How much does paint actually expand during the day?

[SR_matt]

I started playing on 2001 and took a break between 09-23 but this is something I’ve never really looked into.

so how much does paint actually expand realistically during the day heat, humidity, and storage matters but has anyone really recorded this?

I never really cared much as I just bore matched in the morning and went with it, maybe checked mid day and would occasionally go up a size but probably not normally. Now that I’ve seen underbore seems to be the prefers way for closed bolts I started wondering about this more as I am working on my cocker build. I’ve seen that .003-.005 is the ideal underbore but is it ideal to start closer to .003 and let the expansion happen or will I need to check during the day?

so yeah, anyone have a good number on this? For what it’s worth I am in a deflect humid area where the summers are hot a humid.

[Grendel]

I doubt you can come up with a simple number. There will be several things that affect moisture absorption:

• What is the moisture content of the shell at any given time
• What is the relative humidity
• What is the the temperature
• How is the paint stored

Personally I size my paint at the beginning of the day and pick an insert and forget about it after that for the day. I do not worry about the change in diameter during a day of play. I live in SC one of the more humid areas with wide swings in humidity during the day. I do keep my paint in a cooler (no ice) out of the sun during a day of play to make sure it stays relatively stable temperature and humidity.

[iamthelazerviking]

Yes it happens, not sure exactly how much the size of the balls change.

This is why fields need to chrono later in the day. People definitely start shooting hot and no one cares to check. I check my own to be safe and fair. Had a few buddies get really angry after taking headshots that left nasty welts due to guns shooting too hot and no one caring to check.

I've never tried chasing the whole "bore match" thing since paint size from a single batch will vary so much. So you either underbore to stop rollouts or overbore because you're using an open bolt marker.

[Trbo323]

Yes it happens, not sure exactly how much the size of the balls change.

.

I can tell you the answer on this can be "enough to matter"

2 years ago. Supergame West, Friday pump day I sized the paint and everyone in my group just went with the size I chose. Friday went ok but all day Saturday everyone is having issues, terrible accuracy lots of barrel breaks. We are packing up at the end and someone casually mentioned the insert size we were all using and then it hit me that we never checked again. Sure enough the paint changed size and we had an extreme underbore going on. It was bad enough that I was thinking I wasn't going to be buying the mid grade paint anymore because it was so bad. Turns out I was the idiot

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[SR_matt]

I can tell you the answer on this can be "enough to matter"

2 years ago. Supergame West, Friday pump day I sized the paint and everyone in my group just went with the size I chose. Friday went ok but all day Saturday everyone is having issues, terrible accuracy lots of barrel breaks. We are packing up at the end and someone casually mentioned the insert size we were all using and then it hit me that we never checked again. Sure enough the paint changed size and we had an extreme underbore going on. It was bad enough that I was thinking I wasn't going to be buying the mid grade paint anymore because it was so bad. Turns out I was the idiot

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Relying on others bore is something I only ever have done as a place to start checking too. Especially if they are using a different manufacturer or a kit that is a much different age. Granted my friends size like 1-3 balls and that’s it where I try and check a lot with the current variation (then again the field I play at at least offers some decent valken varieties usually so it’s a bit more consistent than some).

i guess I will just have to play with it. Maybe I am overthinking underbore as it’s something I never had done before since back in the day we all bore matched.

[iamthelazerviking]

Somewhat related to this, last year paint seemed to be mid sized 682-685ish but lately the GI crap has been mega small. Like 670 or smaller depending on how you measure, they're more oval than round. So with swelling I'd hope to get a nice whopping 675-679

[SR_matt]

Jesus… the graffiti variants my field gets are probably 687 maybe 686. When I came back last year I was expecting stupid small paint and was confused with hot big this stuff is. But from what I’ve gathered the valken stuff seems to be much more true to size for whatever shot 20 years ago.

[Mps18]

I played in a tourney it was so hot balls were sticking and getting too big to go through the loader lol

[flyweightnate]

I too have had paint swell .010 or more, causing some breakage issues. I went from using a .670 to a .682 once - actually had to switch to a different barrel system since I only had .670 - .680 in the one, and was still getting breaks. At the time, the .682 was the largest I carried.

If there's a 30F swing from the proshop to outdoors (hi Texas) that accounts for the first .002 assuming 50% glycol-water, but anything waxy would be worse.

[cougar20th]

I believe it really depends on how it is stored and the weather conditions of the day.

Back in 2019 I had paint that when I was bore sizing it inside the field shop was 0.686ish loaded the kp3. By the first game it had swelled to the point it would not roll thru the opening in the feedtube to the barrel. So it swell to absolutely large in less then a hour. Yes it was a hot humid day and the paint definitely sucked it up fast.


More often now I find as the day progresses i have to increase the insert size.

[Jonnydread]

Quantitative I cannot give you, like others have intimated there are just too many factors. I don’t generally size my paint cause I use wedgits and the like, but on the rare occasion I use an insert system I tend to go up by .003 in the afternoon if it’s humid out. .682 has never really steered me wrong for the most part.

[SignOfZeta]

If only there was a way to measure this…

One thing nobody seems to point out is the temp diff between when you measure and when you fire. If you brought your paint out of a fridge and measured it before playing in 100F heat then it will grow considerately. If it’s the same temp both times it’s measured the measurement will be a lot closer.

This year at Monster Game I shot two year old Valken Graffiti as well as three year old and four year old. Nothing from this year or last. Some of this stuff has been to Monster Game and back four times! It’s been in the heat that many times, still shoots fine with wedgits in closed bolt guns.

You guys make it seem like as soon as the paint is made it starts bloating and melting and is useless in a day. I don’t play in the south but the very paint I shot last weekend was use on days almost too hot for ME to not start bloating and melting to uselessness so it has all the temp resistance I’ve needed.

[SR_matt]

Yeah I mean I think paint can take a lot more abuse than people likely think. Maybe the old stuff was notably different but I know my friend shot 15+ year old ultra chronic when he was trying to get an impulse running before we went back out after our break.

I feel like I’m going to get bored once day and try and chart some actual changes based on heat and humidity… or I will add that I to my pipe dream of a massive experiment to end the bore sizing debate once and for all (once I win the lotto and all haha).