A good reference about this can be found here:
http://m4carbine.net/showthread.php?t=37
BravoCompanyUSA posted that thread and it is very useful.
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A good reference about this can be found here:
http://m4carbine.net/showthread.php?t=37
BravoCompanyUSA posted that thread and it is very useful.
wow interesting! so Colt M4 barrels and FN M16 barrels appear to use CMV instead of 4150. However BCM stated that ORD 4150, ORD 4150 Resulfurized, and CMV can all be considered as milspec.
thanks grant. I know now why 4150 is not necessarily milspec. Close but not quite.
I have learned much, thanks to this forum, from my "bushmaster is just same as colt but cheaper" days...![]()
Standard rounds do not cut it. They have to be high pressure rounds.
A lot of companies play the "shell game" and about the only way to be sure that the company is doing thing per the TDP is to have the manufacturer issue a detailed and very direct statement as to the chemical composition of their barrels & bolts, the certifications they require, the type of HPT done, what stage it is done, the type of MPI done, the MPI standard followed, the MPI acceptance and rejection criteria their company issues.
C4
As an aside, do you have any idea what the reject rates are on the HPT test results for the companies (Colt, LMT) that HPT their CMV mil-spec steel barrels?
I'm assuming it's less than 1%, but I'm curious when you start with high grade steel to begin with, what the reject rate would be.
Since this thread has been resurrected, I want to clarify the record.
The barrel steel in our D-M4LE is MIL-B-11595E, CrMoV Grade. (Some call this CMV for short.) ((ETA: This is not "vanilla" 4150.))
When we first started selling our guns we mistakenly were under the impression that all 4150 barrels were the same. Later, as I've learned more, I came to understand that was not the case.
All of our D-M4LE barrels are MPI'd and batch HPT. We are evaluating doing HPT on all barrels but as of today we still only batch HPT.
I hope this clears up any confusion as to the composition of our barrel and the testing we currently do.
Sincerely,
Last edited by Charles Daly; 07-21-08 at 23:54.
Michael Kassnar
President, K.B.I., Inc.
Thanks for contributing. Would you be willing to discuss your rationale for performing batch testing vs testing every unit?
Out of the samples of CMV you've tested to date, have any failed your HPT test? If so, what percentage of all batches tested?
Lastly, would you be willing to share where you source your steel from, and whether or not you mfg the barrels or do you outsource them?
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