I’ve been doing the inspection, disassemble and cleaning of any new firearm purchased. I’ve found the past few years some companies drench the firearm with oil, I believe for sometimes long storage before purchase.
I’ve also found, I think what is some machining dust or grit. One time not long ago I had an acquaintance at the range with a new firearm, handgun semi-auto which would not eject the spent cartridges. I field striped it cleaned everything possible, inspected all parts and workings, reoiled lightly with my best gun oil, reassembled and went back to the firing line.
The firearm operation was flawless from that time on.
I’m only mentioning this so any new folks to our enjoyable sport who may have come across problems with their new firearm and think it might be themselves doing something wrong. It may not be you.
Also, if you are new to using firearms please have a certified instructor help you, it will turn-out more enjoyable and safe in the long run.
Excellent advice. I’ve done this myself for two people that I know who have firearms that they were either unfamiliar with or, who purchased a handgun and left it in the box untouched.
Agree with the above. Some manufacturers may drench the gun with oil for long storage in case the firearm is not purchased right away. You should always check it yourself and wipe it down and clean it before firing it. Then oil it lightly and repeat the process. The firearm will work fine.
Strongly agree with @William377 .
I made my own procedure for every new firearm.
I disassemble and soak them in isopropyl (91%) for 1 - 2 hrs, dry with compressed air, then clean and lube.
This way I’m sure I get rid of anything that shouldn’t be there.
Isopropyl is harmless, removes oils and greases, dries really fast.
No adverse reactions to various coatings? Do you remove grips (especially rubber) or anything else before soaking the frame assembly in alcohol? Do you do anything different with a striker fire vs. hammer pistol?
My understanding is most of the companies coat the oil with a rust preventive coating, not lube. I always take them apart to clean an lube before shooting.
The only parts I do not soak in are wooden or rubber grips and rubber baseplates.
I didn’t find any problems with any kind of firearm’s finishing nor polymer frames. Alcohol doesn’t do anything wrong to them.
No differences between hamer and striker fired handguns. Just be sure it is cleaned and lubed at the end.
The crucial part is stricker / firing pin channel. This one is tiny and has to be cleared from parts before cleaning and drying out.
It looks complicated, but it is not.
But worth evey second spent. The firearm will serve well for next 100 years.
Thanks @Jerzees, there is hopefully a new one in my near future, so always happy to pick up new (to me) tips.
Mass production guns will appreciate isopropyl bath.
I found a lot of debris in there.
The worst was RIA 1911.
The two Staccatos I’m using now were completely clean from anything right out of the box.
Every new tool gets field stripped, cleaned & lubed before 1st round goes down range. RIA 1911 needed the most cleaning…holy crap- that’s a lot of protectant product.
I don’t have a whole lot of experience with this but I can tell you this much,
I was horrified when I unboxed my Kimber EVO, it was bone dry. Made me wonder if they had even fired it… My Ruger LCR, it was nearly dripping, the inside of the packaging was coated with thick nasty oil. Either way, I must agree, a good cleaning before the first round goes down range is an excellent idea.
Some of us older GI types may remember dipping our M16 in a barrel of WD-40, worked pretty good for getting into some of the tight spots BUT I found it impossible to pass a white glove inspection after my weapon had been dipped, you just can’t get all of that stuff off of every part.
WD-40 never worked for me for that purpose. It is what it was designed for - good penetration and water displacement… nothing else.
WD-40 contains mineral spirits and some kind of lubricants… but these were made for specific characteristics to do their job - penetration, water displacement and soil removal (as WD-40 website explains).
Cleaning and lubrication with WD-40 was never good. Perhaps it somehow works but what would be reason to use it if there are better products?
New guns have oil for long storage. You should go uncrate an original Mosin Nagant. The Cosmoline they are packed in is like industrial grease.
I swear I am not making this up, the 1st three pistols I bought new were taken straight to the range and not one of them has ever had one issue.
By the time I bought the fourth new pistol I had been educated it should be cleaned before it went to the range. It is the only one that has ever had any hiccups. 
I will say the cleaning had nothing to do with the hiccups, it is just a coincidence,and I intend to clean new gun(s) before taking to range in the future.
As @William377 mentioned in OP there is always a chance to find “some machining dust or grit”. Even the new firearm is ready to go right out from the box… I would clean and lube by myself before first shot.
Most of new polymer handguns have a huge tolerance for anything which can stick inside… even mud, soil, sand or machining dust will not prevent these tools from firing… 
It just only shorten their lives…
I always clean my new gun when I buy one. I think, similar to what you stated, it helps clean anything that may be left from manufacturing process as well as the think oil that may be on the firearm for rust prevention in storage.
I also like cleaning them before going to the range so that I can understand how that particular firearm is made. Yes, most guns within a specific category are similar, but there are always small differences that could be important to know at the range if there is a malfunction.
I have a Beretta 380 when I first got it had no problems with it at all, that would have been my first pistol. Anyway after that I got a Glock 19, shot that for a while, when I went to shoot my 380 again when you go to rack it it just doesn’t have enough to get the shell all the way into chamber, I can tap it one time and it goes but I know I shouldn’t have to touch it after I rack the first one, I thought it might be the spring? I took it to range the guy loaded it with oil and then tried to say I was limp wrist is why it was doing that, made it home tried again let someone else try still doing it. Would this be the spring or what?
Zane5, when you went back to the .380 did you clean it before the 2nd usage? Our did you change ammunition, from FMJ to JHP or reloads? I’ve found over the years that certain manufacturers of ammunition I use in a few of my firearms their JHP’s don’t Chamber correctly alot of times. These are just a few of the simple first things I would check out.
It started with critical defense hollow points so I thought maybe the Lil teeth on those the only fmj I can find are repack from the guy at the range I will try other ammo. Yes I cleaned it well and oiled I’m pretty sure the guy at range wants me to sell it back to him, I bought it brand new when I took it to him like I said he loaded it with oil the first one did it on him then he did get 2 or 3 off that’s when he tried to say I was limp wrist, I will try ammo first if that doesn’t work the spring was only like 5 6 dollars