What does the following mean? "originally made for Purdeys as manufacturers mule"?

Outsourcing.

I won this 10 bore rifle at Holt's yesterday. The Mule part wasn't in the description when I bid on it. Just wondering if it was used to test loads or something?

UNSIGNED IN THE WHITE 10-BORE (2 7/8IN.) FALLING BLOCK RIFLE, serial no. 10010, 27in. very heavy nitro proofed (in 2013) barrel, fixed rifled choke with knurled cap, 2 7/8in. chamber, fitted with a Schmidt & Bender 6x42 telescopic sight, serial no. 236386 on a picatinny rail, plain action, believed to be built by G. Whittome, 15in. figured pistolgrip stock including ventilated rubber recoil pad, no fore-end, weight 19lb. 9oz., in a slip, originally made for Purdeys as manufacturers mule

Light artillery.

Best,
Ted

In English a "Mule" is often used as a factory term for an item that is kept for work in house. By that I mean trying out materials, parts, accessories, testing ideas, looking for issues reported in by customers, in fact any task or investigation that might be needed with that product. It might also be used to loan out to outworkers, suppliers etc for evaluation, trials and learning.

When I was in industry, we kept 'mules' so that new software could be trialled, problems reported by customers investigated, etc. It is a bit like a reference model, but is available to be changed, worked and have ideas and situations trialled.

It’s good to know the term is used the same on both sides of the pond.

My guys just installed a mule for An auto maker..

Essentially, the front half of an SUV that allows them to test the fit of body components, lights, bumpers, etc.
It can be driven around, though slowly.

They also uncrated some kind of a 3-D printer that was 25 feet long.

Makes you wonder what they’re going to do with that.

A manufacturer's mule or shop mule can be anything a company keeps on hand as a fixed asset to aid in their daily operations. It's typically not part of their product line, but rather a necessary accessory, made by and purchased from others, that in some way enables them to do business.

Extreme example: A young woman I knew in the 1980s worked for a major local concert promoter. Her main job was collecting the cheque from the venue on the night of the performance. Another part of her job was, say, collecting Céline Dion at the airport, in style. For both functions, she was afforded the use of the company's shop mule, which was a Guards Red Porsche 944 with black leather interior. I first encountered the term when that very same Porsche was mentioned in an entertainment section newspaper article about the promoter and his company. "Company X is clearly doing all right. Their shop mule is a bright red Porsche 944..." or words to that effect. The term stuck wth me, and I use it at work, to the consternation of some.

All this to say that the term isn't specific to British gunspeak. Its use is far wider-spread.

I agree with John, CZ and Fudd. It implies to me a test device, standard for comparison etc. Until I've seen more pictures of Mike's gun I'm not even going to speculate. I would like to know how much of the bbl is smooth bored, where the join comes and how the transition from smooth to rifled is accomplished, also bore and groove dias of the rifled section would tell us a lot. Any input or ideas????

Likely used to develop the loads for the recent 10 bore paradox gun they built for the chap down under.

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