Yet Colt Rail Gun frames cracked very early in the M45 tests. From above on the M45 tests.
Below is a summary of broken or cracked components produced as a result of this reliability test:
6 broken slide stops
5 broken ejectors (legs sheared)
4 cracked slides
3 broken thumb safeties
2 broken front sights
1 cracked frame at the accessory rail
1 broken extractor
1 broken plunger tube (legs sheared)The slide cracks were attributed by some to stress risers from the sharp front cocking serrations, but the round count, on its own, when the cracks were noted did not seem high enough to warrant cracking. The location of the FCS resulted in the slide being very thin in that area. The frame crack was at the accessory rail. I would note that the material of the M45 test units was 410/416 stainless. I suspect a high carbon steel like 4140 would be much more resistant to notch failures.5.3.1.3 Test Observations
The following are some test observations made during the reliability test effort.
1) Roughly 10 times more Class I failures were experienced when no accessory was mounted to the UUTs vs. when the AN/PEQ-6As were mounted.
2) Operators noted that the recoil from the UUTs was noticeably sharper and/or heavier than the recoil from the current MEU(SOC) .45 pistol. Most attributed this to a weak recoil
spring.
3) There were a few instances of UUTs with high Class I failure rates that were corrected by replacing the recoil spring with a new one (UUTs 11B14 and 11B15).
4) After firing 150 rounds, the recoil springs reduced in length from 7.32 inches to 6.46 inches. After 450 rounds, the recoil springs measured approximately 6.38 inches in
length. After 4,500 rounds, the recoil springs measured approximately 5.94 inches in length.
5) On multiple occasions when replacing the recoil spring with a new one, the new recoil spring would kink and bind the slide so that it would not cycle (similar to what occurred with UUT 11B13). Pulling out the new spring would reveal that it had received a permanent bend as a result of this binding (see Figure 10). Depending on the severity of the set in the spring, some of the new recoil springs had to be replaced again without ever firing a round so that the slide could move without binding. The assembly procedure used by the personnel replacing the recoil springs was verified to be as specified in Colt's provided Armorer's manual, so this was not attributed to operator error.
I would also note that the tests showed issues with recoil springs and the GI spring guides binding. Felt recoil was noted by the shooters to be higher than existing pistols. All suggesting the recoil spring was not properly specified for the application.
That only points out that adding material in and of itself is not a panacea when it comes to 1911 frames and slide cracking. For me, a true high round count gun starts with major components made from carbon steel with springs properly specified for that pistol. I am not a 1911 smith of the stature of Mr. Burton, but I have seen two "identical" STI Trojans that needed two different recoil springs as one would throw the brass into the next county while the other using the same spring dumped empties into a pile onto a tarp about six feet away. Just an anecdote but educational.