Don't make a move till you have cleaned the gun properly
www.graybeardoutdoors.com have a very active handi forum and they have som good stickys on what to do to prep your handi for shooting. I pulled all the wood off of mine and flushed the action with brake cleaner.
If after the cleaning (and don't let the latch shelf get oily after that) you are still getting auto openings, you need to check how much engagement you are getting on the latch shelf.
So basically you meed to remove the barrel "smoke" the latch shelf ( the lower part of the "V" on that barrel stud) when you reassemble and close the action the latch pin will put a mark in the smoke (do the smoke mark test a couple of times just to make sure you are seeing the results correctly).
Basically if everything is OK you should see an even mark that is about about 3/32 " to 1/8" in. If it is not you have got a couple of options
1. Wait for it to wear in because a high spot on the shelf is interfering with latch engagement.
2. Send it back (How many weeks would that take)
3. Fix it yourself ( thats what I did with my 204 with the same problem)
My 204 had the same problem and as problems go I think it a good one to have. An action that is too tight is better that an action too loose. On my 204 the latch engaement was not enough or even, and the fix was simple.
Get an ultra fine sharpening stone (a pocket finishing stone is what I got). and slowly (I cannot stress this enough) hone the latch shelf. If it was un-even remove from the high side (the side with the thinest engagement) first. After a few
light strokes (5-10 max and the closer you are to good the fewer) re-check engagement.
You really don't want to over do this, on my gun all I did was get it even and the problem went away. I can't remember how many strokes it took but it was not many
For me I worked slow and it was still only about a 15 minute job.
Just for encouragement at this point I have 4 loads that shoot under 3/4 moa and 2 that dip under .5 moa. And most of those groups where shot with the latch issue not fixed.
Here is my rig
on a custom built for handi's shooting rest.