Clean vs. dirty barrel accuracy.

[RestrictedColt]

I've repeatedly read that a clean bore will be less accurate than one that's got some rounds through it so I stopped the religious cleaning after every outing that I was doing early on. Today I decided to test the theory out with my .338WM. It's had around 150-200 rounds without a cleaning so after verifying that it was shooting about the same as the last several trips out I gave it a cleaning. The clean group, last five rounds of the day, was a little tighter than the dirty groups it's been doing. 4 were in an almost straight horizontal line, continuous broken paper about 1" wide center to center, and one that went 7/8" high. That same load did a 4 shot group 1" wide by 1 3/8" high, none touching. There was 15-30 MPH gusting wind all day which may account for some of the inaccuracy on all the groups. The best group unexpectedly came from a book max. charge loaded to magazine length, 4 shots measuring 1/4" wide by 5/8" tall.

I also decided to play with my 16" AR with the Primary Arms 4-14 ACCS scope. I found a rock about 10" diameter about 450 yards out, used the 450 hold-over in the reticle and to my surprise it was pretty much on the money with every load I tried; multiple 55gr. reloads, 69gr Federal Match, 77 gr. SMK reloads, and some others. I threw some 55gr. HP Tula at it and they too were right in the area, just a little wider of a group than most of the others. Had it been a torso sized target all would have been hits.

[Divernhunter]

The main reason not to go hunting with a fresh cleaned barrel is some firearms with print the 1st or the 1st coupe of rounds away from the normal group.
Example I had a friend(now dead) that had a very accurate hunting rifle in a mag cartridge. It would shoot 3 shots touching at 100 yards constantly......that is with a barrel that had at least 3 rounds fired after cleaning. After cleaning the 1st shot would be 5-5" to the side and low. The second would be closer to what he had it zeroed in at. The 3rd usually was pretty good but the 4th was always dead on where he wanted it. Then if you did not clean it and shot the next day the 1st shot would be dead on as well as following shots.

I have also seen other firearms not care either way.

Each firearm is different and one in itself.

[billped]

Divernhunter, there could be an explanation:

Remaining cleaning material, either liquid or cloth-threads, could be ununiformily found in the barrel grooves (likely near the crown) leaving just enough junk in there to send the projectiles off by a bit. After one or two shots, it's gone.

Could that be happening and, if so, does it matter? Dunno.

[mjmagee67]

My 30-06 hunting rifle shoots low right on a clean bore and after a few shot zeros right up. I alway clean the barrel up at the end of the season and put it in the safe. At the start of the season I verify zero, clean the barrel, and shoot 5 shots. After that I don't clean the barrel until the end of the season, even if a have to verify zero, like when I dropped the damn gun.......

[russ69]

The data is already in. The benchrest shooters know the process for best accuracy (hint...clean).

[mjmagee67]

The data is already in. The benchrest shooters know the process for best accuracy (hint...clean).

Oh it's far from settled, head over to accurateshooter.com and look around. Some like clean, some like not too clean, some shoot a whole match without cleaning, some clean every string, some use bronze brushes, some hate bronze brushes. The only consintent theme is inconsistency...

Basically find what works for you. I clean every 100 rounds or so and use patches and jags. Haven't brushed a barrel in years, but I more of a hunter.

[Divernhunter]

^^^ As I remember(I am not a benchrest shooter) They may clean but do they not get a couple of fouling shots before their string???

As a hunter I do not really care about all the why's but I do care that the firearm shoots where I point and want it to hit. So I always check sight and then not claen the firearm until the season is over ................. or much later.

[DRM6000]

Every rifle and barrel is different. It's good that you know how your barrel performs and have the data.

My rifle for example, groups tighter after a few rounds through a clean barrel. The POI of the cold bore shot is .1 mil high. I can't remember the POI of the clean cold bore shot. I don't store it with a clean barrel.

[aspenvalley]

There is a theory that you need a few rounds to put the copper and powder fouling back in the barrel. Then it starts to build up and needs to be cleaned again. https://www.shootingsoftware.com/fouling.htm

[russ69]

^^^ As I remember(I am not a benchrest shooter) They may clean but do they not get a couple of fouling shots before their string???...

...My rifle for example, groups tighter after a few rounds through a clean barrel...

There is a theory that you need a few rounds to put the copper and powder fouling back in the barrel. Then it starts to build up and needs to be cleaned again. https://www.shootingsoftware.com/fouling.htm

Clean, then a couple or 5 fouling shots. That is the standard in benchrest, as far as I know. Different competitions have different routines to match the requirements of the match. In highpower, I shoot my slighters and don't clean until the match is over but the short range bench shooters are the experts.

[Thefeeder]

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Every rifle I have shot...match or hunting......foul the barrel, then use

[BrassCase]

I clean after every trip to the range, must be my OCD. I do find that it takes two to three rounds for any of my clean rifles to settle in for the day. I usually shoot a string of range ammo before switching to match type ammo so I don't waste the good stuff.

[timeexposure]

Using a pistol, I fired a fully cleaned 9mm in a match and scored poorly (relative to my perceived "skill").

On the next match, I had about 200 rounds through it without cleaning. I scored much higher than I did with the freshly cleaned pistol.

Makes me wonder, but of course there could have been some variables at play, like did I clean it properly? Was I over-caffeineated during the previous match? I'm not really sure, but I think if I do another match, I'll use a gun that has fired some rounds without a cleaning. Not thousands of rounds but maybe up to a few hundred.

[kmas]

Usually it's debris in the grooves

[RestrictedColt]

My quick cleaning at the range may have only removed 'excess' fouling and not been a true deep cleaning which may be why it didn't loose any accuracy. Most say you need a few fowlers to regain accuracy, especially in non-match barrels. This is a stock Ruger 77 stainless.

When I got home I gave it another cleaning and there was lots of black and some blue-green (copper) and there had only been 7 rounds shot after the field cleaning. When I get to take it out again I'll know if the truly deep cleaned barrel shoots any differently.


Bench rest guys have different gear and have different expectations. I assume my 1-ish MOA would be unacceptable to a bench rest guy. They also use 'perfect' components, shoot from stable rests, and have the best gear. Those guns may shoot best being perfectly clean every single shot. I'm shooting a factory wood stocked gun from a folding plastic table teetering on rocks and sitting on an ice chest on top of a rifle case to get almost the right height, less than ideal. And I doubt any benchrest guy is shooting .338WM. I have to really think to avoid flinching when I know that bytch is just waiting waiting to kick me.