Primers

[onehole]

Hi ,Can anyone who "really" knows about primers come on here and let us know the real differences.Generally speaking I use Federal GM small and large and have rarely used anything else.I have never needed to push velocities to absolute limits to acheive what I like to see with regard to accuracy etc etc and to use "magnum" primers to ward off pressure signs so what/when please should we be using standard/magnum/match/br type primers etc etc.

My basic understanding is that standard primers have less material/strength in their cups compared to magnum but do magnum primers provide a hotter ignition as well?I hate to admit it but I really don,t know and feel I should by now!?

I appreciate their are quite a few different brands all with their own definitions but in truth guys what is it all about,what and who,s does what and when does it do it better ?

Any examples of significant,factual and proven scenarios would be appreciated,thanks Onehole.

[rabbit fingers]

I stumbled across this some time ago,Its a shame he didn't test small rifle primers. Hope it helps. http://www.castingstuff.com/primer_testing_reference.htm

[TonyH]

Hi ,Can anyone who "really" knows about primers come on here and let us know the real differences.....

Any examples of significant,factual and proven scenarios would be appreciated,thanks Onehole.

 

Hi Dave. The best info I've seen in a long while on this subject is by Arizona marksman German A Salazar, who contributes quite a bit of stuff to the 6mmBR.com site. He has this review of small rifle primers, and a parallel one on large rifle primers, both to be found by searching the lengthy articles index on his very useful & interesting blog. I find it really surprising to look at photos of different primers in action, then read the figures for comparative performance: there is not at first sight any connection! I've used Rem 7.5 primers for years, widely recommended, but i never knew they had such a powerful "brisance" (= flash/flame)...

HTH, Tony

[Laurie]

+ 1 on Tony's recommendation./ There are odd other posts on German's blog about primers too that are worth fishing out too.

 

There are differences between large and small size primers when making a choice. LR and LRM / BR have an identical cup thickness of 0.025" - the difference is entirely in the percussion compound make-up and charge weight.

 

SR primers use a thinner cup size - 0.020" - and are designed for small, low pressure cartridges in the .22 Hornet, .218 Bee class. You just get away with them in .222 Rem, but a full pressure .223R, .204 Ruger etc load producing 55,000 psi or more will see bad primer cratering and in a typical Remy type factory action with a slack firing pin - bolt body fit risk piercing. So you must use SRM or SBR primers with their thicker (0.025") cups with full pressure loads in most cartridges.

 

If you read German's conclusions carefully, you see that 'mild' is good with LR types, even between standard models in .308W, .30-06 class cartridges giving less pressure variation and smaller velocity spreads. Beware old articles on the Internet as many models have changed over the years - eg you still find articles on .308W for short-range (up to 300yd) US shooting that tell you to use the Remington 9.5 as it is the 'mildest available', but recent reviews like German's generally say it is a 'hot number' now. Sadly, we can't get the Russian manufactured PMC primers now in this country - the standard LR is amongst the best going for .308W size cartridges. (They are sold as 'Wolf' in the USA.)

 

For many years, the 'in' primer amongst American .308W Palma Rifle shooters (pre the new SR dimensioned Lapua brass) was RWS which was allegedly the mildest on the market. Unfortunately and unusually, German quality control wasn't too good and some manufacturing lots gave terrible results with huge MV ES numbers - such a batch was on sale here back in 2008 and it caused mayhem in F-Class with Gary Costello and Stuart Anselm going from leading to last in class positions between GBFCA rounds. So, US shooters carefully checked lot numbers before buying once the word got around about a good batch. We only rarely see RWS here and it's very expensive - if you're offered this make in the LR size at a good price, it may or may not turn out a wise buy!

 

I have found a lot of difference in SRM / SBR types in my .223 F/TR rifle - the CCI-BR4 is MUCH hotter than the CCI-450 and PMC SRM giving up to 40 fps more velocity behind 90gn bullets, double the velocity spread and large groups. Dropping the charge weight to get the MV back into the sweet spots didn't work - still 2X spreads and 50% larger groups. I haven't compared the Rem 7.5BR against this trio although I've used it with .223 / 69-80 for years and got small groups and MV spreads so it must be OK. It seems to be a little 'softer' cup strength wise than the CCI-450 SRM though, so will crater / pierce at slightly lower loads. (The CCI-450 is the primer of choice for most American 6BR precision shooters.)

