Comparing .45 GAP and .45 ACP +P Factory Ammo

Let's be very clear that the .45 GAP was originally developed to emulate “standard pressure” .45 ACP velocities. Therefore, it is perfectly fine and legitimate to compare .45 GAP ammo against “standard pressure” .45 ACP ammo. My sources have stated that Speer factory 45GAP ammo typically runs between 19,900 psi and 22,500 psi (slightly under to slightly over the standard pressure 21,000 psi maximum for the .45 ACP; maximum +P ACP limit is 23,000 psi). GAP handload data runs between 16,400 psi and 22,500 psi. The GAP was not marketed to equal or outperform .45 ACP +P ammo, even though the .45 GAP can dip into the general ballpark of +P rated .45 ACP velocities. In fact, Double Tap .45 GAP ammo brings the velocity up to the same level as +P .45 ACP ammo velocities. Remember that while .45 ACP has more space for powder, +P ACP brass still only has a 23,000 psi SAAMI pressure maximum just like the .45 GAP. So 45ACP can be handloaded dangerously over-pressure if one is not careful, especially since modern powders don't need as much space to perform as the old time stuff. Side Note: It takes two cases of .45 ACP to handle both standard pressure and +P pressure ammo, while the .45 GAP uses one and only one strong case for all of its loadings.

45 GAP Factory Ammo Listing

Winchester went beyond the original development specs and showed us that the .45 GAP can handle 230 grain bullets after all. We were also originally told that maximum pressure .45 GAP ammo will equal standard pressure .45 ACP ammo velocities. This statement is wrong, or should I say too conservative. When you look at the charts and facts below you will find out two important facts: No. 1: “Maximum pressure” 45GAP ammo velocities generally lie between “standard pressure 45ACP” and “+P 45ACP” velocities (can be a little faster than standard pressure ACP velocities and is less than +P ACP velocities). Full power GAP ammo is roughly 55-70 fps slower than +P ACP ammo velocities when using the same barrel length (see apples to apples comparison in the next chart). Double Tap GAP ammo is an exception since it actually matches .+ P .45 ACP ammo velocities. No. 2: 45 GAP can be downloaded (not using maximum pressure) to enter the “standard pressure ACP” arena, making the GAP more pleasant to shoot as in less recoil, depending on the pistol platform of course.

Apples to Apples Comparison Chart

This is a good comparison since each GAP and ACP pistol has a similar barrel length, same barrel profile, same polygonal rifling, same pistol manufacturer, and same ammo manufacturer.

## Generally, a test barrel produces higher velocities than an auto pistol of equal barrel length.

This is a stout load. If I'm going to shoot a string of 200 to 300 rounds in a sporting event, I do not want to be shooting this stuff! Sporting IPSC Major Power is 165 and Minor Power is 125. That comes out to pushing a 230 grain .45 bullet at 720 fps and 545 fps respectively; Are these IPSC Power Factors easy to manage? “Absolutely”. Do some folks still like to shoot full power ammo? “You bet”. In this case, handloaders have the advantage.

Another way to view the above chart is that a Glock 37 .45 GAP pistol with a 4.5 inch barrel pushed a Winchester 230 grain Ranger 11.5mm bullet at 887 fps, with a 204 Power Factor, with an energy of 401 ft lbs, and produced a velocity within 52 fps of a +P .45 ACP Ranger ammo (out of a Glock 21), using similar barrel lengths, same barrel profile, same polygonal rifling, same pistol manufacturer, and same ammo manufacturer.

Bottom line: Ammo compnaies are already producing .45 GAP ammo equivalent to mellow standard pressure ACP loads and entry level stout +P ACP loads (see the next two charts):

# A full power GAP load fired from shorter barrels would produce slower velocites and lower power factors, and the perceived recoil may increase due to the smaller, lighter pistols. Example: 4.5” barrel: 993 fps., 199 PF; 4.0” barrel: 950 fps, 190 PF; 3.5” barrel: 900 fps, 180 PF.

Lets' look at “Official Factory” +P .45 ACP ammo from Cor-Bon

Here's a look at “Official Handload” +P .45 ACP info using Alliant 'Power Pistol' powder

Here's a look at “Official Handload” .45 GAP info (powder brand in left column)

And here's a look at “Unofficial Handload” Full Power .45 GAP info.
4.5 inch Glock barrel (not a standard length 5” test barrel such as the ACP uses by the way)

Hodgdon Longshot Powder

Handload reference: Hodgdon Longshot data

• The multiple times fired reused Star brass (stronger than Winchester brass) of these full power GAP handloads still dropped completely into the Glock barrel chamber all the way, even before resizing. The primers looked normal, although using primers to judge over-pressure is not a good idea. The fired brass had no bulging or pressure signs of any kind and only expanded between .005 to .0065 inches (based on brand new ammo with a case diameter of .470).

• Compared to the above +P Corbon loads, the handloaded gap loads look darn good.

