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A warm gun...


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A warm semi auto rifle may cycle a bit easier when warm.

Bullets will perform better when the powder is warm. You get a faster (more efficient) burn which will give more velocity (range). This is only the case for EXTREME distance shots, well beyond 1,000 yards.

No warm barrel will ever outperform itself cold.

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Steel can move as it changes with temperature. That's why the first shot or two  is often at a slightly different point of impact than the follow ups.

My buddy, who was the designated sniper on our SWAT team, always said the same thing. He would go to the range once a month and set up a bullseye target @ 100 yards and take one shot with a cold rifle. He would then take the target to the P.D. and have the Chief initial it with the date, time  and weather conditions and put it in a file. He felt that if he ever had to go to court on a shooting those targets would be the most representative of his abilities under the conditions he would be shooting in. Fortunately, he never had to 'Take the shot' before he retired.

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My 10/22 is almost a worst-case example.  The first two rounds go in random strange directions.  Then,  with the metal warmed a bit,  the rest of the shots group close together.  For 'fun' target shooting it is easy to disregard the two fliers or to shoot a few warm-up rounds at a different target.  If dinner depended on that rifle taking a squirrel or rabbit,  there would be a lot of hungry days.

I think that some of the reason is warm lube within the gun (more pronounced in something like this blow-back rimfire) that causes mechanisms to move more slowly when cold (the bolt might not close as tightly by a few thousandths;  the first two cartridges might not slip into place as easily or not quite completely at all until the chamber has expanded its diameter from heating?) and some is expansion and contraction of the bore diameter as the steel warms and cools.  An engineering analysis (a link here somewhere) discussed droop of the muzzle and harmonic movements of the barrel.  All that might change with temperature of the steel and as the bore and external diameters changed with heating,  also?

I have wondered for some time if a heater of some kind that could bring a specialty rifle to a consistent working temperature,  a temperature similar to how hot the rifle might be after a dozen (?) rounds in a relatively short time and keep the rifle at that temperature,  might be desirable for critical Police sniper work and perhaps for some kinds of shooting competition?  (Or,  pack the rifle in dry ice and keep the rate of fire slow enough that every shot is from that super cold condition.  <lmao>)

Clearly,  as already said by others,  for a target or competition rifle where many shots will usually be fired in a limited time,  sights need be set at 'warm rifle' POI.  For hunting or Police/Military sniper work,  the sights need show POI for that cold gun first or only shot.

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OK, good to know... I posted this here to get some responses. My 308 shoots well cold and warm but my little 22 doesn't shoot in good groups until it is warm. I posted over on the 22 form but nobody posted, I knew here I could get feedback and learn something.

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  • 5 months later...

Depends on the mission. 

A police sniper is going to be most times, a long time in position and then with luck only firing a few rounds.

A combat sniper may be called upon to engage multiple targets or to a recon by fire so he has to know how his gun responds to a heated barrel much more so than his civilian counterpart but the the police sniper would still know what changes a warm barrel will make in his POI.

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It is all about what the rifle is used for . A Sniper /Hunter , will want to set up for the first shot or maybe two , where a target rifle( or one that will be shot at multiple & frequent targets ) that will see a bunch of rounds down range will need to know more about how it shoots cold & warm ,because you always ( or should ) take a few warm up shots before you shoot for groups.

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