M&P15 OR Gas Block

[Damien]

Hi All
I screwed the barrel of my M&P15 (don't ask) and have to change it out (first barrel change I'm doing - Thank God for youtube LOL). As long as I'm changing it I'm thinking of going with an 18" SS heavy target type w/free float handguard I think. It all looks straight forward, but I am ignorant of a few details. I love the rail height gas block and want to put it on the new barrel. It appears to be mounted with a taper pin? Does this just get taped out with a brass punch? If so from which side? When putting it on the new barrel, if the barrel is not notched for it can I just line it up and drill in the notch? I take it the gas system from the factory is carbine length, if I go with a mid or rifle length is the buffer and spring good to go or should I use a heavier or lighter set? The rifle now only has about 200 rounds of 223 on it. Do I need to change out the bolt or is it still new enough to break into a new barrel?
Lastly as long as I'm pulling the top apart I'm going to change out the trigger for a RRA 2 stage NM and JP 4lb springs.
Thanks in advance for the answers and please let me know if there is any anything I'm planning on doing that I shouldn't!
Thanks Again!
Damien

 

[WR Moore]

OK, trying to cover all your bases. First question: have you checked with S&W about a barrel change? If this is a bulged barrel from a plugged bore, don't bother, sorry I asked.

1. If you change the gas system length, the only thing you have to change is the gas tube. Be careful to align it properly so it doesn't rub on the goose neck on the bolt.

2. You drive the taper pins out from the small diameter end.

3. Check to make sure the barel and the gas block are cross drilled for taper pins. You don't want to screw with drilling & reaming the tapers in the barrel. PITA.

4. If you buy a barrel, get a bolt headspaced to the barrel from the vendor. The bolt you've got should be OK, but you're taking a **** shoot on proper headspace.

5. If you don't have all the proper tools and some experience (That you had to ask which direction you drive out the taper pins is a clue you might be.....challenged in this area.), this is an expensive way to get that experience. You might be better off to find a local person with skills and tools and let them do the work. That way, if there's something wrong, you have some one (else) responsible.

Good luck.

 

[jepp2]

You talk about going with a heavy SS barrel, if so there is a good chance the diameter for the gas block will be different than your barrel diameter. Just means you need a different gas block. Drilling and reaming for taper pins is a lot of cost and effort you don't need to do if you go with a new gas block.

Bolt may work but headspace needs to be checked.

Assume you are running a carbine buffer? The buffer you need can depend on gas port diameter, and gas system.

The taper pins can be challenging to drive out.

Don't know what barrel you are planning to go with or how much you intend to spend. The WOA SPR is a nice barrel for the $$ Whit Oak Armament link

 

[Damien]

Thanks Moore
As long as you asked, the barrel got screwed via.... It was non threaded. I thought it had a barrel band so I cut into it intending to thread it with a CNC Warrior Kit. Alas, NO BAND! Oppps. (that was the only expensive mistake I intend to make. that's why I'm asking questions now)
As Far as the Taper pin .... Now that you said tap it from the small end I took a closer look and saw that one end is smaller ... Both ends are very very close in size and I didn't notice the difference before... I was just taking a shot at calling it taper (may have been compression fit for all I knew, but didn't think it was). And actually right after I did the above post I bought a Nordic Components XL 15.5" free float hand guard. It looks cooler/sleeker than any guard I've seen and is dirt cheap relatively. So I need to get a low profile block to fit under it anyway.
The reason I asked about the buffer weight/spring is because I'm not sure what length barrel I'm getting. But seeing the rifle length gas system is a fixed length, an 18 vs 20 vs 22 vs 24 inch barrel will have different dwell times, thus the question.
Re Bolt question. Knowledgeable people I've talked to have told me a good quality bolt and/or barrel are made to very tight tolerances and head space should be fine when mating the 2 quality parts new. I'm not sure of the quality of the Smith bolt or if 200 rounds old would still consider it new/unworn. I'm kind of leaning toward getting a MPI, High Pressure Tested bolt from BCM or PSA anyway, but may not depending on funds.
Re: 5. If you don't have all the proper tools and some experience (That you had to ask which direction you drive out the taper pins is a clue you might be.....challenged in this area.), ...... I'm 60 now and don't have the time or a place to do it any more but when I was younger I rebuilt car engines regularly ...... I am mechanically inclined just never blue printed up a rifle like this is turning out to be and the details of a car engine vs and a rifle are obviously apples and oranges.... I have confidence in my ability, just ignorant of some details in this project.
Thanks again.... and if anyone else has any input that might help with what I'm doing I would greatly appreciate it!

 

[Damien]

Thanks Jeep
Actually I'm a little leaning toward a 20" and evolving this gun into a tack driving range queen a little at a time. I've been looking at Black Rain barrels. The company is only a few years old I understand, but every thing I've read about them is good and the barrels I've looked at from them are comparatively well priced
As far as "Assume you are running a carbine buffer? The buffer you need can depend on gas port diameter, and gas system." right now its 100% factory stock M&P15 OR. I guess after I decided an what barrel I'm getting and make the change, I may have to buy more than one buffer till I see what works best, But I'm relatively sure I'll be going heavier than whats in it now

 

[WR Moore]

The Smith bolt is of very good quality, whatever the source. I wouldn't have any hesitation using one. (we use industrial quantities of the M&P15 rather harshly with no problems.)

Saying that all the bolts and all the barrels, regardless of quality, are interchangable is dangerous. That's why they make headspace gauges. They would probably be acceptably close (not accept a field gauge-which is OK if you're fighting a war), but if you intend to build a tack driver, don't cheap out on making sure the bolt & barrel are a matched set.