im assuming you have the grip as far forward as possible, so unless you buy some kind of mount that goes over the front lip you would have to shave it to effectively mount a rail, to mount a front grip farther forward.

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And shepards we shall be, for thee my lord for thee, power hath descended forth from thy hand, that our feet may swiftly carry out thy command. We shall flow a river forth to thee, and teeming with souls shall it ever be.
In nomine Patris, et Filii, et Spiritus Sancti.