Carbine vs rifle

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    • #102116

        It’d appreciate your thoughts on 16 vs 20 inch barrels.

        I have an upper in each size , and am about to turn the ” box of stray parts ” into a complete rifle. I’m leaning towards another 20 inch. But based partially on personal irrationality. I just feel that a full sized rifle is proper – having learned to operate one way back when with an M16A1.

        I guess the logical debate is increased range & velocity vs portability.

        I’d appreciate your thoughts.

      • #102117
        Brian from Georgia

          I’m probably the odd man out, but my “go to” is a 20″ A4 with an A2 buttstock. I’m a rifleman and not a door-kicker :-)

          It certainly has the advantage of range and higher velocities. I’ve hit D targets at 600 yards prone no problem. It comes at the expense of added size (duh) and weight, but it’s manageable with a VCAS or VTAC sling.

          I used it at CRCD with good results. Just keep that muzzle out of the dirt when you go prone!

        • #102118

            For what the M16 series rifles were designed for, the 16 inch M4 pattern probably makes the most sense in terms of carryability and shootability.

            As long as all other variables are the same, you do not lose any noticeable accuracy going to the 16 inch. You do lose about 200-300 FPS in terms of muzzle velocity. What does that mean? The mil-spec 5.56 rounds (both 55 and 62 grain) derive a lot of their effectiveness in soft targets from their ability to tumble when it strikes. (google Fackler wound ballistics). Tumbling occurs because mass is a conservator of momentum and the tail of the bullet has more mass than the tip. The tip slows down, but the tail wants to keep going and thus tumbles. This is velocity dependant and usually requires the 5.56 bullets to be over @2500 FPS (google “Taking Back the Infantry Half-Kilometer). While I can’t reference it right now ( I am pretty sure it is the aforementioned article) the @2500 threshold occurs 80-100 meters in the 16 inch barrel and 100-120 meters in the 20 inch.

            What does this mean? As far as I am concerned, practically nothing as the most important thing in the equation is software and not hardware.

            Just something to be aware of if you are concerned about the loss of velocity.

            Assuming you zero the rifle per mil regs, the 16 inch will have a higher maximum ordinate and it will occur sooner. If I recall correctly it is 7-8 inches@180m for the 16 inch and 6-7 inches@ 200m. Don’t quote me on those numbers though as there are a lot of variables to control for.

            If you are using irons, then sight radius becomes an issue. The 20 will have a further sight radius than the carbine M4 length or mid-length. This translates into greater applicable accuracy as you can see the front sight more clearly in the 20 inch than the shorter lengths and it easier (usually) to hold it stiller in a longer barrel. It does not necessarily affect the absolute accuracy, just your ability to apply it.

            Red dots and scopes typically negate this advantage.

            Just my 2 cents

          • #102119

              Ultimately it boils down to what your mission is. If you expect mostly long range then go with the twenty. Mostly close in then go with the sixteen. Dont sweat it too much either way as both will work

            • #102120

                I always felt 16 inch is the sweet spot for our rifles, especially with the mid lenght gas.

                It’s Long enough to give plenty of oomph and accuracy but short enough to give a significant and useful handling advantage over the classic 20 inch..

              • #102121
                Greg Owens

                  War fighters have spoken- short is better. Most think the 18-inch
                  spr is too long.

                  20″ ar with a-2 buttstock has advantages and disadvantages.

                  Adv.- 3 ways to kill. Shoot, bayonet, and beat to death.
                  More velocity, more ergonomic for auxiliary to shoot.
                  Less concussion, flash, and recoil.
                  Solid shouder weld, nose off charging handle, and improved
                  point shooting.
                  Buttstock length decision eliminated. Protected action
                  spring and buffer.

                  Dis.- Length of pull less maneuverable in prone.
                  In full battle rattle, shoulder pocket weld can be dif-
                  ficult. Keeping buttstock tucked inside vest strap increases
                  eye relief for magnified scope solved by infinite eye relief
                  red dot.
                  Sling swivel needs to be cut flush with buttstock and a
                  different sling system used.
                  Heavier, longer, and harder to ” get small”.
                  Easy to crowd cover and not be able to get weapon up.

                • #102122
                  Greg Owens

                    3 examples

                  • #102123
                    Joe (G.W.N.S.)

                      A 20″ barreled AR15 is about 39.5 inches long with fixed stock.

                      A 16″ barreled AR15 is about 31.75 inches long with collapsed stock closed, 35″ extended.

                      If you are more comfortable with rifle length, enjoy it’s a great platform.

                      I personally don’t think the 16″ route is that great for anything but BATFE compliance.

                      Either will get the job done though.

                      I have used a M16 rifle in Afghanistan and had no issues except younger guys thinking Old Man has Old Style. :-)

                      I am considering a Daniel Defense 10.3″ Hammer Forged Chrome Lined Barrel. Thick woodlands and swamps for me though.

                    • #102124

                        It’s all been said earlier however I think your AO needs to be your guide. Thick woods with 100 yard or less shooting lanes – Go with the 16″. Long shooting lanes like North Dakota I would go for the longer barrel to be able to “reach out and touch someone.”

                      • #102125

                          I always felt 16 inch is the sweet spot for our rifles, especially with the mid length gas.

                          It’s Long enough to give plenty of oomph and accuracy but short enough to give a significant and useful handling advantage over the classic 20 inch..

                          This. The Middy’s are a game changer for the 16″ platform.
                          There’s also some supposed other benefits such as less recoil and part wear, but maybe somewhat subjective.

