Tuning Webley Tempest power tune.

[Steveoo]

Ok its been a bit of a nightmare this one, but drawing on all my experience of tuning pistols I finally powered up a Tempest into 500 fps territory.

The Tempest is a bit of a nightmare. It looks great, hefts well and promises so much, but nobody has been able to easily boost its power...here is why. The Tempest TP travels up through the barrel housing block from the cylinder...a distance of 12mm. It then bends through 90 degrees in this block to travel a further 5mm to get to the breach seal housing. If that is not enough, it then has to include the passage through the 5mm thick seal.

Thats a distance of 22mm x 3.2mm diameter. Coupled with the 90 degree bend, that adds up to the worlds least efficient TP and one of the longest.= lost volume.

Ok this is not a great start and it will reduce any attempts of added preload to little more than a few FPS. Pre loading the mainspring can also increase slam and create extra heat which can cause additional ignition problems with any lubes you put in. It just is not worth the return for the 10fps it might make before additional spring binding occurs. Forget it.

The key to improving the Tempest is to increase its cylinder volume. Its stock cylinder volume is just under 20 cc. This is to say its stroke is approx 60mm x 20mm cylinder diameter. Do not forget to Subtract the lost volume of the ultra long TP....small wonder this is a 3 ftlbs gun.

So...I turned my attention to the cylinder volume. I had a problem in so much that the piston nose is machined with a groove to accept the piston seal. This is unlike the piston nose of its more vintage cousins and a real headache. There is not enough piston length to allow machining off the groove and re-machining an identical groove further along the parent metal of the piston. You will also run out of cocking slot, before the end of the piston collides with the cocking stirrup. Thus...there is no way to keep this pistol as stock design and increase its cylinder volume/stroke.

The only thing left to do was machine off the piston nose groove, doing away with this idea of mounting the seal but revert to drilling and tapping the shorter piston nose to use a 6mm screw and more traditional seal similar to that fitted to the Webley Premier. The new seal machined from Polyurethane.The end result is a shorter piston....or 2.7mm extra stroke.

Going from 457 fps (Avg Hobby) I got 502 fps successfully breaching the magical 500 fps mark i was aiming for. Piston slam is if anything decreased. 

 

[Airgun Advisor]

Excellent write up! I absolutely love those pistols.

 

[vmaxpro]

Wow, where were you when I was a kid! 50fps gain on a little tempest is just too cool! Nice job!

 

[Steveoo]

Thanks, This only happened because it was an old beater that a friend wanted testing to destruction if i needed to.

Since doing the non reversible mod to the piston, he ordered a new Plastic forend and now looking at some wood grips. Sometimes a major re-work like this can breathe new life into an old gun that might otherwise be consigned to the bin...so it was a win win.

The best shooting Webley in my experience was the old Post war mark 1. Before all the seasoned collectors start jumping up and down....Yes I know the Senior was considered the Flag ship model and more expensive in the 50s but the Senior did away with the trigger adjustment in favour of a huge curly polished trigger.. A mistake IMO. The Mk1 trigger can be set at half the weight resulting in much better accuracy. While its leather piston seal had less slam than the Senior Piston ring and Leather seals can be made to function beautifully if you know what you are doing. Later Premiers had seals which take too much of a set and the piston was was way too heavy.

The Mk1 lacked the double cocking linkage which all the other variants had. The idea of the duel cocking linkage was to reduce the strength required to cock the gun.....so have i gone nuts here. Well its been said, but not this time. The duel linkage does reduce the cocking force but the cocking distance is longer. The Mk1 achieves sear at short 90 degrees but the duel linkage requires a long 120 degrees swing, which at some point during this throw, requires you to shift your hand position to make the full 120 degrees. IMO, best described as a lighter but more awkward operation. The duel linkage is also prone to stretching and can jam on the return stroke if this occurs. The little Mk 1 linkage is simple but stouter pull which i prefer. If strong like me its not an issue but if a bit toy armed, I would choose a Premier and try and source a red seal which does not take so much of a set as the teflon.

 

[Luckyshot]

Interesting, but where would the Tempest fit in to your ranking of Webley's? I love my Tempest with the optional combat grips but hate the trigger which pulls like a nail.

 

[Steveoo]

From best to worse....

Early straight grip Stoeger Webley Senior .177....Beautiful in construction and capable of 500 fps stock, due to minimum lost volume of its piston ring position. PB Piston ring has never been bettered in these guns, with all seals since causing issues of one type or another....The Stoeger American importer requested engraved grip to the trigger blade which was a lovely touch..along with Walnut grip and gold pellet medallion.

Early Slant grip Senior, best built and handling Webley ever. Trigger better than the heavy later variant, only marginally pipped by the above gun.

Mk 1...nice adjustable trigger, well made and running a leather seal. Heavy cocking, but nicest firing cycle by far.

Premier Mk1 in its earlier A and B series.....Good gun but piston way too heavy...Plastic seals in these annoying to get running right. Temp sensitive.

Senior post war. Very best engineering ruined by a heavy trigger, but many will place this 3rd..(no strong argument from me.)

Tempest...the best of the cost cutting move from firearm arm grade blued steel to Alloy construction and paint.

Webley Premier Mk2...Poor design appearance, paint which scratched and trigger adjustment issue..

Junior MK1...all steel but no rifling and 100 fps less power.

Junior MK2 alloy and paint version.

 

[Luckyshot]

Great example of an early Webley. I loved the Webley's as a kid in the 60's, drooling over the advertisements in the "Gun Digest". In terms of your ranking of the Tempest, I have no reason or basis to disagree. If the design had not been "economized" , perhaps it would have suffered the same fate as the BSA 240. Even with a healthy dose of plastic, my Tempest has stood the test of time. With the original internals, it still propels 7.9gr pellets 425fps and still retains almost all its original finish. I'll take mine into the hereafter with me.

 

[Steveoo]

Do not forget in my ranking, i am only talking minimal difference between all the models. They were all well made and each will have its fans.

The Tempest, for all its Alloy and plastic, looks somehow chunkier and more purposeful...you can also take advantage of the wood grip options available.

 

[Luckyshot]

I bought the combat grips back in the 90's and love them. Almost not the same air pistol without them.