Starting my 25 Pdr... Mirbat Gun.

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Adrian Harris
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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Adrian Harris » Sun Dec 22, 2019 11:22 am

This picture was taken by Steve Stuart at Muckleburgh:

DSC_0975a.jpg

Adrian.
Contact me at sales@armortekaddict.uk for details of my smoker fan control module and other electronic gadgetry

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Chris Hall
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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Chris Hall » Sun Dec 22, 2019 12:35 pm

Robert -

Just caught up with your thread, and noted your questions. Dave and Adrian seemed to have answered the question on the wedge - my 25pdr (built by Phil Woollard) has a tiny sticker on it, which I assumed was something like a ranging chart. Or possibly the canteens menu for the week :lol:.

As for the colour, I found this document some time ago that I'm taking as my reference for my Korean War (1950/51) Quad, limber and 25pdr:

http://www.warwheels.net/images/British ... liott1.pdf

(it's on other websites too, and seems pretty authoritative). That states that the correct colour for British Army vehicles up to the early 1970's was BS224 Deep Bronze Green. If that's not the exact colour for a Land Rover Series I then it must be pretty close ! The quality of the early paint mix (up to 1956) was very poor, leading to peeling and blistering that must have given most RSM's heart failure :wink:. But it improved up to the time when it was finally realised by the Ministry of Defence that shiny paint wasn't a good look for the modern battlefield .......

Where is the Mirbat Gun now ? I believe it's at Larkhill, on the east side of Salisbury Plain near Stonehenge (which is only about 10 miles from where I live !). They're planning a new Firepower Museum there, which was supposed to open in 2020 but I think will be delayed. But I think there's little risk of the collection being spread around the country (fingers crossed).

All the best,

Chris
Mark IV (Liesel, Abteilung 14, France 1918)
Morris Quad, 25-pdr & 2 x limbers (45RA, Korea 1951)
M3 Lee (25th Dragoons, Burma 1944)
Rolls-Royce Armoured Car (10(RN)AMB, German E. Africa 1916)

Robert Reid
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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Sun Dec 22, 2019 9:58 pm

Thanks, Chris! And also thanks Dave Dibb... I got the e-mail!

I am playing with colors now, but I probably will end up ordering Land Rover Bronze green. They want a boatload for that stuff! But it is correct. And worth it.

Got a lot done today, but forgot to take any pictures... lots tomorrow! Actually spent a bunch of time trying to restore a broken set of ivory grips from my 1911... but that's for another forum. Success, though.

Playing with the elevation mechanism. Kian sent me a new sector gear and it is lovely. But I still have to do some filing of the small gear pair and some fitting to get them to work smoothly.

Also got the bottom trail and pintle ring done with some upgrades incorporating a lot of the good ideas here.

And made an oil can holder... I have one of Dave Dibb's tool kits and it is brilliant for the 25 pdr! Even though it is probably for the Chieftain or Challenger or other post-war vehicles, it is fantastic for both the 25 PDR and also for the Rolls-Royce Silver Ghost chassis or Armoured car. Not everything... but much of it!

More to follow but, as always, thanks everyone for the inspiration here!

Cheers,

RPR

PS. Dave.... wondering if your Photobucket has decided that they have hosted enough for free and now want you to pay. That happened to me before I switched to Imgbb. Though the Photobucket fees are not terrible and your material is such amazing reference stuff... hope you get it all to come back! Cheers, RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Sun Dec 22, 2019 10:03 pm

All credit for these images goes to Dave Dibb who sent them via e-mail.

For anyone who wants to do some engraving, here is what goes on the sloping 'note-pad' plate. My guess is that they used grease pencil on this to record firing instructions when setting up in battery.

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Image 2

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Cheers,

RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Mon Dec 23, 2019 10:41 pm

Got a ton done over the last couple of days... despite late starts and visitors to the shop. I need to install a perimeter minefield. Claymores anyone?

Anyhoo....

The main progress of the last couple of days has been pulling together the T&E and some small stuff. Painting/varnishing wood boxes, detail stuff, etc.

