Difference between Large Rifle and Large Pistol Primers

[eyehawk]

Does anyone know the affective difference between the large rifle and the large pistol primers?

In other words, are there applications where large rifle primers can be used in place of large pistol primers?

AJ

[462]

Large rifle primers are taller than large pistol primers, which will/can create seating issues. In my view, that makes them non-interchangeable. Buy the correct primer for the particular application.

[tomme boy]

Large rifle also should have a thicker cup to handle higher PSI. Some of the new super duper mags for pistol use rifle primers because of the higher PSI that they run at.

[Rocky Raab]

Both the above are correct.

[atr]

remember that the load data you are using was compiled using specific components, including primers
....technically if you change the components you invalidate the load data

[BruceB]

Yeah.....BUT

Many folks here use Large Pistol primers for cast-bullet RIFLE loads, in the belief that a "gentler" ignition sequence assists with accuracy. Exactly WHY accuracy improves in some loads, I don't know. However, I've seen it often enough that there's no doubt in my mind that it MIGHT help.....this is in lower-pressure loads, of course.

I've also seen (and used) rifle primers in pistol-caliber brass. It can be a useful technique IF

(a) the handgun in question will reliably fire the rifle primers, and

(b) the primers can be seated flush with case-heads. I think the use of a RIFLE primer-pocket uniformer could help with this, but I've never had to do it. Let me be very specific: in MOST pistol brass, including my current stocks of .45ACP and .44 Magnum, it IS POSSIBLE to seat Large Rifle primers to a flush condition. I demonstrated this for NVCurmudgeon not too many months back.

For many years, Canadian Industries Limited made ONLY .44Magnums for carbine use, there being literally no market for .44 pistol ammo in Canada. They used the same #8&1/2 primer that was used in .303, .30-30, .30'06 and all other large rifle cases. Those factory .44s with RIFLE primers functioned perfectly, even in double-action mode in my S&W revolvers. Those same .44 cases also worked fine in all my .44 handguns when loaded with PISTOL primers.

So....there is some crossover room. Definitely, do NOT interchange them willy-nilly; do some careful observation and work-up when putting LR primers in LP cases.

[madsenshooter]

Does anyone know the affective difference between the large rifle and the large pistol primers?

In other words, are there applications where large rifle primers can be used in place of large pistol primers?

AJ

It appears you're asking mainly about using LR primers in pistols. But I took the advice of some the fellows here and tried using LP primers in low pressure 30/40 Krag loads. Because the cups were thinner, and the overall height of the primer thinner, I often got pierced primers in my Krags. They weren't really pierced, I think that what was happening is they couldn't stretch back to the boltface with a firing pin sticking in the middle of them as the LR could. They tore at the firing pin indent as the rest of the primer stretched back to the boltface. Since the loads were relatively moderate pressure, no harm done. This was during the primer shortage or I wouldn't have tried it at all. If one was to use primer condition as a pressure indicator, using LR primers in a pistol might have you going over the cartridges safe working pressure before any signs were apparent.

[DIRT Farmer]

I think any serious shooter who want to get the last bit of research on reducing the group has tried large pistol primers in rifle where pressure and fireing pin allows. In some rifles and loads there will be results that are very noitceable, both ways. Look at the pressures in load manuals for some of the pistols. Some of them are well above pressures that CB loads generate. I have found use of LP primers help avoid shoulder set back in light gallery loads with out drilling flash holes that can lead to a very unsafe condition if one small screwup happens.

[303Guy]

The theory is that the less powerful pistol primer doesn't dislodge the boolit from the case mouth before the powder lights up. In the hornet (which uses small rifle primers), better powder burn has been reported with the use of small pistol primers. In that cartridge crimping is reported to improve burn consistency and so does the use of SP primers. I used a heavy bullet with no case neck grip at all and a heavy powder charge. That applies largely to Lil'Gun powder.

I used to interchange LR and LP primers in my 44mag but that had enough hammer blow to set off the LR primer. Seating depth was no issue for me, neither was pressure but I did work up with the LR's. My load was mild enough to absorb any difference the primer might have made. I could not tell the difference in accuracy. The terrible trigger pull would have negated any difference anyway!

[NickSS]

I have used LP primers for sometime now for black powder loads in my BPCR ammo. For some reason unknown to me this has resulted in smaller groups at longer ranges. I one time loaded up 50 rounds of 45=70 with LP primers and AA 5744 and got terrible results with handfires and inconsistent ignition so that the ammo was a total bust and I pulled down most of it to save the components. But they work good with BP.

[eyehawk]

I will try some large rifle primers in 45 acp to see if I can detect any noticeable difference.

Thanks again for the input.

AJ

[tomme boy]

Be careful. They may slam fire on you!

[Skitzen]

What about using magnum pistol primers in .30-30 cases with the "magic" 10 to 12 gr's of Unique behind 159gr (that's what my RCBS mould is dropping plus the weight of a Hornady GC on the back) FP's? Anybody think I may have a problem once they're in the magazine tube of my '94 Winchester?

