Lapua Primers size/ID?

A friend has a case of Lapua 7.62x39 that he picked up in mid-1980, which he finally shot all of it…
He then proceeded to begin reloading operations, and discovered a different primer size…
Can anyone tell me WHAT primer size and designation is used, and a possible source?
Neither a quick IAA archive nor a googlie search yielded positive results.
I am awaiting delivery of a deprimed case as I type this, in the event that a photo of HS and primer pocket measurements will assist.
Thanks, all!

normally ,primers used on 7.62x39 (mostly eat bloc origin) are slighty larger than “large rifle primers”
but it strange that lapua does the same thing instead of using standard large rifle primer

According to a Chinese manual that was made available on this forum, primer diameter for 7.62x39 is 5.55 mm (Chinese primer designation WD334 and WD334A).

Would Lapua actually make a specific primer size per Chinese dimensions?
Does not seem likely… especially since all foreign reloadable 7.62x39 brass cartridges I have seen [granted not ALL of them] use standard size primers.
I should have the deprimed cartridge in my hands tomorrow for measurements and photo.

You asked for the primer size. Don’t you think that quite probably the Chinese use the same “slightly larger” size mentioned by ammogun as other former Soviet bloc countries?

Edit: I have to correct myself. 5.55 mm primer diameter (and a primer pocket close to 5.46 mm) is the standard dimension for a Berdan rifle primer. There is nothing “slightly larger” about it, because its the dimension the German 7.9 Patrone 88 used, as well as 7.62x39 and 7.62x54R as produced in East Germany at least.

Hi BadgerJack. I’ve attempted to measure a Lapua one for you, which is approximate as I can’t get into the primer pocket as I don’t have a de-primed one, but it’s coming in at around 5.2mm. It’s similar in size to the S&B one in the image beside it, but both these are smaller than the Romanian primer example beside it. A friend reloaded the S&B example, so the primers should be readily available, Pete.

That is the problem he is having: too small for Large Rifle Primers, too big for Small Rifle Primers.
And he forgot to bring me a sample that I can measure, (we had a fairly busy LGS, but at least I got some neat and inexpensive ammo, but wish I had more $ to spend, for a later post).

The problem is: What is the primer ID/Designation, and Where can they be had here in the USA?
As I mentioned, he failed to bring me the de-primed case so I can get measurements, hopefully later this week…

Standard Berdan primer used by Lapua in the 80’s for a cartridge of this caliber is designated No. 2 and measures 5.5 x 2.75 mm. It was made by Vihtavuori.

I’m wondering, what other type of primers have been used in 7.62x39 during last decades…during 50’-90’ majority od military cartridges were 5.5 berdan. There are few adjusted by 4.5 rifle berdan (same like used on 7.62x45 Czech) and the rest after 1989 swap to 5.33 rifle boxer … mainly due to reloaders. No others i have met so far.

I have only my friend to rely upon for this info, and I stress I do not have the cartridge in my hands yet:
Since he de-primed with a standard US made set of dies, I do not see how it can be Berdan priming, so are you saying there are Boxer primers made to the dimensional standards of Berdan primers?
And, if so, what is the ID/Designation, and where can they be bought, (which is the point of this entire post), so he can complete reloading the cartridges?

I checked my Lapua brochures (1975, 1987 & 1988), & they’re all showing the 7.62mmx39 Boxer as being the No.3 primer. The 1987 catalogue states they offer 7.62mmx39 cases for reloading in both Boxer and Berdan.

BadgerJack - with no aspersions towards your friend, what evidence did he find of “a different primer size”? What US Boxer primers did he try, and what/why didn’t they fit? Was a standard LR primer too tight? If so, could the primer pockets need decrimping? Was a standard LR primer too loose? If so, could the primer pockets be expanded due to over-pressure loads or excess cartridge headspace?

Edit to Add: I went out to my shop and sorted through a bin of processed 7.62x39mm brass waiting to be loaded. While the majority was Winchester, IMI, and PMC, I pulled out the first 5 Lapua cases I came across. I measured the primer pockets with digital calipers, all 5 measured 0.208 inches +/- 0.0005 at the bottom (deepest). The standard Larger Rifle primer has a cup OD of 0.210 inches. I then primed 3 of the 5 with CCI 34 primers, US Mil-Spec Large Rifle typically used in semi-auto 7.62x51mm, .30-'06, etc. They all primed perfectly.

Of course, your friend may have different Lapua brass than the 5 random fired cases I tested.

What everyone here seems to overlook isthat ALL primers (Boxer or Berdan) are an " Interference Fit"…the Primer diameter is larger by .001" or .002" thanthe Primer Pocket.
That said, the Primer diameters are standardized: Boxer (.210" & .175") Berdan (.254", .250", .217", .199", .177"—6.45, 6.35, 5.5, 5.0, 4.5 mm)
Pockets will vary in “thightness”, but making a pocket exactly the size of the primer will result in gas leakage.
Check original case drawings that show pocket dimensions in either
'000" or mm.
( not your modern reloader manuals or SAAMI, but original
Factory specs/ military design specs…back in the late 1800s, and pre WWII, these were very carefully
Drawn by manufacturers.

Doc AV

Doc AV, not everyone. I wrote: “5.55 mm primer diameter (and a primer pocket close to 5.46 mm)”, the latter number being an average from several case drawings.

Again - not everyone. Of course primers are press fit. All 5 Lapua cases that I measured the primer pockets for had a diameter (at full depth) of 0.208 +/- .0005 inches. Primer pockets are typically tapered, wider at the mouth than at full depth.

The CCI 34 primers averaged 0.2105 inches in diameter and press fit nicely into the Lapua brass. BadgerJack’s friend may have different Lapua brass than my 5 random samples - thus might have different a primer pocket size.

Not everyone! As a reloader I presumed that was a given. Just trying to highlight that it should be a readily available size of Boxer primer to reloaders, in Western Europe at least.

I have loaded Lapua 6.5 x 55 mm brass for years, and primer seating with any Large Rifle primer of the Boxer type made and sold by various American firms, and also RWS LR Boxer primers, is simply not a problem.

John Moss

Berdan Primers:

Boxer Primers:

Chickenthief - a very nice, concise listing of primer information. Thanks for posting.

John M.