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.


Arthur said...

I know this is a seriously old post, but I didn't see any other contact info on the main page.

What sort of chamber support does your Norinco 1911 offer? Standard 1911 thumbnail barrel ramp style, or do you have a fully supported ramped barrel in it?

If the case head was partially unsupported did you see any signs of the cases bulging when the primers flattened out?

Felix Estrella said...


The barrel in my Norinco is a Baer match, meaning it's a tighter chamber, but otherwise is "standard" as far as support and ramp is concerned.

I was a little worried at first, having read about the need for full support when shooting hot loads, but I saw no signs of case bulging.

I have, however, since switched to 45 Super cases (i.e. 45 ACP with thicker base) just to be sure.

Arthur said...

Wow! Thanks for the quick reply.

As far as cases go - from what I have read, Starline 45+p cases are actually the strongest you can get(actually stronger than their 45super cases). They made the case walls thicker near the head to help support the case in chambers without full support.

Again, thanks for the info.