I only shoot black powder.  I put a .030" veg fiber wad over my powder charge and breech seat the bullet ahead of the case.   

It seems to me that the wad is going to cross the gap to the bullet base and slam into it, potentially damaging the bullet base.

I'm pretty confident that the wad makes a measurable imprint on the base as I've recovered LDPE wads shot under paper patched bullets and found imprints of the folded paper on the wads.  Those wads are reasonably tough.

Are any of you guys breech seating the bullet with an additional wad at the base of the bullet to protect the base?  I've been doing this with breech seated paper patched loads in one of my .38-55's with pretty good results.

Chris.

Chris, Harry Pope used felt wads cut from old hats.  Though I'll never be a Harry Pope - if it was good enough for him, it's good enough for me also.  I use felt for my breech seated and fixed cartridge reloads for nearly every caliber except 22LR black powder breech seated reloads.  They are capped with a construction paper wad.  At an average 980 fps with pure lead bullets, there is no noticeable accuracy degradation 

At the time when Pope and other shooters were using the felt and postcard wads, were they still duplexing?  Did they use the wad to hold everything in place or had they moved totally to smokeless by then?  Bob 

I use LDP wads in my 40/65s with BP and duplex loads.  Never a problem, no fouling, higher scores, yes. That's with fixed ammunition.

When breech seating with BP, I use cork or Walters wads, card wads or styrofoam wads. The styrofoam seems to be the most accurate. Punch them out of plastic targets or plastic dishes. 
Have also had good luck with no wad at all. The difficulty arises when inserting the case in the rifle.  The floral foam wads are to crumbly and hard to handle. 

             Joe.

all I know is the guy showed me some plastic wads he was using said they were LDPE and asked if I wanted to try them. I told him no that I was afraid of plastic fouling in the throat and barrel. He told me LDPE didn't do that and many BPCR people were using it. 
Later that day I found him scrubbing the bore. He told me he had fouling in the throat. He cleaned and scrubbed and brushed Nothing would touch the hard pathces of fouling on the chamber and streaked into the first few inches of the bore. He was done for the day. Long story short by the time he got it cleaned he ruined the barrel. Soaking wouldn't touch it so he started to use more aggressive measures. 
He was shooting AA#9 and Emerts lube. 
This confirmed my distrust of all things plastic. I now use only natural products in my loading cork, Wool felt, cardboard, ect.
40 Rod

I've heard a few stories about people having fouling issues with LDPE wads.  I've used a couple of thousand of them with no troubles.   

Chris.