Using Large Pistol Primers in Place of Large Rifle Primers (308 Win)

[MUSTANG]

Got in a Range day this morning. First time this year. The day was a Challenge.


Gathered all the range equipment together an loaded into the Jeep after shoveling snow off it and from around it. Jeep has sit for 3 months “Snowed In”. Most years I drive it once or twice a week all through winter; not this year. Battery was dead, so go to the Tractor to get it to “Jump Start” the Jeep. Tractor has one front wheel that starts to roll; then binds. It only turns 270 degrees instead of 360 degrees – I suspect it has a 1/moon key or some other piece that has broken/shifted; or worse yet an axle problem. Oh well, 3 to 6 weeks and I’ll take it to the John Deere Dealer. Was able to jump the jeep from the Car, but battery is gone/dead/dead. Guess that week of minus 32 degrees temps killed it since I did not have a Trickle Charger on the battery. Started driving to Costco for a new battery and the steering felt funny; so stopped, got out, and looked up front on the Jeep; One front tire is Flat. Get the Jack out and put on a spare. At Costco buy a new Battery and install. Drop by and have the Tire Store repair the flat. Then on to the range. Once there – Discovered I left my sunglasses at home; Range is covered in ~ 20 Inches of snow so some difficulty in shooting caused by brightness due to snow reflection

A couple of months ago I started wondering about using Large Magnum Pistol Primers in place of Large Rifle Primers since I have not been able to buy LR’s for more than 2 years. The Large Rifle Primer is “Taller” (about .128 inches tall) compared to the Large Pistol primer (about .120 inches). Both primers were seated into Federal .308 Win Brass (shot multiple times), fully seated to bottom pf primer pockets. Visually obvious that Large Pistol Primers were seated deeper than the Large Rifle Primers. The obvious concern will be if the Firing Pin in a particular rifle will have sufficient travel to ignite the seated Large Pistol Primers.

I wanted full house loads to compare the Large Rifle and Large Magnum Pistol primers in this effort. Rounds were fired in a Remington 700. Load data follows:

The first test was with the Large Rifle Primers:

Rifle: Remington 700 ADL Varmint .308
Barrel Twist: 1 in 12

Wind: 5

Temp: 35 degrees F.

Bullet: 175 Grain, Flat Base 8S nose swaged from 5/16 Copper Tubing
Ballistic Coefficient: 0.546
Brinnel Hardness (Core): 9.8
Core Alloy: 96% Lead, 3% Antimony, 1% Tin
Powder: IMR4895 42 Grains
Primer: Remington 9 ½ Large Rifle Primer
Case: Remington .308 Winchester
OAL: 2.800 Inches
Distance: 100 Yards.

10 Shot Group Size: 2 & 1/8 Inches

311666

The second test was with the Large Magnum Pistol Primers:

Rifle: Remington 700 ADL Varmint .308
Barrel Twist: 1 in 12

Wind: 5

Temp: 35 degrees F.

Bullet: 175 Grain, Flat Base 8S nose swaged from 5/16 Copper Tubing
Ballistic Coefficient: 0.546
Brinnel Hardness (Core): 9.8
Core Alloy: 96% Lead, 3% Antimony, 1% Tin
Powder: IMR4895 42 Grains
Primer: Federal GM155M, Gold Medal Large Magnum Pistol Match Primers
Case: Remington .308 Winchester
OAL: 2.800 Inches
Distance: 100 Yards.

10 Shot Group Size: 2 & 1/4 Inches

311665

Observations:

1. Groups for each of the two strings were almost identical in size.
2. No Flattening or piercing of Primers observed in the Pistol Primers.
3. ALL Pistol Primers did back up even to the base of the case/bolt face when fired.
4. I did not set up the Chronograph for these evaluations today because of all the Vehicle delays earlier. There was no apparent differences in velocity/recoil/ignition between the two test groups.

Assessment:

I would use the Large Pistol Magnum Primers in this Particular Remington 700 .308 Winchester if I did not have Large Rifle Primers available; even with full loads and heavier bullets. For Magnum Rifles, very heavy bullets with full loads, etc… there could still be issues. Warrants further testing with other rifles and calibers should Large Rifle Primers be unavailable in the next 6 to 24 months.

Anyone else done any tests using Large Pistol Primers as an alternative to Large Rifle Primers? Your results?