But the assembly of the T&E is worthy of posting some details on, which may help some other builders, because none of the build logs I have seen have really gone into the details of getting it to run really smoothly. It's more complex than the pictograms may indicate! Nothing 'hard' but some tips for builders may help others.

So in no particular order... some progress pictures:

Nothing too difficult. Using a chunk of ebony to make the holder for Dave Dibb's great "Kaye's Patent Oil Can." The originals had a Hammerite silver finish on the commercial models. Anyone know what the MoD did? These were OEM supplied on W.O. Bentley's, BTW. That's why the surviving originals get stupid money on eBay!

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This was much of yesterday's project... getting the tail pieces done. I used a combination of Dave Dibb's Armorepax parts and small screws (10BA) and nuts to make the whole assembly really come out well. The 'all-brass' ones that Marcus and Jeff have done are magnificent, but I was trying to strike a balance between full-fabrication and using available parts to get 80 percent of the effect. I think it came out great!

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One of the armor-carrier plates. I took the original Armortek piece and added some 8BA bolt heads (these are blanks... threaded into the aluminum, but just a head with nothing protruding. Then I cut some brass pieces to fill in. Note that I have done some filing on the part and have bead blasted it to look more like a casting or forging than a machined piece. Softer edges, fettling, etc.

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Here are the finished trunnion plates. Note that before bolting on the trail, it is important that these pieces are aligned. For that, I used the actual front armor. Fit the armor using the four cap screws (I'll replace those later) to align the side pieces... THEN bolt them to the trail and later remove the armor. Otherwise, they will not line up and your armour will be warped. Also, if you want the barrel assembly to be able to traverse 'a bit more,' then bevel the inside rear's of these plates with a file or on a belt sander. With a bit of a bevel, you can significantly increase the traverse of your barrel assembly. And more movement is good, right????

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So on to the elevation mechanism. First, there is some real fitting that goes on here! First of which is getting the brass gear through the aluminum housing without them locking up! Some gentle sanding and, ultimately, lapping compound are your friend. Before that... use some sandpaper wrapped around a file to de-burr the hole and some paper around the shaft to make sure it has no burrs. If you just 'push the gear in' it can lock and whey aluminum and brass lock together... good luck getting them out! Fit this with .001" clearance and use lubricant! Also, make sure that you fit the two gears together and INDEX them. Then clean off any burrs, etc. The gears appear to be laser cut and they are very nice. But finishing work is required to make a nice smooth T&E action. I have live artillery antitank pieces and can tell you that the screw mechanisms are so beautifully-made that the whole mechanism is smooth like a Swiss watch. The model should be the same!

Note that I have added an extra hole that I am tapping to 8BA here. This is to hold the elevation drum on in three places. Why? Stay tuned. Also note that the traverse block is held with some nice little 8BA bolts/nuts. No reason other than it's nicer than the big metric bolts. (big being a relative term!)

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Test fitting the gearbox. Note that the driven gear is not centered. It was set slightly off center to ensure that there was minimal lash on the worm gear. At the 5:30 position is the new hole drilled for an 8BA bolt that will hold the gearbox on in three positions, not two. This is because I wanted a gasket and you can't secure a gasket with just 2 fasteners. Note the gland nut (technically, this sets end-thrust on the Armortek kit) in brass at the top of the gearbox. This needs some significant attention so that it sits hard against its flange... while setting the end thrust on the worm gear. The less end thrust, the smoother your elevation action. The gear was first de-burred. And then the brass nut was gradually reduced in length on a lathe (you could do it on a flatplate with some sandpaper) until upon full-tightening of the gland nut, the worm gear turned, but had no back-and-forth movement. The back and forth would create un-necessary lash in the gear train.

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After the lash was minimized, everything was coated with lapping compound and the worm gear and housing were run for a couple of minutes on an electric drill. This final smoothed everything out and after cleaning, the mechanism was ready for assembly.

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WIth everything cleaned spotless from the lapping compound, it's time to assemble the gearbox. But as it is a real, working gearbox, it should be filled with lubricant. And if you don't want your lubricant leaking out... you need gaskets. So with the addition of a third fastener and a couple of paper gaskets, I know the gearbox won't leak around the outside flanges (it will leak around the shaft... but I wasn't about to put in rope packing there... sorry.) I made the gaskets from a page in the Armortek Instruction manual. Recycling at its best! The sealant is a non-silicone gasket sealant. Want to make your 25 PDR impossible to paint? Use Silicone on it. This sealant is fully paintable.

