RWS Diana 52 - tuning update...

[Hellequin]

A bit of an update on my tinkering with the 52 'Ultra Carbine'...

A few weeks back I posted this thread: http://www.airgunbbs.com/showthread....tuning-options asking for advice regarding 'fettling' my 52K.

When I got the rifle it was standard and, as far as I'm aware, had never been apart. It was in great condition but when I chrono tested it I was surprised & a bit disappointed to find it was only doing a shade over 9ft.lb power wise with Superdome pellets. It was also a bit twangy, hence my original post on the linked thread.

As already discussed on the original thread, there are quite a few options for this rifle with varying costs & levels of work/expertise required. I decided to go for a 'home tune' option and bought a Tinbum kit and some new seals. In the kit is a tophat, spring guide, washers, lube & a 'Diana Export' spring. I also got from Nick one of his prototype short stroke extensions for the 52, but more of that later...

Whilst the rifle was apart I discovered that the breech seal was damaged so I removed it to fit a new one. I also removed the 2mm transfer port restrictor. This allows the rifle to breathe through the original size 4mm TP.

Unfortunately, once the Tinbum kit was fitted (without the short stroke extension) the resulting chrono test was a bit scary, as the ft.lb number started with a '2'... Given I no longer hold a FAC, it came back apart there and then.

I decided to rebuild using the short stroke extension, which is about 20mm and to take two coils off the spring which came with the Tinbum kit to see how I went on. Bear in mind that the spring in the kit was about 30mm LONGER than the spring which had come out of my rifle and had 33 coils total...

It was still way too hot, although it had reduced power by 3ft.lb. It came apart again and another 3 coils removed. Rebuild, test and.... still hot! I was getting somewhere though as it was down another 4ft.lb. The rifle was stripped again and another two coils came off, by which time I was getting worried that the spring was going to be too short. I was also getting fed up of re-finishing & polishing the end!

I put the rifle back together with the spring now measuring about 235mm and down to 26 coils. Very little preload compared to the original as you can imagine, so it was much easier to assemble. The chrono test at last put a smile on my face; an average over 10 shots of 590fps with 14.5gr Superdomes meant 11.2-11.3 ft.lb!

A lot of work but worth it to keep the rifle 'legal'. I'm now going to put another couple of hundred shots through it and then test again. If the power rises slightly there's room to leave it alone and if it drops I can add a preload washer or two. Firing cycle isn't bad (I'm sure it'd be better with a 22mm conversion, but that's over £200's worth of work) and certainly miles better than the twangy thing it was when I bought it. The rifle is in good nick cosmetically and accurate, so it deserves a bit of effort, I reckon.

A few points to bear in mind:

1. These rifles are BEASTS. If you're going to tinker, it goes without saying to make sure you use a chrono and if you remove the TP restrictor you WILL need to make other adjustments, either a different spring, short stroke or both. BE CAREFUL & stay legal.
2. I got some good info from a blog by Tony Leach (Airguntech) detailing his work short stroking a 52. He's done much more since then with 25 & 22mm conversions but his short stroke info was what I was interested in. Bear in mind though that my 'prototype' SS extension from Tinbum was only 20mm whereas Tony used a 38mm extension along with a standard Diana 280 spring which he still shortened by 2 full coils.
3. Firing cycle. It's still not as 'smooth' as I'd like (but it is much better) so I'll see how it beds in. It may be that the spring is now too short and it might be better with a short stroke of 38mm and one of those shortened Diana 280 springs which Tony used, although to be honest if I had more work done to it now it'd be the full 22mm conversion.

Anyway that's it done for now and I can at least enjoy shooting it, until some other toy catches my eye...

[TonyL]

Nice post, sir.

As you say, maybe good to let it all bed in and see how you get on with it. Reducing the stroke more and going for a different spring may well give you a quicker feeling shot cycle of that's what you prefer. However, many "lazy" feeling guns can be very accurate and forgiving.

