I thought so too.
I'm going off what it says in the Browning A-5 field service manuals - and I have two. One that looks like it's from the late 70's or early 80's, and one that looks like it's from the 90's.
Both of them have the same diagnostics for:
- Failure to lock open on last shot using heavy loads
- Bolt fails to lock in rearward position when last shell is fired
and both of them contain "weak recoil spring" with a corrective action in the later manual of "replace recoil spring." Well, I can see replacing a weak recoil spring, certainly, but I'm not seeing how it leads to failure to lock the block back. Yet both manuals say this.
The same question you have has been sorta rattling around in my head this evening while working on stocks: If the recoil spring is weak, then the block & barrel are going to come rearward with, if anything, too much force. The only place where a weak recoil spring might matter is just as the barrel is going into battery.
I've been pondering how a weak recoil spring can result in a failure to lock the block open on the last round, and all I can conceive of is timing issues with the carrier latch - which I'm not ready to believe yet. I'll look at an A5 in the next couple of days and ponder this problem if no one has a flash of brilliance before then...
I found an online copy of the earlier of the two manuals I have from Browning:
Please reference #10 on p. 14.