Went today nov 1. Pistol target side. Came early 730 was able to get a spot. by the time the line went hot at 8am had waiting list. Was a good day. Tested out some 38 special reloads my cousin did (first time reloader) out of 100 4 was a no go. Looked like primer was seated too deep. Light firing pin dimples. There were more that looked deep seated but went off in single action on second go round. Was great to finally get out and shoot. My cuz was excited too because he got to fire his new to him dan wesson revolvers along with my model 19 all 6" barrels. I did notice that factory 357 is a bit more snappy in the k frame then my old man n frame 28 highway patrolman.
Had a mishap with someone else's reloads though. Looks like it was a missed\low charge and the primer was enough to push the bullet into the barrel just enough to lock the revolver up. Lucky it happened in the dw, after looking at it was decided to remove the barrel since it's easy in the dw as opposed to the Smith. After he got the round out the bullet was still partially seated in the case. Really lucky that this happened on the last round and that the bullet didn't go partway into barrel letting a next round to chamber.
We took it as learning experience 
And we will most likely be at it again next week. I have 4 revolvers thats getting out of jail on thu 
3 smiths and 1 ruger.
My experience with primers being set too deep is extremely rare. It is is usually caused by using a pocket reamer that is not the type that keeps one from going too deep and being used too much. I have one of these and it is over 40 years old. Most pocket reamers are set so you cannot go too deep. I assume the primers used are of the correct size. If it turns out the primers are set too deep then I would discard the brass. There are also very hard primers such that a pistol may have difficulty striking it hard enough to set it off. For instance, someone may have used a small rifle primer that is designed for use in an AR type rifle that has a floating firing pin. Also, some European and Russian primers are known to be more difficult to set off. These primers use a much harder cup and some pistols may have a hard time properly striking them. One more thing I have noticed and that is Winchester primers have been less reliable than other brands. Winchester usually uses brass cups instead of the silver colored cups. I bought a case of them once and probably 5 or 6 out of every 1,000 never ignited even when hit well.
There is one other thing to consider and is something I have found to happen more often in revolvers, and that is a weak hammer spring or the hammer spring tension is set too soft. This happens sometimes when a revolver has had a trigger job and the trigger is set too light. It could be a light spring was put in or too light of a setting. With SA/DA revolvers, the hammer does not come back as far when shot in DA mode. If you cock the hammer and use it in SA mode it brings the hammer back farther allowing more energy to hit the primer than in DA mode. If the hammer spring is too weak, or the hammer spring tension is set too soft you will see light hammer strikes more often in DA mode as in SA mode. And that can happen in SA mode as well but is less likely. The S&W revolvers have a hammer spring tension screw that can and does back out during shooting and can cause light hammer strikes. It will be more noticeable in DA mode first and then you might start seeing it in SA mode. I have had it happen to almost every one of my S&W revolvers. It is an easy fix. Remove the grips and screw the tension set screw back in.
Overall I would say that primers being set too low is something to check but it is more likely one of the other things I mentioned. I would look at those things first such as harder primers and/or weaker hammer springs. It could also be a combination of these things as well.
One thing I learned to do during reloading is to look into every single case before setting the bullet. Make sure you have powder in there and that the powder is at the same level as all the other cases. This helps prevent squib loads.
I hope this helps!