Communion Of Dreams


It is done.
April 21, 2008, 3:26 pm
Filed under: 2nd Amendment, Ballistics, Guns, Predictions, RKBA, Science

Well, as I mentioned in this post, after we did the schedule of ballistic tests using the custom Thompson/Center Encore pistol and had all the “ideal” data relating to barrel length versus bullet speed for a wide variety of ammo and calibers, we still wanted to use the same ammo in a number of “real world” guns – actual handguns from our various collections.  That would give us some head-to-head comparisons to see how they would compare to the “ideal” performance.

Well, yesterday Steve and I had a chance to get out and do this additional testing.  Here’s a message I sent to our third partner in the previous tests:

Thought I would drop you a note, let you know that Steve and I (with another friend tagging along) went out and shot all the “real world” pistols today, using the full run of ammo available.  Lots of good data points on those.  About 6 hours, plus a bit for cleaning up.  I will get copies of the data sheets sent off to you in a day or two.

Mostly, it went smoothly.  The little Berettas in .25 and .32 were a right pain to shoot, and problematic in getting data (we did, but we really had to work for it).  The .380 Walther was OK, the .327 Ruger rough, the big .45 Colt and .44 Mag more pleasant than either of us expected.  We also supplemented with Steyrs in .357 Sig and in .40 S&W, along with the .357 Python, big .357 S&W, .38 Diamondback, .38 S&W 642, and Para Ord .45.  We shot the .357 revolvers with both .38 special and .357 magnums, to have those data points.

Vanes were hit, bullets bounced off the armour plate in front.  Sunburns were earned.  But we got all the data, done done done.  I’ll probably write something up for my blog in the morning, as documentation.  I also took pix today, to go along with the pix from the previous tests.

I heard back from Jim, who said that he knew a number of people were eagerly waiting for the data, and that one fellow in particular who has done a lot of ballistics testing of his own using ballistic gelatin was really looking forward to the comparisons between the “ideal” data and the “real-world” data.  John, he said, expected some real differences but was curious just how much there would be.  My response:

Well, tell him that his expectations will need to be changed.  Here’s some quick head-to-head comparisons:

  • .45 ACP (5″) – almost no difference, advantage to the Para Ord!
  • .40 S&W (4″) – marginal difference (less than 50 fps), advantage to the Thompson over Steyr M40
  • .357 mag (6″) – Significant difference, advantage to the Thompson over .357 S&W (by about 200 fps), more over Python (another 100 fps)
  • .38 sp (6″) – A little difference, advantage to the Thompson over .357 S&W, more over Python (about 100 fps across the board!)
  • .38 sp (4″) – Almost no difference, advantage Thompson over Diamondback.
  • .38 sp (2″) – Significant difference, advantage to S&W 642 – between 100 and 200 fps!
  • .357 Sig (4″) – almost no difference, advantage to the Thompson over Steyr M357.

I don’t know the barrel length for the rest of your guns, so can’t really say.  Interesting, but not too surprising, that the semi-autos seem to be closer to the Thompson “ideal” than do the revolvers, except with the 642.  Really odd, that.  Oh, wait . . . that could be the difference between the measurement including the chamber and not.  We’ll have to be very careful to note that in the data display, with information about the comparisons.  Hmm.  That would make the revolvers look even worse, since you would effectively be comparing them to a ‘longer’ barrel in the Thompson . . . say between a 3″ and 4″.  OK, checking that, the data makes more sense,  The 642 falls right there between those, so is fairly comparable, or a little on the underside.  Clear advantage to the semi-autos for power, head-to-head barrel length, then, though with a revolver you get “extra” barrel.

Interesting!

And of course, there are variations between ammos, with some up and some down more than noted.  Once the data is plotted, be interesting to see what the curve comparisons look like.

So, yeah, very interesting!  I do look forward to getting everything entered into the spreadsheet programs and plotted, so that the relationships between one and another are easier to visualize.  But now the testing itself really is done!

Jim Downey

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