It has been my experience that Gordon and Microflite numbers are not comparable, ie #7's with both mfg are not the same spine nor ID/OD. Can't remember which is stiffer but think it was Gordon.
I have Gordon #8's and their inside diameter is the same as # 7's, .260, OD is .325.
In fact all mfg of fiberglass shafting made them in pairs to facillitate less inventory of inserts, ie. 1/2, 3/4, 5/6, 7/8, 9/11 and 10/12. Don't know why the pattern chaged on those last two but they did. Inserts for 7 will fit 8's and 10 will fit 12. Inserts/nock adapters were all based on inside diameter.
FYI, 1916 inserts fit my #8's perfectly, pretty sure if my memory is correct that 2016's fit 9/11 and 1816's fit 5/6.
Ron, do you find the added pieces of 1/4" dowels increase spine?
Biggest problem with fiberglass shafts was the shaft splitting on the point end from a hard impact. Have driven many inserts into the shafting.
Don't suspect you have this problem Ron with a 6" piece of hardwood dowel epoxied in, do you?
Fiberglass shafting is one of my all time favorite and there was a time about 8 years ago that I looked into mfg them again but it required way too many $$$$ and minimum first order was 100,000 shafts @ much more than a buck each.