S&W Sport / Colt 6920 Comparison

Louisiana Shooters Unlimited has purchased two new rental rifles for folks taking our Defensive Carbine courses who have not yet bought a rifle, or who experience a major failure with their rifle. We are using this as an opportunity to gather data about two popular M4 style carbines. The carbines will be shot in the same conditions, using the same ammunition, by students going through the same POI. They will be cleaned at regular intervals and well lubed with Mobile 1. Round counts in our courses is 400/day. We will do regular throat erosion measurements and accuracy evaluations.


Initial measurements and data:

Our Colt 6920 was recieved with 4 position Rogers SuperStock. The SuperStock turns 5-8 degrees on the reciever extension axis under about 20 ft pounds of torque. It cannot be moved forward or back with handstrength when locked and no movement is observed when getting a cheekweld in normal shooting positions. The handguard rotates 10-12 degrees on the barrel axis under 10 ft pounds of torque and moves forward and back about 3/32's of an inch. There is minimal play between the upper and lower. When pushed together, no light passes through. When pushed apart, light and the corner of a 20 lb sheet of printer paper can pass through the gap, but 2 sheets of paper will not. The carbine weighs 6 pounds 14.8 ounces. The bolt carrier group weighs 11.6 ounces and the bolt is marked "MPC". Our three measurements on an RCBS trigger pull scale were 7-14, 6-8, and 7-8, for an average pull weight of 7 pounds 4.667 ounces.

The M&P 15 Sport has a regular M4 style stock which moves easily forward and back about 1/16 of an inch in all 6 positions and rotates 5-8 degrees with minimal torque. The handguard rotates 3-4 degrees under about 10 ft/lbs of torque and moves forward and back a detectable, but less than 1/64 inch amount under about 30 pounds of force. The Sport weighs 6 pounds 2.7 ounces. The complete bolt carrier group weighs 11.2 ounces and the bolt is marked "MP". The extractor has a doughnut o ring around its spring. Play between the upper and lower is on par with the Colt. Trigger pull measured 6-2, 6-12, and 6-4 for an average of 6 pounds 6 ounces.

Since the Colt was recieved with 2 20 round Colt magazines with black followers, we have purchased 8 of the same for the evaluation. Ditto for the 30 round Pmag shipped with the S&W in that we bought 9 more so each carbine begins with 10 magazines identical to what it was recieved with.

The Colt has a forward assist, an ejection port cover, and a grenade launcher cut which the Sport does not. Both have A2 style flash suppressors and bayonette lugs.


Front sight base markings:
Colt- "F" on the left, "<B>1" on the right
Sport- "A J F" on the left, "o 8 2" on the right

Handguards:
Colt is 2x shielded, 7 3/8 inch front 8 1/16 inch rear circumferences
Sport is not shielded, 6 3/8 inch front, 7 inch rear circunferences

OAL:
Colt 32 13/16- 36 1/8 inches
Sport 32 7/16 - 35 11/16 inches

Extractor spring
Colt- 4 coil with black insert
Sport- 4 coils with black insert and black o ring

Extractor
Colt is "C" marked
Sport is "I" marked

Colt bolt carrier is "C" marked

Throat

Colt - .15 on W.H. Merchant gauge
Sport- .14 on W.H. Merchant gauge

Barrels:

Colt is marked "C MP 5.56 NATO 1/7"
Sport is marked "5.56 NATO 1/8 5R"


Creep, reset, and overtravel

If we define creep as the distance between when sear movement begins and hammer fall occurs, overtravel as the distance between the triggers breaking point and stopping point , and reset as the distance the trigger must move forward for the disconnector to release, we get the following:

All measurements are of the movement of the tip of the trigger where the trigger is closest to the bottom of the trigger guard. Although the trigger tip moves in an arc, measurements are linear from point to point.

Colt- 3/32 inch creep, 2/32 overtravel, 5/32 reset
Sport- 2/32 creep, 3/32 overtravel, 5/32 reset

100 yards 5 shot groups in inches Sport 095 with Leupold VXIII 3.5-10x50
Lake Charles, La
Error numbers are based upon sample sizes and environmental conditions

Win q3131 1.91
Fed 50 gr jhp 1.631
AE 50 gr tipped Varmint 1.031
Black hills new 69 gr match king hp 2.097
Win 45 gr varmint hp 2.303
Wolf 62 gr fmj 1.707
Fed 62 gr otm 1.645
Speer 63 gr jsp 2.188

Avg of 8............... 1.814 +-.4
avg of 5 55 grains and heavier ......1.909 +-.6

Fed m196 tracer 4.4839

100 yards 5 shot groups in inches Colt 6920 883 with Leupold VXIII 3.5-10x50
Lake Charles, La

Win q3131 2.337
Fed 50 gr jhp 3.817
AE 50 gr tipped Varmint 1.448
Black hills new 69 gr match king hp 2.166
Win 45 gr varmint hp 8.311
Wolf 62 gr fmj 3.016
Fed 62 gr otm 4.238
Speer 63 gr jsp 3.680

Avg of 8............... 3.627 +- .6
avg of 5 55 grains or heavier..... 3.084 +- .8

Fed m196 tracer 4.619

We are open to suggestions regarding things to measure.

