Sunday, July 29, 2007

Dangers of squib loads, part 2

In this post we examined 45ACP squibs. Here we examine powder-less squibs in 9mm Luger and 357 Magnum. The goal of the experiment is determine whether the squib is merely annoying or dangerous. By definition, if the squib allows unobstructed chambering of another round, in a semi-auto, or rotation of the cylinder, in a revolver, it's a dangerous squib; it allows the firing of another round right behind the squib if one is not paying attention.

For the 9mm, I constructed a powder-less round from a Winchester 124gr FMJ bullet and a CCI 500 (small pistol) primer. It was then fired in a CZ-75B.

The bullet lodged just inside the lands, so another round could not be chambered behind the squib.


For the 357 Magnum, I constructed a powder-less round from a Remington125gr JHP-GS bullet and a CCI 550 (small magnum pistol) primer. It was then fired in a S&W 686.

The bullet lodged well into the forcing cone, WAY past the cylinder gap, thus allowing rotation of of the cylinder. NOT GOOD!!!


Saturday, July 28, 2007

The lusting is over and the deed is done—Glock 21 range report

Took my Glock 21 to the range today. I’d installed a Wolff guide rod and 17lb Wolff spring.

Let’s just say it was anticlimactic. I was expecting fireworks and the earth to move, and instead all I got was 100% reliability and excellent accuracy. I was shooting standard 230gr RN jacketted loads (around 830fps), unsupported, one- and two-handed at a target 15yds away. This target was shot two-handed,

and this target was shot one-handed (strong hand).


What I LOVE about the pistol:

  • The weight is great
  • The balance is great, not muzzle heavy
  • It’s very pointable and the sights (white outlined rectangle for the rear, white dot for the front) are awesome for flash shooting- “FRONT SIGHT!!! FRONT SIGHT!”
  • The ergonomics of the grip are perfect for me, i.e. big, bear pawns for hands.

What I don't much care for:

  • The sharp edges of the mag. release cut into the meat of the thumb of my left (supporting) hand. It’s nice to have an extended mag. release, but does it have to be so friggen sharp?
  • Takedown is not great. Those little tiny serrated tabs on either side of the frame that have to be pushed down are difficult to activate. Not sure I could take down a Glock under pressure, if my fingers were covered in sweat or blood and my life depended on it.
  • Without a butt-plug, the hole in the butt makes the gun look .... unfinished. Get a butt-plug.

I fired about 60 rounds (yes, barely broke a sweat) and didn’t experience a single failure. Mind you, they were my handloads so I’d have been surprised if I had experienced a FTE or a FTF.


The heavy trigger took a little getting used to as all my 1911s have 2lb triggers, or lighter, but for a combat trigger it’s not bad. There’s a fair amount of take up, but the trigger is smooth and even.


Is it my favorite 45 pistol? Don’t know, but I don’t hate it.

Tagged?

In the comments for this post, reader Kevin writes:

I found your blog by way of TSM, and I've seen you on the boards at the gunthing. Nice blog sir! BTW, I just tagged you...

I haven't responded to this prior because I didn't realize the full meaning of being tagged. I'm still not sure which of the following it means
  1. starting a meme, or
  2. posting 5 things about myself that most people don't know, or
  3. posting 8 things about myself that most people don't know.
For now, I'll assume it means the last one, but like The Mrs. I refuse to forward the meme/tag to anyone else; I hate chain letters and I'm not much of a joiner.

I drafted up a list of "eight things few know about me" and then sat on it for about a week. I just didn't feel right about posting it. And then it struck me. This new "Intarnet" socialization phenomenon just doesn't sit right with me. I don't want people whom I've never met knowing more about me than casual work acquaintances.

So, I guess, indirectly I've revealed something about myself ... bummer. Here's the revised list, albeit a shorter one ....
  1. I'm a quasi-misanthrope, in that I don't like most people and prefer to keep my own company than hang out with people I don't really like.
  2. I don't own a cell phone, don't have cable service, and don't watch TV.

Sunday, July 22, 2007

The dangers of squib loads

What's a squib load you ask? It's when, instead of a bang following the squeezing of a trigger, one hears nothing or a pop. Typically, the situation is associated with a barrel obstruction in that the bullet of the round just "fired" hasn't cleared the barrel and is now obstructing it instead. The danger of the situation is that someone who isn't paying attention will simply eject the just "fired" case, chamber another round and squeeze the trigger again. Kaboom!

The most common manifestation of a squib is a round constructed without a powder charge; primed case, bullet, but no powder. Apparently, the pressure developed by a fired primer in the small space of a pistol calibre cartridge is sufficient to drive the bullet partway down the bore. The question I always had: will the bullet be driven far enough down the bore to allow the unobstructed chambering of another round in the chamber? Here we find out.

For this experiment, I built a powderless 45 ACP squib using a Remington 185gr JHP bullet and fired it in a model 21 Glock. Note, that this should not shed poor light on Glocks. This was an INTENTIONAL squib. After chambering and firing the squib, I disassembled the weapon and looked into the bore. Sure enough, the bullet was stuck slightly ahead of the chamber.



How far in is the bullet? To answer this question, we use some high tech measuring equipment; a chopstick, a black, felt-tipped marker and a measuring tape.

We first insert the fired case into the chamber, and ascertain where the base of the case sits with respect to the barrel.


We then remove the case, stick the chopstick into the breech-end of the barrel as far as it will go (until it touches the barrel obstruction) and mark the chopstick at the point where the base of the case would be.


