The story behind small primers in .45 ACP

[Blacksmith]

A friend asked me about the whys for using them and how to reload .45 ACP cases that use small primers and since I was interested I did some research.

The thumbnail version is the .45 ACP with small primers were made to reduce lead on firing ranges by using primers that use DDNP (you can read the long name in the paper) this is also sometimes referred to as Diazole or Dinol, instead of Lead Styphnate primers commonly used. In an effort to make these special primers work other changes have been made in such things as flash hole diameter and crimp strength. I suspect special powders and other things like neck tension may also be employed but these would be less obvious.

Currently these primers are not widely available and although the major ammunition makers are making ammunition with them they are not selling the components separately. These primers have different characteristics from conventional primers including blast pressure waves and smaller flame footprint which result in less reliable ignition. So unless you want to start from zero and try various conventional primers and powders with new size primer pocket flash hole and work up loads with no published data my recommendation is skip it. Trade the brass or sell it as scrap.

In researching I turned up this technical article that was published in WSTIAC Journal in 2011 which covers the subject pretty well:
http://wstiac.alionscience.com/pdf/WQV11N2_ART01.pdf

Comparing Blast Pressure Variations of Lead Styphnate Based and Diazodinitrophenol Based Primers

Here is the abstract:

This article describes the blast pressure waves produced by detonation of both lead styphnate and diazodinitrophenol (DDNP) based firearms primers measured with a high-speed pressure transducer located at the muzzle of a rifle (without powder or bullet). These primer blast waves emerging from the muzzle have a pressure-time profile resembling free field blast pressure waves. The lead based primers in this study had peak blast pressure variations (standard deviations from the mean) of 5.0-11.3%. In contrast, lead-free DDNP-based primers had standard deviations of the peak blast pressure of 8.2-25.0%. Combined with smaller blast waves, these large variations in peak blast pressure led to delayed ignition and failure to fire in brief field tests.

Yes it can be done, if you want to go right ahead, I am just trying to put some facts out there so people can make better choices. Your mileage may vary!

[higgins]

I don't see the problem if one is using standard lead-based small pistol primers with powder and bullet combinations that have previously produced safe loads with lead-based large pistol primers. I don't have to deal with the problems SP .45acp cases cause in progressive presses, but I like the flexibility of being able to load .45acp with either large or small primers.

[dragon813gt]

You do realize the people have been loading it with no issues for awhile now. I prefer the small since 45acp is the only cartridge I reload that takes a LPP. I am able to stock fewer different components. Once my current stock of LPPs is exhausted I should have more than enough SPP brass to keep me going.


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[tcbnick]

Thank you Blacksmith
I asked that ? awile back, now I have an answer
Thanks Nick

[Blacksmith]

tcbnick
You are welcome.

[Iowa Fox]

I am really surprised the industry went this route on a 100 year old design considering the number of progessive presses. Knowing they exist and being causious I had a small primer case get mixed in with large while pushing the production rate on the Dillon. I'm sure I'm not the first and only guy.

[MikeS]

Iowa Fox: the 'industry' doesn't care about reloaders when they make a change to the case, they only care that the originally loaded cartridge goes BANG when the trigger is pulled. Personally I like the small primer 45ACP brass for the most part. One thing I've noticed now that I've reloaded some of it more than once, and that is that the primer pockets seem to stay cleaner than the large primer pockets do. At first I figured that was because of the original primers being the unleaded variety, but now I've reloaded some with wolf small pistol primers (and I doubt they're lead free) and notice that even when firing the wolf primers that there's less carbon crud in the primer pocket. I don't know if it's due to having less priming compound, so it burns more completely, or if it's some other reason, all I know is that my large primer brass NEEDS to have the pockets cleaned each time I reload them, but the small primer brass really doesn't. So far I've been cleaning them, just because that's how I always do it, but I tried loading some without cleaning the primer pocket first, and the primers seated the same in cleaned or uncleaned primer pockets. The last time I was at the range I did notice something that makes me want to use the large primer brass. I was shooting some 45ACPs in a single action revolver, and occasionally the firing pin wouldn't hit the center of the primer, but rather on the edge of it, and so the round didn't fire. If it had been large primer brass the cartridge would have gone off, but with the small primer it was right at the edge, the firing pin actually hit half on the primer, half on the brass. I'm not sure why it was doing this, unless the cylinder wasn't locked up correctly, as the primer strike should always be in the same place on the primer.

