SR primers in handgun brass or "shooting rubbers"

[AtlLaw]

I got a bunch of 38 cal rubber bullets to use in my basement range.  But SP primers just don't seem to have enough "oomph" when used to propel them.  This is compared to the LPM primers I use for the same thing in my 44's and 45's.
 
Do y'all think the SR or SRM primers would be as effective in launching a rubber from a 38 Spl. case as the LPM primer is from a 45 Colt case?   
 
I'm also fixin to look see if maybe I can drill out the 38 Spl. primer pocket to take a LPM primer!   

[Bigeasy]

Richard - I only ever used the Speer plastic case version, but I read somewhere that when using regular brass, you should drill the flash hole slightly larger, not the primer pocket.  I don't recall the exact size bit to use, though I do remember there were 2 sizes noted, based upon small primer / large primer cases.
 
Larry

[1sourdough]

 There was just an article in Handloader magazine about loading & shooting rubber bullets. I don't know if I can find it but he had some tips on loading them that would be helpful.

[spruce]

I'd try BigEasy's tip - drill out the flash hole in a couple of cases and try them.
 
I used to shoot wax bullet loads in a .38 spl and had to drill out the flash holes to get good functioning.

[GH1]

According to "Handloader" magazine, your .38 flash holes should be drilled to 7/64", but if you don'yt have a 7/64" drill bit 3/32" will suffice. Apparently 1/64" doesn't make much difference, you might even be able to get away with 1/8".
GH1

[AtlLaw]

Thanks for the input folks!
 
I decided to do another meaningless and statistically insignificant experiment!     
 
I took 2 unmodified 38 cases; one nickle and one brass.  SP primers went "pop" and the rubber bullet got to the target but bounced off the cardboard backing.  SR primers made a nice loud pop and penetrated the cardboard.  Neither backed out of the case as happens with LPM primers if you don't drill out the flash hole.  Don't ask how I know...    Anyway, SR primers will do!   
 
So now I grabbed a drill and opened up the flash holes.  First point, solid brass cases are a whole lot easier to drill then nickle plated cases!     Second point, I felt the drilled cases added a little velocity to the projectile.  Just a feeling, so maybe someday I'll put a few of each over my 'graph and find out for sure!   
 
But for now I'll be satisfied with drilling out the flash hole of a bunch of brass cases and using the SR primers I have.  Hi-ebber, and day always be a hi-ebber, I still wonder... what would I gain by enlarging the 38 Spl. primer pocket to take LPM primers... 
 
 
 

[AtlLaw]

There was just an article in Handloader magazine about loading & shooting rubber bullets.

I found that article you were referring to this morning.  It took me a long time to get through the "weights and measures" article that was before it in that issue!     It just confirms what I have learned through the last few years by trial and error.
 
I've shot wax and plastic bullets for quite some time, and glu-lets also, but only started using the rubber projectiles 3 years or so ago.  I like them best of all.  I only wish they made them in .308...    and maybe a few other predominately rifle caliber sizes...