[kliff]

What about using magnum pistol primers in .30-30 cases with the "magic" 10 to 12 gr's of Unique behind 159gr (that's what my RCBS mould is dropping plus the weight of a Hornady GC on the back) FP's? Anybody think I may have a problem once they're in the magazine tube of my '94 Winchester?

I was thinking almost the same thing, 'cept I was perusing the idea of LP primers(NON-magnum) and 8.5 g of unique under a 150g boolit.

So what about it guys? Anyone used an LPP with 8.5-10.0g of unique, 150 g boolit, in a 30/30? Hmmmmmm?:CastBoolitsisbest:

[Rocky Raab]

I have tried CCI 350 (LP Mag) primers in my Savage 340 .30-30 with less than satisfactory results. Often, the first firing pin strike would not fire the primer; I suspect I had not gotten the anvil fully bottomed. Second strikes would usually fire but gave wide velocity spreads, so something was still wrong.

I only tried it because I have 500 or so of the 350s and not much use for them in any of my regular revolver rounds. At least they'll keep....

[stronghorn]

The difference in height between WW Rifle and WW Large Pistol is the rifle being
.008 taller. Enough to where if loaded for a revolver they will hang up the cylinder. Ask me how I know this..That is why I mark the end-flaps with an LP or an RP since the boxes are the same color. And seperate them on the shelf too. Use the right prmer for the job, don't try to re-invent the wheel.

[nanuk]

the lighter ignition of the pistol primers, I think is one of the reasons some have tried a piece of newsprint disk under the primer. to "lessen" the initial fire of the primer.

I have read reports where it does help accuracy with BP, and lighter smokeless loads with slow pistol powders...

I wish I had saved some of those articles that discussed that issue.

[Slinger]

No!!!!!!!!!!!!

[tarbe]

Came across this discussion and it reminded me of how necessity can become the mother of invention when it comes to us crafting ammo to keep us shooting.

I was in college and understandably poor. I came across a great deal on Remington 2 1/2 primers (LP) at a store going out of business. IIRC, I got them for something like $5/1,000 (this was around 1980).

I started shooting Hi-Power silhouette while still in school, and ended up using those LP primers in my .308 during practice and matches. I was using a moderate load of IMR 4895 and a 180gr Sierra BT.

Here is the thing...I chronographed and shot for accuracy identical loads with CCI 200 and the Rem 2 1/2. The loads with the Rem 2 1/2 had lower standard deviation and were more accurate than the CCI 200 sparked loads.

Sometimes you just never know until you experiment some.

I would not have tried the LP primers if I was going for anywhere near max velocity, mostly due to the thinner cups.

Thought I would add to this discussion in light of the difficulty many are having now in finding the exactly "correct" components to load their ammo. Sometimes you have to be a little creative....just don't sacrifice safety!

[John Boy]

BPCR reloads with smokeless powder need the LR primer specific to the powder type.
Flip side: BPCR reloads with black powder can use LP primers instead of LR. BP powder columns need the least amount of brisance to deflagurate properly ... where as smokeless powder by type needs the greatest amount of brisance to explode properly

[Garyshome]

Just checking because I cannot fond LPP's at all.

[truckjohn]

Rifle primers in a pistol is asking for issues chambering because they are too long... AND issues with too much blast on ignition causing high pressures... LP primers in a rifle is asking for blown primers unless you are shooting very reduced loads...

thanks

[HARRYMPOPE]

i shoot LP primers in all of my cast Military 30's(30-06,7.62 x 54 etc..) with loads of 2400 and Unique or other medium to fast powders.I don't shoot much above 1600 fps and haven't yet blown a primer or had delayed ignition(no fillers ever used).This is over a 20 year stretch BTW.I accidentally loaded LR in a 44 mag once and had no issues in my Super BH.

[jackmanuk]

i use 16 grains of 2400 behind a 210 grain cast round in my 44 mag , since i use the same 16 grain of 2400 load in my 7.62x39 behind a 110 grain fmj the pressure should be less , so using a LP primer should be fine as long as the firing pin protrudes enough

[tew45]

I have found very little difference but I normally use the correct primer. I have a falling block works rifle I built many years ago and the hammer had a weak fall no matter how many different springs I made. So I use pistol primers in it with good results.

[17nut]

215790
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[FromTheWoods]

Wow. Old thread given new life.

Rifle primers will sit higher (protrude above the base of the brass) when used in handgun brass. I don't know if that applies to all handgun brass, but it does apply to enough to not take chances loading your cartridges with the wrong primers.

If the handgun is a revolver, and you've loaded it with the taller rifle primers, in turning the cylinder, the primers will likely drag or get stuck against the recoil shield. Therefore, your gun is jammed. Were you to force the cylinder to continue turning, you might get a nasty explosion.

[bob208]

its all in the name large pistol is for pistol larger rifle is for rifle. this mixing and matching components other then listedin the manuals is asking for troubles.

[donald duck]

I have a full box, old wooden box. of large pistol primers. Is is possible and safe to use them in cast 30-30 loads and 7-30 loads in my Contender barrles??? These are not hot loads but light loads with 120 grain and 115 grain cast bullets. Thanks