The 1st shot/Cold bore shot?

[HeyU]

Does the term and reference "Cold Bore"apply to air rifles, especially spring air rifles. It may not be necessarily related to the bore of the barrel as that relates to centerfire rifles but would most likely be linked to the reciever. Wether that effect is coming from the spring or from the parts that make up the piston and sleeve and lube. And would certain weather conditions effect it more or less depending on the enviromental conditions. I notice a poi shift from my very 1st shot to the the subsequent shots.

 

[Airgunmann]

Depends on the gun per say

 

[Mycapt65]

Yes. Some springers are better than others. Most of mine will shoot minute of squirrel first shot. Others are dead nuts on. Some I couldn't reliably use for hunting. Once I figure out what makes the difference I'll let you know. I'll be playing the lottery the same day.

 

[Vetmx]

I used to chase my pellets around with my scope when I broke a springer out that had been sitting a while. Then I learned to just keep shooting it because my scope always wound up right back where I started. Last year I finally installed a tune kit in my TX200HC. I haven’t tested it after it sat to see if this phenomenon still happens.

 

[Sawney Bean]

I wonder how much of that might be present in a PCP as well. I'm thinking of things like the valve sticking the tiniest bit, drag on the hammer from lube settling, etc... With a firearm, it might just make an imperceptible difference in locktime, but with an airgun it would affect the velocity.

 

[A.G.R]

Springers are lube and seal as well as tune. dependent
If done from factory and you let it sit for 3 months chances are it will be all over the place and either honking on cocking or cracking on firing

Then there is the other side of the coin
over lubed heavy molybdenum smeared pistons from the shade tree tuner who watched a bad home tuner on the internet do this.. it will settle when sitting and solidify or worse liquify and fuel the gun for scatterville

A good springer is like a good girl.. 1 use the proper lube and you can expect great results.. 2 use it as much as possible, you are not gonna wear the gun out.. 3 If it’s malfunctioning ,open it up and look inside, and fix it, a gun sitting is a gun that will love someone who will use it.

 

[dens228]

I use my M3 to hunt squirrels in warm to very cold. It has minimized, pretty much eliminated poi shift for me if I don't cock the rifle, pressurize the shot, until I'm about to take aim on the critter. My thinking is that if I leave my 70 degree house and go out with it already charged into 25 degree air by the time I fire off a shot the pressure drop from the air in the rifle cooling can be quite a bit........ opposite going out in the heat, pressure can increase quite a bit.

 

[nervoustrig]

For a regulated PCP, going from warm to cold is mostly self-correcting in terms of pressure. The falling pressure in the plenum will cause the regulator’s valve seat to open and bring it back up to the setpoint.

However, going from cold to warm will drive up the pressure and squeeze the seat closed harder.

By the way, with any PCP, the process of pressurizing the shot is done automatically either instantly or within a few seconds of having fired the last shot. There is no mechanism by which the operator can postpone it.

 

[beerthief]

A chemist @ BP developed a grease to be used on space craft (he was a life long friend ) and gave me a baby food jar of the stuff . said i had about 4K worth in the jar (Government price ,final product ) supposedly it does not freeze up ? I used it on the car lug nuts , never had any problem changing a tire in Chicago winters . i often wonder what it might be if used in a springer ? I know it contains extremely micron fine moly powder and is about the viscosity 2x of toothpaste , maybe a bit more ?

 

[JimD]

I tested my pcps first shot versus subsequent shots earlier this year. It took about a week to fire a first, second, and third shot with each PCP, then let it set a day, and then repeat. I found that the POI at 30 yards did not change significantly for any of my guns. But that does not mean it does not happen to other PCPs. I think it's a good thing to test. I think I posted the target here.

I've also found that my first shot velocity will be low if my hammer spring is set to a little under the point of maximum velocity for that regulator setting on my P35s. The difference was not enough to affect short range POI but it was lower. How much "off" the hammer spring was would determine how much low the velocity was. Maybe 20 fps maximum in my testing.

