Relum/FEG LG527

Hi everyone, I'm new to these forums and looking for a bit of info and advice, hopefully from someone that owns an LG527.

Ultimately, my questions are...
- Should I ditch what seems to be the rattly but well performing double spring for a new double/single spring that hopefully won't rattle.
- Why were double springs fitted, when single is now the norm?... chatbots gave a more thorough/convincing answer to search engine results but I don't know if it's a reliable answer.
- What were the original/expected ft/lbs of the rifle? I'm measuring 9.5-11.5 ft/lbs, which must be wrong (!) but I've done an audio test many times... 550fps (aprrox 0.023-0.025s to hit a target 4m away) with a 14.89gr pellet. Somewhere someone linked a Relum/FEG catalog/brochure but I now can't find the link.
- Age? The serial number is 36xxx
- Any other info out there worth knowing about the rifle? Was it possibly purchased at a time when 12ft/lbs wasn't the max? I'm confused by the measurements I'm getting, but I'm quite sure they are right.

The story!
I found my old air rifle in a rusty, pitted, bent barrel state not long ago and decided to try to clean it up to re-live lots of childhood fun. This thing was bought second-hand >35 years ago and other than a bit of 3-in-1 on the breech seal (25 years ago, most recently) it hasn't had any maintenance done to it.

After what started out as delicate barrel straightening and light rubbing down with 1200 grit sand paper it ended up in a vice with a file, g-clamps, lump hammers etc etc but now it's re-blued and hitting Smarties and smashing terracotta pots at 20 yrds, consistently. I'm mightily surprised it's working so well, still.

But it still hasn't had any maintenance to the mechanism. I'm planning on changing the breech seal, piston washer, greasing etc but I'm wondering about the spring. I believe it has a double spring. Proteksupplies have a replacement set of double springs that is said to be of higher specification than the original. I have also learned a Titan XS No7 will fit. Has anyone tried either? I'm wondering because the fps (at least for how I can measure it) seems good, but it rattles a bit.

Thank you for any replies.

Have a search on here, I've got a thread where I've restored a couple of these and so has @Danthepainter . Quite surprising little guns when fettled correctly.

Here you go.

Yep they're nice little rifles and a perfect first tinkering project. Wouldn't part with mine ever.
As @Landyman says, they are very easy to work on, just photograph everything as you go. Since I put my overhaul thread up I've done more to it. Yes ditch the double springs, they're pointless. A HW30 mainspring is a good replacement. If the piston seal is ok then it only wants cleaning or you can get a replacement from Protek Supplies.
Lately I've lightened the piston in mine and fitted a 26mm @Brit Seals. It's a simple job but first things first- take it to bits, clean everything and see how it goes. It's a 5-6fpe rifle in good fettle so yours is burning something internally. I have seen this before. When I got mine the first two shots registered thus- 19.1fpe, then 2.2fpe. It was in pieces on the bench straight away.
Here'a few photos of mine-

I finally got around to taking my LG 527 apart, after it was dieseling and seemed to be getting worse. I had never taken an air rifle apart before so was a little nervous.

I had put it over the chrono and was getting around 10 Ft/pd.

It was easier than I thought to pull apart. The insides were coated in think black grease, which absolutely stunk. Cleaned it all down with brake cleaner and found that the piston had the original leather seal, and surprisingly in good condition. So leather oiled as it was in goood condition.

I did look at other spring options, but thought I’d stick with the original. I think I was worried it wouldn’t be the same, as the rifle is really sentimental.

So all cleaned and re-greased with the proper stuff this time, double spring checked and put back in.

I fired about 20 pellets through it, the first few did diesel, however quickly cleared. Quick clean of the barrel and then back on the chrono. I was surprised as it did fluctuate between 7 to 8ft/pd but I’m sure it was settling more towards 8.

Anyway I was glad to take it down the range and it did shoot a lot better. No more dieseling and no harsh recoil and a big smile on my face.