Question About BCG in M&P 15 Sport

[Magnum Brown]

Hey guys,
New member and 1st time poster. In the last two years I've really developed a passion for firearms, especially the AR-15. I've purchased both a M&P Sport and the Colt AR15-A4 with the FDE Furniture. (I also picked up a Glock 21, Remington 870, and Bersa .40, but enough about me)

I didn't know much about rifles when I bought my Sport, but after doing research and spending a ton of time at the range, I'm really glad I did. It's worked great since I got it and I've made a few upgrades to it. (Magpul furniture, Vortex Strikefire Red Dot scope).

I recently purchased a BCG from Cryptic Coatings (Mystic Black) and plan on running that thru my Colt. I want to take the BCG from my Colt and run it thru my Sport. There's nothing wrong with the current BCG in the Sport (I know I know, if it ain't broke don't fix it) but I've read on forums that the heavier BCG from my Colt may run a bit smoother and less recoil

My question is... And I know this has probably been discussed here a billion times... But do I need to make anymore modifications to my Sport to run the heavier BCG?

Thanks for any input....

 

[MichiganScott]

You can use the Colt bolt carrier in your Sport, but you need to use the bolt that came in the gun. Although not likely, you can have headspace problems when swapping bolts.

 

[Magnum Brown]

You can use the Colt bolt carrier in your Sport, but you need to use the bolt that came in the gun. Although not likely, you can have headspace problems when swapping bolts.

Thanks man... I really appreciate that, I had no idea

Any idea on what would happen if I didn't change the bolt? Just curious

Do I need to change the bolt for the Cryptic Coating BCG as well?

 

[sgtsandman]

If everything is of the same spec, swapping back and forth should not be an issue. BUT there is a chance that the parts variation in specs could be wide enough to allow a case to rupture. So it is best to check just in case.

https://en.wikipedia.org/wiki/Headspace_(firearms)

 

[Magnum Brown]

If everything is of the same spec, swapping back and forth should not be an issue. BUT there is a chance that the parts variation in specs could be wide enough to allow a case to rupture. So it is best to check just in case.

https://en.wikipedia.org/wiki/Headspace_(firearms)

Interesting... Maybe I should just leave it alone

I'm glad I asked... With so many aftermarket BCG's... I thought I could just swap them with no issues

Thanks for the link and info

 

[sgtsandman]

Interesting... Maybe I should just leave it alone

I'm glad I asked... With so many aftermarket BCG's... I thought I could just swap them with no issues

Thanks for the link and info

In theory you can and in many cases, there isn't a problem but there is always that chance. My luck with Murphy's Law, I would get a set of go and no-go gauges at a minimum...

 

[Magload]

I been told that Colt is not Mil Spec and some parts are not interchangeable. I would be sure before I start swapping parts. We all know what we are told sometimes is not always the way it is but this guy was a gun smith so I just kind of took his word for it. Don

 

[cyphertext]

I been told that Colt is not Mil Spec and some parts are not interchangeable. I would be sure before I start swapping parts. We all know what we are told sometimes is not always the way it is but this guy was a gun smith so I just kind of took his word for it. Don

What? Colt is not mil-spec? If a gun smith told you this, you need to find a new gun smith.

Colt is one of the primary suppliers of the M16 / M4 to the military, and those that are provided by other contract holders are built to Colt specs. And that Colt is often the "standard" by which all other ARs are judged.

Seriously, the guy at the big box store is not a gun smith...

 

[Scottrh2]

As discussed swapping bolt Carriers is fine all day long. Swapping bolts 99% of the time is fine BUT you really need to ensure your headspace is within spec to ensure safety. Mostly headspace issues will cause issues with your brass long before a failure.
Mil spec? A baseline, many times a minimum requirement that was written over 25 years ago and continues to this day. Many AR makers exceed "milspec" in materials, finish and mfg techniques rendering then as Non milspec but shoot highly accurate, are 100% reliable, and are superior in corrosion and wear resistance.

 

[Magnum Brown]

What? Colt is not mil-spec? If a gun smith told you this, you need to find a new gun smith.

Colt is one of the primary suppliers of the M16 / M4 to the military, and those that are provided by other contract holders are built to Colt specs. And that Colt is often the "standard" by which all other ARs are judged.

Seriously, the guy at the big box store is not a gun smith...

I was also under the impression that Colt rifles were "Mil Spec"... But I'm no expert, so I was surprised when the poster above said that.

I'm going to call my local gun shop and see if they check headspace... I'm still a newb... I have no idea how to do that

 

[Magnum Brown]

As discussed swapping bolt Carriers is fine all day long. Swapping bolts 99% of the time is fine BUT you really need to ensure your headspace is within spec to ensure safety. Mostly headspace issues will cause issues with your brass long before a failure.
Mil spec? A baseline, many times a minimum requirement that was written over 25 years ago and continues to this day. Many AR makers exceed "milspec" in materials, finish and mfg techniques rendering then as Non milspec but shoot highly accurate, are 100% reliable, and are superior in corrosion and wear resistance.

Thanks.... I appreciate the info

 

[WNC Seabee]

I'll go against the grain and say "Don't worry about it."

Those referring to headspace on an AR are citing a statistically insignificant problem. Check any serious 3-Gunner's stash of spare parts and you'll see bolts, carriers, complete Bolt Carrier Groups, waiting to be swapped out in case of a failure (broken extractor, loose gas key, something stuck, etc.). I'd be shocked if more than a handful of them check 'headspace'.

