magnum primers in small cases - .222/.223?

[bewsh]

does anyone use them?

 

I have 500 of the bloody things and no normal SR primers anywhere to be found locally

Going to try a load with 40gr and N133 in .222 but just wondered if anyone was using them out of choice?

[Laurie]

Standard primers are likely better in .222 Rem with its modest pressures. They may cause problems with full house loads in the higher pressure 223 Rem through cratering and blanking with their softer cups. (Standard SR primers have 20 thou' thickness cups, SR Magnums / BRs use 25 thou', and all Large Rifle primers irrespective of type are pressed from 28 thou' thick brass sheet.)

 

I and many others use SR Magnums / BR types in all 223 ammunition unless very low pressure loads where the less powerful models may give slightly smaller velocity ES values. Having tried 14 makes / models of SR primer in 308 Palma brass loads recently, I found a MUCH smaller range of velocities produced in an otherwise identical loading than when I did the same thing with LR primers last year. The average velocities produced by the 14 had an 18 fps variance between mildest and hottest (in a load that produced a bit over 2,800 fps) compared to 35 fps with a similar performing combination in large primer 308. There was also much less variance between ES values suggesting that there is less difference between choices of make / model / type, and choice is less critical. Certain models will always suit a particular cartridge and powder grade more than others though.

 

SRMs work just fine with Viht N100 series powders in both 222 and 223 Rem.

[henryo]

Yes I use CCI 450s for everything

[Geezedtee]

Laurie, you have left me somewhat confused. Am I correct in understanding your post that we should use SR Magnum primers in the .223?

If so, why do the load tables (Sierra, Nosler and Ramshot) stipulate SR Standard primers? I've always used CCI SR Benchrest and haven't noticed anything odd.

Could you please clarify so I can rest easy?

[gbal]

Geeze,I think you are ok with standard sr primers in non exteme 223 loads-with exceptional high pressure loads ,maybe magnums offer some comfort- Laurie knows more about this than most ,having pionereered 223 to it's limits-but he will clarify-what may be so for 308 Palma is another issue-again Laurie is the man.....in normal use ,standar 223 primers are ok for SAAMI 223 loads...

gbal

[Laurie]

Laurie, you have left me somewhat confused. Am I correct in understanding your post that we should use SR Magnum primers in the .223?

If so, why do the load tables (Sierra, Nosler and Ramshot) stipulate SR Standard primers? I've always used CCI SR Benchrest and haven't noticed anything odd.

Could you please clarify so I can rest easy?

 

First forget the 'standard' / 'magnum' labels in SR types. Whilst there are considerable perormance and primer compound brisance, hence peak chamber differences, between standard LR and LRM types, the performance / pressure differences are much smaller with this type. Your CCI-BR4 is in effect the high price / tight inspection variant of an SR Magnum. Most people don't see any pressure / MV differences between the CCI-450 SRM and the CCI-BR4 BR model. In fact, in my current lots of the two models, the BR type gives substantially higher pressures, and as a result larger groups, in my .223 Rem L-R match loads.

 

Perhaps as a result of their small size, I sometimes wonder if there is as much performance variation between production lots of SR types as is found between different models.

 

Then, there is the nomenclature issue. Several companies only make a single civilian model of SR primer. Since a considerable part of the output will end up in the US shooter's favourite tool, the semi-auto AR-15 or its clones with a free-floating firing pin, they need to be tough little beggars or else the customers will soon be complaining of blanked primers, gas getting back into the bolt and its carrier and generally bad-mouthing the product on forums. So the Magetch 7 1/2, Winchester WSR and most or all such single product makes are in effect milspec products with the thicker cups.

 

That's the crux of the matter, the cup thickness and hardness. As I explained earlier, 'standard' SRs come with 20 thou' thick cups, and sometimes a pretty soft 20 thou' at that in Brinell terms. 'Magnums' BRs and military spec come with 25 thou' and sometimes a very much harder brass with it.

