LW Poly barrel fouling: too fast/in need of pellet lube/something else?

One thing I learned while trying to get my marauder to shoot accurately is how much bore diameters vary from barrel to barrel.I ordered a marmot militia barrel after giving up on the original barrel. Well right before I received my new barrel I decided to check bore diameter with pin gages and found the barrel to be .218 in diameter. I order the largest pellets I could find which were H&N FTT in 5.55 and it shot very accurately. Anyway when I received my new barrel it measured .209 in diameter. It fouled pretty quickly. I believe alot of the problem with fouling is using pellet that are too big for your barrel. Try measuring your bore size and buy pellets slightly larger than your bore diameter, I think you will find that it fouls less. Just my experience for what its worth.

Couldn't hurt to try washing and lubing. I use hot water and a strong solution of dish soap let them dry then spray them with napier pellet lube. seems to cut down on the pellet gunk for me.

My guess is that the choke is the culprit here.
I have a lot of experience with poly barrels, and have found out that the barrels without choke hardly foul at all.
My converted .25 Boss was accurate for thousends of shots without cleaning.
And if I cleaned it, it was clean within a couple of patches.
My opinion is that a good barrel doesn't need a choke.

JSB pellet lead is "softer" than some other brands. Your barrel diameter and twist rate might be more susceptible to fouling with the softer lead. Also, I think the pellets you are using are a 4.52mm head size? Try H&N pellets, the lead is much "harder" than JSB, and try smaller head sizes, 4.50 and 4.51. I too clean and lube my pellets, and I always clean the barrel after a tin of 500.

Pappy

I have a poly barrel on my Steyr, shoot Monsters out of the tin, and after severaltins it is still shooting accurately. No cleaning necessary.

I too was getting a very dirty barrel so decided to wash and lube. I’ll say first that my barrel has been polished by Ernest Rowe. He has a good video on how to do that. If you use a paste I’d recommend Mother’s Mag wheel polish as it’s got a finer abrasive than JB. But even after polishing I get a lot of funk in the barrel which I believe to be the releasing agent used on JSB combined with lead. I have started washing with acetone and lube w FP-10 oil. I cleaned after a session and one patch removed 99% of the crud and the second patch was clean. I use a 50/50 mix of Shooters Choice Bore Clean and Kroil on flannel patches. . It works good for me. I plan to keep washing with acetone and next up will be Napier’s power lube. Gotta wait for the rain and wind to die down. The acetone really gets the pellets squeaky clean. Anyway this has been a big improvement so far. Will post when I get a chance to see how it all works in the end

I think "deal with it". ie, for accurate target shooting you have to learn the best way to clean your barrel.

I have a LW poly .177 on RAW platform that I use to shoot benchrest. The cleaning routine I use may not be the best of all possible, but it works for shooting cards of about 35 bulls or so (score + sighters):

One wet (WD40) patch followed by two dry. Then I waste about 5 shots and it is pretty accurate for the next 40 or more.

The gun is set at about 800fps (with 13.4 gr pellets). I've heard that higher velocities = more fouling but haven't tested this myself.

I read a thread somewhere about guys using chainsaw premix to clean pellets-said it worked pretty well. When the gasoline dried the pellets had a very light coat of lube left on them to prevent lead oxidation, without any garbage to change pellet weight and balance in flight. As with any flammable solvent, extreme care would be used though. I have never washed pellets myself, but have seen the junk that cleaning can produce-may consider doing this in the future if it becomes necessary

Best is to find the exact spot of the fouling and try to see/feel if there's anything rough causing the fouling. It probably is the choke because that's the point where pretty much all barrels will foul. You can find the fouling spot by completely cleaning the barrel and checking the cleanliness with a small light. After that shoot 50 shots or so, at this point you will see where the barrel is fouling the worst because there will be lead traces visible in those spots.

I polished all my barrels with JB and it certainly helps reducing the cleaning interval and it makes it easier to clean since there will be less storing space for the fouling.