I was curious about which insert size would be best for testing using Reballs. For those that aren't familiar with Reballs, they are much smaller than a standard paintball (closer to .679). I have the Freak system with stainless steel inserts, that are exactly the bore size as labeled. Smart Parts also made a Reball insert, which is bore size .670 and supposed the same size as the Reball size.

However, when trying to do the "blow through" test, the Reballs are a VERY tight fit inside of the Reball insert and actually match the .682 insert that I have perfectly. Not knowing which is best to use, I decided to do a test. I took my Reball insert and inserts .682, .684, .687, .689, .691, and .693 to look for a trend in performance. That should range everything from underboring to drastically overboring the Reballs.

For the test, I used my ION, which has a TechT L7 v2 bolt, AKA 2 Liter Plus Dual (not fully broken in), SP 360 QEV, and All-American Apex-ready front and aluminum Freak back. Those are the only relevent mods for consistency for this test that I thought I should mention. I also used the F1 Chrony, which is accurate within 0.5% (or approx 1.4 fps). I used the ION to get the best possible consistency for this test.

Here is the data that I obatined:
Google Docs - Inserts and Reballs

As you can see, the Reball insert outperformed all the other inserts by quite a margin. I used sample standard deviation because 20 shots is too small of a sample to confidently portray as all possible combinations of the performance of the gun and inserts. Using the Reball insert yielded the best standard deviation, range, and experienced the smallest average velocity drop.

The reason I think it does so much better is because Reballs tend to slide easier than paintballs due to less friction. So when given a tighter insert to fit into, it seals up the gap for any gas to escape around the ball without having to worry about getting a barrel break. Even though Reballs are made much better than paintballs and tend to be closer to a perfect sphere, they still have imperfections in them. A perfect ball to barrel match still allows fluctations in the amount of gas to escape around the ball. The Reball insert actually squeezes the ball and ensures no gas escapes every shot. The larger the bore size gets, the worse the consistency it gets.

So those of you using your standard insert, you may want to reconsider and use the Reball insert for testing purposes. I would highly recommend either getting the Reball insert or the smallest bored barrel you can get that is close to a .670.

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