[pop_pop]

So I know all paint has different sizes, and I've heard people talking about changing their barrel backs a bunch of times over the day.

My question is, when i get to the field in the morning, how do I know which back to use? Do I pull out a paintball and see how it's size matches up to the barrel? what am I looking for?

[cmdrsuds]

Always use like 10 balls to test the size. You might pull out the smallest one in the batch if you just take a single ball. To answer your question you will have to choose weather you like to underbore, match, or overbore you paintballs. These 3 are determined by a blow test under bore is you put a ball in and it doesn't budge. A match is it doesn't took through free but you can blow it out. Over bore means the paint rolls straight through the barrel every time Recent studies and experiments have shown that matching your paint to bore is the least accurate. While under and overbore remain highly debated. Please do a search on here and YouTube for that info.

I have done both over and underbore on 2 different guns side by side using the same paint. They shoot the same in my eyes however I was using high grade paint. If you like to buy cheaper paint.. which you shouldn't since paint determines 90% of your accuracy.. I would say overbore so you don't have problems with the occasional ob long ball.

[cmdrsuds]

And they talk about switching backs because paint tends to swell and get bigger as it warms up. Again choosing your back is up to you but if you under bore in the morning you will need to switch later so the paint doesn't get too tight.

[pop_pop]

oh awesome. I usually wind up shooting field paint (not usually much of a choice...), since that's often low quality it sounds like overbore is the way to go. thanks!

[drgonzo]

I just use .681 for everything. Only ever had a problem when the paint was boring .700+.

[SKI008]

.679 for everything.

Done. That will almost always be a good underbore where I live. Maybe in the summer I will bump up to my .684 but usually .679 isn't anywhere near the .008 limit for underboring. Paint in California is tiny. Your results may vary.

[tvise]

.693.... It's all I have... It works for me..