I purchased a new(old stock) holster for my 6906. It is thick leather and very stiff and I think has been somewhat flattened during storage. I have been using shaped wood to gradually force it open and have it to where the gun slides in and out without much friction when the wood is first removed.
After it sits empty for awhile the gun will go in but it takes some effort. I have increased the thickness of the shaped wood in hopes that the additional expansion will cause it to stay open enough to obtain a decent fit.
My question is this. Would working the leather with a wooden mallet while the wood is in help to make it more pliable and would warming the leather while the wood is in make it more likely to stay shaped?
Any input will be appreciated. Thanks!

Soak the holster in water until soaked. Let dry a bit. While it is pretty damp, put the gun in it and mold the holster to the gun. remove the gun and let the holster dry. If you can hang it to dry it will be less likely to collapse than if it dries laying on it's side. I think the mallet would destroy it.

What he said. The only thing I might add would be put the gun in a freezer bag or wrap it in plastic. Maybe put a coat of oil on it for extra protection.

You do not want to completely soak the holster, only enough to make the leather pliable. Depending on the quality and thickness of the leather, I generally dip the holster in warm, not hot, water for 1 minute or less (I usually add a couple of drops of dish soap to make the water "slicker"). I coat the gun with a thin film of oil and work it into the holster. I use my hands to stretch the leather into position around the gun, i.e., the safety strap of thumb break. I use a an old spoon to mold the exterior if I want that feature. I let the holster dry overnight with the gun in it. I've never had any problem with surface rust. After I take the gun out of the holster, I spray it with WD-40 to displace any water that may have gotten into it and wipe it down with a silicone cloth. The holster may still be damp, so I let it dry another day without the gun in it, and then it's ready to carry. I try to let the holster dry in the same position that it will be carried, i.e., upright for a belt holster, on a hanger for a shoulder holster, etc.

What safearm said, but I wrap the gun with saran wrap which is thinner and conforms better than plastic bags. I leave in until leather is pretty dry, at least over night.

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H Richard
SWCA1967 SWHF244

That process has worked quite well for me, also.

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Richard Gillespie
FBINA 102

Likewise. I've started making holsters and that's what I did. I did the boning in of the two tuckable IWBs I made using my fingers and the handles of a couple of my leather working tools.

The thing you might run itno is that finished holsters are usually finished with some sort of acrylic that seals them from moisture. You may have trouble getting the leather wet enough to work. As for the plastic bag, I've heard of people using them, but I haven't found a need for them.

You may want to give this a try. I think one of the holster makers gave this tip. Warm up the holster with your blow drier and put the gun in it. Then give it a couple of once-overs with the gun in the holster with the drier again. It will soften the leather and let it conform to the shape of your gun. Keep the gun in the holster overnight and see how it fits the next morning. That worked really well for me.

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Why duck?? It's a 9mm!

Thanks to all for your comments. I am not far from having it to fit. Will try the heat and if it don't get it will try the wet holster path.