Swing Rifles - History for Wikipedia

[R.G.C]

Swing f pin.jpg

swing bolt.jpg

The easy way to make the Swing bolt open easier is to replace the huge firing pin spring with Belleville washers. It's an easy conversion, and it transforms the rifle's useability. The washers can be obtained from HPS-TR. Approximately 60 are required.

Pete

But then you'd loose that almighty twang as you fire it, something several people shooting alongside me have commented on. But I can admit to being tempted by the Belleville washer conversion to make opening the bolt a little easier.

To the best of my knowledge on the principle of the Belleville Washers use, I feel the number of 60 washers quite excessive and reveals most certainly inadapted characteristics of the washers used.
The C.G-RPA, Quadlock and Millenium used originally 35 washers 12,5mm OD for a FP travel of 4mm.
There was also a model using only 26 washers 16mm OD for the same 4mm FP travel. This one was an ideal solution and I believe this washers diameter could be adapted to the Swing, subject of the internal bolt tube diameter allowing?
The Swing firing mechanism suffered of some misconceptions :
-1-Too strong F.P spring, with an enormous rate imposing a big force to move from decocked to cocked lenghts.(L1 to L2).
-2-Too long F.P travel (.6,35)
Points 1 and 2 above are in close relation for cocking force, added to the 50° of bolt rotation and increased friction additions.
-3-The excessive effort on cocking, exerted on the right side (R/H action) of the sear pin bearing only via a small tangential contact on the raceway slot make the too soft receiver steel to wear at this point. Only solution is to remachine the slot and adopt a new sear pin with larger bearing surfaces.
Not having a Swing FP assembly at hand, I cannot determine the ideal Belleville washers ‘Power Pack’ number and dimensions needed.
I have done the transformation in the past, but do not remember the details.

R.G.C

[Pete]

The Bellville washers that I used were "second hand", removed from RPA's that had been "converted" to coil springs. No idea why anyone would want to do that............
The excessive number may be due to them having been stressed in use before I got hold of them.
I decided on the number required for my Swing by trial and error, adding them until the bolt cap just started to compress them at the last 1/4 turn of it's travel with 1.6mm of firing pin protrusion.

They work brilliantly................

Pete

[shugie]

I can get a bag of 30 washers from here - http://www.springfasteners.co.uk/depart ... e_washers/

The 16mm OD washers have an ID of 8.2mm, and thickness of 0.4 to 0.9mm, which thickness is likely to be most suitable for up to 30 washers? And is the ID of 8.2mm ok?

[R.G.C]

The Bellville washers that I used were "second hand", removed from RPA's that had been "converted" to coil springs. No idea why anyone would want to do that............
The excessive number may be due to them having been stressed in use before I got hold of them.
I decided on the number required for my Swing by trial and error, adding them until the bolt cap just started to compress them at the last 1/4 turn of it's travel with 1.6mm of firing pin protrusion.

They work brilliantly................

Pete

Pete,
Yes, converting Bellevilles to coil spring is stupid, recommended only by those who make money with the conversion…
There is more users who do the contrary for the same benefit as you mention.

The Bellevilles as you stacked them are compressed a only 50% of their full capacity , therefore, their lifespan is infinite as opposed to the coil spring weakening with age as compressed at 100% of their capacity . I would even prefer already used ones, as they are already set in with mated contact surfaces and this is beneficial.
I understand now the number of ¼ x ½ x .012 you prpbably had to use.

My personal modification long ago was usins (I think to remember) ¼ x 5/8 x .012 as the Swing/Paramount bolt tubes inside diameter allowed. This was giving a little more flexibility and even a little easier bolt lift.

I would need some dimensions to recalculate the datas for both Belleville dimensions.

R.G.C

[Pete]

Here's a more detailed view of my Swing firing pin set up with some dimensions.
I have no idea what impact this has on lock time, but I recently hit 4 V's, 6 5's and 5 4's with 15 shots on an F-class target at 1000yds on Stickledown, fired off a bipod, and with aperture sights.............I'm happy with that !!

Pete

[Pete]

My Bellevilles are 12.5mm OD, and 0.50mm thick. The ID is 6.40mm, and is a snug sliding fit on the pin.
Up to 15mm OD could be used. These would fit into the recesses in the hammer and the rear retaining cap.
A word of caution: if you're going to strip the bolt completely, there is a tiny socket head grubscrew that locks the hammer onto it's thread on the firing pin.
You need exactly the right size allen key to undo it. On mine, it's 1.27mm or 0.050" across the flats. No idea what the thread size is.
Chew this screw up and you are well and truly screwed. It'll be a total pain to drill out as the hammer is hardened.

Pete

[R.G.C]

I can get a bag of 30 washers from here - http://www.springfasteners.co.uk/depart ... e_washers/

The 16mm OD washers have an ID of 8.2mm, and thickness of 0.4 to 0.9mm, which thickness is likely to be most suitable for up to 30 washers? And is the ID of 8.2mm ok?

No, it would not work. Be;llevilles are guided by their ID sliding on the shaft. As this is 6,35 on the Swing, a
8,2 ID would not allow the washers to line and center perfectky and would hang in the tube with their OD.

I may cone with a solution if I I can obtain the OD of the two collars front and rear of the spring, or the ID pof the bolt body tibe.

R.G.C

[Pete]

Robert, the collars are 17.65mm OD. They are recessed-the recess is 15.45mm diameter, and approx 1.5mm deep. (I measured without dismantling).
Despite it's age, the collars are a perfect sliding fit in the bolt body.

Pete

[R.G.C]

Robert, the collars are 17.65mm OD. They are recessed-the recess is 15.45mm diameter, and approx 1.5mm deep. (I measured without dismantling).
Despite it's age, the collars are a perfect sliding fit in the bolt body.

Pete

Pete, Thank you. It appear your stack is 56 washers and this give an enetgy of some 145-150 Newton. Theoretical kocktime 1,8 ms.

R.G.C

[Pete]

I have often wondered why the front collar (hammer) is hardened steel. Would it not have been easier to achieve a short locktime by using a less massive material eg one of the hard aluminium alloys, and a softer spring? I might try that..............

Pete