This is my first post about my first AR. I am a very green gun owner. The other day I bought my first firearm, a Colt LE6920. Although I haven't shot it yet, I am very pleased with it.

I have educated myself to what I believe is a good knowledge base about the innards and workings of the rifle and in general about AR-15s.

I originally wanted to purchase a rifle with a  mid-length gas system due to the reduced recoil and stress on the bolt. Due to the availability and eagerness to purchase, I opted for this Colt. Being a new AR owner, I'm not sure if it is a justifiable worry, but I asked the folks at the gun shop if they had any recommendations on how to reduce the stress on the bolt. They said I could put in a heavy buffer, so I picked one up. This evening I opened 'er up and noticed on the stock buffer that came in the rifle, there was an "H" imprinted on the flat side of it. The same "H" was one the new heavy buffer I purchased. Does the "H" symbolize that it is a heavy buffer or is this a regular stamp on all buffers?

If I do indeed have a heavy buffer in the rifle I purchased I will be returning the one I bought.

Also, can I get some feedback on my worry about stress to the bolt with a carbine gas system? Is this something I should be concerned about for a rifle that I would like to last me for a great deal of time?

Sorry for the noob questions. Looking forward to my new hobby :)

The h mark means heavy. I wouldn't lose any sleep over the carbine gas system being hard on the bolt. After 30k rounds when you replace the barrel you should replace the bolt too. If carbine length was so detrimental .mil would have swapped over to mid length years ago for all 14.5 carbines.

Thanks for your reply. I will be returning the buffer then!

The H buffer has 1 Tungsten & 2 steel weights in it. If you go to the H2 (2 Tungsten, 1 steel) and a heavier buffer spring, you will notice the difference in a carbine gas system.
Conventional wisdom is to run the heaviest buffer & spring combo that will reliably function and lock the bolt back when using the weakest ammo you regularly shoot. This will smooth the recoil impulse, prevent bolt bounce and reduce parts wear.
In my 6920's I use the Sprinco Blue heavier buffer spring and the H3 buffer (3 Tungsten weights). It feels the same as the H2/Sprinco combo when shooting .223 but is slightly more controllable for me when shooting full power 5.56 and has been 100% reliable w/PMC .223 (the weakest ammo I currently shoot, I think I'll pick up some Wolf or Tula for reliability testing).
HTH...
Tomac

You know someday you will want another buffer, and it will cost more.  They are called spare parts.

Cause the military always does the right thing.  The bolt wont last 30k, dont spread this bs.

like a few have mentioned, a 6920 can take a H2 or H3 as well as an enhanced or extra power action spring and still handle almost all ammo available. I wouldn't be to concerned with being hard on the internals. here's a maintenance schedule for you to use as a guideline.  

2,500 round interval,
Inspect and replace as necessary extractor spring, insert and O-ring on bolt

5,000 round interval
Replace extractor spring
Replace extractor insert
Replace extractor
Replace Crane O-ring
Replace gas rings
Replace action spring (not necessary with CS springs like Sprinco)

10,000 round interval
Replace bolt
Replace lower receiver parts

15,000 round interval
Replace barrel

To begin your quest in becoming an AR-15 Jedi Master, this article by Mike Pannone will offer insight on increasing a 14.5"/16" carbine gas system's reliability; and at the same time decreasing internal stresses by increasing bolt lock time.

The Big M4 Myth: ‘Fouling caused by the direct impingement gas system makes the M4/M4A1 Carbine unreliable.’ by Mike Pannone

Unless you're in combat, or carry your rifle as a duty or survival rifle (in which case, by all means follow the schedule outlined above), keep spare parts on hand, and shoot it til it stops.

Let it surprise you, if it ever does.