Carbine, mid length and barrels

Just interested in your thoughts.

I have been doin a ton or reading on these ar's. Still haven't scratched the surface but would like to hear what you guys have to say about....

Carbine and mid length gas systems.
I know we can get picky here and maybe what I read is. I understand the carbine length systems are hard on bolts and are pretty violent in operation while the mid length is much softer in operation. Is the difference really that noticeable and does it really make a difference? I know I am talking to maybe the wrong crowd here since most have the carbine length but since you have them what do you think? Is this really a big deal?

Now about barrel material. Ok the scout used the melonite coating and there is also chrome and chrome moly. Is the chrome moly really one to stay away from. I am also considering a build and a chrome moly barrel. Is there a big difference here? I know the chrome lined is bored oversize then the chrome is applied then resized. I guess the question is about the melonite and the chrome moly. Is this really a big deal?

One last thing.. Would you consider the sport a shtf rifle? Not that I expect it just asking for your thought on toughness and reliability. Would you take it to stake your life on it?

Just goin back and forth with buy or build. I was thinking about a Del Ton build, the Sport or Palmetto State Arm AR. All three are about in the same price range.

thanks

Mid-length is easier on the action because there's less gas available to cycle it.

The Sport can serve as a SHTF rifle, but then again, ANY rifle can fill that role when you get right down to it - even a .22 if that's all you have.

QUOTE: "One last thing.. Would you consider the sport a shtf rifle? Not that I expect it just asking for your thought on toughness and reliability. Would you take it to stake your life on it?"

Oh hell yeah!! The Sport model will stand up to any major brand. It would make and excellent SHTF rifle.(if you like 5.56) I'd stake the my life on it!

Remember one thing! This rifle is only good if the owner does good maint., lubes the rifle properly, and feeds it decent ammo. So you see you have responsibilities as well.

thumbs said:

I understand the carbine length systems are hard on bolts and are pretty violent in operation while the mid length is much softer in operation. Is the difference really that noticeable and does it really make a difference? Is this really a big deal?

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Here's my take on it. I'm no expert. Take this for what it's worth. The more experienced memebers will correct me.

Given the same bolt carrier group, buffer spring, and buffer weight the kinetic energy needed to cycle the bolt carrier group is the same regardless of the position of the gas block.

Bleeding off gas to cycle the bolt closer to the chamber gives you higher pressures than further down the barrel.

Think about it. The same energy is needed to cycle the bolt, regardless of the position of the gas block. Gas pressure is higher closer to the chamber, then drop off toward the muzzle.

Yes. A carbine length gas system will provide gas pressure that cycles the BCG more vigorously than a mid length gas system. Logically, the gas from a carbine length gas system will be a little hotter than the gas from a mid-length gas system. The mid length system giving the gas more dwell time in the barrel & gas tube to cool off. This makes the mid-length a little cleaner subjectively.

Given the same bolt carrier group, buffer spring, and buffer weight an AR's perceived recoil will be different. A little more vigorous with a carbine length gas system than a mid-length gas system.

Remeber, I said "given the same bolt carrier group, buffer spring, and buffer weight" There are combinations of parts that can affect the cyclical rate of an AR.

• Semi-auto v.s. Full-auto BCG
• Buffer weights: Carbine, H, H2, H3
• Buffer types: Traditional v.s. Hydraulic
• Buffer Spring Weight

Increase the weight/mass of the bolt carrier, spring, or buffer and you increase the amount of force the gas needs to provide to cycle the BCG. Given the same gas pressure:

Lower overall "weight" in the action = less resistance = faster cycle / harder cycle.

Higher overall "weight" in the action = more resistance = slower cycle / softer cycle.

Too fast a firing cycle will cause extraction issues & be harder on the BCG because it's slamming back and forth. Too slow a firing cycle will cause short stroking, weak ejection.

Personally, I've addressed the issue with both my carbine length gas systems by replacing the carbine weight buffer with either an H or H2 weighted buffer.

The key is to find the combination that will give you the lightest perceived recoil while still allowing the BCG to fully cycle reliably with the ammo you plan to shoot most.

thumbs said:

Now about barrel material. Ok the scout used the melonite coating and there is also chrome and chrome moly. Is the chrome moly really one to stay away from. I am also considering a build and a chrome moly barrel. Is there a big difference here? I know the chrome lined is bored oversize then the chrome is applied then resized. I guess the question is about the melonite and the chrome moly. Is this really a big deal?

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Melonite is a salt bath nitriding process that imparts to the barrel's metal properties that increase hardness, corrosion resistance, and wear resistance.