[TNFrank]

Not had any issues with SP 45acp brass, in fact it'd be nice if all my 45acp was small primer since the only other ctg. I load right now is 38spl which take a small primer. That way I'd only need to keep one primer on hand to load both. I have about 300 rounds of SP 45acp and 750 of LP 45acp so I had to go out and buy some LP Primers, just adds more expense to my reloading efforts.
I load on a single stage press and sort all my brass out by headstamp anyway so it's not hard to sort out SP from LP. I Can see how someone who doesn't take the time to sort and loads on a progressive press would have fits with SP 45acp brass getting into his brass supply but for most of us it's just another choice that we have and choice is never a bad thing.

[MtGun44]

Interesting issues with these no-lead primers. It would seem that these new primers are
not destined to produce particularly accurate ammo until they are improved in consistency
quite a bit.

As to the small primer brass - it is a PITA for someone with 4000 large primer cases in .45 ACP
because it jams up the Dillon and requires an exta sorting step of my brass now,
before I can load.

Bill

[gew98]

I pitch mine in the scrap bin or give it away...whichever comes first. The CCI and Speer SP 45 brass looks cheezy as all hell compared to RP and Win brass , and just as often the Federal SP brass looks thin and concave at the base as well...garbage.

[beagle]

I like the small pocket variety and have some and have loaded them quite extensively.

I stumbled on to a benefit while working on the article about heavy bullets in .45 ACP cases for the Blackhawk convertible.

I had a few bullets to test and ran short of primed cases with large pockets that I already had primed. I had a box of the small pockets and just for grins, I loaded a few and since I was chronographing I thought I'd see how velocity between the two was affected. Now, that has been a while and I don't recall the chronoghraph results but as I recall the velocity was comparable but the pressure signs were significanly lower with the SP primers and the cases resized easier.

Too bad we don'thave an easy method to measure pressures these days.

The fact that both the .30 American and .454 Casual as well as one of the high end ammunition manufacturers uses small pockets in .45/70 brass leads me to beleive that we're using a lot of overkill in powder ignition in ammunition. Remember the .357 Magnum started out using large pistol primers and then was changed to small way back along the line./beagle

[MikeS]

I suspect back in the day when there were both smokeless primers and BP primers that the size of the primer was more important than it is now. I could be wrong, and I haven't a clue what the differences are between the primers for the different types of powder are.


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[44man]

I don't think many of our primers have lead anymore. Not sure but if anyone knows for sure, let me know.
Anyway, I have posted many times that going to the SP primer for the ACP in revolvers has cut groups by 2/3's. LP primers move boolits before good ignition. The case is too small. We even had better accuracy from the 1911.
Working with a friends S&W was driving us nuts, spray and pray no matter what I loaded. I even went to a good roll crimp. I sat and stared at the brass. I made bushings to take them to a SP primer and results were immediate.
Then he found SP primer brass on line and is fat and happy now.
No, not crazy special primers.

[3006guns]

I pitch mine in the scrap bin or give it away...whichever comes first. The CCI and Speer SP 45 brass looks cheezy as all hell compared to RP and Win brass , and just as often the Federal SP brass looks thin and concave at the base as well...garbage.

I agree.....in fact I noticed the Federal brass (range pickups) was noticeably SHORTER than the rest of the cases. Every CCI case seemed to have an undersize primer pocket also, so they never got loaded. All of the Winchester, Remington and occasional Peters cases were easily loaded.

Blacksmith, thanks for the info on the small primers.....I never could find an answer as to "why" and now I know. I'll stick with the larger primer pockets myself.

