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Cholla

Why Change From LR to LP Primers???

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I am sure OLG will know the answer as well as some of the rest of you. I bought a used Kermitool .40/.45 Primer Pocket Swage Tool that supposedly "converts LR primer pockets to LP depths". It came in a pack of other long-range dies, wad cutters, and molds at an estate sale. Why would I want to do this? I did a search on the Shiloh forums and they seemed to be at a loss as well.

Edited by Cholla

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I found or more truthfully my brother found and I verified that in some large bore black powder cartridges.  Using a Large pistol primer can lower the standard deviation and by doing so marginally improve accuracy at longer ranges. 

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Just a WAG.  Maybe it goes back to WWII when everything was thrown into war production.   Maybe LR primers were restricted to military applications?   I've read some Elmer Keith stories in that era about making target barrels out of car axles. Refilling used primers.  Making jacketed bullets. 

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Hopefully this post does not violate the rules too much... I know we are not to link to other forums in general. But it is not my forum, I have no affiliation. Found it as I was curious about the question.

 

http://castboolits.gunloads.com/showthread.php?139615-Difference-between-Large-Rifle-and-Large-Pistol-Primers

 

In short, your die must cut the primer pocket 0.008" deeper. Including the link above as the discussion includes comments such as revolvers jamming due to the substitution. Affects on accuracy. Real-world experience in trying them...  All highly relevant to this community.

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Aren't large rifle primers taller then pistol primers? The op mentions a tool to convert large rp to large pp depths. Seems like it would be the other way around with the need being to make large pp pockets deeper.

 

The link mentions that some large rp can be seated flush in pistol depth cases. Just as some reloaders seat federal spp below flush intentionally. 

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1 hour ago, twelve mile REB said:

I found or more truthfully my brother found and I verified that in some large bore black powder cartridges.  Using a Large pistol primer can lower the standard deviation and by doing so marginally improve accuracy at longer ranges. 

 

I think this must be it as the long-range shooting thread I started reading and then grew weary of mentioned that that they say minimal difference; not enough to make it worth modifying cases, some of which can cost over $2 each.

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I and many of the local BPCR buddies use LP primers for BPCR.

We can verify what Reb said, 

 improve accuracy at longer ranges. 

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1 hour ago, Smokin Gator SASS #29736 said:

Aren't large rifle primers taller then pistol primers? The op mentions a tool to convert large rp to large pp depths. Seems like it would be the other way around with the need being to make large pp pockets deeper.

 

The link mentions that some large rp can be seated flush in pistol depth cases. Just as some reloaders seat federal spp below flush intentionally. 

I don't have the exact measurements in front of me, but IIRC, Winchester LR are .008" LONGER than Winchester LP primers. Therefore, in pistol cartridges, including .45LC, .44 Magnum, .45ACP,  .44-40, .38-40 and others using LARGE primers (.210" nominal diameter), one MUST USE LARGE PISTOL primers ONLY! I know this difference applies to MIL-SPEC primers as well as commercial.  Using Large Rifle primers in these and some other pistol cartridges WILL RESULT IN HIGH PRIMERS, WHICH COULD LOCK UP REVOLVER CYLINDERS AND POSSIBLY RESULT IN MAGAZINE TUBE EXPLOSIONS!  ALWAYS seat primers flush or .001" below the surface of the face of the cartridge.  Note: For some strange reason, this difference does NOT exist with small rifle and pistol primers! :wacko: 

Stay well and safe, Pards!

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Yes. But the op was referencing calibers with actual large rifle primer pockets so I'm assuming he's not talking about calibers that take large pp. Calibers that require large rp wouldn't need anything done to them to accept large pp.

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The tool reduces the depth of the primer pocked so that large pistol primers seat flush rather than recessed. Once you modify the brass you can no longer use large rifle primers as the pocket is now too shallow causing the primer to sit above the base of the case.

 

From a thread on  BPCR.net

 

Quote

The tool is made by Kermit Hoke. http://www.kermitool.com/ It's not advertised on his website but you can get his contact info. When I bought one about a year ago I think it was $75. Basically there is a piece that replaces the shell holder and one that looks sort of like a sizing die. Once you get it adjusted you put a piece of brass on the shell holder piece and run it up into the die. There is a stem in the die that squeezes the primer pocket from the inside of the case toward the shell holder. I usually squeeze the primer pocket about .002" - .003" smaller than large pistol size and then uniform with a Sinclair carbide uniformer in a Forster crank fixture. The tool works exactly as specified and Kermit is great to deal with. Good luck,

 

They also make a tool that uniforms and flattens the flash hole.

Edited by Sedalia Dave
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Common in BPCR to see. Not in smokeless.

LR primer is taller than LP.

The main issue is the pounding the breechface takes over time from the LP primer movement in the primer pocket.

I only use LR primers ....

My targets agree.

OLG 

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3 hours ago, twelve mile REB said:

I found or more truthfully my brother found and I verified that in some large bore black powder cartridges.  Using a Large pistol primer can lower the standard deviation and by doing so marginally improve accuracy at longer ranges. 

