Fouler shots: What's the real deal?

[Tommie]

Bryan and gang,

Most of us own rifles which throw the first few shots after cleaning the bore. I've heard several theories why foulers are necessary but has this phenomenon been tested/studied? On its surface the idea of a clean bore being less accurate than one with debris seems counter-intuitive.

Thanks again for all your contributions.

 

[AlanWarner]

Tommie:
Simple observation and studies have confirmed the same. A fouled barrel ( from clean ) conditions it to it's normal operating condition.
A clean barrel will always shoot slower than a fouled one.
I did a simple test with the USPT way back in 95 to determine how long we could go before cleaning was needed to restore accuracy.
I also had been collecting data from each rifle and could identify each ones' normal dispersion. 18 guns, same powder, same bullet.

Most all would go well over 100 rounds before cleaning was needed. A few as much as 200.

All of the barrels had a round count of close to the same. The interesting thing was the varying number of shots needed to bring each rifle back to
shooting the groups know of each to the point of "settling down" after cleaning. Some required just a few, others as many as 15.
Go figure---
HTH

Alan

 

[Joe Salt]

I've found that my rifles at 1000 yards take 5-6 shots before they settle in on the vertical. Had one barrel a Hart back in the 90's that even when I cleaned it the first shot was dead center right from the get go! Those are the ones I wish I had a piles of.

Joe Salt

 

[jcampbellsmith]

Tommie:
Simple observation and studies have confirmed the same. A fouled barrel ( from clean ) conditions it to it's normal operating condition.
A clean barrel will always shoot slower than a fouled one. .....

In general I think your observation is correct, but there are exceptions. I have a 6XC which shoots the first round faster than the following rounds.

Regards

JCS

 

[jds holler]

I have no testing to prove this, but I suspect there may be a difference depending on the cleaning fluid that is used. I think that any oil/solvent based cleaner may require more fowling shots than some of the newer copper cutting fluids. Any thoughts?? jd

 

[dcali]

My observations have been that that the first few shots 2-3 out of a really clean bore tend to be a little slower than the ones that follow. In most of the barrels I've had, there has been no change in POI (at short range at least), but the last one I got will throw the first shot significantly. I still have no idea why that would be. It's more than the velocity difference can account for. I haven't really studied it in detail, but it's pretty consistently off on the first shot. I know it's not me, because the last barrel on the same rifle did not do this.

 

[JRS]

When the good Alan Warner speaks, you can take it to the bank Quite an accomplished, shooter, competitor, team captain, armorer, gunsmith, machinist, etc; etc; etc.

 

[Macropod]

My Bartlein barrelled f class rifle seems relatively immune to major changes after a thorough cleaning. From a cold clean bore it gets the job done mostly keeping sighters.


The key is a dry bore with little or no trace of oil. Some gun oils really seem to upset things for the first 5 or 6 shots. One gun oil in particular will never be used in the bore of my rifles. For some reason,the residual effect is persistent for quite a.number of shots before the barrel settles.

 

[LHSmith]

^^^^^ If I may hazard a WAG is it RemOil? Anything with teflon will cause big problems in a bore. For minimal fouling, I like a trace of oil left in the bore before firing, but definitely not Kroil.

 

[alf]

I like a trace of oil left in the bore before firing, but definitely not Kroil.

Funny, I always run a final patch through the bore with a couple three drops of Kroil on it....

 

[JRS]

I found (years ago) Kroil to resemble shellac. Nasty stuff!

 

[AckleymanII]

Run a patch with lighter fluid it through the bore if you are worried about oil in the barrel after cleaning, You WILL see a difference regarding flyers related to solvent left in the barrel. You may elect to do this just prior to shooting vs right after you clean if you like a tad bit of oil left in your barrel.

 

[Travelor]

I have a close friend with a Rem 40X 22LR.

Every time he cleans the gun his first round goes supersonic then settles back to subsonic. All with subsonic ammo from the same box.

 

[bohemR13]

Travelor- That's likely because he has oil in the bore and the first shot has much less resistance. It's a trick in air rifles for extra speed and more consistent velocity to lube the pellets with non-dieseling lightweight oil. In my 22c PCP air rifle it makes about 30fps velocity difference and it cuts the SD down by nearly half, under 15fps.

