The geometry of the M45 guide rod head is quite similar to the GI version. The protrusions are the same diameter according to my digital calipers.
Recently, there has been a bit of interest regarding the dual recoil spring system included with the Colt M45 CQBP. The spring system is designed to improve the service life between replacement cycles, though the Marine Corps still specifies that the springs be replaced at 5000 rounds. This spring setup is not completely new, as a similar setup is used in the Delta Elite, albeit the guide rod in that system is polymer. So the question remains, can we expect the system to work if put into a standard 1911?
The Colt Rail Gun and M45 have identical internal dimensions inside the dust cover.
As Hilton mentioned in his series of articles, there are a number of changes to the M45’s slide and frame. I wanted to see if the internal frame dimension is somehow different to accommodate the recoil system. My calipers say they are identical. I also measured the OD and ID of the M45 spring plug and found those measurements to match those of the plug in the Colt Rail Gun. The M45 spring plug deletes the spring retention tab due to the dual spring setup, though many aftermarket spring plugs are missing the tab as well.
Ultimately, the real test is to drop the system into another 1911 and see what happens. In the above video, I shoot a magazine through a Colt Rail Gun after installing the dual recoil spring system into it. I had no issues with rapid fire of one magazine as seen in the video. Another two hundred rounds or so didn’t yield any different results. While by no means comprehensive, this little experiment, along with the identical internal dimensions of the frame and recoil spring plug, suggest that long term testing MAY yield similar results.
It’s also important to keep in mind that though the M45 recoil system functions in standard 1911s, we don’t know what additional stresses it may add to the frame or slide. Note that material was added to the M45 frame and slide to prevent cracking experienced in test guns. Back in the day, 22 lb recoil springs were installed in MEU(SOC) pistols which caused all sorts of long term problems, including broken barrel bushings. So while the system does work when dropped into an existing 1911, more testing is required before giving any full endorsement for putting the system in existing 1911 platforms.
As an aside, some of my buddies who have shot the M45 report that the pistol shot softer than a standard 1911. I shot three types of ammunition through my M45 and Colt Rail Gun (with their respective recoil systems in place): Winchester “White Box” Q4170, Atlanta Arms 230gr ball, and Winchester Ranger RA45T. In my estimation, any difference in felt recoil was minimal at best as I couldn’t perceive any difference shooting any of the above three loads. Clearly the primary benefit of the system is the extended service life of the springs. Colt engineers have measured the M45 spring rates after over 8500 rounds fired and still found them within specifications.
Tim-Any preliminary thoughts on how the dual spring set-up will compare to the flat spring set-up in a 1911? The purported advantages (increased spring longevity) seem similar.
Best, Jon
It appears to be another approach to achieve the same goal. Colt is having tests done to evaluate long term effects of their dual spring recoil system if used in other government sized models. I have a Wilson flat spring setup in one of my pistols and it is working well so far. Some have noted slightly increased felt recoil with the flat recoil spring setup but I have found it similar to a conventional 16 pound spring. As you know, felt recoil is quite a subjective thing, so your mileage may vary. I will report back when I have more rounds through the flat spring system.
HOW DO I BUY ONE, WHERE AT.