I'll disagree somewhat with the post above regarding triggers based on experience with a number of Ruger .22 LR pistols. Ruger has its fair share of variation in quality of trigger pulls, but:
in general,
- Ruger Mk II triggers are better than Mk I triggers; and
- Ruger Mk III triggers are not as good as the Mk I and II triggers.
However there is a enough overlap that some Mk I triggers will be better than some Mk II triggers, and vice versa.
Plus the Mk I Target Model was around a long time before the Mk II showed up (1950-1982) and the Mark I Bull Barrel Target was around for almost 20 years before the Mk II showed up (1963-1982). Which means there was ample opportunity for Bullseye competitors to have the Mk I triggers worked on, before aftermarket triggers became common.
You'll find the Mk I Target models with the 6 7/8" heavy taprered barrel, the rare 5 1/4" heavy tapered barrel, and the most numerous 5 1/2" bull barrel models with both plastic and wood grips, as wood grips were a factory option as well as an aftermarket accessory.
MK I Target with 6 7/8" barrel (T678), and Mk II Bull Barrel Target with 5 1/2" barrel (MK512).
Only 1 of the 4 pistols above still has the original trigger, as it was already quite good when I acquired it. The others all have Volquartzen target triggers and sears. You can buy those parts for about $70 total and install them yourself. The produce an excellent trigger pull and it incorporates an adjustable trigger stop.
I tried the Volquartzen lightweight hammer and firing pin 15 or so years ago and encountered problems with light strikes. It theoretically improves the lock time, but the lighter, faster hammer also has less momentum. However, your experience might be better than mine depending on your pistol, and your ammo.
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I like the way the 6 7/8" heavy tapered barrel Mk Is and II's balance, and they will shoot just as well as the much more common 5 1/2" bull barrel pistols, with the benefit of a longer sight radius. The weights on the two pistols are almost identical as the slight taper of the T678 offsets the extra length.
And $339 is a very good deal for a T678 if it's in very good to excellent condition.