For the purpose of discussion, let's throw out some static numbers. Let's say a 16" barrel chambered in 5.56x45mm firing a basic XM193 55 grain fmj projectile in a MOA-ish off the shelf rifle.

What effect will a flash hider, a brake, or a compensator have on practical accuracy?

Noticeable? Negligible? Zero change? I know we've got some ballistics guys on here - and I look forward to hearing your experiences or thoughts on this.

I know you didn't ask about suppressors, but they are the most "extreme" type of muzzle device so the hyperbole of a suppressor is useful to illustrate certain principles.

I am going to add the disclaimer here that all following discussion is only in regards to well-made devices mounted on appropriate barrel types and properly installed.

Suppressors can actually increase accuracy because they act like perfect barrel crowns. They will tend to increase muzzle velocity because they act as inefficient barrel extensions (keep air pushing behind the bullet longer).

Suppressors tend to change POI compared with the same gun unsuppressed as a result of muzzele velocity change and changing the barrel harmonics (by adding 1+ lb to the end of most centerfire rifles--not such a big difference on rimfires w/ rimfire suppressors).

[A heavy suppressor on a thin whippy barrel can cause issues, but that has more to do with the barrel than then suppressor]

Brakes and flash hiders tend not to increase muzzle velocity the same way a suppressor will because there's not much of the device left to pass through by the time the bullet gets that far down the barrel (technically, it's left the barrel by the time it gets to the muzzle device).

Muzzle brakes, compensators, and flash hiders also tend not to weigh very much so they don't, as signficantly, change the barrel harmonics.

The "accuracy" people get from compensators and brakes comes from follow-up shots fired in rapid succession, not cold-bore shots.

Where you can lose accuracy is muzzle devices aren't typically removed during cleaning. This means the junk that deposits after each fired round builds up around the crown and can eventually cause corroding of the barrel crown. Honestly, I've never seen this happen to a point where my conclusion was "yup, rifling's still good, but the barrel crown is gone--gonna need a new barrel or have the barrel recrowned."

One thing to add to LDD's excellent comment - a muzzle device that is not concentric to the bore can deflect the trajectory of the bullet, even if it doesn't actually touch the projectile itself.

quote:

Originally posted by bionic218:
What effect will a flash hider, a brake, or a compensator have on practical accuracy?

Back before the AWB every service rifle shooter had an A2 flash hider on their rifle. The AMU found out that anything more than minimum torque caused groups to open up a bit. Once shooters got used to the bare muzzle many stopped using flash hiders on their target guns.

Something to keep in mind about your question is that firearms terminology is subject to change. When Townsend Whelen said that only accurate rifles are interesting, he was obviously referring to rifles that were capable of producing small groups. That was what “accuracy” referred to in all of the discussions I ever read for decades when talking about the rifle itself, and I imagine it’s how most knowledgeable shooters interpret the term today.

Some authors and shooters like Bryan Litz, however, now distinguish between accuracy and precision: Accuracy to them is hitting a specific target, and precision is how closely a series of shots will group together. I’ve also seen a poster or two here stress the same difference; in time I imagine it will evolve into something like the insistence that Heckler and Koch should be abbreviated HK rather than H&K.

Muzzle devices can certainly affect accuracy, or where the point of aim and point of impact differ. I own only one suppressor, but I can use it on several different rifles. Attaching it to the barrel can change the point of impact by a couple/three inches at 100 yards. The effect it has on bullet velocity is so minor that that’s obviously not the reason for such a large POI change, so I assume it’s the effect of the extra weight on the muzzle and, possibly, its effect on barrel harmonics. The well-known authority on military sniping, Major John Plaster, has stated that even wrapping a rifle barrel with tape can affect point of bullet impact, so it’s obvious to me that muzzle devices can do the same.

In my limited experience, precision, or the ability of the rifle (and ammunition) to produce small groups, may or may not be affected by muzzle devices. Attempts have been made to enhance precision by attaching weights to the barrel or devices to the muzzle, so they can obviously have an adverse effect as well.

Something like a suppressor or brake can affect practical precision or accuracy. Anything that reduces felt recoil often helps some people shoot better as a practical matter for a variety of reasons. If, for example, the shooter has the luxury of firing sighter shots before shooting for record or fires multiple shots at one target, a device that makes it easier to see one’s bullet impacts can improve practical accuracy by allowing one to adjust point of aim to the specific range conditions.

quote:

Originally posted by bionic218:
Let's say a 16" barrel chambered in 5.56x45mm firing a basic XM193 55 grain fmj projectile in a MOA-ish off the shelf rifle.

