Another AR question

[qwkdrwmgw]

I am looking for an upper to put on my PSA lower. My question is this what is the difference between M4 and M4A1?

Thanks in advance
Scott

 

[shooter521]

Depends on who's talking, and what they're talking about.

In military parlance, "M4" indicates safe-semi-burst selector and a barrel profile that is lighter under the handguards, and a while "M4A1" has a safe-semi-auto selector, and may also include a barrel that's heavier under the handguards, and an H2 buffer.

Some commercial manufacturers and/or resellers may have adopted the M4A1 label to indicate a barrel that has the M4 profile forward of the FSB but remains heavier under the handguards.

 

[qwkdrwmgw]

I was looking on the PSA website and it says they are sold out of the 16" M4 but the still have the 16" M4A1. I just didn't know what was different because I looked at the pics of both and could tell no difference.

 

[figley]

Thanks eruqewou, for asking the question, and thanks 521, for the accurate answer. You guys helped me learn something.

flakjfaoie, you're not the first to ask the question: M4A1 PSA Upper?

 

[windellmc]

The M4A1 profile was developed to fix the issue where an M4 barrel will split under the handguards after some number of mag dumps in a row. I believe the number was less than 20 mags though. Rumor is all US M4s will be getting M4A1 profile barrels as their standard barrels wear out.

I have the 16" Palmetto M4A1 CHF barrel and I like it. It is heavier but the weight is close to the center of the rifle so it points pretty well.

 

[netsecurity]

Yes, heavier barrel as far as the profile is concerned. The M4A1 has existed for years as full auto, but the new ones have the upgraded barrels I believe. I don't think a heavier barrel is good for civilians though. Only for automatic fire, where the barrel heats up and causes the gun to malfunction, which is the primary problem they've had in Afghanistan if I understand it correctly, not dust. I've heard multiple stories where our guys have had to run their M4's on full auto mag, after mag, to lay down suppressive fire, until the barrel turned red and the gun siezed in the middle of a firefight. To me it sounds like they need more SAW's per squad, or additional LMG's.

 

[Dwight D]

When the M16A2 was introduced it was rated for a sustained rate of fire of 12-15 rds per minute. In other words that was the rate of fire that could theoretically be sustained for an indefinite period of time with no damage to the weapon. Of course that all goes out the window when you don't think you might be alive in the next 2 minutes unless you get some serious rounds down range. No such thing as a perfect weapon, and if the poop really hits the fan you can never have enough belt feds.

 

[windellmc]

If you do get an M4A1 profile you will want an H2 buffer for it.

 

[mvician]

The difference in weight between the barrels, at least Colt barrels, is 4 ounces.