[maximus]

Nice post. I did mine a few years ago, it has a 37,5mm extension with an o ring as the seal. Mine is 177 and still made power like no other gun I've had before (including the HW80).
Mine has a short stiff spring in it now, the piston was lightened bearings added and all sorts. Took a lot of stripping and re-assembling to get it where it is now. Finding the right spring is quite a lottery in my experience. Here's a pic.

Regards

Max

http://i953.photobucket.com/albums/a...diana52003.jpg

[tinbum]

Great! Now I want another 52....

[jonnyone]

Nice post. I did mine a few years ago, it has a 37,5mm extension with an o ring as the seal. Mine is 177 and still made power like no other gun I've had before (including the HW80).
Mine has a short stiff spring in it now, the piston was lightened bearings added and all sorts. Took a lot of stripping and re-assembling to get it where it is now. Finding the right spring is quite a lottery in my experience. Here's a pic.

Regards

Max

http://i953.photobucket.com/albums/a...diana52003.jpg

Thats a mighty fine looking gun. Its good to see one "dressed up".
As has been found out above the Diana 52 was the answer to HW80 in the power crazed yesteryear..
But equally they can.be throttled back and customised to be a very practical and aesthetically pleasing shooting iron.
Dave

[maximus]

Thats a mighty fine looking gun. Its good to see one "dressed up".
As has been found out above the Diana 52 was the answer to HW80 in the power crazed yesteryear..
But equally they can.be throttled back and customised to be a very practical and aesthetically pleasing shooting iron.
Dave

Thanks, it's a shame GinB are no more, they did stocks for many models not covered by other manufacturers.

[Hellequin]

Thanks for the replies gents, and Maximus that's one tidy looking rifle you have!

I think longer term I'm going to aim for some serious work on this rifle, probably a 22mm conversion done by Tony Leach as that work is beyond my skill & tool set.

I'd probably have preferred one in .177 if I'm honest but these 'Ultra Carbine' models don't seem to come up very often so I was just happy to get one in good condition.

I've just bought an LGU in .177 which is pretty clinical for a springer, but I much prefer the looks, balance and character of my 52. They're just bloody cool.

[jonnyone]

Thanks for the replies gents, and Maximus that's one tidy looking rifle you have!

I think longer term I'm going to aim for some serious work on this rifle, probably a 22mm conversion done by Tony Leach as that work is beyond my skill & tool set.

I'd probably have preferred one in .177 if I'm honest but these 'Ultra Carbine' models don't seem to come up very often so I was just happy to get one in good condition.

I've just bought an LGU in .177 which is pretty clinical for a springer, but I much prefer the looks, balance and character of my 52. They're just bloody cool.

Morning Bob. I should also have said in my post above that your account of your tuning project was very informative. These guns are very.much worth the effort and I think they are the Cinderella of the extensive Diana range of guns.
I recall the ultra carbine being sold off very competitively last going off and were real.bargains. Not sure they got produced in .177 though? With the carbine barrel they would definitely need to.be tweaked to get the best of them, but again, more than worth the effort.
I too have read of the amazing conversion Tony has done on these guns and others and can imagine they transform them. Stepping up a gear, I would guess his work to the 54/56 series guns would make them sublime and in my books would make any gun converted that way to be the ultimate progression of a springer action.
Would be good to hear.more feedback as to how you are getting along with your new shooting companion.
Dave

[Squirrelking]

I have a 22mm Tony Leach conversion on my .177, lovely it certainly is. My problem is the lead in on my barrel is well out meaning I can't seat the pellets properly, looks like the only option is rebarreling (ouch!) unless someone has the tools and expertise to sort it as is.

Not to worry though, I have another in .22 on its way so will swap the mod over and see what happens.

Also agree that blue seals are the way to go, SWS sell them and regularly get new stock in so if you did want to do a T06 conversion then you shouldn't have too long to wait. Both mine are T01 though so I've been lucky in that regard.

