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Post by nigelthomas on Aug 26, 2008 19:30:58 GMT 1
Hello, has anyone ever seen detailed instructions for use of the fixed line sight other than in the short revision of SAT Vol 1 Pamphlet No.4, Lesson 19 promulgated in the Weapon Training Memorandum 'War' No.1 dated March 1940? This makes no mention of the azimuth zeroing horns, or of the elevation zeroing lever and block. Was it intended, for example, that the sight should be zeroed to the gun MPI at 78 feet?
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Post by Kev on Aug 27, 2008 0:16:59 GMT 1
Hello Nigel,I have bumped into you at previous Beltrings but didn't see you this year.
The paperwork you list is the sum total of what I have,not sure if Tom has anything else ?
Not sure if I'm reading your question right regarding zeroing the sight to the gun as the sight was zeroed to the aiming post.
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Post by nigelthomas on Aug 27, 2008 12:10:30 GMT 1
Kev: Yes, the normal procedure was to aim the gun at the target in daylight using the gun sights, position the aiming post, and aim the FL sight onto it using the elevating and direction screws (plus quick release if necessary). OK, but the sight has the two horns on the LHS of the bracket which can be engaged by the spring latch on the rotating bottom plate to enable it to be 'zeroed' in a fixed azimuth setting parallel to the bore. For elevation, on the RHS of the ramps there is the 'lever,levelling' (as named on the Vickers dial sight) which when operated engages a 'stop' block on the RHS of the lensatic sight carrier arm, lifting it off the elevation ramp. This switches the elevation setting to a fixed one. The position of the block can be adjusted using a screwdriver and there are screws on each side of the ramps which could be used to tweak the azimuth zero. I presume that it was intended that the FL sight could be zeroed onto the gun MPI at a fixed distance using these controls, but we couldn't find any information on this in the PR library.
Sorry to miss you at Beltring and Detling, Nigel
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Post by Kev on Aug 27, 2008 20:25:29 GMT 1
Nigel appologies for stating the obvious rather than the point you were making regarding the function of named parts.
I had always presumed (probably wrongly) that as the Bren fixed line sight was taken from the top of the Vickers dial sight the parts and function of the items you mention were not applicable for fixed line firing.
Having said that I now need to find a copy of how the Vickers dial sight was calibrated and zeroed for indirect fire and how the parts you mention were used with the Vickers.
If by calibrating the FLS to a MPI at a set distance would this not be deviating into the use of range tables and indirectly controlled fire ?
Just wish I had swatted up on the function use and adjustment of the Vickers dial sights before typing this ! ;D
ATB Kevin
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Post by woodsy on Aug 27, 2008 23:49:02 GMT 1
It makes sense to me that there must be provision to calibrate the zero lines on the FLS to the zero line of the individual gun that it is issued to. Obviously, I don't have such info that is specifically for the Bren FLS, but I do have some good info on the Vickers Dial Sight. I will check it out over the weekend.
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Post by Kev on Aug 28, 2008 1:33:03 GMT 1
It makes sense to me that there must be provision to calibrate the zero lines on the FLS to the zero line of the individual gun that it is issued to. Hi Rod,I'm going to have to take the opposite view regarding firing on fixed lines (as opposed to indirect fire or firing at a previously unknown reference point) As the target is sighted and ranged using the weapon the FLS is only used to fix the position of the gun to a datum point that can be refered to again.The orientation between gun and FLS alignment should have no bearing on achieving this. Well thats my take on it  ATB Kevin |
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Post by woodsy on Aug 28, 2008 8:02:56 GMT 1
Hi Kevin I would totally agree that the FLS does not have to be zeroed to the gun in order to fufil its role for firing on predetermined fixed lines. The sight does have, however, a built-in zeroing facility. This provides for limited lateral adjustment and a bit more elevation adjustment. My preliminary examination of the gun & sight combination today would make me think that the anticipated zero range would be about 400 yards. I will set it up and check it out this weekend.  |
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Post by Kev on Aug 29, 2008 0:31:44 GMT 1
Hi there , yes I appreciate the sight can be fine tuned for azimuth and adjusted for a given MPI (within the limits of the sliding block adjuster) when the level levelling is swung back and allowed to engage with the adjustable ramped block. This zeroing adjustment when the sight is fitted on top of a Vickers dial sight after it has been leveled and with the benefit of range tables and co-ordinates will then (I'm pressuming  ) allow the degress and minutes of elavation and rotation to be dialed in to engage the target. As there is no provision for this on the Bren FLS the features are rendered redundant ? The lack of any calibration marks on the FLS also precludes the Bren from firing on anything other than the one fixed line (unless multiple aiming posts could be somehow arranged). I pressume (again) that the sight was 'beheaded' from the Vickers dial sight but the features were not stripped when used as a FLS hence no reference to them in any Bren literature. Rod can you reccomend any Vickers literature that deals with calibrating the dial sight so I don't have to pressume so much ;D All the best Kevin |
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Post by Richard Fisher on Aug 29, 2008 8:21:27 GMT 1
Pamphlet No. 7, Part II - Training has a chapter on setting the Vickers site.
