Can I convert a P239 double action ONLY to a double action/single action?

With the right parts, yes.

“DAC,” however, is not an abbreviation I’m familiar with. Do you mean DAK?
The DAK and older double action only mechanisms are significantly different in terms of the parts required to convert to DA/SA. If you don’t know for certain, can you post a photo of the gun?

Often the cost to convert from DAK to DA / SA or the reverse makes the weapon very expensive. If you are handy (and I am not at all going to attempt a pistolsmithing job), you can save the money. But, I chose to send a DAK to Sig Sauer to be converted to DA / SA. It was about $300. Hard to remember, as I also had them install X-Ray sights like the Legion has.

I've done it but what I actually did was change out the two systems in two guns.... what I can say is it takes a lot of discipline and my saving grace was that I had a pistol just like both to keep comparing one too and it still took me at least 6 hours....
So, I would suggest paying an expert to do it which is probably going to cost almost as much as a used one with parts and labor.... better suggestion: just buy a SA/DA and then have both.

quote:

Originally posted by sigfreund:
“DAC,” however, is not an abbreviation I’m familiar with. Do you mean DAK?

Maybe "DAO"?

quote:

Originally posted by joel9507:
Maybe "DAO"?

That was my thought, which is why I asked for more information or a photo.

“DAC” might, however, be pronounced the same as “DAK,” and perhaps the OP assumed without seeing it written that DAC was the abbreviation.

DA/SA to DAO is just a hammer swap and removing the decocking lever parts.

DA/SA to DAK is a fair bit more involved.

DAO to DA/SA is just a hammer swap and installing the decocker parts. If you've got the parts and another SIG to look at to see how they fit it's not a hard job at all.

DAK to DA/SA is a pain. The actual process isn't any more difficult than going the other way, but trying to find all the required small parts can be more trouble than you expect. SIG was charging $200 for this conversion and that was pretty much what all the parts would cost. I've got a 226 DAK that I keep meaning to switch over, but just haven't gotten around to pulling the trigger on the project <rimshot>.

The DAK to SA/DA was the flip I did between two P239s ... and yes it was a pure tee pain for sure....