight notch will also move the POI down (If it is higher than the back sight notch) So as suggested do a timed event using sandbags or just take your time to do it to get a correct sight pic each time.
As we all know when you have the mad minute close is not good enough, a friend and I tried it once in the mad minute he aimed as best he could and got off 15 I rattled them out had a rim over after the 4th clip went in which cost seconds to cure which left me only enough time to put a 5th clip in got off 25 and beat him by a couple of points.
Probably by sheer volume of rounds but his slow and steady was accurate enough to show that it is better to get it right, me I had a ball as that is what makes the lee so good and that is slinging lead.

Thank you all for taking time to answer and share your experience. It seems I have to find some range time and workshop time to check all this out.

But Son, I think the issue raised was only in competition, as I read it. Sandbags wouldn't be allowed, so tightening down right across the board is Marksmanship Principles well honed and tested over centuries of sniper deployment.............it will always tighten a group, but one can't help someone who doesn't maintain the same point of aim, using these principles IMHO

Quote:

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Originally Posted by Gil Boyd

But Son, I think the issue raised was only in competition, as I read it. Sandbags wouldn't be allowed, so tightening down right across the board is Marksmanship Principles well honed and tested over centuries of sniper deployment.............it will always tighten a group, but one can't help someone who doesn't maintain the same point of aim, using these principles IMHO

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My suggestion to try the rifle off bags was only to test if the vertical stringing was caused by uneven tension on the sling upsetting the bedding different each time.
No point going looking for an accuracy problem in the rifle if the problem is in the technique. The rest is only to demonstrate that the standard SMLE, correctly bedded, was never meant to be fired using the sling... quite likely for that reason. Basic marksmanship training for this rifle, from the pam says no sling.
Specialist sniper rifles are a whole different ball game, in most cases.... but I can tell you the most finicky of my rifles is this regard is one of my HT's. If the barrel is touching the nosecap on the two points at the muzzle at 10 and 2, the group sizes more than double. When using it in comps I used to test it with a feeler gauge before an event and have had to put a strip of thin packing in the ensure there is no contact on more than one occasion. That is what worked for that particular rifle.

I had a bit of luck yesterday and bought a nice AJ Parker 9G sight for this rifle. These don't appear for sale very often in France. However it does not have the fixing plate for the No1 rifle.
So now I need to find a fixing, or make one. This will allow me to shoot this rifle in modified class and keep the No4 in the standard.
My plan of action for the rifle is:
1, check if anything has come loose
2, re-oil the surfaces of the wood with Linseed oil, to make sure it's not thirsty.
3, use graphite powder at barrel contact points with inner band and front sprung pad
4, check the spacer length (after oil has soaked in) and fit at knox (nocks,) form
5, check nose cap contact
6, test it on a sandbag and prone without a sling.

Zed, here's a couple of pic's of what you want.
Attachment 72246Attachment 72247Attachment 72248

thank you Muffet. That's a nice collection. I take they screw into original bolt holes with longer screws. What thread are these? Is it BA like No4's or are they special?
Let me know if you want to sell any duplicates:thup:

Quote:

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Originally Posted by 30Three

thank you Muffet. That's a nice collection. I take they screw into original bolt holes with longer screws. What thread are these? Is it BA like No4's or are they special?
Let me know if you want to sell any duplicates:thup:

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One on ebay.au atm

---------- Post added at 12:13 AM ---------- Previous post was at 12:07 AM ----------

Or used guns https://www.usedguns.com.au/Product.aspx?p=75461

I'll be using the No1 rifle for the Regional round of the 200metre bolt action service rifle competition tomorrow. I hope I can maintain my concentration and that the rifle performs as well as it can. I've prepared some hand loads for the event.
There should be 15 people shooting at the same time at this range; so far more time to cool the barrel while they are patching targets etc. I hope this will be a good event for me; because a good score will get me into the National final in June.

All the best 30three good luck.

Well the competition went quite well for me. I did not have a repeat of the previous problem. Could be due to there being nearly 20 shooters at the same time, as opposed to just 2 when I qualified. So more time waiting for targets and scoring etc. plus being aware of what happened last time, I was probably more concentrated.
I scored 152 out off 200. As this is only the 4th time at 200 metres with this rifle, so I'm happy.
I have previously used my No4 Mk1/2 (Fultons regulated) for these events; but having put a lot of time into getting this rifle to shoot properly, it was more enjoyable shooting it. And it's actually not far off the No4 accuracy wise now.
I am currently waiting to see if I've qualified for the National finals in June. A score of around 150 is borderline; as they run a quota system, so it really depends on how other people in other regions shoot. Would be great to use it at the National level though.
Attachment 72994

and a photo of the rifle!