What effect will a flash hider, a brake, or a compensator have on practical accuracy?

Many ARs are capable of 1 MOA accuracy, but not with XM193. Oh sure, keyboard commandos will claim MOA accuracy here and there with XM193, but it won't happen with any kind of regularity.

That said, a little bit of accuracy variation from a muzzle device likely will be lost in the accuracy issues of XM193.

IMO, if a FH, brake, or comp is properly designed, properly threaded, and properly torqued to the barrel -- it's doubtful there will be any effect on practical accuracy with XM193. Brakes and comps may change POI a little, depending on their design. They may also improve accuracy if they mitigate recoil effectively, and offset a given shooter's weaknesses in fundamentals.

Thanks for all the insight and information. I am considering something for my AR, and in shopping, have found there are hundreds of designs. What I wanted to find out is if there is any real difference or value in how they might impact accuracy, or if it was more of a 'like how it looks' kind of thing - or worse yet - a negative impact on accuracy.

Good insight on the cold-bore factor. Recoil mitigation also is a real issue for some shooters, but on an AR, it's not a big concern for me.

Some of the 'blast forward' designs seem interesting, but also seem like maybe more prone to having some impact on the actual shot. Maybe not? I don't know.

There are gobs of manufacturers and designs for muzzle brakes. It can be a challenge to wade through the hype, especially if you haven't been around a number of the models. There's also a difference in how a nearby person perceives the effect of a device (blast and noise) versus the shooter.

There are a few independent tests of brakes, comps, and FHs. Google is your friend -- search for brake (or whatever) test, comparison, or shootout. Precision rifle blog and truth about guns are two that come to mind quickly. Certainly there are others. Not all devices will be listed, however.

IMO flash hiders have the least effect on results for the civilian shooter. I rarely shoot at night. When I do, muzzle flash doesn't seem to be an issue. My steel and paper targets don't shoot back, so I don't care if the targets "see" my flash or not. Other than a way to QD mount my SOCOM suppressor, I find a FH to be little more than a way to protect my barrels' crowns.

Effective brakes are really loud and ineffective brakes generally aren't that loud. The blast and the report are usually worse for the bystander than the shooter. IMO the best brakes are those that direct blast to the 9 o'clock and 3 o'clock (i.e. left and right). Upward and downward ports tend to change bullet POI. Downward ports kick up dirt from prone positions. The heavier the barrel profile, the less a brake affects POI. A good brake cuts recoil by as much as 75%. Regardless of caliber, this is a noticeable effect. My accuracy improved when I started using recoil mitigation devices, both brakes and suppressors.

I'm not all that sold on comps for rifles. With properly-designed, modern-stocked rifles the recoil is generally straight back -- if the shooter understands the recoil management and the fundamentals of marksmanship. IMO comps can affect POI too much, generally by pushing the barrel down. This can result in inconsistent POI with a thin, whippy barrel. I've seen this both in live shooting and in high-speed camera footage on pencil-profile AR barrels.

For me the jury's out on forward-blast devices. In theory, a longer barrel does almost the exact same thing, but with added muzzle velocity.

quote:

Originally posted by fritz:
I'm not all that sold on comps for rifles. With properly-designed, modern-stocked rifles the recoil is generally straight back -- if the
For me the jury's out on forward-blast devices. In theory, a longer barrel does almost the exact same thing, but with added muzzle velocity.

I've used a forward defect device on an 11" SBR. The results were dramatic in terms of noise and blast reduction. I don't remember which one it was, but the rifle was an AR in 5.56.

quote:

The results were dramatic in terms of noise and blast reduction.

This is a point of interest for me. One of my favorite ranges has a 200 yard range where the bays are walled three to four feet past the end of the tables. A carbine style AR with A2 hider is almost unbearable in those conditions after five or so rounds. Just an incredible amount of noise and concussion.

At the farm, where I do most of my shooting, I could give two squirts about all that. But at this range - where I am a paying member - I try to be a little more considerate of other shooters and my spotters (kids) when they are around.

If a $30-$50 "flash can" or whatever will help with that while not having a negative impact on accuracy or precision, I would consider that money well spent.