Questions about tension and pins being set or over set

[Oldfast]

...Is that all I'd need to do to take the pins out, just grind it down on the side like that?...

Yes. It's a 4-pin lock, but when you start grinding, you'll see the outline of 5 chambers...
the last chamber contains a retaining pin (it holds the plug in the lock body). With the goal
you have in mind, I'd suggest grinding only the first 4 chambers & leaving the last one intact.

...If I grind my 141 down like in the photos would I be able to repin it if I could somehow replug those holes?

I suppose you could. Although, if you plan to invest a great deal of your time into making a re-pinnable practice lock...
I would maybe suggest setting your sights on a different lock all-together. But yes, you could certainly do it with this one.

Probably the absolute quickest & cheapest way to do it would to simply reseal the chambers with some tape. lol
The other option would be to thread the chambers and use some set-screws as 'caps' to seal each chamber.
Many people round here have done the latter and have provided some nice 'how-to' write-ups that would
help you get some ideas. Jeff Moss, Xeo, and Logan come to mind... probably many others as well.

Some things to be aware of though....
-You want to maintain about the same spring compression that was originally in the lock.
-Pin diameter can vary depending on the brand. Which is something to consider too.
I'm not sure if the pins in a 141 are standard... but if they're not, you may find alot
of the pins you had wanted to throw into it are not compatible with the chambers.

[subver]

Thanks Oldfast. I was mainly curious.. I've got a few locks I can repin.. I just like tinkering haha.

I think I might check out Walmart when I get out of work today and see if I can find another 140.. this 141 is so easy to open! Not gonna give up on this 140, though, but I think I would be satisfied if I opened another one at least, haha.
Eventually I would like to open it up just to see look the pins right in the eye, the evil little things.

[subver]

Oh by the way.. what would be a good lock to pick after the Master Lock 140? Was thinking of getting an American lock, but I'm not sure which one to get.. and I've been reading about Master Lock buying them out and not using security pins now.. I'm a bit confused as to what to get. Thanks!

[subver]

Well they didn't carry the 140 but I ended up getting a Brinks Maximum Security brass padlock. I know it's a bit out of my skill level but I'll get it eventually! Now I have a new goal

[subver]

So I just managed to pick the Maximum Security Brinks padlock (edit: and I can pick it consistently now).. but I still can't seem to pick this Master Lock 140 consistently! It's becoming my white whale!

I guess the next step is to find some old American 1100 or 5200 padlocks? Then an Abus 83/45? Meanwhile.. I'm still trying to get this Master Lock 140!

[Oldfast]

Congrats on the Brinks Don't let that 140 hold ya up... some of them are just freaks, plain & simple... dunno why.
Ironically, it may have to do with the lack of quality (sloppy tolerances & lack of quality control on their pins), lol
I'd do just like you're doing... stay on the hunt for more locks and more variety, and continue expanding your game.

[subver]

Thanks Oldfast! You've been a lot of help, I appreciate it!
I just called my local locksmith and they said they do carry American and Abus padlocks. I asked him if he knew if the American locks were the newer ones or old ones and he wasn't completely sure so I guess I'll have to take a look.
I can get the Brinks lock pretty much withint a minute consistently now... that's my new favorite lock, I love picking it! Can't wait to get started on an American lock!