SMLE zeroing table with and without bayonet

ugly

LE
Moderator
#1
For those amongst us fortunate enough to be shooting gods own battle rifle I thought I would share this with you. I was digging it out for another arsser, I though it was worth sharing in light of the recent threads on the Lee Enfield and also whilst I am on if any arrser wants a No4 or a No1 I have a couple for sale, discount for arrsers;
 

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Bouillabaisse

LE
Book Reviewer
#2
I'm assuming, ignoramus that I am, that these wouldn't work for an Ishapore in 7.62? Although secretly I'm hoping you'll say yes.
 

ugly

LE
Moderator
#3
I would assume being an ignoramous myself that you would test this to find out? The issue Indian Bayonet is shorter so it may be different!
 

Bouillabaisse

LE
Book Reviewer
#4
I have enough trouble as it is without adding the complication of adjusting for a bayonet as well. In any case I have a 1907 as it's quite difficult to get an Indian Army one.
 

ugly

LE
Moderator
#5
I am sure there will be a measurable difference between the 7.62 and .303 regards POI and this may be enough to show a massive difference in the poi when bayonet is fitted but then again maybe it wont!
 
#6
Thanks Ugly, I need to check Zero my No4 and SMLE,

I'd do it at work but the Landmark range wardens are jobsworths....
 

ugly

LE
Moderator
#8
Think of a barrel as a tuning fork, when it fires it vibrates, hanging steel of the end of it either directly or through a spring dampened muzzle cap still will affect the frequency at which it vibrates though not the speed of the bullet so the bullet may exit the muzzle at the low point of a wave rather than at the high or centre point.
Does that help?
 
#10
^ is why sniper rifles such as the L96 actually have barrels that consist of two sleeves, one inside the other.

Reduces resonance, a technique used by Linn on the mighty LP12 turntable platter - a simple steel disc will ring when flicked; having two concentric disks pretty much removes the resonances.
 
#11
I didn't think the nylon composite wrap did anything other than make the barrel a nice green colour while protecting it from the elemenents.

Sleeving metal over metal on a barrel is a bad idea, they always rust internaly.
 
#12
You have to experiment with each combination of rifle and bayonet. Broadly speaking, No1s shoot about a foot high @ 100yds, No4s shoot about 6" low @ 100yds. However, enfields being enfields, each rifle and bayonet combination does its own thing....
 
#14
Bear in mind that a No4 does not have a free-floating barrel. As originally constructed and zeroed the barrel should bear up on the top of the fore-end with 1lbf. Presumably attaching the bayonet leads to some degree of barrel whip which changes range versus sight elevation.

As the NATO 7.62mm round has a rather higher muzzle velocity (by about 400fps for factory loads) you should expect a considerable variation in range versus sight elevation, especially if your No4 sights have not been recalibrated to L8 standard.

Have fun.....
 

ugly

LE
Moderator
#15
Oddly enough fitting the no 32 scope to a 7.62 is fine back to 300 metres with original drums
 
#16
Think of a barrel as a tuning fork, when it fires it vibrates, hanging steel of the end of it either directly or through a spring dampened muzzle cap still will affect the frequency at which it vibrates though not the speed of the bullet so the bullet may exit the muzzle at the low point of a wave rather than at the high or centre point.
Does that help?
That's entirely valid, but it's the the justification for a barrel tuner, or for velocity-matching the batch of ammunition to your barrel; it's not really a justification for why a bayonet affects the point of impact.

Put simply, it shifts the point of impact because a service weapon's barrel is thinner and bendier than a target barrel. If you hang a half-kilo of metal on the end of it, it will bend downwards, and you will have to aim higher to compensate. If you want to verify this, go to the armoury, and sign out a rifle, a small-ams collimator, and a bayonet. Then look for yourself.

The reason I question it is because as a form, it appears to imply that you can shift the SMLE point of aim upwards by a foot and a half at 200yds just by sticking a bayonet on the end. I'd like to hear from a frequent SMLE user who has actually checked zero with and without bayonet fitted. Until then, I'll be a skeptic.


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ugly

LE
Moderator
#17
I was trying the simple explanation and the chart is one given to me to prepare for the hbsa fixed bayonet comp I only shot it for a few years before giving up range work. I seem to recall it was extracted from brig Barlows books!
 
#18
^ is why sniper rifles such as the L96 actually have barrels that consist of two sleeves, one inside the other.