[Alan in Vermont]

I don't have any SP brass now but I wouldn't hesitate to try some. With that thought, if any of you guys want to get rid of any I'd be glad to pay shipping on it.

[wv109323]

44Man,
I am interested in the group sizes before and after SP especially in the 1911. What bullet was you using and what load?
I shoot Bullseye pistol and would be interested in your load development. Could you share.

[9.3X62AL]

I agree.....in fact I noticed the Federal brass (range pickups) was noticeably SHORTER than the rest of the cases. Every CCI case seemed to have an undersize primer pocket also, so they never got loaded. All of the Winchester, Remington and occasional Peters cases were easily loaded.

Blacksmith, thanks for the info on the small primers.....I never could find an answer as to "why" and now I know. I'll stick with the larger primer pockets myself.

My thoughts on this matter were that ammo makers may have been trying to make one parent case work for both 45 GAP and 45 ACP, hence the small primer. I haven't tried the SPP cases in 45 ACP, and likely won't--though I acknowledge the potential mentioned above concerning "over-ignition".

[felix]

I will back Jim (44man) and Beagle (John) up 100 percent. However, the primer diameter is not the problem per se. Ignition comes from the wave front produced by the primer, and NOT the flame as most believe. The addition of nitroglycerin to powder will increase the sensitivity of the load dramatically making deterrents necessary to adjust the rate of BURN. No deterrents, a guaranteed SEE condition with every shot. So, nothing new. Primer and powder must produce a consistent acceleration curve for the boolit-gun combo on hand. ... felix

[tomme boy]

I still say it is a cost factor. They could save countless hours on setup time by staying with the small primer. I don't like it, but it is a savings for the companies that make the ammo. Saving time in setup is making way more $ for the companies. Less primers to have on hand for that style. Piece count is all that matters.

[Bullet Caster]

I've never even seen a SP .45acp case. I know they're out there from the posts I've read on this forum. I always sort my brass by headstamp and would weed out any SP cases. Since this cartridge was initially designed as a LP primed case I don't think I'd want to change a nearly centry old design. I'll just stick with the LP primer cases. I already have to have large pistol primers for .45 Colt so I'd only want LP primer cases. The only small pistol primers I use are for the 9mm. And I'm glad I only use one rifle primer and that is large. BC

[DRNurse1]

Rumor has it that small rifle primers are the same diameter and height as small pistol primers. If this is the case, maybe it provides another reason to convert to small primers in the 45ACP cartridge: one can reload more cartridges with small primer pockets.

As far as reliability and quality, both will shake out as demand for the cases changes.

Right now, I sort out my field brass and give the SPP 45 ACP brass to a friend who uses them exclusively. I also catch my brass in Bulls Eye Competition so I do not have to sort it. At some point, I will likely reload the SPP 45 and then try to figure out a good way to manage that. Hopefully you all can solve this issue before I encounter it.

Rock and roll, keep the lead headed down range.

DRNurse1

[kappy]

When I get a piece of .45ACP brass with a small primer pocket, I get so incensed, I just toss it in the garbage.

[44man]

44Man,
I am interested in the group sizes before and after SP especially in the 1911. What bullet was you using and what load?
I shoot Bullseye pistol and would be interested in your load development. Could you share.
The revolver was crazy with 6" patterns at 25 yards from the bench. I got it to an inch easy with the primer change. We used cast but my friend has the info for the loads, I will see if I can get them for you. I do not own an ACP.
The 1911 is one I built for him long ago and would do 1/2" at 30 yards. It actually shot better with the SP primer. The auto is not as touchy as the revolver and can do well with the LP primer. The difference in an auto is so small it can be ignored but in a revolver, it can be a huge difference. It is the same reason I use a standard primer in the .44 mag.
Let me see if he will answer E mail with loads. I have not heard from him, he was supposed to come and shoot.

[JIMinPHX]

I used some of the Small Primer .45ACP brass when the big primer shortage hit, right after BO got elected. I used WSP primers with the same Bullseye load data that I had used with WLP primers in the past. Everything still shot fine.