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Here we have the gearbox going together for the final time. The outside gasket surfaces have been covered with sealant... and inside is a good dollop of white Lithium hi-temp grease. When all sealed up, the whole unit is just as smooth as glass!

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I think I am out of pictures for this post... so I'll continue in a moment.

Cheers,

RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Mon Dec 23, 2019 10:58 pm

And here is the last of today's achievements....

With the drive gear working smoothly, it was time to make the sector gear work well. Kian very generously replaced one that was cut badly... and the new one is beautiful. But I decided to do some modifications to make it look a bit more like the original. You can see I cut out the web and made it into more of a 'skeleton' gear.

Also, you can't just bolt it on and expect it to match up with the drive gear! I had earlier set up the trunnions and lapped them together and when the caps were tightened, the gears were 'too tight' to work together. So I had to both cut the flange of the sector gear and elongate the screw holes to reposition it to mesh properly with the drive gear. Thanks to the great design by Armortek, there is plenty of extra material to work with. And by thinning the flange and elongating the mounting holes, the gear can be adjusted perfectly into position. The only remaining challenge was re-shaping a couple of teeth to take up tight spots. I don't bring these up as complaints, but as notes for fellow-builders who will likely have to do some real 'fitting' to get everything working smoothly. Total time? At most an hour or so. But totally worth it!

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The mechanism assembled and working well. Note that the wheels have been re-shaped and polished. And this is not final-assembled, but is test-assembled to check on all the workings. And they work great! I reshaped the post for the Traverse wheel to look a bit more like the original casting. Cut the edges and rounded some. It looks the part very well! Note the addition of some brass plates on the 'stock' Armortek seat post as well. These little brass pieces really improve the look of the stock post with very little effort. If you don't want to do with brass, you can easily use styrene sheet. Epoxy'd in place... simple and slick!

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First time I have had things 'together' at this level. This is all test-fitting. In this case, fitted the armour plate to align the carrier plates. And threw the barrel in just to see what it looks like. You know what? It looks good! ;-)

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Just sort of a rough assemble picture showing the assembly and the T&E in place. Again, the key here is fitting, lapping filing and making things SMOOTH!

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Tomorrow, I'll be working on the sighting mechanism and trying to get that together and detailed. There are a lot of cool things that we can do with the sight. At least upgrading telescope and some of the other little bits.

It's all coming together. I can't say enough good things about this kit... it has so many upgrade possibilities, while being so straightforward to assemble. For anyone thinking about doing a tank or armoured car or a 'big kit' I totally recommend tackling a Kompact Kit as a practice project or as a modeling tune-up. Really, there is so much you can do with these kits as a 'blank canvas' and create a museum-grade finished model!

Cheers and MERRY CHRISTMAS to all my fellow modelling-crazies! May there be Armortek and Armorpax under your tree. Even if you do have to buy it yourself!

RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Tue Dec 24, 2019 10:22 pm

Worked almost exclusively on the sight today... and made a few modifications from the stock kit, but not much. What a great little device!

Main modifications were to drill out the tube and step it so that it would take a sight telescope. Also soldered lugs on the sight housing and put a rear flange on that would let me fit a locking screw. Then made a small telescope to fit in and used a piece of ebony wood to make the rubber eyecup. Fitted some blind bolt heads to the outer plate, a mock 'gear cover' soldered on and a flange/tray for the clinometer.

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I am going to make some additional modifications to it after Christmas break tomorrow. Including a dial sight if i am feeling ambitious!

http://www.collectorssource.com/dial-si ... r-gun.html

I was trying to come up with a way to make the 'lenses' for both the clinometers and the telescope I made. And finally decided to use some slow-set epoxy and just let surface tension make it look like a lens. Other than some bubbles you really see only under magnification, it's working pretty well!

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Last a small modification to the arm that goes on the trunnion yoke. Just used a mill to cut a web in it. Easier than making an all new one!

