The generator matrix

 1  0  1  1  1  1
 0  1  1  3 5X+2  0
 0  0 5X  0 5X  X
 0  0  0  X 4X 4X

generates a code of length 6 over Z7[X]/(X^2) who´s minimum homogenous weight is 21.

Homogenous weight enumerator: w(x)=1x^0+120x^21+294x^24+360x^28+8232x^30+3528x^31+972x^35+43218x^36+49392x^37+10584x^38+948x^42

The gray image is a linear code over GF(7) with n=42, k=6 and d=21.
This code was found by Heurico 1.16 in 0.116 seconds.