Domed Primers

[jk2008]

Recently I was given a large lot of miscellaneous ammo--mostly some unknown person's 38 SPL and 357 Mag reloads, but also some less common rounds such as 44 SPL and 6.5x50 Japanese, which may or may not be factory loads.

Anyway, for the rounds in the calibers I can shoot, I will be pulling the bullets and "re-manufacturing" rounds with my own carefully measured powder charges. For the cartridges in calibers I can't shoot, I'll try to salvage the primers and reuse them in low pressure plinking rounds.

However, some of the older cartridges in the lot have domed primers. Since I have no experience with domed primers, I was hoping someone in the forum might be able to answer a few questions about them.

1. What was the benefit of using a domed primer (was it simply a cosmetic difference)?

2. When, approximately, were domed primers phased out and why were they?

3. Since domed primers have not been used commercially for quite a while (as far as I know), should I assume that the domed primers I have are corrosive?

Thank you for any information you might have.

J

 

[rcmodel]

I don't recall the exact date they went away.
And I don't know "why" some companies used them either?
I think I had used some Alcan primers that were domed at one point years ago.

But my first Herters press in 1962 came with both domed and flat Sm & Lg primer seating punches.

I would not assume they are corrosive just because they are domed.

But I would not assume they are not either.

As for salvaging the primers and using them again?
If they are that old, a lot of them very likely are dead anyway, if not corrosive.

I would not waste my time fooling with it.
Just deprime them all and re-prime with new primers.

rc

 

[Waldog]

Your "domed" primers are probably Berdan primers. The only way to tell is to pull the bullets, dump powder and look inside. You may have to cut off head to see. They can't be easily reloaded. If your old stuff is before about 1950 they are probably corrosive. Especially if they are old military cases.

 

[ReloaderFred]

Commercial ammunition has been loaded with non-corrosive primers since World War II, and some prior to that. It was only the military who resisted changing over to non-corrosive priming compound until about 1953/54, though the .30 Carbine ammunition was loaded with non-corrosive priming from the very beginning.

You used to be able to buy primers in either configuration, and priming posts were offered in either flat or domed shape. I still have domed shaped priming posts for my original Hollywood press that I bought used in 1963.

The dome shape has nothing to do with being Boxer or Berdan, it was merely the shape of the primer cup. Old timers liked the dome shape, since that's what they were used to. Reloaders resist change, i.e.: small pistol primed .45 acp brass.

Pull some of the bullets, empty all the powder, and see if the primers will go off in the appropriate caliber firearm. If you want to test to see if the priming compound is corrosive (though that's a misnomer, since they are just hygroscopic, not actually corrosive), clean off a piece of bare steel with steel wool and shoot just the primer at it from a few inches away. Leave the steel outside overnight and if the blast spot is very rusty in the morning, then the priming compound is "corrosive".

Hope this helps.

Fred

 

[jcwit]

Primers being domed does NOT mean they are probably Berdan primers, not at all

I have in my assortment of primers that are domed, they are in their orginal packaging from Winchester, Staynless Primers, 100 Center Fire, Non-Mercuric, No. 115, K1615P.
Winchester repeating Armsd Co., New Haven, Conn., U.S.A.

No zip code of course, they are supposedly from the mid to late 40's.

Yes they all go "BANG" in the cartridges I've loaded them in.

BTW, they have the grooved wooded seperator tray in the sleeved box.

In your case I'd use them, see no reason not to.

 

[ranger335v]

The transisition from the original domed to flat primers took several years, from maybe the early to late 6os, best I remember. There is no 'advanatage' to either form.

Well, maybe there is ONE advantage to domed; it was from them the idea of approximating a guess at chamber pressures had some validity. The change to 'pre-flattened' primers sorta killed that off as a reliable pressure indicator. Today, a really flattened primer is more likely to indicate excessive 'headspace'.

 

[Chindo18Z]

It was only the military who resisted changing over to non-corrosive priming compound until about 1953/54, though the .30 Carbine ammunition was loaded with non-corrosive priming from the very beginning.

Sorry to go off on a tangent, but...

Was WWII era ball rifle ammo (.30-06) manufactured with corrosive primers? How about .45 ACP from the same era?

I was just wondering if pre-50's surplus ammo is corrosive (or not).

 

[USSR]

Was WWII era ball rifle ammo (.30-06) manufactured with corrosive primers? How about .45 ACP from the same era?

I was just wondering if pre-50's surplus ammo is corrosive (or not).

Yes, USGI .30-06 was corrosive until 1950, 1951, or 1952, depending upon the manufacturer. Don't know when .45 ACP became noncorrosive. USGI .30 Carbine has always been noncorrosive.

Don

 

[Jim Watson]

At one time Remington primers were domed and Winchesters were flat.
Or maybe it was the other way 'round; my copy of Sharpe was lost in The Incident.
Any road, presses came with punches for both until everybody settled on flat.

Yes, .45 ACP was loaded with chlorate (corrosive) primers up into the 1950s, too.
The CMP reproduces a chart of changeover dates and lot numbers for the various arsenals and contractors.
http://forums.thecmp.org/showthread.php?t=5821

The intent was go to noncorrosive as part of the return to peacetime procurement right after WW II; noncorrosive primers having proven satisfactory in all US* .30 carbine and .30-06 from Canadian contractors. But low budgets delayed the changeover. Surprisingly, most places made it in 1951-1953 with the Korean War going on.

*Be careful of imported .30 carbine, the French are said to have loaded corrosive .30 carbine military ammunition and there are reports of fresh European commercial imports, too. The carbine was designed for noncorrosive and it would be tough to clean thoroughly enough; unlike the Garand which was meant for use with corrosive and could be maintained.

The residue from firing a chlorate primed round is potassium chloride, an analogue of table salt. It is hygroscopic, absorbing water from atmospheric humidity and the resulting little droplets of salt water are darned sure corrosive.

 

[Chindo18Z]

USSR & Jim Watson: Thank you both for the education.

That chart is saved to my ammunition library folder.

 

[dickttx]

Very interesting info.
I remember the domed primers from when I started reloading in the late 60's . I was out of it from the mid 70's until about a year and a half ago. I noticed I had not seen the domed.
Probably due to standardization of manufacture. Companies bought out, etc.