Hey all so I looked through the forums to be sure that this wasn't already covered.
New to gunsmithing myself and I'm buying tools. I have the Magpul armour wrench (wow, great product) and on the back of the wrench there are torque specifications for flash hider, castle nut, and the barrel nut. For these things, do you actually need a torque wrench? Most videos I've looked at I have seen gunsmiths eyeballing (not using a torque wrench) to tighten their castle nut, barrel nut, flash hider etc. There has to be something I'm missing here, is there a way to know what torque you are using with the Magpul armour wrench?

Secondly, I am about to put together my stripped lower receiver.... Have any of you really needed to use a file to get all the pins in correctly? Any tips?

Thanks.

I do not have the Magpul wrench but in the picture there is a 1/2 hole to put a 1/2 inch torque wrench on.

I've never had to file on an lower parts to get them to fit. Should be a matter of pressing/driving the appropriate pins in place, and assembling as laid out in the thread stickied within this forum. As for the torque wrench, you need to attach a torque wrench to the appropriately milled 1/2" slots in the tool. And, you should make sure your torque wrench is parallel to the wrench when using it. The training manual is pretty specific about that portion, as the torque values given are for the combination of torque wrench and armorers tool first used. Most companies making armorers wrenches now have maintained the same distance from the barrel wrench to the wrench attachment point to preserve the values required. As long as you get it over 30ft/lbs, you're good to go and just need to line up the gas tube holes. In my opinion, the other specs aren't as major of a deal. If using an A2 flash hider, it'll be pretty obvious when its installed right, the crush washer will start to deform, and then you just need to align it properly (holes up, no holes down).

File, yes to the end of the split roll pin that almost always has an edge or burr on it and only do the one end that is entering the hole.  If I feel an edge or burr it will get dressed.

I don't use a torque wrench, because the specifications for the barrel nut are pretty wide. Secondly the Flash Hider and Castle Nut, aren't extremely essential, and I just tight them down and them some for basically all of the parts.

Magpul also makes a block that goes with that wrench. to half engages the barrel lugs for holding the barrel.
Flip it over and it holds the magwell on the lower.

Barrel nut always, castle nut if I am going to stake the nut, and FH depends on the requirements of the design.

Barrel nut almost always, it's a large spread but it's kind of important.
Flash hider... not with a crush washer since you'll likely never even come close to 30 foot pounds. With shims or peel washers it becomes much more important. Too much torque and you can constrict the end of the barrel. Probably not noticeable for most, but on a match rifle with good optics and a good shooter it can affect grouping.

Good luck with your build, and with that magpul wrench.

When I first started building I bought the magpul wrench as well, so far it doesn't get much use. I use a lot of BCM muzzle devises and the magpul wrench is too thick to fit on with them. Also with the closed ends the mapul wrench will not fit over AR pistol buffer tubes.

When it does fit and work I do use a torque wrench.