I was just curious how much different the point of impact can be with a clean, cold bore vs a bore that has been shot? I know the fouled bore shot is easier because you can dial in your poi by paying attention to where previous shots have landed but how much difference is there in actual ballistics?
Cold bore vs fouled rifle bore POI
- Thread starter logan1080
- Start date
I seldom clean rifle bores anymore, so maybe I can offer this.
My unscientific observation on bores that have sat for awhile will often put the first shot out at 50 fps faster than those that follow. If its just a matter of sitting for a day or so there doesn't seem to be much difference at all.
I believe that this is due to powder fouling hardening with time, then self cleaning on the next shot.
My unscientific observation on bores that have sat for awhile will often put the first shot out at 50 fps faster than those that follow. If its just a matter of sitting for a day or so there doesn't seem to be much difference at all.
I believe that this is due to powder fouling hardening with time, then self cleaning on the next shot.
I have always marveled at the need to know the CCB shot. I also understand that copper fouling can affect accuracy. That said, clean the barrel and immediately remove the "clean" barrel variable by firing a couple of fouling shots before you put it away. Then you only need to know the cold barrel variable. The change in POI isn't as significant.
Boltgun
Boltgun
I am not a fan of putting a barrel away uncleaned as I have also read in my sako manual that a dirty barrel can start to corrode after 24 hours, I am also to OCD to leave anything dirty after use. I enjoy cleaning my firearms so I do so after every shooting. Next time I have the chance I will do a POI camparison at 300 yards to see if I can find any difference between cold bore and fouled. Nobody has done this already?
It depends on the gun; some don't care and others do. I like to throw my first shot at my 650 yard gong to blow out all that 24 hour rust.
Manufacturers will always error on the safest side, from a viewpoint of warranty returns. Sako doesn't recomend handloads either, do you follow that?
i can say from experience not; the first shot is ALWAYS "different" from the rest of the string- it's gotten to the point of where i'll discount the first shot unless i've shot the gun within 24 hours and didn't clean it- if i've cleaned it, i can guarentee the first couple of shots weill be off
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
depends on the barrel, the distance, your load tuning AND you.
the further you go, the more that first shot clean bore could be different from the rest.
I have shot match barrels at 200yds that didn't care clean or dirty, putting the first shot into the group. That same rifle and load shot so far out at 1000yds, it was laughable.
So the only way to know is to test.
BUT assume that clean will be different then dirty.
Jerry
the further you go, the more that first shot clean bore could be different from the rest.
I have shot match barrels at 200yds that didn't care clean or dirty, putting the first shot into the group. That same rifle and load shot so far out at 1000yds, it was laughable.
So the only way to know is to test.
BUT assume that clean will be different then dirty.
Jerry
Clean your barrel, take it to the range and run it over a chronograph. Chances are the first through a squeaky clean bore will be faster than the following shots.
How much faster is dependent on too many variables but I have seen up to 100fps difference.
More velocity = different POI
How much faster is dependent on too many variables but I have seen up to 100fps difference.
More velocity = different POI
Farlsincharge
CGN frequent flyer
- Location
- Saskatchewan
I have some rifles where it is significant and others where it is not. In any case the CCB shot is fairly consistent and is marked on my scope dope lest I ever need it.
- Location
- Calgary, AB
Ditto. My .22 RF target rifle (Anschutz) requires two or three 'conditioning' shots before it will group where it normally does.
My centerfire bench rest (.22 PPC) rifle and 308 Tactical Target rifle (both using jacketed match bullet reloads) couldn't care less, the first shot down the pipe is right in the normal grouping.
So whats the explination, ??????
- Location
- Niagara Region, Ontario. For now
My 10/22 target rifle will shoot all over the place with a cold bore. The first 2-3 shots are always flyers from a cold or clean bore. I don't start trying for groups till it has had a mag through it.
Not precision at all, but my 30-30 Marlin 336 I just took hunting was shooting about 3-4 inches right consistently with a clean barrel. I was taking only cold bore shots as I was zeroing it in for the tree stand. So in the last few trips to the range I decided not to clean it. Sure enough those cold bore shots from the dirty barrel sitting for a week at a time were dead on, and grouped perfectly. I then spent the last 2 days in a tree stand with no luck, but today did a little target shooting before I left. It was still dead on.
I used to be really OCD with cleaning my rifles, but now I only worry about leading when shooting cast stuff.
In a gun only shooting jacketed stuff I clean it if I see groups open up, or when I decide to give em all a clean.
Not precision at all, but my 30-30 Marlin 336 I just took hunting was shooting about 3-4 inches right consistently with a clean barrel. I was taking only cold bore shots as I was zeroing it in for the tree stand. So in the last few trips to the range I decided not to clean it. Sure enough those cold bore shots from the dirty barrel sitting for a week at a time were dead on, and grouped perfectly. I then spent the last 2 days in a tree stand with no luck, but today did a little target shooting before I left. It was still dead on.
I used to be really OCD with cleaning my rifles, but now I only worry about leading when shooting cast stuff.