[Ben]

I use large pistol primers in mild cast rifle loads quite often.
I never seat them deep.
I seat them level.
No problems.

[Shuz]

I use large pistol primers in place of large rifle primers in cast boolit loads.

[Winger Ed.]

You might get a false high pressure sign, but with mild-ish loads, it should be OK.

[wesson357]

I've used large pistol primers with mild cast loads in a variety of milsurp rifles. I was fine with most of them, but, in a MAS36 and a swedish mauser, I got a few pin hole pierced primers. (very minimal, could be missed easily)
I would guess, it's a combinaison of firing pin geometry/ force / firing pin hole. Anyway, after 4-5 pierced primers, I've noticed firing pin erosion, I had to reshape/polish the firing pin a few thousand "so, be very aware of that.

[jdgabbard]

I've used large rifle primers in 45acp without issues before. I've also used Large Pistol Magnum primers in 45acp. But never used large pistol, regular or magnum, in large rifle. I guess that is something to test since I'm getting ready to start working up hunting loads pretty soon. Thanks for sharing.

[Pirate69]

Just for kicks, I ran your load through QuickLoad. The bullet used was a 175 g Nosler CC HPBT at a COL of 2.80". At 35F, the predicted chamber pressure is 46,548 psi. Not sure of your barrel length. If 22" then predicted muzzle velocity is 2497 fps. If 24", then 2548 fps.

[Hanzy4200]

Wouldn't call it unsafe, but definitely not optimal. Could easily get a pierced or blown out primer. Big no no in a auto loader. Would likely get slam fire issues due to the thinner cup.

[Larry Gibson]

Just for kicks, I ran your load through QuickLoad. The bullet used was a 175 g Nosler CC HPBT at a COL of 2.80". At 35F, the predicted chamber pressure is 46,548 psi. Not sure of your barrel length. If 22" then predicted muzzle velocity is 2497 fps. If 24", then 2548 fps.

Interesting that QL gave such a low psi. my test of 20 shots of XM118 [ LC match cases, 174 FMJBT, 41.6 gr IMR4895] gave 61,500 psi average for two 10 shot tests. Test ambient temperature was 68 degrees. My own equivalent load with 41 gr IMR4895 under a 175 MK in LC Match cases runs 61,500 psi.

[Pirate69]

Interesting that QL gave such a low psi. my test of 20 shots of XM118 [ LC match cases, 174 FMJBT, 41.6 gr IMR4895] gave 61,500 psi average for two 10 shot tests. Test ambient temperature was 68 degrees. My own equivalent load with 41 gr IMR4895 under a 175 MK in LC Match cases runs 61,500 psi.

I think I can clear this up. The test load used a Remington 308 case (assume 56 grains water capacity) fired at an ambient temperature of 35F. That is the data that I presented. If this load was fired at an ambient temperature of 68F, then QL predicts a chamber pressure of 49,407 psi.

I noted your cases are LC cases (assume 52 grains of water capacity). If LC cases are used, with a COAL of 2.80", and fired at 35F, a chamber pressure of 55,526 psi is predicted. The same LC case load fired at 68F predicts a chamber pressure of 59,027 psi.

Your response is very beneficial. It helps to give some confidence to the QL predictions. Were your loads shorter than 2.80"? As well, the water case capacities are an assumption which may be slightly different from the actual capacities of the commercial and military cases.

[jaysouth]

My standard "range fun" load in 30-30 is a 150 gr. cast powdercoated bullet over 8.3 grs. BR-5 sparked off by a Winchester Large PISTOL primer. It is 2 MOA in my Encore and 3 MOA in my marlin. Nary a bobble.

[MUSTANG]

Went back to the Range this morning. I ran 5 rounds of .308 Winchester - 150 Grain Swaged Bullets I had on Hand. These used the Federal GM155M, Gold Medal Large Magnum Pistol Match Primers once again in the 308 Winchester case. 46 Grains of BLC-2 Powder. Bright Sunshine over snow; so a bit of Eye Problem shooting today. 5 round, 1 and 3/8 inch group. Average Velocity for 5 rounds was 2698 Feet Per Second using the Large Rifle Primers. That bottom shot in the group is actually two holes, for a total of five holes on the Target.

312001

Shot a comparable 5 rounds with Remington 9 1/2 primers - but the Battery went dead on the Chronograph, so I was unable to get a comparison of velocities with a Large Rifle Primer equivalent load.

