Ballistics by the inch

Goodness gracious …

… great balls of fire*:

That’s one of the other BBTI guys shooting a Kel-Tec PMR-30 last weekend.

How was it to shoot?

Actually, pretty nice. Has a surprisingly good trigger. In general, I like Kel-Tec guns for what they are: reasonable quality at a very affordable price. And I downright love my Sub-2000 in 9mm.

But I won’t be getting a PMR-30 anytime soon. Because at the 4.3″ barrel length, it just doesn’t take real advantage of the .22WMR cartridge — you only get about a 20% improvement over a .22lr cartridge.

Unless you like making fireballs.

Jim Downey

*With apologies to Jerry Lee.

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November 19, 2014 Posted by | .22, .22WMR, 9mm Luger (9x19), Anecdotes | , , , , , , , , , , , , , , , , , , | Leave a comment

Stereotomy*

Cross posted  from my personal blog.

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For those who don’t know, one of my other interests is handgun ballistics research. Specifically, in regards to how barrel length effects bullet velocity for different cartridges and loadings. Even if you don’t like guns, the physics behind ballistic performance can be very interesting.

And here’s a wonderfully graphic image showing those physical forces:

Ruger Alaskan .44 Magnum

Text from the source to go with this image (site is Finnish, and English is not the author’s first language):

Let’s talk a bit about .44 Magnum cartridge. Despite of being very close to diameter of .45ACP the .44Mag is totally different beast. Average .45ACP round generates ~650J of hit energy while .44Mag makes easily 1600J and can be pushed much more beyond that. This specific gun however cannot utilize all potential of .44 Magnum cartridge because of very short barrel. It simply cannot burn all powder. As you can see there is huge cone shaped spray of unburnt stuff flying in the air. With longer barrel show would be different.

Ok, you may have noticed the flames. They are something we haven’t seen before. Especially when you look picture below and huge left side flame in it. Interesting thing is that major amount of the flame is escaping between cylinder and barrel. That short barrel seems to puff bullet our so fast that powder mass just flies out unignited.

The site is filled with a bunch of great high-speed camera images of guns being fired. And it also has something else which is new to me: ‘natural stereoscopic’ images of guns being fired. Like this one:

Now, what do I mean ‘natural stereoscopic’ images? Well, this is pretty cool itself. Here’s a reference link & explanation from the Kuulapaa site:

Help: How to Free-View the Stereo Pairs

Each stereo view consists of two images, one for each eye. Free viewing is the technique that will allow you to direct each of these images separately and simultaneously into each eye. Once that happens, you are said to have “fused” the pair of images into a stereo view.

At the bottom of this page a stereo pair of images is loading with which you can practice. All the stereo pairs shown on this site are in the “cross-eyed” format (my apologies to all the “wall-eyed” people). That means that the first (leftmost) image is for your right eye and the right image is for your left eye.

There are then a series of practice image to show what he means and give you a chance to develop this viewing skill. It works fairly well for me, but does tire my eye muscles fairly quickly. Give it a try and see how you do.

Jim Downey

*Couldn’t resist. Lyrics here.

 

February 1, 2014 Posted by | .44 Magnum, Discussion., Links | , , , , , , , , , , , , , , , , | 1 Comment