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The original (G1)Contender was introduced in 1967.
The G2 Contender was introduced in the late 90's, after the larger-framed Encore was introduced, and is basically a G1 Contender with a reinforced frame & an Encore trigger group (which some folks prefer & some hate).
You apparently have an early stainless G1, which (as stated above) will accept any G1/G2 barrel except that:
*Barrels for the original G1 Contender may be used on the later-released G2 Contender.
*G2 barrels may be used only on original Contender frames with a serial number greater than 195000.
G1 & G2 grips are not interchangeable between the two frames, due to the difference in the respective grip frame angles.
So, you should be good to go, vis-a-vis mounting extra barrels, except for the noted Armoralloy barrels.
The original Contender designs also have an adjustable trigger, allowing the shooter to change both take-up and overtravel, permitting user selection of a range of trigger pulls ranging from a fairly heavy trigger pull suitable for carrying the pistol while hunting to a "hair trigger" suitable for long range target shooting.
Unlike the later G2 Contender, the original Contender may be safely dry-fired (provided the hammer is not drawn back from the second notch) to allow a shooter to become familiar with the trigger pull.
The break-action only has to be cycled, while leaving the hammer in the second notch position, to practice dry-firing.
My fave, of the 8-10 Contender's I've owned over the years since introduction, was a G1 that I mounted a special-order T/C Custom Shop (the old Fox Ridge Outfitters) Super 14 barrel w/Muzzle-Tamer on, in .375 Winchester.
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