These days, the only place that I see the SP .45 cases coming from is the "lead free" or "green" ammo that costs about 3 times what it should. In days gone by, some of the foreign military surplus .45 ammo came in with small primer pockets too.

[dragon813gt]

The SP cases are in every box of Federal at Wal-Mart(and every other store that sells it). I'm starting to get more SP range pickups. Used to never get any. Sometimes it's in the range of 65-75%.


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[375RUGER]

I just found out yesterday while teaching a young fella how to load some 45, that I've been picking up SP .45s at the range. PITA now I have to sort out what I have on hand. From now on though I'll sort right after I pick it up.

[tinsnips]

I just came from a store called Runnings an all there Federal and Blazer Brass 45acp had small primers . I wish they would just leave stuff alone .

[Alan in Vermont]

I'm going to have some to try out from a PIF I snagged. Will be interesting at the very least. I want to build up stash of it so I can load a few hundred rounds to take to a pig roast this fall. There is a bunch of shooting done there but it's all on grass and a lot of brass gets lost. If I don't care for how it loads/shoots I won't feel bad about not retrieving it all.

[44man]

44Man,
I am interested in the group sizes before and after SP especially in the 1911. What bullet was you using and what load?
I shoot Bullseye pistol and would be interested in your load development. Could you share.
We went from 3" and even 6" at times, down to 1" at 25 yards with the revolver.
I do not own a .45 ACP and have E mailed my friend for the loads and will post as soon as he reads it. He never seems to read mail.
The 1911 only showed a small improvement, the revolver was the worst and showed a vast benefit.
I will get back.

[9.3X62AL]

I'm prepared to believe that 45 ACP cases ignited by SPPs have better accuracy potential--a couple friends with GOOD 45 ACP pistols saw immediate improvements in accuracy and ballistic consistency with their use.

Will I make a wholesale shift to that case type? Doubtful, unless component and ammo makers shift completely to SPP pockets in 45 ACP brass.

[44man]

OK, John sent the loads. He uses a 255 gr boolit, 5 gr of Unique and a SP primer.
Nothing real special. I do not know the boolit but I will find out.

[Boneguru]

Just returned form the range today and the armorer handed out the green frangible 45 ACP with the small primer. Small primer was the first thing I noticed since they are packaged primer up. At first I thought i had grabbed the 40 S&W ammo by mistake.
The projectile was interesting, the accuracy at 25 yds was not as good as the ball that we normally use for training. I will try to load some of the brass if i ever get any to work with, such a low pressure round that there is room to play. the BBL was noticably more filthy though.... any way no Fail to Feed Fail to Fire issues, and alongside the ball ammo there was no difference in the ammo, just accuracy which I attribute to the projectile which didn't even look concentric to the naked eye!

[Frank46]

I remember when the winchester NT primed ammunition came out. Everyone that I knew scrounged 45acp brass and we were curious about the rather large flash hole. General consensus was just load them with standard large pistol primers. Never had any complaints about accuracy. I have a 40mm ammo can full of mostly rem and win brass and a couple cardboard boxes of speer and sellier & bellot brass. I like to keep the S&B brass separate as sometimes I'll have to run a primer pocket reamer through some and once that is done they load just like normal brass. What I like to do is deprime on a single stage press using a universal de capping dies, then clean the pockets, tumble (nothing like a tumbler full of shiney brass) and prime separately before they go through the dillon. easier with multiple inspections to weed out those that are bad. Frank

[Smiddywesson]

Correct me if I', mistaken, but .454 Casull uses small RIFLE primers. The small primers were purportedly used to make the .454 case stronger. More pressure usually means more velocity, so I don't see how you are getting the same velocity with the small .45 primers, other testing I've read about, see Starline brass article on their site, are reporting @100 fps more velocity and a cleaner burn with the original large primers. A lot of forum posts concern dirty results, and when they reload around the problem by changing powders, poorer performance. Frankly, there's a lot of hype out there about "Today's modern ____ technology." This line is used to convince ignorant consumers that 9mm is the same as .45. Sure, that CAN be true if you dumb down the .45 by loading it subsonic, which is exactly what they are doing here by loading it with small primers. This industry is full of smoke and mirrors, and this is just another example of what passes for "modern technology."