• Now for the Reality Check: Some or all of the “unofficial handload” Full Power .45 GAP info is probably beyond the 23,000 psi SAAMI standard (although Longshot produces high velocities at lower than usual operating pressures --- even the cases expanded less with this powder). I say this because all factory GAP ammo so far, including Corbon, show lower velocities than the hot GAP handloads shown above. Yes, it's amazing that the high powered GAP ammo works so well and has no pressure signs with new or once fired brass. Until more official GAP handloading data is available, use extreme caution, because once you happen to see a high pressure sign, most likely your handloads have already been over-pressure for the past few tenths of grains or so, and some GAP case brands are weaker than others.

• In summary 1: “Official factory” .45 GAP velocities & “official handloaded” .45 GAP velocities can match “standard velocity” .45 ACP ammo. 2: “Official handloaded” .45 GAP velocities can get within 0 to 30 fps of “official handloaded” +P rated .45 ACP velocities. 3: “Official factory” .45 GAP velocities can get within 60 to 100 fps of “official factory” +P rated .45 ACP velocities (note: ACP test barrels are generally at least ½ inch longer than GAP barrels). 4: However, using the new versatile heavy field Hodgdon Longshot propellant can bring 45 GAP velocities up to “equal” factory +P rated 45 ACP velocities at all three standard bullet weights of 185, 200, & 230 grains, although the pressures of these loads may very well be over the 23,000 psi maximum (unofficial handloads).

Gun Tests, Vol 17, No 2 provided a .45 GAP Ammo Test. Four out of five of the GAP loads were full power loads in the equivalent entry level .45 ACP +P category. These loads registered a power factor right around 200 which means that they were a handful to shoot. The fifth load, 185 gr. Winchester Silvertip, was rated at standard pressure ACP and was mellow to shoot (175 power factor) – see chart below.

While “Gun Tests” folks called the GAP loads equivalent to +P ACP because of the power factor I assume, in GAP terms it's still just standard pressure . The GT testers believed that the GAP ammo can be improved and the selection should be broadened to not only include full power GAP factory ammo, but also the equivalent of standard pressure ACP ammo as well. I disagreed with some of their lack of accuracy statements since they did not agree with the majority of folks, both professional and private citizens, who have had a lot of hands on experience. And GT did not have a full selection of mellow and full power loads to test, which skewed their statement about GAP ammo variety. Still, having GAP loads with “Power Factors” of 205, 195, 185, 175, 165, and 125 would be useful for a wide varitey of sports and self-defense applications. I like this idea especially since a lot of people do not handload.

The good news about the “Gun Tests” article is the verification that hot factory GAP ammo velocities can be higher than standard pressure ACP velocities and lower than full power +P ACP velocities. Therefore, ammo companies have some wriggle room to use lower GAP pressures to operate in the more manageable “equivalent standard pressure ACP arena” for certain applications. Apparently .45 GAP ammo can be cranked up a little more than many folks originally thought. Therefore 23,000 psi GAP ammo DOES NOT EQUAL standard pressure ACP ammo. The GAP can surpass standard pressure ACP by a little and it can actually be downloaded in pressure to produce mellow “standard pressure ACP velocities.

On the other hand “some” .45 ACP pistols have the option of shooting full power +P ACP and even .45 Super for those that really like to get a full power buzz, although “most” shooters are not interested in the heavy recoiling .45 Super or even max power +P ACP ammo for that matter. What really matters is what you can handle effectively and not necessarily who has the fastest chariot in town which might do nothing more than make someone feel good because of bragging rights. It's more important to use the correctly tuned bullet for a given velocity.

GT Chart Results: Glock 37 – 4.49” barrel: Millennium chronograph, 65 degrees, muzzle 10 feet from sky-screens, elevation 273 ft above sea level:

# Corbon +P 45ACP factory velocities were used as a comparison reference. Note: I'm not sure what barrel length Corbon used for their .45 ACP +P loads, but I'm sure it was greater than the 4.49” G37 barrel! So the numbers are somewhat skewed, although it still gives you a rough idea.

The .45 GAP does very well with lighter loads that are quite accurate and very tame to shoot. What’s the difference between a 9mm load producing a 130 Power Factor and a .45 GAP load producing a 130 Power Factor. Answer: Perceived recoil difference is minimal except one of the two produces a much larger hole. Check out the very good consistency of full power, medium power, and low power .45 GAP loads. The chart shows a low to high fps spread of 383, demonstrating excellent versatility! I say again, the gap appears to work very well from the slowest heavy bullet loads of 599 fps up to the fastest heavy bullet loads of 974 fps:

You can poo poo the short gap, but it really does work well. You can make fun of Mr Glock. Why not, some do. All I can say is that the Speer engineers did an excellent job.

For those that pick up brass on the range, do not fret about the 45 GAP. Its short distinctive case and small pistol primer is pretty easy to spot. More importantly, some brands of 45 ACP ammo now use a small pistol primer! So it ain't just the GAP you have to worry about. Therefore, check your brass before handloading or you run the risk of flattening or setting off a large primer accidentally.

Abridged: The Main Points of Why we Have the New .45 GAP Cartridge:

Main points of Why We Have the New .45 GAP

Disclaimer/Safety Warning

.45GAP (.45 GAP) Caliber Page; Document Version 11/11/06