                          I’m going to have to spat with Greg for a minute, in that I don’t feel the 20″ with a fixed A2 stock is going to be more ergonomic in any way, especially for a new/less skilled shooter. He already mentioned the cons of comfort ICW full gear, but further, adjustable stocks are widespread for a reason- that is, sizing to fit the individual shooter- you have a 200 pound guy, or a much smaller woman- both require completely different ergos as far as grip/cheekweld/LOP goes.

                          On a side note, unfortunately such stocks are mis-termed “collapsible” stocks by the people that think the only position available is fully-out pos. 6, when they’re “adjustable” stocks, and you pick the length that fits you best.

                          As far as the 16″ vs. 20″ argument, yeah, there’s ballistic advantages to the 20″. For me, they do not outweigh the size/maneuverability advantages of a 16″ Mid. Also, if you hang around the ultra-LR precision shooting community at all, there’s plenty of proof for shorter barrels being effective at ranges far beyond what one would think.
                          It’s a bit of an ammo thing as well.

                          Frankly, if I was concerned about reaching way out, to the point of feeling I need a longer barrel I would be tempted to pick a bigger caliber. Plenty of real nice .308 ARs out there right now. :good:

                        • #102126

                            Concur with mvfmoderator and JARG, the 16″ mid-length gas system is the way to go. The carbine length gas system is extremely violent and hard on the components. In the mid-length configuration, you gain way more than you lose.

                            With that said, I am a purist at heart. The M4 carbine configuration gives me everything I need in a combat rifle. I find the M4 to be accurate, maneuverable, and extremely adaptable to mission requirements. The platform handles ammunition from 55gr to 77gr and will reach out to 500 and 600 meters well enough to do what I need to do. All that and it is a sexy looking little rifle!

                            Bottom line: the 16″ barrel will do anything you need it to and give you better handling characteristics than the 20″ will.

                          • #102127
                            Joe (G.W.N.S.)

                              Just remember both the 20″ barrel and the 14.5″ barrels have a pretty long and successful history of putting bad guys down.

                              It still comes down to the operator more than the gear!

                              I also think it’s interesting that “Firearms and Gear Talk;” even among as dedicated and serious crowd as this Forum, has the most posts.

                              Firearms and Gear enhances the “Warrior,” it doesn’t make one.

                              Training does!

                            • #102128

                                So why not do what the Canadians and Danish do? Put an adjustable stock on a 20″ rifle? As far as barrel length and ballistics goes, I doubt that there is much of difference out to 450 yds or so and both can reach out that far with ease. You should determine what max ranges you will face and choose accordingly. In my area 450yds would be stretching in most cases. So I will stick with 16-18 barrels. Like my C93 rifle.

                              • #102129

                                  Call me a loser but I have always thought 16 inch barrels with A2 stocks looked amazing.

                                • #102130

                                    Or buy a LMT CQB AR and then buy the barrel length you want for what you need it for from 10.5 to 18, they have them. Then its two bolts and shazam you have a different rifle.

                                  • #102131

                                      14.5″ or less should be a carbine length, 16-18″ should be midlength, and 18″-24″ should be rifle length; for maximum reliability. A 14.5-18″ with a good barrel, free-float, and good ammo will do any and everything you need to do out to 600m.

                                    • #102132

                                        A pair of sawed-off and tricked out Barrett/50cal pistols…one for each hand :yahoo: That would even make Arnold double take!

                                      • #102133

                                          I’m a huge believer in mil spec but the 16″ is your best compromise. Remember accuracy has nothing to do with barrel length. Barrel length is just were we get the velocity we need to shoot farther.

                                          I’m currently building a 16″ mid length for a recce style gun. This will be my medium-long range gun.

                                          If you need a 95% rifle go with the 16″ I went with 14.5pinned but that’s because it’s what I’m used to/issues. A 20″ would be (for me) simply nostalgic or as my long range SPR.

                                          Really good discussion!

                                        • #102134

                                            The majority of infantry engagements, and by extension, guerrilla engagements happen inside of 100meters. No pre-SHTF engagement will ever happen past 20M. The 14.5/16″ AR w/ 55g M193 ammo is optimal inside of 150M. It is also near-optimal for work around vehicles and MOUT. For this purpose an SBR is better. But a 14.5/16″ gives up less in MOUT than the SBR does when you you step outside. (Plus, you have to jump through hoops to get an SBR.)

                                            Give me a carbine.

                                            Of course this reality has been skewed by our years in A-Stan, if your AO looks like that you might want to re-think. BUT remember the troops in A-stan are backed by 7.62 GPMGs large caliber sniper rifles, mortars etc. That solution is not available to you, so a shift in tactics is in order.

                                          • #102135

                                              You should be careful with absolutes.

                                              In both Iraq and Afghanistan, the military had many engagements that occurred outside the 100 meter distance.

                                              I agree that the carbine is the optimum weapons choice.

                                            • #102136

                                                Call me a loser but I have always thought 16 inch barrels with A2 stocks looked amazing.

                                                I agree its an interesting look (and no one who is posting here is a “loser”) ;)

                                              • #102137

                                                  I try to have my cake and eat it too. As I disclaimer my experience is civilian only so it is not combat based.
                                                  I have always preferred the longer sight radius to the 20 inch (A2) over the shorter carbine (M4) sight radius. But I’m a hobbit sized SOB so the short the over all length the better so I opted for a faux dissipator upper. It’s 16 inch barrel with A2 length front sight tower with a carbine length gas system. I’m pleased pleased with its reliability and accuracy.

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