Since I have a pile of large pistol primers and a not as large pile of large rifle primers, I'm about to explore the use of the LP's in my .32-40's.

I'm aware of the difference in height between the two, but am curious as to the real world hazards entailed. 1) is battering of the breech face a real concern, and 2) what can I expect in terms of reliable/consistent ignition?

Regarding ignition, I'm contemplating opening up the flash hole slightly, say .010"-.020", to promote better ignition of the powder charge. Is that a sound practice? I'm aware of CBA gurus doing that in larger capacity cases when building "mouse fart loads" with minuscule charges of pistol powders (and am aware of the necessity of keeping said cases strictly segregated from the population of "normal" cases). Is it really an advantage?

For the record, this endeavor is centered only around .32-40, breech seated, with commonly used charges of 4227 and the like, in the 14 grain vicinity.

Thanks in advance for any advice, both theoretical and real-world!

Back in the 80s I was using large pistol primers because several pundits said they would disturb the powder charge less. I still have about 4000 Remington large pistol primers.
Mike

Go to ammo seek and click the reloading link and you can find large rifle primers. They are a little pricey but you have to pay to play.

I've had some fail to fire with LPPs when used in some of my 45-70 and 32-40 cases. They looked like light strikes on the primers.
Have never had the problem when substituting SPP for SRP and visa versa.

John

I've used both Winchester and Federal Match pistol primers since I started shooting Schuetzen back in the early 80s. I've fired them in Stevens, Winchester, Ballard, FBW, and several German and Swiss Martini schuetzens.

As far as I know, everyone who has shot or still shoots with me in San Diego used or uses pistol primers - both large and small.

Federal Match are preferred by most folks but a couple of us use standard Winchester for off-hand with equal success.

This is a link to a lot of good technical information on Primers

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Primer Info & Chart + Milspec Primers for Semi-Autos & Other Primer Applications (sksboards.com)

FWITW,
I've used LPP for years in a 45-70 (Swiss 1-1/2F BP) with a newsprint disk over the primer flash hole inside the case.


gnoahhh wrote on Sep 6^th, 2022 at 10:54am:

Mike
I cut a strip of ordinary writing paper about 3/16" wide and slip it into my LEE priming tool above the primer getting seated.
When you seat the primer into the case it punches out the paper and sets the primer out an extra two thou or so. When I was shooting my 40-60 CPA sometimes I would get inconsistent ignition due to what appeared to be light firing pin strikes, seating  the primers out just a bit cured the problem completely. The fact that the primer flash has to pass through the paper to get  to the powder charge seems to not be a problem. Plenty of loaders put a paper disc inside the case over the flash hole to stop powder finding its way into the flash channel and the primer with no ill effects.
When my problem first started I figured that perhaps my firing pin had shortened after about 10,000 rounds, so I ordered another one from CPA. When it arrived it measured the same as the one in my rifle, so it wasn't a firing pin issue at all.
CPA also sent me in the same package a bunch of parts like springs etc for no charge, CPA are the best people to deal with bar none.
Mike.

Have been shooting nothing but LP primers (magnum, match & standard - whatever I can get these days) in my 40cal & 38cal CPA for the past 3 years and notice zero (none) affects on the breech-face of the block. I seat them with a 21st Century seating tool just like I do LR primers and are good to go.

I have been using a 38cal newspaper wad in the bottom of the 40cal cases for my BP loads, but don't think I'll do that in the future. My testing has shown zero difference with and without the under-powder wads, so no reason to do so.