 

[Treefrog]

Weighing in on the co2 side of things, I found that I get better groups if some time between shots is given. When hunting, the first shot is always a cold shot, so it seems logical to sight it in cold. The group below was shot over a two-hour period.

Cheers,

J~

 

[elh0102]

I have not noticed any "cold bore" effect with air rifles, as in first shot variance. But I have noticed changes in POI with significant changes in ambient temperature. Cold dense air creates more drag, and velocity will be slower. I believe I have read experiments with firearms that indicated a velocity change of about 1.5 fps per degree of fareinheit temp change. As with many variables, the effect isn't going to matter for practical accuracy at practical distances. I wonder if sometimes we experience this and misdiagnose it as a cold bore effect?

 

[HeyU]

I wonder if sometimes we experience this and misdiagnose it as a cold bore effect?

I spose it could be me. Getting these stiff old bones of mine to settle in to my shooting position.

 

[Hateful McNasty]

Naa, the worse first shots cold were in the receiver like spring, lubes, seal . Also I can suspect dirty barrel . Things thicken and thin as temps change on anything.. honestly the worse cold poi miss cold was using krytox as the spring/piston lube.

First shots cold off the unheated shop rack ,50° +/- , cp-hp , 50 yards, irons ( no scopes or peeps) R9.



I guess could be better , then I could be worse too..

 

[A.G.R]

50 yards with irons, THATS Fantastic .. I can’t see them to shoot them. I’ve never sat and done a shot cycle with them. I’m a scope hunter.

 

[Hateful McNasty]

50 yards with irons, THATS Fantastic .. I can’t see them to shoot them. I’ve never sat and done a shot cycle with them. I’m a scope hunter.

Just put in a new " latest" hornet spring I'm liking it better then the old hornet spring I last got ..

 

[A.G.R]

Just put in a new " latest" hornet spring I'm liking it better then the old hornet spring I last got ..

I tested one in a brand new Hw 95 and hated it. . You have the 34 coil x .128 x .538

I also tested a .125 wire x 34 x790 and hated it. BOTH WAY OVER SPRUNG in my opinion

That being said the factory spring could Be reworked if one wanted but I went with custom .
I ended up making my own spring and kit. Still getting 885 with 8 .4 Ftt or 775 with cph 10.5 14.5 ft lbs with both .(pretty linear if you ask me)

much easier to cock and shot cycle is far better in my opinion

 

[Hateful McNasty]

I tested one in a brand new Hw 95 and hated it. . You have the 34 coil x .128 x .538

I also tested a .125 wire x 34 x790 and hated it. BOTH WAY OVER SPRUNG in my opinion

That being said the factory spring could Be reworked if one wanted but I went with custom .
I ended up making my own spring and kit. Still getting 885 with 8 .4 Ftt or 775 with cph 10.5 14.5 ft lbs with both .(pretty linear if you ask me)

much easier to cock and shot cycle is far better in my opinion

Hmmm. Idk.

As is "drop in" but set I hover around 835+850fps with cp-hp.177. now unset they can be hot at first till settled like 920+ , but eventually will settle in about 850 or so .. at least for me anyway.. I been well pleased with arh stuff and really never give the others much thought ..

Edit
Another quick 5 @ 50y ,irons, cp-hp a few min ago. I could say consistent?

 

[Vetmx]

I was able to cold shot my TX200 today. The gun has been sitting for probably 6 months. First shot was low, all the rest grouped in a nice little group at 30 yards. Velocities were very tight, even the first cold shot that went low. I’ve had this gun for a very long time. This is the first time I didn’t have to get it warmed up for it to shoot well. The kit I put in it, the lube, and the one thing I had to machine for the spring made a big difference. Cold shots with PCP’s have to be divided into several categories. Way too many factors with those things to just say it’s this or that. I have never had cold shot issues with an unregulated PCP shooting pellets. Ever.

 

[Trucker3573]

I believe it is a thing but I don’t believe it has anything to do with the bore temp like it does in a firearm.