Bit by bit... really all I have left is the lever mechanism for the firing platform and then paint/assembly and lots of little details as it goes together. I can see a bunch more stuff that I can add!

Cheers,

RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Wed Dec 25, 2019 3:10 pm

So my project for tomorrow is starting to gel... and it doesn't look all that daunting. Except maybe the engraving.

This is the dial sight that fits in the cup on top of the main site. And is carried in the big leather bag on the inside of the shield. As noone has posted detailed pictures... I thought I'd share. It should be large enough that it is pretty easy to replicate in 1:6th!

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I am getting so inspired that maybe I'll go do it this afternoon as Christmas day is turning in to a trainwreck here. Question for the group... if you are invited over to a friends' house for Christmas.... do you bring your 80 pound border collie and throw its ball for it to chase in a house with pine floors and antique oriental rugs and antiques in glass cabinets all over the place? And then get on your speakerphone and spend half an hour taking with your friends in your outside voice??? One of the missus's friends whose BF dumped her right before Christmas. Wonder why?

Good lord.... Not very Christmasy spirit, I guess. Just a few hours to go! Which is going to get spent in the model shop methinks!

Cheers,

RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Marcus Kwa » Thu Dec 26, 2019 10:34 am

Hi Robert,
Christmas is always the time I get most of the building done! Appropriate or not.......
If you take a look at my Flickr site, I have photographed a dial sight in detail:
https://www.flickr.com/photos/82214824@ ... 9887062875

BTW, I have one on my desk so if you need details on a certain part just let me know!!

Marcus

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Thu Dec 26, 2019 11:15 pm

Thanks, Marcus!

I sort of ciphered it out, though did not go to great detail. It definitely fits the part and was not too hard to make! But sure appreciate the offer!

Started with a 1" bar of brass and turned in the major features including the barrel, the mount for the screws, the table and the prism housing.

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With the solid core done, I added the housing for the knobs and made up a couple of knurled (turning!) knobs! The lens/mirror is a piece of German Silver polished to high shine. Came out pretty well! Made an eyecup out of my favorite ebony wood.

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Sight temporarily fitted as I get the actuating bar sorted out. It's a bit long, so I will have to shorten it to get the barrel and the scope moving correctly together. Technically, the scope should have a little down angle from the barrel. Probably about the equivalent of about 20 Milliradians. Because you look at things straight on... but shells follow an arc.

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Lots of stuff test-assembled here... but much will come back apart for priming and painting. Only thing I have left to do is fit the firing platform (it will be in the 'up' position. And the rods on the barrel and to control the sight. Then about 100 more rivets to go in blank holes before priming and painting. On the subject of paint, I did manage to secure a supply of Land Rover Bronze Green aerosol, which is pretty close to the post-war paint scheme. But there will still be traces of red primer, tan and other 'earlier' schemes underneath and in the hard-to-paint areas. I am betting that the repaints weren't done at the Crewe Bentley works... but were done with brushes or spray guns and painted the 'visible' not the details.

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Overall picture of the first assembly. Major parts almost all fit with each other! I have to move one of the box racks inboard a bit. And there are still details to do as the paint comes together. But am pretty happy so far with the results!

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Cheers,

RPR

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Chris Hall
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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Chris Hall » Sat Dec 28, 2019 8:17 am

On the subject of paint, I did manage to secure a supply of Land Rover Bronze Green aerosol, which is pretty close to the post-war paint scheme. But there will still be traces of red primer, tan and other 'earlier' schemes underneath and in the hard-to-paint areas. I am betting that the repaints weren't done at the Crewe Bentley works...
Sorry, Robert, but I think you'd lose your bet :D.

The British Armed Forces are very, very good at painting things, all the way down to individual lumps of coal for inspection. If not, the NCO's will want to know why ! And remember that, for the Royal Artillery, their guns are their Colours (would you follow a tatty flag ? :wink:). So a shabby job would be completely unacceptable. I have a reference to 45RA and their vehicles prior to shipping for Korea, which were described as completely refurbished (my emphasis).

So I really think that, if you're going to do the Mirbat Gun in 'Parade Ground Order', you need to go the extra mile .....

