Springs vs rubber rings

[Svensontini]

Hi Guys,
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I've been using the rubber castration rings for bumpers on my bump keys, but I see that ukbumpkeys has actual springs, as well as rubber washers.
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They posted here on this forum about them in this thread:
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https://www.lockpicking101.com/viewtopic.php?f=3&t=18381
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In which they describe them this way "We're calling it 'spring-bumping' or 'bouncing' and it involves inserting the bump key through a small compression spring (wire width 1 - 1.5mm , wire length between 3 - 8mm seem to work best). Then you've basically got a semi-automatic bump key. here's a nice pic of one of our keys with a LOXPRING (our name for them) over it."
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A spring of that specification isn't easy to find, and loxprings are a bit pricey (but not terribly).
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Has anyone tried using them vs the castration rings?

[Svensontini]

OK, went looking for a suitable spring and I think I found one.

We need a spring with:

*) An inside diameter that will let most key blades slide through. Of the keys I had on hand, most had a key blade width of somewhere around .350".

*) A wire diameter of 1 to 1.5 mm, which is .039 to .059 inches.

*) A spring length of 3 to 8 mm, which is .118 to .315 inches, however the length can be longer as they need to be trimmed for a proper fit anyway.

I took a look on fleaBay, and found item # 232383636866. It's a spring that's 7/16" outside diameter, 1-1/16" long, and made from wire that's .041" in diameter. The brand is Prime Line, their part number is SP 9721, and the UPC is 049793097217.

*) With a wire diameter of .041", that should give an inside diameter of around .397", which should work with most keys fine.

*) The wire diameter is in the range we are looking for.

*) The length is a bit longer, but again we'll be cutting it to fit anyway, and we should be able to get two springs out of each one.

It cost me $4.70 delivered for a pack of four, and remember they can be cut in half, so I should get eight usable springs, so about fifty nine cents a spring. Cheap enough to give it a go and see if they work better than the rubber castration rings. I'll post back after they arrive and I play with them a bit.