Hard Chrome lining is an process that adds a layer to the barrel's barrel's chamber and bore that increases hardness, corrosion resistance, and wear resistance.

Both of the processes above are applied to a finished barrel. Chrome moly refers to the type of steel used to fabricate the barrel.

Chrome moly refers to the type of steel used for the barrel. Chrome moly is short for Chrome Moly Vandium (CrMoV) alloyed into the steel. These are alloyed into the steel to give the barrel resistance to corrosion & oxidation, tensile strength, heat resistance, and some more.

So then you go back to the base steel itself and you have 4140 v.s. 4150 steel barrels, that can be alloyed with CrMoV, that can also be salt bath nitrided or hard chrome lined.

Then there are also stainless steel barrels...

thumbs said:

One last thing.. Would you consider the sport a shtf rifle? Not that I expect it just asking for your thought on toughness and reliability. Would you take it to stake your life on it?

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Yes and Yes.

The only issue with the AR that I can forsee in a SHTF is lubrication. AR's run best when wet. In a shtf situation, once I can't find lubricant from scavenging whatever petroleum based or synthetic lubricant is available, I'll lube my AR with the rendered fat of my enemies.

thumbs said:

Just goin back and forth with buy or build. I was thinking about a Del Ton build, the Sport or Palmetto State Arm AR. All three are about in the same price range.

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When the EBR (evil black rifle) disease gets you, you'll eventually have a rifle you bought whole and one you assembled yourself. I did. I have a 15-Sport, and one I put together than has a non-lined, CMV barrel.

Within your budget, IMO, you can't go wrong either buying a complete rifle (15-Sport) or assembling a PSA rifle kit (complete upper with LPK) to a stripped lower.

The only meaningful advantage (IMO) of purchasing the 15-Sport is that it is backed by S&W's limited lifetime warranty for the original owner. If there's something wrong with it, send it to S&W and they'll fix it.

Now given all of what I've spouted in this post, the next AR I'm drooling over is the new M&P 15 midlength MOE.

• Mid length gas system
• 4150 CMV steel barrel
• Melonite treated barrel
• 1:8 5R progressive gain rifling
• Finger shelf on both sides of the lower above the trigger.
• Special contur to the integrated trigger guard.
• Flared magwell just like on an ACR
• Texturing on the front of the magwell for grip.

That combo is calling to me. Install an "H" buffer and I'll be happy.

JaPes said:

When the EBR (evil black rifle) disease gets you, you'll eventually have a rifle you bought whole and one you assembled yourself.

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I think 9 out of 10 AR owners do this. I did as well.

JaPes said:

Now given all of what I've spouted in this post, the next AR I'm drooling over is the new M&P 15 midlength MOE.

• Mid length gas system
• 4150 CMV steel barrel
• Melonite treated barrel
• 1:8 5R progressive gain rifling
• Finger shelf on both sides of the lower above the trigger.
• Special contur to the integrated trigger guard.
• Flared magwell just like on an ACR
• Texturing on the front of the magwell for grip.

That combo is calling to me. Install an "H" buffer and I'll be happy.

Click to expand...

But now I hate you for making me want yet another AR.

JaPes said:

the next AR I'm drooling over is the new M&P 15 midlength MOE.

• Mid length gas system
• 4150 CMV steel barrel
• Melonite treated barrel
• 1:8 5R progressive gain rifling
• Finger shelf on both sides of the lower above the trigger.
• Special contur to the integrated trigger guard.
• Flared magwell just like on an ACR
• Texturing on the front of the magwell for grip.

That combo is calling to me. Install an "H" buffer and I'll be happy.

Click to expand...

Maximumbob54 said:

But now I hate you for making me want yet another AR.

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LOL. Don't be mad at me, be mad at S&W. The 4150 CMV steel & melonite barrel 1:8 5r rifling with a mid-length gas system is like a turbo version of the 15-Sport.

The EBR disease is horrible.

I agree. I have sold a few off and still have three. And here I go wanting another one. Gun poor forever!!!

JaPes....Great Great Post!!!!

And I have to agree, had you not put the new rifle so succinctly I would not be drooling right now. (A symptom of EBR disease)

Thanks for the help guys

JaPres

Great info thanks. Yeah I was wondering if a stiffer spring or heavier buffer would help with the cycling situation. I guess it will.

When I asked about the shtf situation I was just refering to is the sport more of a toy than a workhorse thing. I know some manufacturers produce stuff just for the once in a while shooter. I really don't want that. Not that I put thousands of rounds through my stuff in a week but I don't want hassles with them either.

