Muzzle devices and their effect on POI?

Hey everybody! Decided to post this question as I read several references online on this particular subject in recent days and still "not in the clear" at the moment as far as what exactly happens when you put something on the end of your barrel. The question to me is both theoretical and practical since I have two rifles with threaded ends (Hog hunter and PC, both in .223) and am real itchy to screw something on 'em. As a matter of fact I went ahead and bought a couple of relatively inexpensive muzzle breaks but neither installed them, nor shot the rifles yet. The main question/confusion of mine is if what I have read is correct and that whatever protrudes past your perfectly cut crown;) is in fact deflecting the projectile somewhat and changes point of impact in compare to a bare crown then how do you compensate for it as the distance increases? This magnitude seems to be (to me at least) neither linear nor in any way predictable so how do you deal with something like that? Thanks in advance for your responses and time taken in reading this!

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Originally Posted by dirtdigger

This magnitude seems to be (to me at least) neither linear nor in any way predictable so how do you deal with something like that?

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Guess and check at various ranges and interpolate in-between...?

Nothing is "deflecting" the projectile, unless it is actually hitting the brake or baffles.The point of impact change is caused by: the weight of the device, such as the weight of a suppressor will make the barrel droop, and a change in harmonics. An adjustment of the scope will cure this. The only way the trajectory will be off at longer ranges is a change in velocity.

will a muzzle brake have any affect at all on the velocity of the projectile as it leaves the barrel, and what would be an ideal tolerance between the ID of the muzzle brake and the OD of the projectile? I actually just ordered a Precision Armament M-11 this morning.

Uneven escaping gasses will affect the bullet leaving the muzzle, no ? That would have to be a very heavy suppressor to make a barrel droop.

High speed cameras slow down the action and the barrel modulation. Yes, it does cause droop. Just because you cant see it doesn't mean it doesn't happen. I personally think the O.P. is over thinking the subject unnecessarily. The m.b. needs to be factored in on the sighting in of the rifle, just as you would a multitude of other factors when the trigger is squeezed. Fortunately, w/a m.b. you can screw it on and forget about it w/all subsequent shots after you see your p.o.i.

Acceptable diameter is usually .040" over your rifle caliber from what I've seen.

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Originally Posted by dieselmudder

what would be an ideal tolerance between the ID of the muzzle brake and the OD of the projectile?.

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.020" over bore diameter, .224 bore = .244 brake.

wow that tight, well I'm hoping I made a good decision with my purchase. it was fairley pricey from the limited shopping around I did but I guess with those tolerances, and whats at stake im willing to spend more for quality. mine will be going on a .308

I put a Griffin Industries compensator on my .223 hog hunter and it changed point of impact about 2 inches. Not too bad. I certainly didn't need the compensator, but like you, I was itchy to put something on the end of the barrel, and I like how it looks now.

I have a CBI barrel & break , The break measures .020 over bore size

drybean

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Originally Posted by dieselmudder

wow that tight, well I'm hoping I made a good decision with my purchase. it was fairley pricey from the limited shopping around I did but I guess with those tolerances, and whats at stake im willing to spend more for quality. mine will be going on a .308

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We cut ours .020 over, example: 308 caliber would equal a muzzle break bore of .328, it's in your gunsmiths hands to insure it's installed correctly which is usually a piece of cake for most smiths.

If the bullet hit any part of the break, I am sure you would know it the first shot.

Dennis

PS: What are you using your rifles for? Hunting . . . Match shooting?

There is a good chance I 'm thinking too much into it as I often do. From what I have read online in some cases folks were reporting that after a device was installed the point of impact on target shifted both vertically and horizontally and that was/is the main thing that is unclear to me still. If the shift was only vertically it would be a piece of cake - simply adjust the scope to POI and compensate for bullet drop for further distances. If it does indeed shift in both planes though how the hell would I compensate for that? How much exactly do I add to the windage knob as the distance increases? If it went for instance an inch high and to the right at a 100 and I compensated for that and pulled my crosshairs over the aggregate POI, should I calculate further windage settings based on a 100 yards value then multiply for example by 1.5 for 150 yards, by 2 for 200 etc? The lateral shift will still be increasing with distance and I will be off "bullseye" to the right again at say 200 if I 'm zeroed at 100 yards and only compensated for the drop at that distance for example, right?

I have brakes on most of my guns..from small .223 to .308 calibers. It probably would affect the point of impact between having it on or having it off. However I put them on and leave them on..as I have no reason to remove them. Accuracy is outstanding in all of them so that is not an issue. Each of them is reamed .020” over bore size.

Ok I may be thinking something way outta wack here but if you are having a different poi wouldn't you just readjust your zero and if your scope has the zero stop just reset it and be good to go? When I put on a break I had to readjust poi and just reset my vortex and bam, done.
Did I not do something right or was it just that simple, I don't really know but it worked for me.

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Originally Posted by Dennis

We cut ours .020 over, example: 308 caliber would equal a muzzle break bore of .328, it's in your gunsmiths hands to insure it's installed correctly which is usually a piece of cake for most smiths.

If the bullet hit any part of the break, I am sure you would know it the first shot.

Dennis

PS: What are you using your rifles for? Hunting . . . Match shooting?

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I read all the Q&A questions in the review section of Brownells before I ordered, one question was if it would work on a Savage 10, the answer was yes. I will still measure just to make sure before I install it. mainly just target shooting, I still have a real bad flinch, and although the recoil is pretty mild im hoping just knowing its on there will help my mind keep from flinching. and I do get a decent amount of jump when I shoot from a bench. im working on stretching my distance. and I may do some varmint hunting with it when I get consistently accurate at long range. the barrel is already threaded, so I was planning to install it myself, what should I do to ensure its on properly.

A good brake will indeed reduce felt recoil, just be prepared for a much louder blast at the shooting position and those next to you. I have a Brake on a 375 H&H that makes it enjoyable to shoot, and a brake on a 300 win mag that reduces the recoil to about that of a 243. Good stuff, but they are really loud.

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Originally Posted by buxman66

High speed cameras slow down the action and the barrel modulation. Yes, it does cause droop. Just because you cant see it doesn't mean it doesn't happen. I personally think the O.P. is over thinking the subject unnecessarily. The m.b. needs to be factored in on the sighting in of the rifle, just as you would a multitude of other factors when the trigger is squeezed. Fortunately, w/a m.b. you can screw it on and forget about it w/all subsequent shots after you see your p.o.i.

Acceptable diameter is usually .040" over your rifle caliber from what I've seen.

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Sorry I re-read my post and mine isn't .040" over caliber diameter, it was actually .032"over. the exit dia.is

.342" on my Benny Cooley JP brake.this is on a .308 model 10.