PS: .357 loads were substantially dumbed down from the original loads, thereby allowing for the switch to small primers.

[44man]

Primers have always been a thorn in my side and I never quit working them. Same in the .44 mag, LP works with every powder best and never a need for a LP mag. Pressure before ignition is not good. The LP in an ACP case is just too much initial pressure in the tiny case. Remember the case was used in a 1911 or Thompson so rifling held bullets back but that does not work in a revolver.
I don't think the LP is right and I don't thing a SR primer is right in the .454 either. There is always a right primer.
I rely on tests and experience for thousands of primer tests with every caliber to see where a change is needed. I don't even like the LR in a .500 S&W, LP mag is still best. Just why did they go different?

[10-x]

Thanks for this thread. Picked up a box of Federal Ball from wally world, did not open the box and check until home, wa- la, small primers. Waiting for someone to comment, now this is the big question, having several 1000 pieces of LP .45 ACP brass and the new is store bought in 50 round boxes, another step in sorting, prep and making sure they stay separate. Is it worth it?

[Artful]

It's not for me - I have less than 1% of something weird, they get sorted out and recycle canned.

[twc1964]

I use both app and lol 45 cap cases. Using 6.0 grains of wsf powder with Lee 452-230 tc. I get nearly identical groupings from either primer size. I shoot mainly combat style and not bench testing the gun except when I test the new loads. Ymmv

[twc1964]

Darn phone, I meant large pistol and small pistol primers in my post. Gotta fix this spellcheck thing

[ole 5 hole group]

I don't waste my time with 45ACP small primer cases either. Don't think for one minute if the small primer case gave better accuracy than the large primer case in the 45 ACP - our Service Teams would be shooting nothing but SPP'ed 45 ACP cases - they are NOT, so that should speak volumes about the accuracy question in a 1911. They may shoot just as well, but surely not any better.

[Outpost75]

.45 ACP, Small Vs. Large Primer

______________________ M1911A1_NM-5"
230-grain FMJ____________Avg.___Sd___ES
TW55 Ball REF____________858____28__72
AlliantBE 5.0 Large Pmr__842____11__29
_________5.0 Small Pmr__811____18__49
LP_Vgain___________31

H&G#68_200grain SWC
AlliantBE__4.0 grs.__Large Pmr___819___7__20
_________________Small Pmr___784___15_46
_________________LP_Vgain_____35
_________4.5 grs.__Large Pmr___863___21__51
_________________Small Pmr___864___46__115
__________________LP_Vgain___-1
_________5.0 grs.___Large Pmr___945__6___15
__________________Small Pmr___922__19__42
__________________LP_Vgain___22
______________AvgLPV_gain_____18.7

[44man]

Go back and read, The SP primer was best in the ACP REVOLVER but not a whole lot different in the 1911. Actually a SP brass could be used for all but nothing wrong with a LP in the 1911.

[DerekP Houston]

Thanks for this thread. Picked up a box of Federal Ball from wally world, did not open the box and check until home, wa- la, small primers. Waiting for someone to comment, now this is the big question, having several 1000 pieces of LP .45 ACP brass and the new is store bought in 50 round boxes, another step in sorting, prep and making sure they stay separate. Is it worth it?

Eh, its just another step for 45 reloads now. I've been getting a mix of 50/50 from my range just a PITA.

[shooterg]

I see no difference in performance. If I was starting out and could accumulate many thousands of SP cases and only stock one size primer, I'd do it. Especially if I could get all you guys tossing 'em to just send 'em to me !

[Freischütz]

I've reloaded 45 ACP SP cases with regular small pistol primers. Nothing unusual was noted unless it was cold outside. I never had hang-fires but did notice variations in recoil and softer report than normal.