Greetings;

I just picked up my first AR15, and finally decided now would be a fine time to join this excellent forum! Any good tips are always appreciated, and I did search for this info before posting this, so please point to specific threads if possible (and thanks!).

I was at a local gunshow this weekend looking for a good entry-level to build up with a couple of friends, but ended up finding a used M&P Sport II (in what I believe is the NJ-compliant version with non-threaded barrel and an original 10-rond mag) with numerous UTG and CAA upgraded parts for under $600 with tax. Took her to the range with a dear friend and excellent shooter, and we put 140 rounds through to test her out after a good initial inspection. Shoots very well, feels great, but had 4 failure-to-fires in the first 100 rounds.

We left the range and tore her down, and discovered a fairly-worn firing pin that needs to be replaced. So, as I search around the web, I see lots of standard replacement pins in the $6-$12 range, and titanium pins for closer to $30. I don't mind investing more money in the better product, but I thought this would make a good first post -- what are your personal experiences with firing pin "upgrades"? If the more exotic pins don't bring extra value, I see no reason to spend the extra ammo cash :-)

Also, just to say -- as a Des Moines native, it was great to see the tributes to the two officers we lost in November, one of which was a member here, and whose posts I would sometimes find as I would Google local gun shops and such. A good group of folks, by all appearances, and happy to have joined up.

Just get a milspec pin you'll be fine

First I would like to see a picture of what you consider a worn firing pin.

Second, just pick up some .mil spec firing pins and you will be fine, there is no reason to spend the extra funds on exotic metal firing pins.

This; pics! I know every company puts out a lemon occasionally, but its hard to say without pictures. What ammo are you shooting? reloads or steel ammo, or good brass? I'd also double check the FCG to make sure everything is correct. And as stated above, just get the "mil-spec" ones from a reputable source.

Keep in mind that changing from milspec has risks as the system was designed around specific part standards.  Lighter material means less mass to the firing pin and potentially lighter primer strikes.
If you go with titanium, be sure you have a full strength hammer spring.

Palmetto State Armory is a good online source for inexpensive AR parts.

If you're replacing the firing pin cause you think it's worn I'd replace the springs in the trigger group as well, most likely the previous owner just put in a lighter hammer spring which is causing your FTF.

Maybe try the springs first and just take the new pin to the range, if it still FTFs it only takes a minute to replace the pin. If springs fixes it you know you have a good replacement firing pin for your parts bin.

It takes a LOT of rounds to wear out a firing pin. Even shooting steel cased ammo with their harder primers usually kills the barrel faster than the pin.

BCM firing pin
Just grab one from there, you know it'll be right, there is absolutely no need to stray from this. Might as well grab a new retaining pin while you're at it
You could also grab an ALG ACT or BCM PNT while you're at it and be set with new springs and a decent trigger.

What ammunition were you using?

Worn firing pins are very rare.  Much more common is a backwards hammer spring.

I primarily use standard firing pins, but I've started using extended 7.62x39 firing pins in quite a few builds so I get better ignition with some hard primered golden tiger ammunition I bought cheap.

Thank you for the comments thus far -- and I know pics are always best, but I won't have a chance to get her apart again until this weekend with work and travel, at the earliest.

Some other points:
1. I do plan on getting a small collection of back up pieces together in short order, as some have advised here.
2. The previous owner did a lot of mods, so perhaps the spring is backwards. That said ....
3. My friend who is working me through how to learn the weapon has an original Colt AR15 from their first year of civilian release, and it is he who suggested we try a different firing pin, as the tip was slightly "mushroomed" or capped backwards on itself, and not a crisp point. The four rounds that failed to fire (2 different factory loads my local range sells, one being Federal, both 55 grain) all had indents on the primers where the pin hit, but not enough to fire. No fancy ammo, nor terribly crappy ammo, but certainly not match grade.
4. I am of the mind to take this at a good pace, and really learn the weapon, so no suggestions or thoughts will be wasted. Perhaps a spring was backwards -- we stripped her down, cleaned her out thoroughly, and gave a nice even coat of oil. I need to take it back to the range and put another set of rounds through her to test, but I figured I might throw this specific question out there until I can get back in the next 7-10 days.
5. We have another full-service range in town that custom builds AR platforms and I believe I can get a quality milspec by several of the brands mentioned here. Since my suspicion is confirmed, I see no reason to spend 3-5 times more for a titanium piece that is not mil-spec, and adds no discernible benefit.

Many thanks to all who replied!

If it's visibly mushroomed then definitely replace it.  The tip should look like this:

Exactly what my friend is thinking. Will likely pick one up in the next day or so, as I have next week off and I plan to enjoy myself!

Get an AR-15 firing pin protrusion gauge. That will start your AR tool kit.

Thank you for the tip -- on it!

I don't have anything else to add, but welcome to the site!

A ti pin would definitely decrease lock time, increasing accuracy.

What

F=MA. Less M, more A, lower T.

The faster the pin moves, the less time there is for the rifle to change position between when you squeeze the trigger and when the primer ignites.

That said, some rifles benefit more from this than others.  I have a precision build AR15 (Recce barrel profile)  that is very accurate and I have not seen the need to go with a titanium pin.  I think that Mil spec is fine for the Sport II and likely to be more durable.

Many thanks -- I would Google info from these forums from time to time, but it is nice to be able to post and interact now. Take care!

Welcome to the site.

My 0.02 worth....milspec has always been gtg for me here, but there was a time when "new" or "better" grabbed my $$. Buy what you want OP, but I doubt you will kill a GI spec pin.
Tig

FWIW, this is the pin I stick in most my rifles.  Works great with regular ammunition and also works on hard Russian primered ammunition that regular pins aren't long enough to ignite.
http://shop.redxarms.com/ENHANCED-FIRING-PIN-FOR-762-X-39-AND-545-X-39-BCGS-EFIRINGPIN.htm

Hey op. what range were you at? Are you sure it was new ammo and not reloads? Being a DSM guy too most the ranges I know around here push their reloads. Not saying it was a ammo issue but could be. As stated above pick up a protrusion gauge. You can get one cheap out in Grinnell.

ETA: also welcome aboard!!! stop by the IA hometown fourm a say hi. Great group of IA members here.