When I put stock grips, which I like best, on my P228 they leave a gap in the back. Not huge, mind you, but disconcerting nonetheless. I don't like to look and see the mainspring.

Contact SIG and tell them your grips dont fit or maybe you can find new stock grips that fit better. Gun shows seem to have them cheap sometimes.

Have you tried several different sets of factory grips? I've also heard that over-tightened grip screws tend to do this with factory grips (which makes sense if you think about it).

you can dremel down the inside frame plastic to let them fit better....

Have tried many sets (4) and all do the same. This is my third P228 and the only one that does this. Unfortunately it's the only one left and it is otherwise an hoonest 99% gun with only 50 rounds through it. It's a Herndon Va import at that. I'm the type of person who doesn't like "good enough" and hope to rectify it w/o modifying an expensive gun.

Something is wrong here.

No offense, but is it possible any internal parts are incorrectly assembled?

For example, could maybe you have the tail of the triggerbar spring in the triggerbar hole instead of the notch?  Or possibly do you have the newer looped triggerbar spring installed (instead of the original “U” shaped one)?

Does anything feel like it’s rubbing against the grips when the trigger is pulled or the decock lever is used?

Are any pins sticking out of the frame enough to interfere with one of the grip panels?

While I’ve never heard of it, Walkure has a point.  If you simply hold the grips in place without the screws, do you still have the gap?

The problem might be with the left grip panel and the decocker lever. I've put the stock grips on my P228 and had the same thing happen to me.
Try pushing the decocker lever down and holding it there while putting the grip panel on. Once the grip panel is in position, let the decocker lever go back up. Then put the right grip panel on.
Hope this helps.

Tried all advice to no avail, I guess it's off to Exeter. I need new night sights anyway.

Please let us know what was wrong with it.
Good luck!

     Are you sure you have the correct grips for the trigger return spring in your gun?  There have been changes to the spring which require the matching set of grips.  I would say a call to Sig could probably clarify for you which setup you have and therefore which grips you need.

later,
AJ

Quoted:      Are you sure you have the correct grips for the trigger return spring in your gun?  There have been changes to the spring which require the matching set of grips.  I would say a call to Sig could probably clarify for you which setup you have and therefore which grips you need. later, AJ

The return spring is at the top of the right grip, the grips gap at the bottom?

Don’t know if this is the issue, but SIGs originally had a mainsping of about 2 inches in length and terminating with a “L” shaped metal clip which engaged a couple of hooks at the bottom of the frame.  Presumably that’s what your SIG has.

However, maybe 10 years ago SIG replaced this with a much shorter mainsping that seats on a polymer piece about an inch long that engages the hooks the bottom of the frame.

At the same time, the grip design was modified on the inside bottom to accommodate this change in mainspring design.

I know the older grips won’t fit the new mainspring design without some Dremeling.  Maybe this is also true with the older mainspring setup and a set of newer grips.

Possibly this is your problem.