How much does the line and position of the bore vary between the point where the trigger breaks, and the point where the bullet leaves the throat of the barrel, with an AR-15?  Is it significant?  If so, how much does it vary from shot to shot?  Is this responsible for differences between mechanical zero and field zero?

I'm trying to make a laser-based home dry-fire practice system (perhaps similar to the military's Weaponeer system).  Any insight or links would be appreciated.

ETA: Another way of asking the same thing: How much of the muzzle rise (and other effects) of recoil happens prior to the bullet leaving the throat of the barrel?  The answer to this question is important to me because it describes a variation between a laser boresight and the actual theoretical (absense of friction and gravity) impact point.

Tag for when I am not drunk.

"Tag for when I am not drunk."

OK.

first post wherein  I can agree with you, carry on

leroy

Quoted: "Tag for when I am not drunk." OK. first post wherein  I can agree with you, carry on leroy

Night of the living troll account, eh? h.gif

Quoted: "Tag for when I am not drunk." OK. first post wherein  I can agree with you, carry on leroy

Post whore.

Quoted: How much does the line and position of the bore vary between the point where the trigger breaks, and the point where the bullet leaves the throat of the barrel, with an AR-15?  Is it significant?  If so, how much does it vary from shot to shot?  Is this responsible for differences between mechanical zero and field zero? I'm trying to make a laser-based home dry-fire practice system (perhaps similar to the military's Weaponeer system).  Any insight or links would be appreciated.

Interesting. Keep us updated.

Oh, and Tag.

Im guessing very very little as you are dealling with a 3000FPS +/- cartridge
less effect than other mechanical variables in the rifle

Having used both, I'd say none.  Yeah, I'm sure there is a measurable interval, but I doubt it matters at all in real-world zombie shootings.  Unless your target can dodge in the micro-second range, don't worry.

Quoted: How much does the line and position of the bore vary between the point where the trigger breaks, and the point where the bullet leaves the throat of the barrel, with an AR-15?  Is it significant?  If so, how much does it vary from shot to shot?  Is this responsible for differences between mechanical zero and field zero? I'm trying to make a laser-based home dry-fire practice system (perhaps similar to the military's Weaponeer system).  Any insight or links would be appreciated.

Not recoil - poor trigger pull and grip/stance changes how the round leaves the barrel.

The difference between battlesight zero and mechanical zero depends on a couple of things;

Condition of weapon - all of our M16a2/M-203 weapon had the zero way off to one side (probably from a slightly bent barrel).

Sight picture - my military zero (R-16, D-4) worked perfectly when I got my AR-15, but changed after I had LASIK.

Quoted: Not recoil - poor trigger pull and grip/stance changes how the round leaves the barrel.

So the effects of recoil are not felt until after the mass of the bullet is no longer acting on the barrel?  This seems a little strange to me, as I always felt that it was the mass of the bullet itself that was primarily responsible for recoil.

On a twenty inch barrel the gas tube is not in play untill about 5 or six inches from the barrel!

Thats when the recoil factor comes into play with the bolt,and carrier and ejecton!  But there is the initual recoil of the detonation of the round in the chamber!  This would be in nano secounds of one another!

On a shorter barrel the effect would be quicker! How fast you can get back on target is in deffinent proportion to these variables!!!

In short I have no Idea of what you are asking??

Tagged for real answer!!!


Bob

Quoted: Quoted: Not recoil - poor trigger pull and grip/stance changes how the round leaves the barrel. So the effects of recoil are not felt until after the mass of the bullet is no longer acting on the barrel?  This seems a little strange to me, as I always felt that it was the mass of the bullet itself that was primarily responsible for recoil.

No - it's still acting, but if you take into account the weight of the bolt carrier cycling - the weight of a 62gr round is negligible.