best bore condition for sight in.....?

[Koda94]

What is better to sight in, a clean bore or a fouled bore?

I was thinking a fouled bore would be more practical for any followup shots but im not certain how quickly a shot fouls the barrel? My guess is if it takes more than 2 shots then the barrel temp changes your POI anyways...

 

[Jim Watson]

Yes.
You might see different POI cold and clean vs warm and fouled. Many forms of target shooting allow sighter shots which let you adjust to the day's conditions and "condition" the barrel. Also consider a time out and resume shooting cold and fouled.

Depends on your application. You need to know the changes as the gun heats up. A SWATter here has POI logged for all barrel conditions. Lots of hunters will set up so they go out cold and fouled.

 

[Koda94]

Depends on your application. You need to know the changes as the gun heats up. ...Lots of hunters will set up so they go out cold and fouled.

The application is hunting.

This is pretty much what Im concluding, I need to set up the zero with cold and fouled. I'll have to start documenting my first cold shot to track its grouping... This seems like a lot more work than most hunters realize. It also seems odd to zero on a cold shot when practicing will be with a hot barrel, but a hunting rifle will never be used in the field with a warm barrel...

 

[44 AMP]

a hunting rifle will never be used in the field with a warm barrel...

Define "warm".

People hunt in conditions where the barrel (and everything else) can be over 100 degrees.

My guess is if it takes more than 2 shots then the barrel temp changes your POI

There is more involved than just the barrel temperature. How fast a barrel heats up, and how much depends on a number of factors. Some powders heat guns noticeably "faster" than others. High pressure cartridges can be different than lower pressure rounds. Physical configuration of the barrel itself (thin light weight sporter vs havy varmint, etc) to name just some. And, of course how close together your shots are in time.

It is a long observed fact that first shot from a clean barrel can have a different POI than follow on shots. Sometimes the difference is a couple inches.

I've known guys who will not clean a rifle bore during hunting season, unless they HAVE to. And, if they do, they fire a couple of fouling shots THEN check their zero to be sure.

For a hunting rifle, I think the important thing is not the size of a 5 or 10 shot group, its having that FIRST shot hit where the sights are. Rapid follow up shots should be close enough to stay within the "minute of deer" or whatever you are hunting.

Look at it this way, if you were (or are) using a single shot rifle, how would you sight it in? Generally speaking, while there can be a significant difference between that first shot from a clean bore, and the next shot from a now fouled bore, there is usually much less difference between shots after the barrel is "fouled".

I would foul the bore with a shot or two, (which removes any traces of oil in the bore) then sight in with enough time between shots that the barrel doesn't noticeably heat up. Once your bullet strikes the point of aim, you're good to go, with a reasonable expectation that your first shot in the field will be on target (assuming you do your part, properly)

 

[Hal]

What is better to sight in, a clean bore or a fouled bore?

Sounds like a fun backyard experiment.....or range experiment if you can't use the backyard.

My guess would be - six of one, half dozen of the other.

(Edit to add)
Out of curiosity - I searched around to see how benchrest shooters address this.

Chris Dichter, Owner, Pac-Nor Barreling
“My preference is cleaning every 20-30 rounds.

That would seem to indicate that - there's not a whole heck of a lot of variation between a clean bore and one with a few shots through it.

I don't know - since I don't shoot a rifle since I can't hit the broad side of a barn with one.

 

[Jim Watson]

Well, those benchrest shooters have premium barrels, straight, tight, and lapped. They are more consistent.
Real advice to the OP is to shoot the gun. It will take a lot of cleaning and cooling but hey, what else were you doing before hunting season?

 

[jmhyer]

I always prefer my firearms to be clean. I am probably guilty of excessive frequency of cleaning because I always clean after I shoot...even if I fire only a few rounds.

Specifically for hunting applications (deer, in my case), I have always figured it didn't matter. My goal is always a one-shot kill. So, if I am confident in the accuracy of my firearm with a cold, clean barrel on the range, then I am good. After all, that's how it will be when I take that first (and, hopefully, only) shot at an animal.

