Gonna put a new key on a new carrier. I have a foot/pounds torque wrench but not in inch/pounds. An online conversion says 55 inch/pounds is equal to ~ 4.58 foot/pounds. That small of a measurement might be a tad difficult to accurately get on my current wrench (which I bought for re-barrelling).
Is it necessary to buy a seperate inch/pounds torque wrench? Not too mention that it’ll be a challenge to get my current one adapted to such a small allen wrench.
Yes, it’s necessary. Even good torque wrenches can be off on the lower ends of their scales. I’ve had good luck with a Wheeler Fat Wrench.
You really need to use an in/lb specific torque wrench. The Wheeler FAT wrench only runs about $50 and works fine for that application.
Yes. Torque wrenches are only accurate in their center+ 70% of range. So if you have a torque wrench rated for 100lbs. then is only accurate between 20 and 90 lbs/ft. For 55 lbs/in you will need a tool with that figure in its accuracy range.
You really don’t need a torque wrench for this. Clean all the threads and then apply red Loc-tite. Tighten them down and stake them.
would a torque screwdriver be easier to work with in the OP’s case?? 
Tighten to the German spec of “gut-en-tite”.
I believe the most important thing here is to stake the fasteners.
Beam type torque wrenches are the most accurate if you decide to get one.
If you have a hard time finding a beam type torque wrench in in/lbs, try a local bicycle shop or an online bike store.
You need a good inch/pound torque wrench when setting your pinion preload on a differential.
See, they’re worth having around. 
I seldom use a torque wrench but when I do, for inch-pounds, I use the one that Manson Precision Reamers sells, I think it’s call the Borka Wrench.
Couldn’t resist Ned…
Agreed. Torque specs are for mechanically retarded folks most of the time.
COMMON friggin sense will get you the right torque on a key fastener. Snug the fastener up… but don’t break off the fastener doing so.
This ^^
True, but anyone serious about firearms should own a good Torque wrench.
Between action screws, optics, mounts, rings, ect, you will need one sooner or later. No reason to fuck up a $3K optic by over torquing the tube.
Check out the Borka. Very highly recoomended in the long ranger/sniper community. Designed by an engineer and shooter.
I was highly skeptical at thought it was silly at first, but am now a beliver. Keep one in my sniper kit and one in my range bag. Trully an awsome little tool.
There are some good threads on it over at snipershide, with input from the designer/maker : http://www.borkatools.com/
I use a Brownells adjustable in/lbs T-handle quite frequently. Action screws, optics mounting, DTA barrel, etc. Useful little guy. I actually use it a lot more than my ft/lb wrench, which comes out for AR barrel, castle nut, and rifle receiver extension installation only.
To convert ft/lbs to in/lbs just multiply by 12:
Exp: 1ft/lb = 12in/lb, 2ft/lb = 24in/lb, etc.
I’m one of those uptight folks who would use a torque wrench.
Sale at Harbor Freight.
$10 for torque wrenches. Any size. 1/2, 3/8, or 1/4 drives. 1/4" is an inch/pounds wrench.
I bought one today. Looks good. Not for NASA, but fine for gas keys, etc.
This link says $15, but they’re 10 bucks in the stores.
http://www.harborfreight.com/1-4-quarter-inch-drive-click-type-torque-wrench-2696.html
Own two borka kits and am very happy. But if you don’t have one yet. As others have pointed out your particular dilemma does not require the utmost precision, so you can get by without.
I bought a Borka kit for use with a precision rifle and have found it very well-designed and useful. It is also very portable. Money well spent.