[Hellequin]

Morning Bob. I should also have said in my post above that your account of your tuning project was very informative. These guns are very.much worth the effort and I think they are the Cinderella of the extensive Diana range of guns.
I recall the ultra carbine being sold off very competitively last going off and were real.bargains. Not sure they got produced in .177 though? With the carbine barrel they would definitely need to.be tweaked to get the best of them, but again, more than worth the effort.
I too have read of the amazing conversion Tony has done on these guns and others and can imagine they transform them. Stepping up a gear, I would guess his work to the 54/56 series guns would make them sublime and in my books would make any gun converted that way to be the ultimate progression of a springer action.
Would be good to hear.more feedback as to how you are getting along with your new shooting companion.
Dave

Thanks Dave and you're right that the 'ultra' carbines were sold off at cheaper prices but in .22 cal; I think Tony mentions that too in one of his blogs.

For me the really short barrel does add to the good looks (I know some folk think these sidelever rifles are ugly no matter what) regardless of any extra issues performance wise. I've always liked them & fancied one but never owned one until this came along. If I have any more done to it or tweak it further myself I'll certainly put another update on here and, I keep meaning to and haven't yet but I really must get along to a boinger bash next year, so I'll bring it along if I finally make it to one...

[Phil Russell]

A very nice read, thank you.
I note the original TP was 2mm but you removed 'the plug' to reveal the 4mm. Then the high power issues set in.
I wonder: could you not have tinkered with the TP to get what you wanted ... maybe trying 3mm or 2.5mm etc? I am sure there must be a good reason ....
Interestingly my daughter has a 52 at about 11.5 and it is really quite pleasant. I do not know the TP size but can say that we have never changed it.
Maybe way off topic but I had a 'Chuntsman' ... Chinese version of the Huntsman Mk2 ... that had consistency and low output issues. The TP was quite small (sorry can't remember now, maybe 2.6mm?) so I experimented with ports of different diameter ... they were simple delrin, drop in units easily made on the mini lathe. I seem to recall that 3.5mm went hot and I settled eventually on maybe 3mm for a nice consistent 11ftlb.
Cheers, Phil

[Hellequin]

A very nice read, thank you.
I note the original TP was 2mm but you removed 'the plug' to reveal the 4mm. Then the high power issues set in.
I wonder: could you not have tinkered with the TP to get what you wanted ... maybe trying 3mm or 2.5mm etc? I am sure there must be a good reason ....
Interestingly my daughter has a 52 at about 11.5 and it is really quite pleasant. I do not know the TP size but can say that we have never changed it.
Maybe way off topic but I had a 'Chuntsman' ... Chinese version of the Huntsman Mk2 ... that had consistency and low output issues. The TP was quite small (sorry can't remember now, maybe 2.6mm?) so I experimented with ports of different diameter ... they were simple delrin, drop in units easily made on the mini lathe. I seem to recall that 3.5mm went hot and I settled eventually on maybe 3mm for a nice consistent 11ftlb.
Cheers, Phil

Hi Phil, yes the TP restrictor probably could have been taken out to 3mm but it is a REALLY thin piece of metal which sits behind the breech seal. Apparently TR Robb does one at 3mm but I've not been able to order it (or find it specifically) via his website and nor have I got hold of him on the phone, so I gave up!

As said earlier, I think I'll shoot it as it is for a while then likely send it to Tony Leach for 'the works' doing.

All the best

[Squirrelking]

IIRC the blue ones from SportsWaffen are 3.5mm, there is only one size now. If I remember tomorrow I'll measure my spare for you when I'm up the loft.

[Phil Russell]

Hi Phil, yes the TP restrictor probably could have been taken out to 3mm but it is a REALLY thin piece of metal which sits behind the breech seal. Apparently TR Robb does one at 3mm but I've not been able to order it (or find it specifically) via his website and nor have I got hold of him on the phone, so I gave up!

As said earlier, I think I'll shoot it as it is for a while then likely send it to Tony Leach for 'the works' doing.

All the best

Seems like a good enough reason. I had imagined the TP plug to be more substantial.
Good luck with it.
Cheers, Phil