EXPLANATIONS (1)   I  assume  Turbo  designed  the  placement  of  the  trigger using  a  standard  Remington  trigger.  But,  most  folks  use Jewell triggers. The Jewell sear connector is shorter than a standard  Remington,  so  the  firing  pin  spring  is  not  pre- loaded enough. A lot of early Turbos have this problem. It can be corrected. The last several Turbos I have used pre- load the firing pin spring very well with resulting excellent ignition, but early Turbos I rate poor. (2)   The  Kelbly  has  a  unique  firing  pin  and  unique  way  of mechanically stopping it. It is a thin flat piece of stock that is  broad  enough  to  strike  the  rim  of  the  case  and  also strike  the  breech  face  of  the  barrel  which  is  how  it  is mechanically  stopped.  I  do  not  like  this  as  it  causes  the firing pin to strike the edge of the rim of the case. This kills ignition.  If  you  have  enough  mainspring,  you  can  strike the  edge  of  the  rim  and have good ignition and although this action has a strong mainspring, it ain’t THAT strong. (3)  Factory  Turbos  do  not  have  enough  closing  cam.  One  of the big complaints I hear is from shooters having to push on  the  cocking  piece  of  the  breech  bolt  to  get  the  bullet seated into an engraved chamber. This can be corrected. (4)  Turbo locking lugs need to be lapped. The left locking lug seat  is  machined  in  a  different  operation  than  the  right side. And I have found that a lot of times both lugs do not make contact as one seat is cut deeper than the other. (5)  Best ever regarding ease of loading! (6)  The Kelbly is about the same outside diameter as the Hall or Turbo, but it is not as stiff.  It has a very large barrel thread, a very large cut-out for that great drop-in loading.   The loading ramp is a large round block of metal that has a corresponding cut in the action and it has race ways cut for the mid-type locking lugs. It uses a guard screw in the tang.  The  Turbo  and  Hall  get  away  with  having  a  guard screw in the tang because they are so stiff. (7)The Hall barrel thread makes possible the use of a straight barrel,  breech  to  muzzle  of  no  less  than  .875".    I  very seldom use barrels over .850" so a barrel of this size must have a step in the barrel. Straight barrels, end to end, are just  easier  to  make  the  bore  uniform  from  end  to  end. Barrels with an enlarged breech can be made fine, but it is tougher. (8)         The Kelbly uses a barrel thread that is far too large.   Any normal size barrel has to have an enlarged breech.  In the case of the Kelbly, this barrel thread can’t be made smaller because you cannot get that large loading ramp in place. It is installed back through the barrel thread opening. You have the same problem with a 40-X Remington or my XP 100 conversions. They both require enlarged breech sections for threading and they are successful.  But, straight barrels are so much nicer to work with. Ratings: E=Excellent, G=Good, F=Fair, P=Poor.                                                                  Turbo        Hall        Kelbly Is the action face perpendicular   to the bolt raceway?                                 E              E               E Is the barrel thread perpendicular   to the action face?                                    E              E               E Is the supporting surface   for the cartridge head in                           E              E               E    the breech bolt nose square   to the action face?   Ignition?                                                P/E (1)          G           F (2) Closing cam?                                         P (3)            E               E Locking lug contact with   their seats in the receiver?                   F (4)            E               E Ease of loading?                                      P              E            E (5) Potential for good bedding?                     E              E            G (6) Rating of barrel thread size?                   E           G (7)         F (8) Extractors?                                             G/F             E               E Provided courtesy of ARA News.   Rimfire Action Comparison