Finally, we remove the chopstick and place it on a tabletop alongside the tape measure. We now remove the bullet obstructing the barrel by placing a wood dowel into the muzzle end of the barrel and then gently tap the dowel into the barrel until the obstructed bullet pops out the breech end of the barrel. We then line up the case alongside the chopstick so that the base of the case is flush with the black mark on the chopstick, and the end of the chopstick is flush with the base of the bullet. Tada! We have a measure of how far the bullet traveled down the bore before it stuck.


By my measure, the bullet was forced down the barrel a good half-an-inch past the case mouth ... JUST ON PRIMER PRESSURE ALONE. That's certainly enough to allow an unobstructed chambering of another round behind it, potentially leading to a dangerous kaboom for one who is not paying attention.

You have been educated ... and warned. Be safe and remember: the only safety you can rely one is the one between your ears.

Friday, July 20, 2007

Handloading for defensive loads for the 45 ACP

In this post, I talked about handloading for 185gr +P 45 ACP loads. In this post, we talk about pushing the envelope a little. As a disclaimer, if you repeat the experiments performed here you will most certainly exceed SAAMI pressures, thus voiding manufacturers' warranties. You have been warned.

So, just how fast can one push a Remington 185gr Golden Sabre bullet out of a 1911, before overpressure signs show up? First, let me be clear about what I mean by "overpressure signs".

  1. Signs of stretching near the base of the case, usually seen as shiny spots,
  2. Bulges near the base of the case,
  3. Flattened primers
The following picture clearly demonstrates an example of flattened primers. Note, in this case it's not the edges of the primer that are "flattened" into the primer pocket of the case (as is typically the case when talking about overpressure), but the firing-pin-strike dimple is flattened back out.


A little preparation is in order before one attempts to experiment with super-pressure handloads in a handgun not set up for shooting such loads. For this experiment I used a, already, customized Norinco 1911A1. I had previously fitted a match Les Baer barrel and King bushing, shaped the frame to accept a Ed Brown extended beavertail, and added a combat hammer, and lightweight trigger and sear combo. The gun is shown in the following picture.



Under no circumstances should the barrel and slide unlock/separate before the bullet has left the muzzle of the gun. If separation occurs prematurely, chamber pressures have not dropped to safe levels, resulting in a potentially dangerous situation for the shooter. By the law of conservation of momentum (MV of bullet = MV of slide/barrel combo) as soon as the bullet starts moving up the barrel, the barrel/slide combo starts to move backward. Factory recoil springs are chosen so that premature unlocking doesn't occur for FACTORY LOADS no stiffer than +P. Chosen weights are typically between 16 and 18 lbs assuming one shoots loads no stiffer than +P, meaning 230gr bullets traveling under 900fps or 185gr bullets traveling under 1050fps.

If one wants to shoot stiffer loads, a stiffer recoil spring is needed to retard the unlocking of the slide/barrel further. I chose a 26lb spring from Wolff. Another trick I employed to further retard unlocking is to replace the factory (rounded) firing pin stop with a squared off firing pin stop, like the one obtainable from EGW. Some fitting is required since the EGW part is build oversized. To understand why a squared off stop retards unlocking compared to a rounded one, one needs to visualize a rock-on-a-string being spun around. If the radius of the rock's flight path is large, less force is required to keep the rock spinning at a given speed. If the radius of the rock's flight path is small, more force is required to keep the rock spinning at a given speed; force is proportional to angular acceleration. A rounded stop (large radius) implies a smaller acceleration of the hammer and thus less forward force is exerted on the slide. A squared off stop (small radius) implies a greater acceleration of the hammer and thus more forward force is exerted on the slide. More forward force on the slide means less backward acceleration of the slide and more time spent in the locked state.


For the load workup, I used CCI 300 (Large Pistol) primers in Winchester 45 ACP cases, Power Pistol powder and Remington 185gr hollow-point Golden Sabre bullets seated to a depth of 1.230". I varied the powder weight from 8.2grs to 10.8grs. The following graph shows the powder weight vs. velocity curve.


At 10.8grs of Power Pistol, the velocity was 1279.4+-16.8fps. However, flattened primers were observed as showed in the picture at the top of this post. At 10.5grs of Power Pistol, the velocity was1248.4+-13.2fps and no overpressure signs were observed.

I think we have a winner. Roughly 1250fps on a 185gr HP bullet.

Tuesday, July 17, 2007

Forgive me father for I have sinned. I’m having lustful thoughts

... about the new (used) mod. 21 Glock I brought home tonight. I’ve always been a disciple of St. Browning, but I now find myself looking lustfully at the ergonomics of the Glock, fondling the Glock, and lusting for a rangetrip with the Glock. Please father. What am I to do?

On my list of "nevers" had been the Glock. I once rented a Glock 19 (in 9mm) and hated it. But when I tried a model 21 (in 45 ACP) I changed my mind. Something about the ergonomics of the thing really clicked with me.

The local gun-pusher had a used model 21 on the shelf, so naturally I looked at it and it followed me home.

Some comparison pics. First, side-by-side with an XD-45 tactical,



and a side-by-side with a 1911A1.



Why the ergonomics of the model 21 work me, can be seen in the following picture. Though the stock thickness of the 1911, the XD-45 and the G-21 is about the same, the length of the G-21 is a bit longer than either the 1911 or the XD-45, and I have gorilla paws.



The front-strap finger grooves don't hurt either.



And a few more for the simple pleasure of viewing gun porn.



With a Scherer butt-plug already installed, and Wolff guide rod and beefier recoil springs on order, I'm off to burn offerings at the altar of St. Browning, and beg for forgiveness for my heresy.