I ordered grizzly el grande 150s and 100 grain steel inserts.  When I test fit the insert, it does not insert flush with the bottom ridge of the insert.  It only goes in to the first ridge from the bottom.  Shouldn't the insert go all the way in?  Will I have potential problems with these if I try them like this?  Thanks, Paul.

Paul,
There was a post a couple of weeks ago here, someone had that same trouble and the momentum of the shaft drove the insert into the broadhead as it hit the target and split the ferrule. I have some 190's on the way and also have 100gr inserts, if they don't fit we may have to go to the short 75gr. But Dr. Ashby has been having trouble with the 75gr adapter breaking. Hope this helps.
John

The short 75 grain adapters won't be any better. The problem isn't that the adapter is too long, but rather that the ferrule is too small of a diameter.

Thanks fyrfyter for clearing that up. I was under the assumption they were too long. I have some 190gr Grizzlys coming and have never used them before.
Does anyone know what adapters Dr. Ashby uses/recommends? Or does he somehow modify the adapter or ferrule without weakening the broadhead?
My 11/32 steel adapters also wont seat all of the way into old green Bear razorheads, about 2 threads of the adapter are exposed.
Thanks,
John

As long as the tapers match on adaptor and ferrule, then I wouldn't waste a lot of time worrying over 1/64" or even 1/32" difference in diameter.

As far as short adapters causing compression failure of the Grizzly ferrule, that can be overcome by use of a slow cure epoxy attachment or by filling the ferrule so there's no "running room" for the adaptor.

Mike is dead on, the Grizzly ferrule is closer to 21/64" than anything.  No problem with a little adapter sticking out...Charlie's suggestion is a good one.

PDP actually makes (or made) a 21/64 aluminum adapter that fit the Grizzlies insanely well.  They are hard to find (if even still in production) and were also the soft cruddy aluminum grade most non-Magnus adapters are made of.  Magnus aluminum adapters are the bomb but are 11/32" and 5/16".  I'll have to try a Magnus 5/16" in a Grizzly.

I was planning on using epoxy, so I will just fill the nose a bit.  I also ordered some 125 inserts for some Magnus IIs I have with aluminum inserts that I wanted to swap out.  The 125s had 2-3 ribs sticking out and I didn't think to try the insert from the Magnus in the Grizzly, but I think it would be too small.

I checked the 5/16, they overlap about a 16th of an inch, not the way you want to go I believe.