Chris
Mark IV (Liesel, Abteilung 14, France 1918)
Morris Quad, 25-pdr & 2 x limbers (45RA, Korea 1951)
M3 Lee (25th Dragoons, Burma 1944)
Rolls-Royce Armoured Car (10(RN)AMB, German E. Africa 1916)

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Sat Dec 28, 2019 2:20 pm

Hi Chris:

Thanks for that!

Not going full parade-ground (as the restored gun is now), but more in post-war livery of bronze green. But I am thinking that unless the gun were stripped down to bare metal, it's not going to look like a museum restoration. It will be a highly-presentable paint job, but, for example, I question whether the gun would have been turned up-side-down to paint every niche under the trail? Would the insides of the wheels themselves have been painted (even from the factory?) or left in that heavy read high-lead primer so prevalent on pre-war and even early post-war British vehicles.

I would bet that the barrel was probably treated the best. But that the rest was largely brushed and brushed 'over' a wire-brushed finish where the loose rust and scale and paint were removed with aggressive wire brushing and 'picking' but if you looked close, you saw layers.

Thanks for the input! As always, always learning and always valuing comments!

Cheers,

RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Mon Jan 06, 2020 8:30 pm

So only got a few hours in this weekend and ran out of time over Christmas week to get as much done as I wanted. But, really, all I need to do are some linkages and final assembly.

My marathon riveting session Sunday resulted in all the rivets being fitted. And I got primer on 'most' of the trail as well as primer and paint on the shield, sight and wheels. The paint is Land Rover bronze green, which is dead nuts on, despite the funny hue that the LED lights in my shop give it on 'film.' In person, the colors are right on. For our American builders who have trouble getting Land Rover Bronze Green in rattlecans, the paint I bought is from Pangolin 4 x 4 center in Oregon/PNW. It is not inexpensive, but it is a perfect match and is nicely done and fast drying. It went on fine over SEM self-etch rattlecan basecoat which works great on the aluminum, steel and yellow metal.

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here is the trail 'almost' finished. I need to add a few more details and then give it one more coat of primer before starting the paint. Everything has been pre-assembled at this stage. So I know it all goes together! Order of assembly is very important with these kits! As is pre-fitting... and check, verify and recheck!

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Wheels and turntable painted in a first coat. Did the wheels 'assembled' by priming first and then masking before color. The 'back' of the wheels is still in red primer with hints of desert tan. Of note, some research on the actual Mirbat gun... it was not British at the time of the battle. It was owned-by and maintained by the Omanis and had been given/sold to the Sultan as part of the BATT supplies and arms purchases. As such it was not necessarily being kept up to British standards. In fact, during the battle of Mirbat, the Fijian trooper Labalaba, who was servicing the gun himself until he was killed, was yelling at the Omani troops to "Come out of the barracks," which were less than 20 feet from the gun... to help him. The Omanis stayed hidden through the battle, even though they should have been manning the gun and manning the line with the SAS. But I digress. One thing that I am taking into account in painting is that there are some pictures that appear to show the gun with 'tan' wheels, but a green carriage and barrel. But the 'tan' could also be dust from the Omani desert that is built up inside the wheels. At this stage, I am going with that explanation and will do my 'weathering' accordingly to include a lot of tan/dirt inside the wheels themselves.

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Last, the shield. I ended up having to spend a few minutes on Sunday turning the hinges around as I had them all in backwards, so the shield went backwards, not forwards. Oops! Problem corrected with lots of little nuts and bolts having to come off. But all good! Remember my point about check, recheck and re-verify?

Now off to learn how to weather things properly. Because that's going to be what makes this final model!

Cheers,

RPR

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by simon_manning » Mon Jan 06, 2020 9:27 pm

Interesting, and clever workmanship, great to follow, regards simon manning.

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Re: Starting my 25 Pdr... Mirbat Gun.

Post by Robert Reid » Sun Jan 26, 2020 8:51 pm

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Shot some more paint. The LED lights and flash make the green look all wrong, and the photo looks kind of goofy. But in person, it looks great.

Going to have to do another coat before assembly and weathering. But it's pretty good!

Cheers,

Sirhr

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