M5 thread repair needed, looking for engineering company in the Peterborough area

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Hi all, I need an M5 thread, tapped into aluminium, repaired on the bottom rail of my air rifle. In short it's a piece of ali U channel formed from approx. 4-5mm thick material and one of the threads stripped due to the screws barely being long enough to engage in the metal! I've been advised on the airgunBBS that Timeserts are the best insert to use but buying a kit just to do one thread is prohibitively expensive as they're around £95. Do any of you know of an engineering company in/near Peterborough who could do this? I know I can ring round but I thought I'd ask in case there was anyone who could recommend someone.
I'm going to look at if it would be possible to fit an M6 screw with the heads turned down to fit the countersunk holes in the stock but would rather go this route as it would be less hassle for me (I think!).

 

[BrokenBiker]

Just out of interest, what air rifle is it? I had to do a similar repair to an air airms s410 I bought

 

[BrokenBiker]

Also, helicoils are cheap to buy, easy to instal and as they are stainless they are a much stronger thread than Ali...you don't have to worry about galvanic corrosion either as it will never come out and you get to keep the OE fastener

 

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Funnily enough it's an Air Arms Pro Sport, I'd always thought that they were better made than this but I'm starting to wonder. I had the trigger assembly off yesterday to polish some of the sear faces (as advised on the Air Arms forum) and it definitely seems to be out of sight out of mind with some of the components in there! The damaged part is the base for a screw-on assembly which attaches the cocking lever to the cylinder and it's one of the screws which hold the stock onto this part which has stripped the thread. I wasn't too sure whether their practice of Loctite-ing the screws is was advisable, as a steel thread in ali is surely always going to damage the softer metal when removed?
I very carefully removed all four screws I'll have you know pdg Since one of the screws had been drilled through it's centre (really can't fathom the reason for that?!) I can only assume that at some point the stock has been off, so if anyone's been heavy-handed it weren't me guv!
I was again advised, this time by the airgunBBS, that helicoils tend to wind out again when you remove the fastner, hence the recommendation for Timeserts. I had looked at Keenserts but they need a minimum metal thickness which I haven't got. If the consensus is that helicoils will be OK I'll look at getting a kit. Do I need a minimum metal depth for these or is it a case of 'try it, you should be OK'?

 

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Oi, I wasn't accusing you Maybe the machine that put it together in the factory...

Uhhh huhh, 'ere we go, backpedallin' now 'ees been caught out!! (just so everyone knows, I am now kidding)
I suppose with Helicoils it's the same as everything else, you've said you had a Timesert come out, others have said the same about Helicoils. It probably comes down to how well they were fitted in the first place? When I've a bit more time I'll have to have another look and a think.
Brokenbiker you said about keeping the OE fastner, I'll have to get some longer ones (there's room to do so) to make sure the same thing doesn't happen again.

 

[500e]

Always used Locktite on helicoils just a drop on finger then wiped over mating surface or a drop on a cotton bud & wipe the parent thread have had them come out on magnesium gear casings

 

[Shox Dr]

You dont need to buy a kit, just one insert will do. Drill to size and press in.
I'wouldn't use a helicoil because of the material thickness.

As 500e says drop of thread lock.

 

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The material thickness is one of my worries, d'you think I'm wasting my time trying to repair it? The other thing I thought about was to chemical metal the hole and then re-drill and tap?

 

[Shox Dr]

Picture would help. Is there clearance on the back to reinforce. Have you spoken Air Arms

 

[BrokenBiker]

Funnily enough it's an Air Arms Pro Sport, I'd always thought that they were better made than this but I'm starting to wonder.

My air arms was the reason I stopped shooting air rifles and moved to rimfires. I already had a .22-250 and a shotgun when I had the air arms but the amount of problems I had with it was unreal and it was cheaper to buy a cz452 than to keep messi g about with the air rifle

 

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The annoying thing is that I had an Alros Trailsman, the 400cc buddy bottle 8-shot model, and I sold it as I was bored and had heard about the legendary Pro Sport and wanted to try one. Now, part of my trouble may be down to a less than competent previous owner, I don't know, but the finish on some of the trigger components is making me think I've made a bad purchase. I'll get this fault fettled and keep it for a while, but if I get too many more problems I'll be looking for something else.

 

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Managed to get this sorted, I bought some longer stainless screws from a supplier in Peterborough to replace the two rearmost ones and fitted them, dunno whether it was the extra length or better-quality screws (?) but they tightened OK. The two at the front I bought two stainless screws the same length as the original ones and filed 2mm off the ends and they now fit flush with the inner face of the rail when tightened to don't bottom out against the underlever stop. Need to have a play with the adjustable stock and get some pellets through it to get used to the best hold etc