F spring for SP5 and Z5

[DocHolliday]

I shoot my MP5ish sbrs suppressed with 147 and 158gr ammo and I’ve noticed that the carrier is impacting the back plates of my wood 93 stock. I installed plastic buffers, but I still think the carrier is moving too far/fast and I fear the receiver dimples from the rollers (not yet evident). So I’m thinking F springs might be in order?

If I go to an F spring assembly I know I need a new carrier too, but do I need to replace anything else or will the stock SP5 bolt head work with the F carrier? Am I going to open up a bolt gap can of worms?

Should I just not worry about it?

 

[esh21167]

Curious whether a different locking piece would be in order? I know HK recommends a #28 for the K gun. Don't know about the full size.

 

[AGG]

Curious whether a different locking piece would be in order? I know HK recommends a #28 for the K gun. Don't know about the full size.

Here is an LP chart:

HK Locking Pieces

Tony

 

[DocHolliday]

Here is an LP chart:

HK Locking Pieces

Tony

The only full size MP5s on that chart are the SD and 40/10s. Can/should I use a LP from a 40 or a K gun? I've read a few places that the full sized 9 should keep the 100 degree LP when you suppress it?