 

[mysticplayer]

A clean bore is no more nor less accurate then a fouled one.

Prove to your self by developing an accurate load for a clean bore. Yes, you will be cleaning after every shot so hopefully, conditions are really really stable through your testing

So in practical terms, the bore is only clean for 1 shot. From that point on, it is a varying degree of dirty.

Modern powders and jacket are designed to not really build up a cake of fouling. That would be really really bad in full auto weapons. So they "normalize" and that is the condition we load tune for. Some barrels do it in 2, others 5rds or..... The further you shoot, the more obvious this change can be viewed.

As long as the bore stays in that state of condition, the loads work well. On either side of that, the tuning is out so the barrel looks to be less accurate.

Jerry

 

[NINERUN]

I've noticed as my barrel installing and bedding improve, the first few shots have minimal poi shift from my groups. Especially since I've started using several brands of premium cut and or button rifled barrels. Also the bore conditioner and break-in seem to minimize groups as well.
https://www.facebook.com/pages/Nine-Run-Gun/281869551825477

 

[mikecr]

+1 mysticplayer
It could not be credibly declared that all(or even most) barrels can go hundreds of rounds without cleaning -and without copper fouling away from best. That's for sure. A good aftermarket barrel, yes. The rest, no.

There have been good tests showing that petroleum based cleaners left in the bore will have to be burned out before stable fouling can be relied on. That is, unless you go ahead and remove it beforehand.
I prefer cut rifled barrels and dry prefouling to ensure first shots are as good as any to follow.

 

[Sniper338]

I wont agree or disagree, I have barrels that seem to like a few rounds down them before the hone back in, and I have barrels that shoot, I mean just flat out shoot clean or dirty. (currently working on a 308 and cant get it to shoot at all though lol)

One thing that I find that has held true for me is: modern gun powder is not black powder, nor share the same properties. I hear it all the time clean the barrel, keep it clean... For me, that was true back in the old days where everyone shot black powder... Or even now days when you shoot black powder (or substitutes)...

I find that all my barrels build up "a dirty" they like, then they plateau so to speak where the next shot cleans out excess debris/fowling, and lays a new layer... The guns all shoot great on this plateau... Every barrel is different though as to how long/ how many rounds that plateau last for. When the barrel starts reaching the end of that plateau I see little pressure spikes start and thats when I clean. Just a few patches, then a few dry patches... Then go shoot again... I never clean a barrel good as new, I try to keep it in that plateau of "dirtiness" where it likes it..

Then on the other hand I have had a few that just shoot clean or dirty...

Hard to explain, but maybe someone will understand..


As far as the original question, Itd be interesting to see actual test data and even pictures... but no barrel is the same...

 

[XTR]

My experience at 1000 yards is that the first shot from a well cleaned, unfouled 308 barrel will be 8 ring low on an F class target, (about 1 ¼ MOA) and usually about 9 ring right (about ½ to 3/4). I've seen this with Kreiger and Bartline barrels.

Two, on occasion three, shots and they are usually back up to the correct elevation.

7-15-15 update to my above post: Was at the range today doing a little testing with my 308. The barrel was scrubbed clean with Pro shot and Iosso. My first three sighter shots were down on velocity, shot #1 was way down; after that the velocity was up to where it should be and consistent (9FPS ES)

 

[jlc204]

My experience at 1000 yards is that the first shot from a well cleaned, unfouled 308 barrel will be 8 ring low on an F class target, (about 1 ¼ MOA) and usually about 9 ring right (about ½ to 3/4). I've seen this with Kreiger and Bartline barrels.

Two, on occasion three, shots and they are usually back up to the correct elevation.

7-15-15 update to my above post: Was at the range today doing a little testing with my 308. The barrel was scrubbed clean with Pro shot and Iosso. My first three sighter shots were down on velocity, shot #1 was way down; after that the velocity was up to where it should be and consistent (9FPS ES)

My Bartlein mirrors your results exactly. 1st shot is about 1 MOA low, 1/2 MOA right, and down on velocity after a good cleaning.