[truckjohn]

The primer cups on pistol primers are considerably softer/thinner than rifle primers. I had significant issues with blown primers every time I've swapped them on full power loads.

I haven't tried switching them on low power cast loads. I would guess they were fine. Since I have plenty of rifle primers, I don't use pistol primers in them anymore.

[MUSTANG]

For the loads/powder used in post #1 and Post #12 there were NO pressure signs, and NO signs of piercing primers.

Most of us do not have the equipment to actually measure pressures like Larry Gibson has (Post #9 above); but - Using the Richard Lee Modern Reloading 2nd Edition Manual as a reference the following estimated pressures for each load. My approximated pressures from the reloading manual are a few thousand pounds below his actual measured for a lesser load.

175 Grain, 42 Grains IMR4895 - Approximately 56,000 PSI.
150 Grain, 46 Grains BLC-2 - Approximately 58,000 PSI.

I am comfortable with these two above loads using the Large Pistol Primers in a .308 Win case; given no pressure signs. When the "Ice Break Up" completes in next week or so; I mayget one of the M1a's out of the safe and try them in a semi-auto rifle.

My driving force for personally trying Large Pistol primers in the .308 Win cases is that I have not seen a Large Rifle Primer available for over two years. Yet, I have periodically been able to pick up the Large Pistol primers in limits of 200 each time I could buy them. I have a "Stash" of Large Rifle Primers; but it is slowly diminishing. My thoughts are to begin to limit the Large Rifle Primer use to 300 Win Mag and other Higher Pressure load applications.

[schutzen-jager]

been using rifle primers for pistols for years with no problems, but i would hesitate to use pistol primers in rifle cartridges -

[TurnipEaterDown]

I haven't really seen much info on primers definitively traced to primer manufacturers on relative cup thickness, cup hardness, or priming material volume and resulting temperature of gas produced.
There is likely good business reason (competitiveness) on some of this -- why would a manufacturer tell a competitor about priming mix details, if there really is an advantage to be gained by changing the priming mix?

Also, limited testing in an non controlled, non DOE nature tells you limited things, and may be confounding.

Flip side, multiple people know things that are helpful, if incomplete.

For instance: Large Pistol primers can be successfully used in pistols that generate 40-50,000 psi. Some specialty round load data in this pressure range is even issued w/ warning against using LR primers in the application. The Linebaugh cartridges were this way, and I know first hand they work very well w/ pistol primers.

Firing pin shape, condition & fit to bolt/recoil plate/breech block do matter as to what pressure is containable. Headspace clearance also comes into play.

Tests have been run by people in limited context that have shown that in some conditions (at least) there are pistol primers that provide an increase in ignition capability versus some rifle primers. I have posted result myself previously of 13 different primers in one cartridge & one loading condition. In that test, a pistol primer generated the second highest peak pressure, with the second shortest rise time in the pressure curve (as would be expected).

I have also recently seen a thread on this site that Ginex small pistol primers do have a cup thicker than some brand small rifle primers.

There is also the undeniable fact that a certain critical minimum threshold exists for primer energy and temperature being required to initiate self sustaining combustion in a given cartridge / powder type & charge / bullet combination.
Using "too much" primer can cause issues that may or may not be evident in gross observation (abnormal reduction in ignition time, faster than desired pressure rise, bullet movement from primer force before powder combustion commences, etc.), and "too weak" of a primer may contribute to hazardous pressure characteristics (S.E.E.).

I think there are just too many factors that exist to make a blanket statement "can" or "should", "can't" or "shouldn't".

About the only thing that seems firm is that the higher end of current metallic cartridge peak pressures, and loads for bottleneck cartridges with higher weight powder charges w/ heavily deterred powders, really are best supported w/ primers classified as "rifle".

[dondiego]

I have used pistol primers in rifle rounds at pistol pressures with no problems.......

[Larry Gibson]

Mustang

It is my understanding [I could be wrong and if so please cite the reference?] tha the data in Lee's manual does not come from his own testing but rather is plagiarized from multiple sources. Thus, I have had reservations about the published pressures in his manual. Especially so when if also states "approximately"..... it would be nice to know where or how that "approximation" was obtained.

I wasn't questioning your use of LPM primers in the rifle as many such primers have the same cup thickness (same material probably) as LR primers. I've read several articles now stating the primer cups of all primers are essentially the same as they are of the same material(?). What i questioned was the quite low pressures you got with QL.