If you buy quality parts (which the OP has done), you're good to go. If you're buying unknown brands from suspect sources, then, yes I'd be hesitant.

 

[cyphertext]

Mil spec? A baseline, many times a minimum requirement that was written over 25 years ago and continues to this day. Many AR makers exceed "milspec" in materials, finish and mfg techniques rendering then as Non milspec but shoot highly accurate, are 100% reliable, and are superior in corrosion and wear resistance.

True, but even all those new fancy parts with the new finishes and materials are still mil-spec dimensions... which is really what we are talking here, being able to swap parts from rifle to rifle.

 

[Magnum Brown]

I'll go against the grain and say "Don't worry about it."

Those referring to headspace on an AR are citing a statistically insignificant problem. Check any serious 3-Gunner's stash of spare parts and you'll see bolts, carriers, complete Bolt Carrier Groups, waiting to be swapped out in case of a failure (broken extractor, loose gas key, something stuck, etc.). I'd be shocked if more than a handful of them check 'headspace'.

If you buy quality parts (which the OP has done), you're good to go. If you're buying unknown brands from suspect sources, then, yes I'd be hesitant.

Nice...

I did reach out to Cryptic to see if their BCG's would work with both rifles

I also reached out to Smith and Wesson.... Just to be safe... Plan on doing something heavy shooting this weekend

 

[cyphertext]

Nice...

I did reach out to Cryptic to see if their BCG's would work with both rifles

I also reached out to Smith and Wesson.... Just to be safe... Plan on doing something heavy shooting this weekend

They will work...

Get yourself a set of go/no go gauges and check headspace for yourself.

With that said, I am always curious as to why one would do this? Why replace perfectly good parts with aftermarket parts? Things that affect comfort or versatility, such as stocks, grips, optics, etc., I can see, but BCG? That money is better spent on ammo and range time in my opinion (that nobody asked for ).

 

[Magnum Brown]

They will work...

Get yourself a set of go/no go gauges and check headspace for yourself.

With that said, I am always curious as to why one would do this? Why replace perfectly good parts with aftermarket parts? Things that affect comfort or versatility, such as stocks, grips, optics, etc., I can see, but BCG? That money is better spent on ammo and range time in my opinion (that nobody asked for ).

I'm very thorough when cleaning my rifles, and after finding out about Cryptic Coatings BCG, and how easy the cleaning process would be... Plus the lifetime warranty....I thought they were too damn sexy to pass up. Expensive, but it the long run I feel like it would be worth it. I was going to run the Colt BCG thru my Sport, because I've read that the heavier BCG would run smoother and have less recoil (Even though recoil isn't an issue). Just wanted to try it out to see how it would run

Plus.... Ill have an extra BCG now... I think I may do a cheap AR build from PSA

I will say, I've had zero issues with my Sport.... I love it

 

[REM 3200]

I will say, I've had zero issues with my Sport.... I love it

Then why change it. If the recoil is the only issue, run a heavier buffer. Much cheaper than a new BCG.

 

[JaPes]

*SIGH* Warning. Old curmudgeon about to post.

New Barrel + New Bolt/BCG = OK. Check headspace to be 100% sure.
Used Barrel + New Bolt/BCG = Sometimes OK. Do not skip a headspace check.
New Barrel + Used Bolt/BCG = Sometimes OK. Do not skip a headspace check. Even though it's OK, I won't do it.
Used Barrel + Used Bolt/BCG not from the same rifle = NO. Not ever. Never.

Energy is energy. Recoil is recoil. That always remains the same. It's how you perception of recoil that you're trying to change. When you monkey with either the weight of the static mass the combustion gasses must overcome and/or the progressive resistance the combustion gasses must overcome you are changing the cyclic rate of your rifle. That leads to perceived changes in recoil.

Heavier BCG
Heavier Buffer
Hydraulic Buffer with progressive dampening
Buffer springs
Trigger Springs (the carrier has to push back the hammer to reset it)

If you monkey with any of the above, you will alter how your rifle functions. Too much one way or too much the other, and you'll induce malfunctions.Your 15-Sport comes from the factory with a carbine buffer. It's also a tid-bit over-gassed. This is to ensure proper function across a wide variety of commonly found commercially produced ammunition available to civilians. Firearms manufacturers do this so that we don't clog their support lines of communications with "My rifle won't fire using ammo X. Why?"

From my experience (it has been both expensive and stupid), the 15-Sport's BCG, buffer, buffer spring are just right for 99% of the shooters out there.

If you're truly interested in decreasing perceived recoil, try a muzzle brake. Cuts down on perceived recoil, but the shooters on the lanes to either side of you might not appreciate it.

Good luck. Safe shooting.

 

[noscivic]

If it were me, I would leave the BCG alone in your sport. Keep your colt BCG for a spare. If you're worried about recoil, put in a heavier buffer and aftermarket spring. The AR I built for my wife has a H2 buffer and a Damage Industries spring, with a Bushmaster BCG. She loves it, not much recoil and cycles just fine. The shells on her gun eject at 3-4 O'clock every time. As for the Cryptic coatings BCG, thats a pretty slick piece, literally! I have the bronze one in my favorite AR15.
Like the others have said get some gauges if you are worried about it, but in all the guns I have built, I have never had any problems and nothing out of spec.
Gary

 

[Scottrh2]

I personally can not imagine any 5.56mm AR platform having harsh recoil.
Recoil? Let's talk 8mm Mauser bolt rifles.