In a gun only shooting jacketed stuff I clean it if I see groups open up, or when I decide to give em all a clean.
In all of my barrels, in every caliber of bottleneck rifle, the first shot in a cold clean barrel is always slower by about 30-50 fps. But, my normal cleaning routine is with Butche's Bore Shine, which is petroleum based. It likely acts as a lubricant, and reduces pressure and muzzle velocity similar to moly or hBN. It's going to depend a lot on your cleaning routine and the solvents and oils you use.
The CBS will group with the following shots at 100 or 200 yards. But, as Mystic points out, the farther you go out, the more that velocity difference has an effect. I always foul the bore with a hand full of shot the day before a competition, especially if that CBS will count for points.
The CBS will group with the following shots at 100 or 200 yards. But, as Mystic points out, the farther you go out, the more that velocity difference has an effect. I always foul the bore with a hand full of shot the day before a competition, especially if that CBS will count for points.
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
@logan1080, do you have a factory barrel or a match (custom) barrel? (the chief difference relevant to this thread is that good match barrels are lapped, and therefore have a much smoother surface finish than factory barrels).
My experience with match barrels matches kombayotch's - namely, the first shot out of a clean barrel is ~40fps slower than the rest. Observations:
- it takes only one shot to foul the barrel. Shot #2 is indistinguishable from all the following shots
- shot #1 shoots to exactly the same point of impact - it does not get "thrown"
- if the first shot is fired at long range (800y-1000y) it will strike lower than your sight zeros, by an amount that exactly corresponds to the amount that the shot is slower than your mean muzzle velocity. This can be completely and accurately accounted for in shooting a match. I'd rather shoot a long range match with a fouled barrel, but if I have to shoot it with a clean barrel and have the first shot out of the barrel count, it can be done.
I don't have any meaningful experience or measurements of clean barrel POI or muzzle velocity from factory barrels.
@Cyan1de I am really intrigued by your measurements, since they are opposite to what I have seen. I wonder what is going on?
My experience with match barrels matches kombayotch's - namely, the first shot out of a clean barrel is ~40fps slower than the rest. Observations:
- it takes only one shot to foul the barrel. Shot #2 is indistinguishable from all the following shots
- shot #1 shoots to exactly the same point of impact - it does not get "thrown"
- if the first shot is fired at long range (800y-1000y) it will strike lower than your sight zeros, by an amount that exactly corresponds to the amount that the shot is slower than your mean muzzle velocity. This can be completely and accurately accounted for in shooting a match. I'd rather shoot a long range match with a fouled barrel, but if I have to shoot it with a clean barrel and have the first shot out of the barrel count, it can be done.
I don't have any meaningful experience or measurements of clean barrel POI or muzzle velocity from factory barrels.
@Cyan1de I am really intrigued by your measurements, since they are opposite to what I have seen. I wonder what is going on?
rnbra_shooter,
Guessing that you probably are patching it out really well too and aren't putting any oil in afterwards, right? Anytime I've done that, the first shot has been completely unpredictable and it takes a few before it settles down.
Guessing that you probably are patching it out really well too and aren't putting any oil in afterwards, right? Anytime I've done that, the first shot has been completely unpredictable and it takes a few before it settles down.
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
@komayotch my cleaning regimen is pretty modest. I'll leave the bore soaking for days or even weeks with plain old Hoppes - basically I'll leave the bore wet, and run a wet patch through it anytime I'm in the gunroom and think about it. Before I shoot the rifle I dry out the bore with 2-3 dry patches. Nothing too ferocious, I wouldn't describe it as "patching it out really well", more like just making sure the bore isn't wet. I'll also dry out the chamber (1"x3" patch wrapped around a .45 cal brush). I don't put any oil in the bore.
@komayotch if I understand you correctly you are saying that you have found that an oiled bore takes several shots to settle-down?
@komayotch if I understand you correctly you are saying that you have found that an oiled bore takes several shots to settle-down?
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rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
@logan1080 in that case the easiest thing to do is to test it and see if there is/is-not a difference in POI with a cold clean barrel. There might be none at all, or there might be enough to matter or be noticeable. You'll need to have your rifle more or less sighted in at a convenient known, short distance (eg 100 yards or meters). Use your best ammo.
At home, clean your rifle the way you normally do.
Go to your range, set up your target. Spend a fair bit of time setting up your position, dry-firing, and making sure everything is absolutely perfect. When everything is ready, fire a perfect shot.
Set up another target(s) and fire one or more groups. If you have the time ammo and inclination, fire five 5-shot groups.
See if the first shot out of your barrel is inside the groups that you fired, or not.
At home, clean your rifle the way you normally do.
Go to your range, set up your target. Spend a fair bit of time setting up your position, dry-firing, and making sure everything is absolutely perfect. When everything is ready, fire a perfect shot.
Set up another target(s) and fire one or more groups. If you have the time ammo and inclination, fire five 5-shot groups.
See if the first shot out of your barrel is inside the groups that you fired, or not.
