Hmmm,
Sounds off to me. Is the issue one of warranty, or of getting it right?
I've bought mainsprings before and swapped them myself. Here is a link to some:
Hi Power mainspring at Midway
If your HiPower is a modern one [since mid-1970s] the correct spring weight is 32lbs.
Sometime between 1960 and 1977 Browning swapped from 26 [or was it 28] to 32lbs.
Taking them apart is FUN!!!
However, I am no gunsmith and was able to swap them out.
If you gunsmith can't find these springs, it seems something is weird to me.
Now, if it is a matter of warranty: I can see Browning requiring a trip to Utah to see the gun and work it over.
If you are paying for the work and the mainspring itself is the only issue, you can get it on your own.
Become familiar with the website
http://hipowersandhandguns.com/ also.
GREAT source of practical advice!
As to your original problem, I will admit I can't see how a mainspring would cause that problem unless it was broken.
I don't have a stock hammer/sear in my Hi Powers. I've fitted EGW Sears to C&S hammers, Warner hammer/sears, and Garthwaite hammer/sears-plus tuning factory ones on a gun that was sold.
The safety does NOT contact the hammer spring. The safety shaft rotates inside the hammer and the safety 'tab' [part that has to be fitted to sear] moves up into engagement with the sear, so that it can't pivot to release the hammer. The only thing that 'might' contribute is a big burr on the hammer/mainspring rod/spur/thingy. If one existed in just the wrong spot it could, theoretically, rub the safety rod.
However,
that is about .00000001% likely. In other words:
forget that idea.
The sear rotates [bottom of L shape goes forward, as the top drops into the hammer hooks.] and a section of the safety moves into contact with the back side of the sear. This prevents rotation of the sear in the opposite direction, which releases the hammer to fire the gun.
If the sear spring doesn't push forward hard enough on the sear itself, it won't allow the safety to move into 'safe' position, as the sear will be rotated too far to the rear [bottom section, obviously].
Hammer follow can happen if the sear spring is tuned to light also.
With brand-new fitted hammer/sear combo I had hammer follow, but re-tensioning the sear spring fixed it. No creep, crisp break, but around 6.25lb pull weight.
If you had someone try to lighten the trigger weight by reducing sear spring tension you can obtain a lighter trigger pull, but it isn't always reliable.
A bad sear tip/hammer hook can also cause problems.
If the angle is dinged up on them, or wrong to start with, the hammer may not be cammed back far enough to allow the sear spring to push the sear enough for positive engagement. And this means your sear interferes with the safety when you attempt to put it into 'safe'.
A gunsmith should be able to solve this. Not all people who earn their living as a gunsmith are equal though-and younger ones may only know Glocks and 1911s.
If he is saying the gun has to go to browning because he can't get a hammer/main spring-I become a bit concerned about his knowledge of Hi Powers.
And, if I were Browning and a gunsmith told me they needed a mainspring to fix the hammer follow/sear engagement situation-I would probably ask for the gun to be sure my customer got it fixed right.
