Fouling Shots

[Cracko]

Hello,
I've been away from the forum for quite some time, so if this topic has been addressed, my apologies, and please give me the link.
OK, My Anschutz smallbore rifle requires about 5 fouling shots for the zero to stabilize. Note that this is after a week since I shot it last, and no cleaning or solvents or oils were used in the bore. Barrel temperature is not a significant factor based on observations in subsequent relays.
Questions: Is the powder fouling absorbing atmospheric moisture (hygroscopic) in between range sessions? Or is it changing in some other way?
Secondly, if the bore must be cleaned (to restore accuracy), what is the best solvent to use? I have heard that using a petroleum-based solvent like Hoppe's will require an inordinate number of fouling shots to settle the barrel. How about the chemical product TSI 301? Thanks

[Tim S]

Firstly, I believe the powder residue is hygroscopic (less so than black powder, but enough that I wouldn't put a fouled barrel into long term storage), although the fouling actually seems moister when fresh, and dries and hardens as it cools. That's possibly the reason you need a few fouling shots after a week, that those first few shots have to fight through the cold dry crud, and normal grouping resumes once there is a coating of fresh residue. You might try a dry patch or two straight after shooting to remove the bulk of the residue without leaving the bore squeaky clean.

Secondly, no I don't believe that you always need many foulers after cleaning with Hoppe's, or similar products, unless one leaves the bore wet, which is not recommended for other good reasons. I have heard that excessive fouling shots happens with Teflon-based cleaners though, but I ran out of Breakfree years ago, so can't comment. You may need foulers after cleaning with a solvent simply because the barrel is clean, and it shoots better with a little fouling (friction affecting acceleration and barrel time being a plausible answer). I clean with Ed's Red, a home brew solvent that's 75% petroleum based and usually need no foulers. I know of very high"mileage" Anschutz barrels that took many shots to settle after cleaning, but this was attributed to being knackered, with extensive wear in the throat. Lower quality barrels with a looser chamber than often need a few dozen foulers to fill in any loose spots and reduce freebore in the throat.

If you want to try a different solvent Bore tech Rimfire Blend contains citrus oil and is very effective, if expensive.

[atomicgale]

Fowling shots:

[NMC_EXP]

Not much evidence to back it up but I've come to believe the bullet lubricant is a factor. Specifically the relationship of residual lubricant viscosity and internal barrel temperature.

I shoot outdoors. Actual ambient temperature range of 38°F to 102°F. After a 20 shot string with the barrel warm and fouled there is a delay of several minutes to change targets and the barrel cools down. I've noticed that if the ambient temperature is 90F or higher only 2 or 3 foulers are required. At 50F or less it may take 10 foulers. It seems that the viscosity of the residual bullet lube in the bore would be bore temp dependent and this would affect the coefficient of friction of the bullet in the barrel.

Regarding Teflon based lubricants in the bore: Long ago after cleaning the bore of a centerfire rifle I would apply BreakFree to the bore. This was dry patched to remove before firing. However it took several shots for the point of impact to settle down. Teflon is unaffected by solvents and I assume some Teflon was left in the bore and was eventually worn away by the bullets. If the bore was left dry after cleaning the rifle shot to zero. Now I do not use anything with Teflon in a rifle bore.

[marky-d]

I've read similar comments about Teflon for muzzleloaders. In that world, it's common to fire off a few caps or a squib load to purposely foul the barrel before hunting.

marky-d

[atomicgale]

Melting point of lead = 621.4 f
Melting point of Teflon = 620.3 f

I'd scorn any barrel-application of Teflon as PTFE begins to degrade around 400° with full decomposition at 660°. Despite what the "Marketers" would have you believe, Teflon is great, except for chamber or barrel.

Instead, look towards:
Molly-disulfide
or
HBN

[40xguy]

I don't know diddly about hydroscopic stuff, but 5 shots is what it takes me in the morning to get my barrel ready to shoot for score. after that, 2 or 3 shots per string ... this assuming a reasonable day temp(about 65 to 85 F). as someone I have a most high regard for once said, "You gotta do whatever it takes." re cleaning: a friend of mine who is a very good smallbore shooter was asked how often did he clean his barrel..... "Every Leap Year" was the answer :-)

[PaulB]

My recollection is that Art Cook, 1948 Olympic gold medalist in prone, national champion and several other international medals as well as a pretty good shot for 50+ years, saying that he did not clean his barrel at all and I don't recall him shooting any sighting shots (I was on a number of teams with him from about 1980 until he retired from shooting). Also, I only ever fired one fouling shot, most times none.

Sometimes you really need a fouling shot. Mike Anti (2004 Olympic silver in 3P) had an Anschutz rifle when he was a junior (if I am remembering what I heard correctly) that at 50 feet indoors on a standard NRA A-36 12 bull target would hit the #1 record bull in the top left corner if he shot his first shot at the upper sighting bull out of a cold barrel. That is like 3 to 4 inches off at 50 feet. Next shot would be right on call. No one could figure out why.

[beye]

I agree with Tim about it being dried fouling. I clean my prone rifles after every 1600 match with BoreTech's C4 carbon remover and a nylon brush. Usually takes about 5 rds. to settle down for a good X count at 50. I shoot outdoors year round and some matches are near or below freezing. When changing targets during a stage in cold weather (doesn't take long), I always fire a fouling shot on the new target. With the usual 15-20 min. between stages, I then fire about 3 or so until it settles -- I think the lube has cooled and hardened somewhat. When I haven't done that, I have often regretted it. On more pleasant days, I usually fire 1 round on the sighter target just as a wind check, but often skip this sighter when wind is not much of a factor. I have several prone rifles of different mfg. with some having custom barrels and I use this procedure with all of them. All of them are bedded, which I believe is important to maintaining zero, particularly if one shoots a tight sling.

[Cracko]

Thanks everyone for the input. Good information based on experience. I will keep the Break Free, PTFE suspensions, and other colloidal snake-oils out of my barrel.