Is there a real problem with the chrome moly barrels? Is it a big deal? Like I have read before and have experienced none of my rifles have chrome lined barrels, except the Saiga AK, and they do fine. Is there a thing with this kind of platform that kinda requires a treated barrel of some kind?

thanks

thumbs said:

Thanks for the help guys

JaPres

Great info thanks. Yeah I was wondering if a stiffer spring or heavier buffer would help with the cycling situation. I guess it will.

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Start with replacing the buffer with an "H" buffer. It's the easiest and relatively least expensive option to try first.

thumbs said:

When I asked about the shtf situation I was just refering to is the sport more of a toy than a workhorse thing. I know some manufacturers produce stuff just for the once in a while shooter. I really don't want that. Not that I put thousands of rounds through my stuff in a week but I don't want hassles with them either.

Click to expand...

IMO, while the 15-Sport will not satisfy the mil-spec purists it definitely satisfys my practical needs for a rifle. Taken together as an entire system, I have confidence that the 15-Sport will see me through any acronym worthy calamity.

As I said, the likelihood of an acronym worthy calamity is a debate all on it's own. Just my opinion, but I rate the likelihood to be relatively low for my geographic region. YMMV.

In my case, having the S&W factory warranty will cover 99.99999999999999999999999% of any issues my rifle will encounter during my routine, boring existence.

If I end up in an acronym worthy local/regional/national/world-wide calamity, the S&W 15-Sport is an AR pattern rifle. I can drop in any mil-spec replacement part (trigger, bolt carrier group, springs, firing pin, etc) and get my 15-Sport back up and running.

Yes I don't have a forward assist or dust cover. To appease the mil-spec purists I accept that chances of survival in an acronym worthy calamity might infinitesimally dropped.

I might as well succumb to the forces of evil because I don't have a forward assist. Lord knows what might happen if I cant get my finger to nudge the bolt into battery through the ejection port.

And OMG every acronym worthy disaster involves copious amounts of dust, so I'm up a creek without a paddle because I don't have a dust cover.

thumbs said:

Is there a real problem with the chrome moly barrels? Is it a big deal? Like I have read before and have experienced none of my rifles have chrome lined barrels, except the Saiga AK, and they do fine. Is there a thing with this kind of platform that kinda requires a treated barrel of some kind?

thanks

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I have no issues with my CMV barreled AR. Does it take a little extra effort to clean as compared to a chrome lined or melonited barrel? A little. The sum total of my effort is pulling an extra two dry patches through it to get the crud out, and then finish by pulling a lightly oiled patch through the barrel (which I do on all my firearms anyways).

Again I say this with the caveat that I consider myself to be a casual, informed AR enthusiast. I know enough about construction details to make informed decisions based upon my purpose of use. There are others with more in-depth, encyclopedic knowledge about every aspect and component of the materials used in an AR to construction.

I shoot my sport once to twice per week, I have done my own training exercises as I was taught by Uncle Sam, just to stay sharp if I have to pull it out at home.
This is my go to close range weapon, with a 1911 for back up.
Th sport is every bit as capable as other carbine platforms, not including the full auto group, that's a whole different monster.

oneyeopn said:

JaPes....Great Great Post!!!!

And I have to agree, had you not put the new rifle so succinctly I would not be drooling right now. (A symptom of EBR disease)

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Yeah. I held a Bushmaster ACR. The ACR was origially the Magpul Masada, and Magpul sold it to Bushmaster.

I paid attention to all the ACR's improvements. I noticed some ergonomic considerations implemented on the ACR were ported over to the midlength 15 MOE.

Good stuff.

I'm sure it takes a little more to clean the CMV barrel, but really, I wouldn't notice the difference. I don't really keep track of how many rounds go through a given gun before I decide to clean it. So I just clean them when I feel like it, usually an evening of watching Andy Griffith re-runs. I seem to enjoy the care of the gun as well as shooting them.

All my guns seem to shoot fine and generally hit what I aim at, regardless of the treatment, lining or lack there of. It's something I don't get worked up about.

SSgt M said:

I shoot my sport once to twice per week, I have done my own training exercises as I was taught by Uncle Sam, just to stay sharp if I have to pull it out at home.
This is my go to close range weapon, with a 1911 for back up.
Th sport is every bit as capable as other carbine platforms, not including the full auto group, that's a whole different monster.

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^ That right there is one of the 15-Sport endorsements I personally consider to be credible.

I agree completely !

I took a ride to a lgs where I had never been before. I am out of town and this was the lgs. Anyway great guy and we hit it off with the AR's.
I was talkin builds and through in the SW Sport. He said if I could find one buy it. Great little rifle and a good price. Funny he had a few AR's and no Sports. He is just a new small shop and really can't get them. Thought that was interesting.