BBTI cylinder gap tests coming.

[Jim Downey]

Well, this past weekend we celebrated our first anniversary of the Ballistics By The Inch project, as noted on the BBTI blog. And we've made an announcement there which I thought would be of interest here:

Announcing the Cylinder Gap Test!

We’ve had a Single Action Army clone in .357 magnum modified to allow for adjusting the barrel position from a standard 0.006″ to 0.001″ to no gap (barrel snug against the cylinder). We have a dozen or so different ammunition loads in .38/.357, and we’ll be essentially repeating the BBTI procedure for each of these, with the normal gap then the minimum gap then without any gap, starting with an 18″ barrel and going down in increments of one inch to just 1″ . Actually, one slight difference – to make sure we get a better statistical sample, we’ll be firing 10 (ten) rounds of each type of ammunition at each point rather than just 3 (three) as we did with the BBTI tests. Because we are limiting this test to just one caliber, we thought this was a reasonable step to take. We hope that this will allow us to conclude with some actual data what the effect of having a cylinder gap in a revolver actually amounts to.

We’ll probably be conducting these tests in the spring of 2010, and if past experience is any guide will have the new data sets available on the BBTI site sometime a couple of months later.

If you're not familiar with our project, take a look. And there are some more musings about future tests we're interested in in that blog post.

Cheers to all - thanks for helping to make our project such a popular reference (we crossed 1.5 million hits about two weeks ago!)

Jim D.

[DefensiveCarry.com]

[Stevew]

That will be an interesting test. I have read that there can be 400 fps difference in 357 mag when switching from vented (cylinder gap) to non vented. I believe this was from SAAMI testing.

[pax]

You guys have done a service for the whole community with that site -- and I'm looking forward to seeing the new data!

pax

[Jim Downey]

Thanks - we think it'll be very interesting to see what the data actually shows. And we should have enough of a range of different ammo to feel pretty confident in the results.

Jim D.