[MUSTANG]

Larry:

The Extrapolation was made by me. The Lee Manual lists a pressure for the "Max Load"; the charges I used were not Maximum loads listed in the Lee Manual. A little math "Extrapolation" to get a guesstimate of the Pressure level on my part; lower than the manual listed because of lower powder charge.

I do not have Quick Load. It was another person commenting on the Quick Load they ran.

I had previously measured the thickness of previously fired LR and LP primers I used in this effort. They appeared to be about the same thickness using a dial caliper; so thought it would be low probability of a pierced primer. I was more concerned with sufficient Firing Pin Travel to ignite the deeper seated Large Pistol Primer. Moving to the M1a in a few weeks after the "Melt Off" when I will go to my primary Spring/Summer/Fall Range - that should give some clarification (Sample of Bolt and Semi Auto) application of the LP primer in .308 shot in the M1a.

Should I find that the M1a (or other rifles in the future) show a "Fail to Fire" due to the firing pin not sufficiently engaging the deeper seated Large Pistol Primers; I was thinking that a piece of onion skin paper might form a shim between the Large Pistol Primer and the bottom of the Brass Case pocket; giving a higher seated primer. I have used the Onion Skin paper as a primer mixture cover between the Anvil and Primer mixture in some of the experimenting I have done with "Reloading Primers". The onion skin in those experiments was totally consumed on firing; of course questions of micro-second delays in ignition or slower ignitions rates could always creep up in that experiment/evaluation.

Thanks for your comments.

[Pirate69]

It was me that provided the low, predicted, chamber pressure data for the load as given. The load used a Remington 308 case (assume 56 grains water capacity) fired at an ambient temperature of 35F. That is the data that I presented. If this load was fired at an ambient temperature of 68F, then QL predicts a chamber pressure of 49,407 psi. I failed to point out, at that time, that this load would potentially have a much higher chamber pressure at higher temperatures.

For Larry's load, if LC cases are used, with a COAL of 2.80", and fired at 35F, a chamber pressure of 55,526 psi is predicted. The same LC case load fired at 68F predicts a chamber pressure of 59,027 psi. LC brass assumed to have a 52 grains water capacity.

Needless to say, additional increases in temperature will predict higher chamber pressures. As well, the case capacity of the brass can greatly affect the generated chamber pressure. Personally, I do not have any feel for whether or not LP brass will contain pressures greater than the pressures they were intended to see.

[Larry Gibson]

MUSTANG

In todays climate of primer shortages the onion skin under the primer amy prove to be a viable solution if the primers get pierced because of set back in the pockets. Good idea.

[Larry Gibson]

Pirate69

Tes, the ambiant temperature conditions do indeed affect the pressure, especially with most of the older powders that are/were more temp sensitive.

[VariableRecall]

Pirate69

Tes, the ambiant temperature conditions do indeed affect the pressure, especially with most of the older powders that are/were more temp sensitive.

Another thing to consider is that I am also limited in reliability due to my brass. The best I could find is a scattering of mystery brass. Perhaps some pieces of worn out brass also have a deeper primer pocket, perhaps making an already difficult to set off primer even more so?

Also, the temperature was a bit cooler than the last time I had used this combination of brass, powder, and primers. However, I'd assume that once the barrel gets a bit hot, the whole temperature issue cancels out to some degree.

[Kraschenbirn]

I've been watching this thread (along with one or two others on the same general topic) and decided to toss in my two cents worth.

Like Mustang, some time ago, I began reserving my stock of LR primers for full-house loads with jacketed bullets and substituting LPs. Results have been pretty much the same as his; no significant differences in MV or group size of my cast boolit loads. Now, I must admit that I haven't test-fired all of the rifle calibers I load and shoot but, for the ones I have...like .308, 8x57, .243 Win, .38-55, and .30-40 Krag...no change observed. Matter of fact, groups from the .243 may have been slightly improved.

So far as seating depth, I seat full-depth without issue. Out of several hundred rounds fired, not a single FTF and I can recall only two pierced primers...both in the same Yugo M48 using brass formed from GI 30-06. My primers, by the way, are Win. WLP labeled 'For Standard or Magnum Pistol Load' and, as such, should be good for anything up to 36K PSI - the SAAMI max. for .44 Mag.

Bill