 

I'm currently running side by side comparisons between standard Lapua .308W brass and the small primer dimensioned 'Palma' version, and will be doing a full run of primer tests later in the year for publication sometime towards the end of the year. This will involve .223R for small cartridge / small primer; .308W for mid size cartridge / large primer; and a .300 Magnum for large cartridge / large primer / large magnum primer. I'll also include two cartridges with a choice of size - the aforementioned Lapua .308W and 6.8mm Rem SPC that has both SR and LR cases depending on manufacturer. What I can say about the .308W Lapua issue now is that the SR version using the 'hot' CCI-BR4 still drops MVs by 25-40 fps compared to the same load with a CCI-200 standard primer and that in least one commonly used load (155gn Scenar + N140) the SR Palma version gave much poorer results with the BR4 compared to Fed 210M in the standard brass, but not in another combination tried with N150 where groups ended up near identical, but with the Palma brass reducing velocity spreads as it's supposed to. So .... we'll see.

[onehole]

Thanks guys for your leads and posts,still digesting it all!- Laurie-your testing later in year should be interesting but it seems that "primers" by their very nature can only be "tried and tested" to see what works best.Thanks Onehole.

[oaken]

Not quite what you wanted but this link has some useful information

and a chart showing various primer dimensions and cup thickness.

http://www.jamescalhoon.com/primers_and_pressure.php

Rup

[Chris-NZ]

Not quite what you wanted but this link has some useful information

..

 

 

I wonder if the data has changed since 1995 when it was published??

You'd have to suspect at least some differences

 

Chris-NZ

[oaken]

Why? I can certainly see companies bringing out new "improved" versions but

not changing the existing specifications.

I have been using Remmy 71/2 and 91/2 primers since the article was published

and even the packaging is still the same

Rup

[onehole]

Mmmmm from what I,m reading then most of us should be on the Match/BR/Mag type as we run close to the higher nodes and pressure I guess and go for a brand that you like or find good value as they "pretty" much all do the same thing.?Thanks again for your comments guys I expect many others found that interesting reading too,cheers Onehole.

[oaken]

Dont forget that primers cannot be posted and, as with bullet heads, brass

and powder, they tend to sell out. Sods law says that if you work up a load

with an unusual primer you may well find that supplies dry up for many months,

even years, at a time, so once proven, buy lots.

I found this out the hard way

[Chris-NZ]

Here's an interesting summary article on primers:

 

http://www.chuckhawks.com/primers.htm

[325WSM]

Primers are as much a variable component as any other in reloading and can alter velocity and trajectory and therefore accuracy quite considerably.

 

I have long been an advocate of using primers in the same way as powder to vary a load with great effect.

 

We dont choose our case because one looks shinier than another but because of the chemical composition that is most suitable for our particular load. Neither do we choose a Powder just because the local shop has it on the shelf and so with Primers - choose your primer to do the best job possible for the load you are generating.

 

A change of primer can in some loads require a drop of 3 grains and the difference in velocity without any increase in pressure can equally improve by 100fps. Use your primers in the same way as your powder and you will be surprised at the difference your loads will provide.

 

Here is a basic heat chart - from top to bottom drop about 5-6% in powder and work from there.

 

 

 

http://smg.photobucket.com/albums/v356/mry716/Shooting%20-%20other/?action=view&current=primerheatchart.jpg

 

 

Use it as a guide and add in your own primers when you have assessed them. eg, the Prvi Partizan Primers although burning approximately as hot as the Winchester range do because of their different construction not seem to require a reduction in powder when changing from say Remington. Try for yourself and let us all know your test results as it will expand the above chart considerably.

 

Use of Magnum primers is normally reserved for the Ball Powders but I am finding I can use them to great effect in the shorter stumpier cases such as the WSM and WSSM range of cartridges. Logically this should also be valid for the Benchrest PPC cartridges.

 

The same is true for the H4831 SC powder in 243 - A Federal Magnum primer seems to provide anything up to 120 fps higher velocities than standard primers yet seemingly without additional pressure.

BUT

do drop the powder weight and build up again.

 

 

Please remember to drop powder weights when changing primers and do also remember that in the hot summer weather you need to reconsider all those max loads and take out a little powder.

 

A 10 degree rise in temp requires a 5% decrease in powder. If we are going to get such varied weather in coming years it may be best to have a min, intermediate and max load to use dependant on weather temperature.