 

Now here are two interesting facts. For years, Remington had a warning on its material not to use its Rem 6 1/2 standard SR primer with a whole list of cartridges. When you looked at what's left, it was the Hornet, Bee and a few low pressure numbers from ye olde years. This warning got harder and harder to find on its website over time, and now seems to have disappeared entirely. It's left to some of the more responsible retailers to reissue the warning now. Here's what Midway USA says:

 

Warning:

• Remington does not recommend this primer for use in the 17 Remington, 222 Remington, 223 Remington, 204 Ruger, 17 Remington Fireball. Use the 7-1/2 Small Rifle Bench Rest primer in these cartridges.
• This 6-1/2 Small Rifle primer is primarily designed for use in the 22 Hornet.

The same can be said to a lesser degree of the CCI-400 as it's also a thin brass model, but the cup seems rather tougher than that of the Remington.

 

Now look at Hornady's reloading data for the .223 Rem and its older, lower pressure .222 Rem sibling. The lower pressure cartridge loads use the Rem 6 1/2, the 223 loads the very much tougher, and in my own experience very much more vigorous WSR which I'd class as an 'SRM type' if we must use this term, although Winchester never describes it as such.

 

My curiosity was first piqued over this issue when I first started to load 223 in a Remington 700VS in the far back days when that was a new model and people used to come up and ask about it and its H-S Precision composite stock on the ranges. My modest pressure loads caused moderate cratering with whatever I used at the time, probably CCI-400 as CCIs were generally very widely available back then. Primer cratering was banged into you as a VERY BAD THING, one step away from blown cases and perdition, in those days. A friend then bought a Remy 700PSS and got very bad cratering even with book starting loads with 400s, his firing pin obviously an even poorer fit in the bolt than mine. By then I'd learned a few things and told him to get Remington 7 1/2 BRs which Hannams stocked in vast numbers at cheapo prices in those good old (pre shortage) days. Note the '7 1/2' bit, that = 'SR Magnum'. Problem solved. Then I got a 223 straight-pull AR with its fully floating firing pin and learned a lot more about primer hardness, not to mention chamber pressures. In my rifle at any rate, the thin-cup 'standard' primers were a total no-no, yet I knew pressures were modest compared to what most people run through ARs. Not only did QuickLOAD say they were in the low to mid 50,000s psi, the chronograph backed the resulting MVs to that, and best of all I had very easy, sweet bolt opening with no or barely no initial primary extraction check. (You learn a great deal about real pressures in a straight-pull.)

 

At same time, I read Glen Zediker's book on the competition AR-15 cover to cover several times and the WSR was the primer of choice of the US high-power Service Rifle people, although that was the old 'silver' (nickel plated) model, and many reckon the more recent 'gold' (unplated brass) type is softer.

 

The ideal SR primer for the 223 and most people's uses here is one we've never had and for the foreseeable future at any rate have no chance of seeing, the Russian Murom KVB-556 (I think !?). It's the hard SRM cup with the priming mix pellet from the standard (very soft cup) model. I've had tremendous results fropm the old PMC / Murom SR in MV spreads and groups, but its cup is so soft it's only usable in realtively low pressure loads even in tightly breeched custom rifle chambers with bolts with a small dia. firing pin that's a close fit in the bolt face aperture. The reason we won't see any more Muroms for a while is that Comrade Vladimir P. has been naughty and we and the EC are slapping his wrists with trade sanctions.

 

So, forget about standard or magnum or BR names and unless you're loading very 'soft' rounds, go for the thick cup / tough models. I'll have a side by side test of 14 SR primers in 308 Win Palma brass loads out in Target Shooter online mag in a few weeks time. Whilst somewhat (!) larger charges than in 223, this made for some very interesting findings including which ones blanked when I went to my usual 3,000 fps + FTR long-range loading.

 

 

................ and here is a very interesting exposition of the issues from an AR-15 user's perspective. (But if it works well in an AR, it'll also work well in any conventional turnbolt action.)

 

 

http://www.calguns.net/calgunforum/archive/index.php/t-476110.html

[Geezedtee]

OK Laurie.

Have read the www.calguns link. It says Quote "CCI BR4 - match primer with a thicker .025" cup". Followed by "CCI 450 - same thicker .025" cup as the BR4".

Therefore, for standard 40gr and 50gr bullet loads at average muzzle velocities I am OK with my CCI BR4's.

Interesting about the BR4's higher pressure in your .223 Rem L-R match loads. I will bear that in mind.

Thanks.

[Laurie]

Both primers are an excellent choice for 223.