Yesterday evening, we had several experienced shooters try 4 different rifles with populer AR triggers and rate them 1 - 10. Here are the average ratings:

Colt 6920 stock trigger................ 4.0
Bushmaster with ALG ACT............5.7
M&P 15 Sport stock trigger...........6.3
Bushmaster with DPMS 2 stage.....7.8

Trigger feel is very subjective. I believe that before buying a Rifle, one should try that rifle's trigger for oneself.

Sock Puppet said:

Very, very informative! Thanks to all involved for recording and posting such great information!

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It is an honor to participate in this wonderful forum, and we have certainly seen benefit from the information others have shared here. Data is limited in its usefulness if it is not shared.

One must add shipping and/or tax, but the Sport is about 40% less than the 6920. Many extra features come along on the 6920 with the higher price: chrome lined chamber and bore, hpt mpi barrel, forward assist, ejection port cover, Rogers superstock, cleaning kit, sling, and 2x sheilded handguards. It is up to every buyer to do a cost/benefit analysis and factor in their own wants and needs before making a buying decision. We just hope to provide data for people to use when doing that analysis.

RCArms.com said:

Odd that the Lowly Bushmaster/DPMS combo (considered to be junk by many) scored highest on the trigger while the highly touted Colt had the worst rated trigger from the actual shooters....... Interesting.

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Not odd at all considering it is an off the shelf mil spec trigger. The upgraded mil spec ACT ALG tirigger in one bushmaster was second from the bottom, even though it is highly polished and plated in self lubricating nickel-boron. Mil spec triggers are designed for raw recruits without any prior trigger finger discipline and/or designed to work when the rifle's action is full of mud or sand. I know of several military ammo types that the DPMS 2stage trigger is not reliable with.

That's the plan.

taliv said:

definitely looking forward to the results, but keep in mind, the plural of anecdotes is not data. sample size of 1...


does the sport have a gain twist? i just looked at their website and it said 1-8 twist. nothing about gain. did i miss something?

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Actually, your statement is misleading. Collecting anecdotal data is the beginning of every meaningful discovery process. Increasing sample sizes results in a higher level of validity, and may well result in an unexpected outcome, yet that does not change the reality that one cannot gather data from multiple sources before one has gathered data from one. Newton's own words describe him developing the theory of gravity from seeing a single apple fall from a tree. More items would have to fall before we would have the law of gravity, but we must always begin somewhere.

It would be much more honest to state that the plural of anecdotes is not necessisarily valid data. Denying that all data sets are simply collections of anecdotal data is akin to making the ill advised statement that all guns are always loaded; we understand what a person is trying to communicate, although the words chosen can be confusing to those at whom the communication is most likely directed.

Another example would be a diabetic who takes blood sugar readings and records them to bring to his next appointment with his MD. He records his meals, physical activity, everything. Since all the information is about him, it is the definition of anecdotal data. It is also the most valid data available for managing his diabetes. Plus, by combining his data with data collected by other individuals, we can get a valid data set for managing diabetes generally. So the plural of anecdotes can be valid data.

gotigers said:

I am surprised that the colt's groups were so much bigger. Both rifles' groups of Black Hills surprises me.

What kind of bench, bag, sled system were the rifles shooting from?

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The rifles were shot from a bench with a Caldwell adjustable rest under the handguards and caldwell sandbags under the buttstocks. The groups from the Blackhills ammo didn't suprise me at all. The Blackhills groups were the most consistent from one rifle to the other and were quite small for semi - auto rifles which had neither been broken in nor had their barrels free floated.

So you admit that before one can repeat an experiment, an experiment must first be conducted? That is all I was trying to point out, that this is the beginning of a process, not and end unto itself. Our hypothesis is that each rifle will have strengths and weaknesses. I hope you noticed that our accuracy averages had margins of error that reflect the small sample sizes and the environmental conditions.

Duble Naught Spy said:

Looking at the numbers it appears as thought the Sport actually out shot the Colt and sometimes drastically so.
I think the big thing here is proof that the 5R rifling is doing exactly what its hyped to do.

I foresee a lot of folks swapping to 5R barrels.

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Given the fact that there are several variables at play and such a small sample size, to conclude anything about 5R rifling v standard rifling would be little more than a wild donkey guess. One barrel is chrome lined, the other melonite treated. One is 8/1, the other 7/1. They have different handguards, which may pressure the barrels differently and their throats have differing measurements. Plus, there are plenty of barrels with standard rifling that outshoot this 5R barrel by a wide margin.