Sentry gun and EMP gernades

Sentry gun issues-

1.  Sentry gun blows up for no apparent reason.  On a flat surface, sometimes by a wall or on the ground the sentry gun will explode upon deployment.

2.  Can not deploy sentry gun.  Having a sentry gun deployed already and then getting ammo from a box or Angel's drop, you then can not deploy another sentry gun until you die.  Doesn't matter if you pick up the old one or wait to the sentry gun spawn timer.

3.  Sentry gun locates and locks onto target and then shoots a small burst giving the player enough time to destroy the sentry gun before it rearms.  Players can take them down with less than a magazine unlike the Ranger which takes a lot of damage.  Possibly give sentry guns the same health as the Ranger.

EMP gernades

1.  Blows up in your face, sometimes when you are by a structure, other times when there is nothing but wide open spaces.  Also if you throw one by friendly sentry gun it will blow up in your face.

2.  Too short of disable period for some vehicles.  Tanks seem to only have a 5 sec down time while the bolt and lav have a longer down time.

3. M1 tank seems to be unfazed, I am continually getting killed by the main gun right after I hit them with an EMP grenade.