There's other ways to reduce ES that doesn't risk breechface damage.

OLG 

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59 minutes ago, Trailrider #896 said:

I don't have the exact measurements in front of me, but IIRC, Winchester LR are .008" LONGER than Winchester LP primers. Therefore, in pistol cartridges, including .45LC, .44 Magnum, .45ACP,  .44-40, .38-40 and others using LARGE primers (.210" nominal diameter), one MUST USE LARGE PISTOL primers ONLY! I know this difference applies to MIL-SPEC primers as well as commercial.  Using Large Rifle primers in these and some other pistol cartridges WILL RESULT IN HIGH PRIMERS, WHICH COULD LOCK UP REVOLVER CYLINDERS AND POSSIBLY RESULT IN MAGAZINE TUBE EXPLOSIONS!  ALWAYS seat primers flush or .001" below the surface of the face of the cartridge.  Note: For some strange reason, this difference does NOT exist with small rifle and pistol primers! :wacko: 

Stay well and safe, Pards!

ALWAYS seat the primer to the bottom of the case's primer pocket ;)

OLG 

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9 hours ago, The Original Lumpy Gritz said:

ALWAYS seat the primer to the bottom of the case's primer pocket ;)

OLG 

Are SR and SP primers interchangeable?

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15 minutes ago, Captain Bill Burt said:

Are SR and SP primers interchangeable?

 

Yes and no.

 

The metal in SP primers is thinner than SR primers. so they can only withstand so much chamber pressure before rupturing and allowing hot gasses into the action of the firearm.

 

If you look a load data for some very hot pistol cartridges they actually call for LR primers in the loading data.

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45 minutes ago, Sedalia Dave said:

 

Yes and no.

 

The metal in SP primers is thinner than SR primers. so they can only withstand so much chamber pressure before rupturing and allowing hot gasses into the action of the firearm.

 

If you look a load data for some very hot pistol cartridges they actually call for LR primers in the loading data.

So if I wanted to substitute SR for my .38 loads, 125 grain over 2.7 of Clays, I would be ok?  
 

What about hardness? Are SR as easy to pop as SP?

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2 minutes ago, Captain Bill Burt said:

So if I wanted to substitute SR for my .38 loads, 125 grain over 2.7 of Clays, I would be ok?  
 

What about hardness? Are SR as easy to pop as SP?

 

You would be Ok for loads below max. However as with any loads approaching max changing components may increase pressures and would require backing off the powder and working up a new load.

 

SR primers are made to withstand higher pressures so I doubt that firearms tuned for SASS will set them off reliably. With stock springs they should work just fine.

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2 hours ago, Captain Bill Burt said:

Are SR and SP primers interchangeable?

Sedalia Dave is correct.

 

I have a large supply of srp from years ago. Used in 38 supers to make old major factor in another game.

 

When I first learned of the "shortage" I dug out some of these and tried them.

All my cowboy guns will set them off.

 

Get some and try them in your guns. That is, if you can find some.

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Thanks Ringer and Dave!  


Fortunately Sharyn and I aren't hurting for primers.....yet.

 

Back of the envelope calculation tells me we're good through 2021 without having to scale back, BUT, it's good to know that SR will work, and if I come across some I'll probably pick up a couple of bricks just to be safe. 

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9 hours ago, Captain Bill Burt said:

Are SR and SP primers interchangeable?

Dimensionally, they are the same.

SR and SP mag, are pretty much the same in 'flash'.

OLG 

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A separate question: Wonder what the shelf life of primers and loaded ammo might be?  I've got plenty of Winchester LPP and Remington LRP...that are between 20 and 50+ years old.  They've been stored in my dry basement on shelves as I bought a bunch, but never got around to using them.  Even got some TW54 M2 Ball that is now 47 years old.  Wonder how reliable they will be?  Also, wonder about the brass age-hardening. Won't be able to do any testing for months. :(

Stay well and safe, Pards!

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2 minutes ago, Trailrider #896 said:

A separate question: Wonder what the shelf life of primers and loaded ammo might be?  I've got plenty of Winchester LPP and Remington LRP...that are between 20 and 50+ years old.  They've been stored in my dry basement on shelves as I bought a bunch, but never got around to using them.  Even got some TW54 M2 Ball that is now 47 years old.  Wonder how reliable they will be?  Also, wonder about the brass age-hardening. Won't be able to do any testing for months. :(

Stay well and safe, Pards!

 

All depends on how they were stored and the humidity.

Basement is not the best.

OLG 

Edited by The Original Lumpy Gritz

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3 hours ago, Trailrider #896 said:

A separate question: Wonder what the shelf life of primers and loaded ammo might be?  I've got plenty of Winchester LPP and Remington LRP...that are between 20 and 50+ years old.  They've been stored in my dry basement on shelves as I bought a bunch, but never got around to using them

 

 I have personally shot some (over 200) Winchester SRP and LRP that my dad gave me that he bought in 1956 and they all have gone bang so far.  As far as storage they were in an old G.I ammo can in the garage.  On a side note the the small rifles worked fine in my revolvers with Wolf springs. 

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