I see many pics of M4s and their clones with cans on them. Do they affect negatively accuracy?? Do you have one on your SHTF or go to gun? If so, why?

Most quality .223 cans slightly improve accuracy and velocity but all have at least some point of impact shift. In other words, the bullet hits in a slightly different place with the can on than it does with the can off. Some have very minute POI shift. For example, my Surefire FA556AR shifts the POI about one or two inches at a hundred yards, depending on the ammo. The shift is also repeatable because that can only attaches one way. I have two main SHTF rifles. One is a RRA 16" M4 style with a TA01 ACOG and a Surefire M951 weapon light. It wears the can almost perpetually. The other is an Ameetec 14.5" M4 type rifle with an Aimpoint ML2 and a Pentagon light. The latter is my main home defense weapon but is in the shop right now having the pinned and welded Phantom replaced with a pinned and welded Surefire adapter mount for the can. There are so many benefits and so few disadvantages to sound suppressors that it just doesn't make any sense to not at least have the option of mounting the can.

I can't predict the nature of SHTF, if I could, it probably wouldn't be SHTF, but I can't imagine a scenario in which I would not want the can mounted. A .223 can reduces the sound of the report to something that sounds very much like an unsuppressed .22lr rifle. It essentially eliminates muzzle blast leaving only ballistic crack. It nearly eliminates muzzle flash as well. With a .22lr conversion kit installed and subsonic ammo the only real sound that can be heard is the action cycling, the bullets impacting and the cases hitting the ground. If I had to defend myself or shoot my food in a SHTF scenario, I'd prefer not to attract any more attention than necessary. I didn't buy the can to be some kind of 007 super ninja assassin but if things got bad, you can bet it would be on my rifle.

ETA: I just noticed you live in AZ, if you live in the Phoenix area and want to shoot my can, PM me.

Thanks blueflacon. I am the same guy that asked about your camping spot on the Rim and your crawdad recipe!! You IM'ed me your number already. I shall be calling really soon. BTW, I'm in Mesa.

My AAC can noticeably shrunk my groups.  We tested it at 50 yards and my groups with iron sights went from 1.5-1.75 inches down to 1 inch.  A good can shouldn't hurt accuracy, and the weight on the barrel reduces barrel whip which seems to be why you pick up accuracy.

(Edit:  I do not keep the can mounted for SHTF or Home Defense.  I consider it a special application device.  It adds too much length and weight to the gun for general purpose fighting)

MarkM makes a good point. Some suppressors add a lot of length and they all add a fair amount of weight. As with anything, there are pros and cons. In my case, I’ll be using a reflex style can on a 14.5” barrel which will mean that with 5” is added past the muzzle, the effective barrel length is under 20”. This is not too unwieldy in my opinion and the advantage of not being disoriented by the blast from discharging intermediate rifle cartridges in enclosed spaces is worth the extra length and weight to me. Everyone’s situation and risk assessment is different. If things got bad, I would definitely grab a rifle that is capable of mounting my can, whether I mounted it or just kept it on my IBA. In short, it’s a great tool to have in the tool box, but because of the limitations it may not fit in every application.

Hey markm...what's your can length and barrel length????

The KAC sucks because it can be mounted wrong. They all make the gun longer, and all affect accuracy to some degree. For combat ops in the city we would put them on the 10" barrells with eotechs. For recon-type ops in the desert, etc. we would put them on our 14.5 uppers, and use a ACOG. For GP shit on a truck, most guys would go with 14.5, acog, no can.

Could you explain this? The can sucks because someone f'ed up installing it correctly? There may be more to the story but from this it sounds like.....user error.