 

[Koda94]

@44_amp "warm" being just after shooting. But your point is still valid.... I hunt in the late fall with this rifle so while its summer its best to not sight in on a blazing hot day where the ambient temperature of the unfired barrel will be much warmer than on a crisp cold late fall morning.

 

[Koda94]

@jmhyer this depends on the average range of your quarry. Our goal is always a 1 shot kill but most deer are taken under a 100yds where the difference between a clean cold zero and a clean fouled zero is negligable on most production hunting rifles.
This is true with my rifle but the area I hunt often produces shots out to 2 and 300yds. A one shot kill at those distances is virtually impossible if you dont know how far off the first cold shot will be at longer distances...
(All other things being equal here....)

 

[cw308]

I always start off clean and dry , your rifle will let you know . Depends on the barrel and a good shooting day , all conditions being the same to be fair.

 

[Shadow9mm]

Depends on the caliber and use. for 22s, I have found my rifle takes about 20rnds to settle in after cleaning due to the wax on the bullets. Centerfire are not nearly as much of an issue.

like cw308 said. start off clean and dry. See how the gun does

 

[cw308]

For my 22 lr. , I'm shooting a CZ452 Varmint the bullets that shot best was Wolf Target Match 40 gr. Standard velocity, the bullets have a oil coating so using Ballistol in the barrel with a very light coat , it is the only rifle I don't shoot dry , the bullets are so lubed I don't think it matters.

 

[44 AMP]

I searched around to see how benchrest shooters address this.

Benchrest shooters are "hunting" the smallest groups on paper. Not everything they do has the same degree of effect when shooting sporting rifles, big game rifles, especially.

Generally, the biggest shot to shot change in the bore happens between clean and 2nd shot. And individual rifles can and do vary.

Easy enough to check, all you need do is shoot two groups.
Start with a clean bore. Shoot your first round, and see where it hits, relative to your point of aim. KEEPING the same point of aim, shoot a group.

Then, later with the rifle cold again (but now "dirty" shoot another group with that same point of aim, and see what, if any, difference there is from your very first shot.

Odds are, that very first shot from a clean bore will be a bit further away then the rest.

Lets say, for example, tht your first shot from a clean bore is 2" left and 1" high from your aiming point, but all following shots from the now "fouled" barrel are within 1" of your point of aim. This is not an impossible example.

Do you sight in so that very first shot (clean bore) hits POA precisely? Or do you sight in for where the majority of your shots will hit?

Either way works.

 

[Koda94]

@44 AMP.... Thats the million dollar question im after. I think what Im going to do is zero on a cold fouled barrel... Seems most practical to not have to worry about fouling the barrel in the field, basically I wont clean the barrel until after hunting season is over.

 

[Hal]

Benchrest shooters are "hunting" the smallest groups on paper.

Yes - and what's wrong with using that to see how a clean or fouled bore shoots?

I mean - those people are dedicated to finding out what does and what doesn't make a difference in how a gun shoots.

What's wrong with using that?

 

[cw308]

I agree with Hal . You want to hit what your arming at , if it's a deer or the head of a ground hog . A one inch group with a scope at 100 yards can still be improved , why wouldn't you try. That just reminded me , about 3 years back the guy next to me at the range was sighting in a new rifle for a moose hunt he was going on . The target backing was 3'x4' you would staple a target to it . After the first round of shooting he said he was sighted in , one bullet hit his target the others were in the 3x4' area . I said to him , that's sighted in , he said it was good enough for moose. All I said was good luck on you hunt and be careful , see ya. So I guess sighted in is what you except is good enough. Funny thing is he'll probably be the guy who gets a moose.

 

[Paul B.]

To me it all depends. Where does you rifle hit from a cold clean bore vs a cold fouled bore? I have a few rifles where it apparently makes little difference but the majority do hit differently when the bore is clean vs fouled. Easy way to fine out if start with that clean barrel, fire one shot for score. Shoot a few more to ensure the barrel is fouled that wait until it thoroughly cooled down then try a single shot on the same target. Any radical difference will give you what you need to know. After all, it's that first shot on that buck of a lifetime that counts. it's nice to know it with go where you want it if you do your part. I always start my hunts with a fouled bore.
Paul B.