Stripping the Diana/Original Mod 16

The Mod 16 is the small one above the BSA Mercury.

This is an old smooth bore junior air rifle, and it only shot a pellet two inches down the barrel when i first got it. Letting some synthetic oil soak into the large leather breach seal and piston seal and letting it soak for a day got it firing, inch groups at ten yards on average. Still not owning a chronograph i could still tell it was well short of its full power, so why not strip it and see what could or needed to be done to improve on this.

Checking out Chambers exploded chart and spares list i could see that a lot of parts were obsolete, but my bodging skills are improving nowadays. To take the stock off two flathead screws on the fore stock and one screw which held stock, trigger, and housing were removed. 

One of the two front stock screws

The rear screw is one long screw that screws into a circular bolt with a flathead driver fitting, the trick with this was to take an old flathead screwdriver and grind the middle out leaving two flatheads spaced far enough apart to grip the round bolt leaving the long screw to undo freely. Out came trigger, trigger spring that rests in a hole in the stock, and spring cylinder and barrel.

The rear stock bolt/screw that holds a lot of stuff together.

I pulled the tight fitting metal end cap off and and the spring guide retaining pin fell out, as the metal spring guide had two tabs that twisted into small slots at the back of the spring cylinder. The spring was worn so pushing the back of a screwdriver into the end of spring guide and giving it a twist i slipped the tabs out and out came spring guide, spring, and piston.

Using a rod i  wrapped some wet and dry dipped in white spirits and thoroughly cleaned the inside of the cylinder, then removed all residue with kitchen towel. Using the same method i polished it with OOOO wire wool and cleaned it again with kitchen towel, then finally gave it a really good polish with Autosol metal polish making sure to clean it out a good four or five times. This method was repeated with the piston and the spring was given a good clean with white spirit and a kitchen towel and each end polished, i slightly roughened the leather piston seal with wet and dry and let some Abbey SM50 soak in for a few hours.

Adding some more Abbey SM50 to the side of the piston seal and Abbey LT2 grease to the last inch of the piston i carefully slipped it into the cylinder, two metal washers either side of small rubber sink washer lightly smeared in LT2 grease were placed in ahead of the spring also lightly coated in LT2 grease. Spring guide also greased was pushed back in with the back of a screw driver and the tabs locked into their slots, then the pin was replaced and the end cap tapped back on with a mallet.

It took a couple of attempts to line up stock, trigger and spring, and the cylinder body together and slip the screw through but it was no biggy, the rifle actually dents wood with Hobby's instead of slightly marking it now. 

See the trigger tension spring behind the trigger?

I can't really justify spending much money on the Mod 16 just yet, the price of a replacement spring for this rifle is the same as one for the BSA Mercury and that is a wicked air rifle. But it was fun doing it and its got a little more poke to it now, and hopefully should do better groupings at ten meters now its had a clean and relube.

TTFN

Wing Commander Sir Nigel Tetlington-Smythe  

 

Two Breakbarrels, Big and Small

 Today I shall take a look at two break barrels, and see the odd bits of repair that have been done to them to get them up and running. Both guns are classics in their own right and deserve a little TLC at least, so here is what has been done so far to the Original Mod 16, and BSA Mercury mk11.

Diana/Mod 16 with BSA Mercury and scope

Firstly I picked up the Mod 16 which was looking in fair condition, but alas when i cocked, loaded a pellet and fired it, the pellet did not move more than two inches down the barrel. The Mod 16 is a small rifle made from pressed steel with a brass smooth bore inner barrel. It has a leather piston seal and a large leather breach seal on the cylinder which runs flush with the inner barrel and the large outer barrel - the outer barrel is a a tad smaller in diameter than the piston cylinder. The cocking linkage is pressed steel with a notch that locks onto a pin under the cylinder, you can cock it with one finger once unlatched. Cosmetically it just needs a paint job as the wooden stock is in pretty good nick.

Mod 16 breach and sight

Large leather breach seal on barrel and liner

Barrel catch is the loop piston lever

To get it working I popped a few drops of synthetic oil on the breach seal to rejuvinate it, and a little bit more of the same down the transfer port to put some life back into the piston seal. I then stored it barrel up for 18 hours to let the oil soak into the leather, and sure enough it fired just fine after that. I was getting 1 1/2 inch groups at 10 yards with the simple open sights, but I knew it should do a lot better than this. This is a junior rifle and is working just dandy at at the moment, but it does need a new spring and piston seal really. I reckon I can get away with soaking the leather in WD/40 then oil to bring it back to its former glory.

Tis a dinky lil' rifle, and pooch

Mod 16 shoulder stock

Pressed steel trigger

Whole barrel presses onto leather breach seal

Getting on to the BSA Mercury ... I find an air rifle that looks in a tidy condition, the bluing is fine and the stock just has a few surface dinks on it. The Airsporter is basically the underlever version of the Mercury and has the same trigger unit that creates a flowing curve from the piston cylinder to the stock, which makes for a a rather sexy looking air rifle in my mind. However, at one point someone has pulled the trigger while the rifle was cocked open, resulting in a very noticeable bend in the barrel at the breech. Also the rifle has had the open sights removed at some time, the jaws holding the breech are slack so the barrel moves from side to side a little, and the original spring has been taken out and replaced by one from a SMK B2. Why? I don't know, but it's sure easy to cock and probably produces about 8 ft/lb if it's in a good mood.

Smooth flowing lines of a Mercury

Ventilated rubber shoulder pad

So the first thing i did was to remove the stock, then tapping out the pivot pin i removed the barrel from the action. Clamping the breech end in a vice putting pieces of leather between the vice jaws and barrel to protect it, i used a piece of pipe slipped over the barrel till it came just short of the bend then pushed like mad till the barrel looked straight. Metal used to make gun barrels needs to be fairly soft, so it wasn't that hard a job to do. Using a long metal rule i held it flush to the barrel to see if any fine adjustments were needed, of which two or three were needed but the barrel was now true.

Straightened out barrel

Breach seal still in good nick

For fixing the barrel side play i used dial calipers to check if the jaws were out of alignment, and sure enough they were. By using the 90 degree angle on the end of a small rule i found out which jaw was bent, and again i used the vice to remedy this. By placing a 5 mm piece of metal at the end of the bent jaw i close the vice around both jaws and the end of the piston cylinder, on releasing the vice the jaw sprung back but only so far as to make a tight fit for the breech. Whoopee! Problem solved.

Articulated linkage on piston rod

I then slapped a Crosman 4x20 scope on it and it fired on target no problem, the only problem is that the scope is rather short and i have to crane my neck to use it, and the magnification is more like x2. With a lot of older BSA's in .22 the bore is a tad wider than most other .22's, so i found that using Eley Wasp no2 pellets work the best as they are 5.6 mm as opposed to 5.5 mm.

Cheap Crosman scope soon to be removed when i get something better

Some time soon i will get to sevicing and tuning the springers, but for now they seem to be doing fine. It's all down to when i can afford to buy the spares and springs for them, so it looks like i'll be doing a fair bit of busking to finance this air gun habit of mine.

Trigger guard needs a spot of paint i think

TTFN

Salutations, Wing Commander Sir Nigel Tetlington-Smythe O.B.E.