Reduces resonance, a technique used by Linn on the mighty LP12 turntable platter - a simple steel disc will ring when flicked; having two concentric disks pretty much removes the resonances.
Errr... No. They don't. They use a single barrel, made from a single piece of steel. Go to the Border Barrels website, and read it; they supplied L96 barrels. Go to any of the other serious barrel manufacturers; single piece, not sleeved.

http://www.border-barrels.com/articles/listarts.htm

Perhaps you're thinking of Naval guns...

As for Linn, I worked in their R&D department for a year, and thanks to the staff purchase scheme have some of their hi-fi. To be fair, I didn't do any work on the LP12, it was mostly their networking kit and some of their preamps and CD players. As I recall, they were big on bearings, high mass platters, decent tonearms and cartridges, and really good power supplies - I don't remember them making a big deal about having the platter in two parts...

http://www.linn.co.uk/all-products/turntables/sondek-lp12

Edited to add, I had a trawl through the owner's manual, and it mentions an outer and an inner platter; just goes to show...

http://small.linncdn.com/product-catalogue/documents/Linn_Sondek_LP12_Owners_Manual.pdf
 
#19
I was trying the simple explanation and the chart is one given to me to prepare for the hbsa fixed bayonet comp I only shot it for a few years before giving up range work. I seem to recall it was extracted from brig Barlows books!
I'm sitting here with a 1942 copy of "The Elements of Rifle Shooting (Dealing the the Service Rifle and Open Sight)" by Lt.Col. J.A. Barlow - nice Xmas present from Mum ;)

Rather depressingly, it doesn't mention the effect of the bayonet, I'd hoped to be able to add the opinions of a King's Medallist... But let's be honest - a foot and a half at 200yds, that's a nine-minute shift in the POI. It just sounds a bit big. What's really strange is that it insists that the POI shifts upwards when the bayonet is fitted, that doesn't make sense.


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#20
I'm sitting here with a 1942 copy of "The Elements of Rifle Shooting (Dealing the the Service Rifle and Open Sight)" by Lt.Col. J.A. Barlow - nice Xmas present from Mum ;)

Rather depressingly, it doesn't mention the effect of the bayonet, I'd hoped to be able to add the opinions of a King's Medallist... But let's be honest - a foot and a half at 200yds, that's a nine-minute shift in the POI. It just sounds a bit big. What's really strange is that it insists that the POI shifts upwards when the bayonet is fitted, that doesn't make sense.


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Its entirely true.


I've tested about 400 No1 rifles in the past few years, of which about 30 with bayonet fitted. I've probably tested the same number of No4s. In LERA, HBSA and my other clubs, we often shoot practices with bayonet fitted, so its vital to check zero.

As many 1907 bayonets are a "rattle fit" and/or point slightly to one side or the other (in service, they were probably matched to the rifle), its usually necessary to try several rifles and bayonets to get a combination that seems predictable for the range.

The average deflection for a zeroed No1 when adding a bayonet is about 12" to 18" UP at 100 yds. The deflection is not linear (it is a No1 after all!) and it is often the same at 100yds as at 200yds. Thus the deflection has to be tested and memorised at each range. I have no doubt that professional soldiers did this as a matter of course.

The theory of the deflection was widely researched, but IIRC no firm scientific conclusion reached. On a No1,the bayonet hangs off the nosecap and forend - not the barrel. In theory, the barrel itself is free to harmonise exactly as it does without a bayonet fitted. That the deflection is UP is obviously counter-intuitive, but its a fact. One theory is that the bullet creates an air compression along the top of the bayonet blade as it travels along, and that this compression is enough to push the bullet up in its trajectory - the rifle and bayonet being comparatively massive and inert. This could explain why the deflection seems to be linked to the geometry and finish of the bayonet.

Having said that, some No1s/Bayonets shoot much less deflection, and I had one that shot DOWN. They made 4+ million No1s, but somehow they all ended up as individuals....

The No4 is completely different. The bayonet hangs off the barrel itself, and thus changes the actual harmonics of the barrel. In the 1930s there was initial experimentation with barrel weights, so it was understood what was happening with the No4 barrel and the bayonet was designed accordingly. Although the bayonet was famously made just long enough to lethally penetrate a Russian soldier's clothing (it was reckoned Russian had the most padding), it was also kept short in order to reduce the bullet deflection effect seen on the No1.

A 2A1 or 7.62mm No4 will react differently, as the barrels have completely different harmonics to their .303 forebears (hence the difficulty in getting L8/Charnwood No4s to be reliably accurate with standard military No4 bedding).
 

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