I'd like to know if the fallout wiki is accurate on this point : when I have a deathclaw gaunlet 100 % repaired, 7 in luck + finesse + ninja, I should be at 7+5+15=27% base critical chance. the gaunlet has a x5 critical multiplier so I should do critical on every hit, right ? I don't. is there a cap or something ?
the wiki also state the total chance as
critical chance =base chance x critical multiplier x weapon condition%, so I took the test with my novasurge nearly broken, let's say less than 5% condition, but I still did something like 20% criticals wich is way more than it should as the wiki state it... so is there a minimum critical chance ?
if anyone could enlighten me...

I always figured the critical multipler was the damage multiplied when critting instead of the chance to crit, but I have to admit I've never looked into the math of Fallout 3

that makes more sense. it's normally 3x or something.

there is a value added to the normal damage when a critical happens, all is explained here http://fallout.wikia.com/wiki/Fallout_3_weapons

I spotted some inaccuracies, though

Yes but most items has a critical damage pretty much like the normal damage. How often do you get a critical with the deathclaw gaunlet? half the time, more or less, I have never thought about the critical multiplier before.
Might be an error in the official faq or even the manual like oblivions luck affect loot who was wrong.
The effect should be very visible for you because the large base chance with ninja so the difrence between the gauntlet and a power first with 1x critical multiplayer would be very visible.

it is visible indeed. I have something like 75% effective critical chance with the gaunlet, much more than with the power fist. but it should be 100%, according to the wiki...

My guess is that it has 3x critical multiplier, does not have the geco installed now but it should be in it stats, however it might be other issues like the 85% cap on armour.
perhaps I should leave this issue to my character who have 100 in science but it's fun to figure things like this out.
I might want to reconsider sniping rifles found Lincolns repeater more useable but it look like they would do more average damage because of the 5x critical multiplier with luck 9, lucky 8 ball and finesse I would hit critical 5*(9+1+5)=75% making them far more formidable.

don't forget he wiki states it depends to the weapon condition, too. I tested it with my novasurge, so your calculation is ok for 100% condition on your Lincoln but your critical chance SHOULD be halved for 50% condition.

haha case solved.

Condition is 90-100%, a easy weapon to fix with hunting rifles.
One other thing I react on is that full auto weapons has a very low chance of critical, vengeance has only 0.05*15= 0,75% chance for critical, however it leaves ash heaps far more often perhaps 10% of the time. yes a critical does more damage but not so much more that the kill shot would be a critical hit 10% of the time, vengeance is also seldom fully repaired.

I usually find the wiki to be accurate, but as you pointed out, it has it's flaws.