Summary for continually diminishing taper Discussion
The focus keyphrase, continually diminishing taper, is at the center of this thread about hard chrome plating 50 caliber M2BMG barrels. Paul Duncan says the government FAT is failing because the plating vendor is producing reverse taper instead of the specified bore profile: a continually diminishing diameter toward the muzzle, with only limited variation allowed under SAE AMSQQC320. The excerpt does not include any replies, so there is no named expert advice or corrective action in the source text. The practical issue is simply that the plated bore must match the required taper profile after chrome deposition, and the current process is not doing so. Because no answers are shown, the page mainly documents the problem statement and the dimensional requirements rather than a solution.
April 23, 2013
Q. We produce 50 caliber barrels for the M2BMG. we are going through F.A.T. with the government and are having an issue with our plating vendor. Our requirements are specified as:
Plating shall produce a continually diminishing taper towards the muzzle.Except that from origin of rifling to within 4 inches of the muzzle end.A variation of .001 from a continually diminishing diameter is permissible,and .0005 variation over the remaining length, provided that the resultant surfaces remain within the overall dimensional limits. per SAE AMSQQC320. The issue is we are getting reverse taper after plating. Any feedback on how this taper is obtained and possible corrective actions would be appreciated. Thanks.
Paul Duncan
Mfg. Engineer – Spindale, North Carolina, US