Rich
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Post by woodsy on Aug 29, 2008 9:04:32 GMT 1
I have SAT Vol 1, Pamphlet No 7, Part I which covers the Dial Sight basics, and Part II & Part III have advanced use instruction. SAT Vol 1, Pamphlet No 4, LMG 1939 has some info on the use of the FLS. None of these have any info on zeroing of a sight to the gun. This subject should be confined to Armourers Instructions only and my 1931 edition is too early. What would be needed would be Armourers Instructions from the 1938-40 period. PL might have something in the Warminster library on the subject. The more I study the Bren FLS the more I am convinced it is about as useful as a lawnmower to an Eskimo! It would certainly appear as though the FLS has just had a top transplant from the Vickers Dial Sight, without any regard to the zeroing facility. They probaly figured that they may as well leave it there rather than create a new and complex manufacturing problem. |
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Post by nigelthomas on Aug 29, 2008 13:43:19 GMT 1
Lesson 46 of the 1951 Vickers manual (courtesy of Richard Fisher) gives instructions for checking the zero of the dial sight at 30 yds. (But doesn't actually state that for line this has to be done with the spring catch engaging the horns!) I have found no reference to the use of the 'lever, levelling' however: we need advice from a veteran Vickers gunner about that.
If the FL sight is set at zero it would be possible to position a zero post in front at the point of aim of the collimator.The sight could then be adjusted onto a separate aiming post in the normal manner, leaving the 'off-zero' settings. Suppose that the gun is then aimed at a different target. To return to the FL setting one would traverse and elevate to bring the collimator aim back onto the aiming post, but has the mounting moved?
To check, set the FL sight back to zero (latch and lever) and verify that the aim is still on the zero post. (It would then be necessary to reset the FL sight onto the aiming post.) ...my theory.
In practice one might not want to leave the zero post in the line of fire, so perhaps it should be located below it and the stop block for the levelling lever adjusted to suit.
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Post by woodsy on Aug 30, 2008 0:14:15 GMT 1
Gentlemen, I have successfully zeroed my FLS this morning, on the tripod, at a range of 400 yards. It would appear that the optimum range for this would be between 400 and 600 yards. There would appear to be insufficient windage adjustment at ranges much below 350 yards as the sight offset to the left would require a steeper angle of inclination towards the gun than the adjustment will accommodate. There does seem to be more room with the elevation adjustment, presumably to allow for barrel variation.
My earlier comment about lawnmowers and Eskimos is still valid! ;D
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Post by Kev on Aug 30, 2008 20:42:39 GMT 1
Pamphlet No. 7, Part II - Training has a chapter on setting the Vickers site. Rich Thanks for the link Richard,I'll have a read tommorow and have a go at trying to understand it ! |
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Post by Kev on Aug 30, 2008 21:13:16 GMT 1
Well Nigel,you certainly have given me a good excuse to dust off the FLS and give it an oiling as well as a bit of head scratching !
Other things relating to the FLS I would like to find out are the vast serial number range variations and to find a contemporary picture of one mounted on a Bren.
Rod,thanks for reporting with the zeroing experiment and that the range that zeroing coincides is minimum ? of 400 yds.
As Nigel has given 30yds for the Vickers (not known if sight is locked) have you got a Vickers to do the same trial ? Can the sight be zeroed on a Vickers with the horns locked ?I presume there is a difference between sight to barrel hight and sight to barrel horizontal distance between the 2 guns ?
Re - "lawnmowers and Eskimos" with scientists saying this year may be the 1st time the north pole will not be covered in ice you may have to come back and edit this in a couple of years ;D
ATB Kevin
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Post by woodsy on Aug 31, 2008 7:48:13 GMT 1
I will drag the Vickers out in the morning and try the 30 yard zero. It seems like a good way to start the working week!
Another good thing might be to experiment with a heated seat and steering wheel on the ride-on! ;D
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) allow the degress and minutes of elavation and rotation to be dialed in to engage the target.
