Vely Difference: Mag Primer vs Regular Primer

I

I Dont Care About You

CGN Ultra frequent flyer
Rating - 100%
3   0   0
During COVID and the primer/powder shortages, I ended up buying a couple of bricks of Magnum Small Rifle primers ... because those were all that were available at the time.

I decided to chrony the two primer types to see what, if any velocity difference there might be in 223 Rem reloads.

Same rifle, same powder charge, same bullet, same batch of cases, same day. The result was the Mag primers produced a 10 fps increase in velocity. So I am going to use the Sm Rifle Mag primers interchangeably with the regular primers in my 223 loads. I'm not loading anywhere close to max.
 
I did a similar test in my 223 and the results were negligible with 2 different powders, I have a good supply of both SRM primers and standard SR primers so have been using the standard in my 223 as I also have a 6mm creedmoor and lots of SR primer brass for it, I keep my CCI450 SRM primers for my 6 CM. I also have some brass that takes LR primers for the 6 CM and did a test with LRP vs SRMP I posted all the results of that test over in the reloading section. Fortunately I have a good supply of primers for everything I load, all acquired before the #### show started and prices went insane, I guess that makes me a hoarder, but a happy hoarder.
 
I was told if your powder less than 60 grains, there is no issue to use large rifle primer, otherwise go with large rifle magnum. I used LR primer on my 300wsm with 180g bullets. works perfect. But I still transfer to LRM since we hunt deer in 3rd week November in Manitoulin.
There is difference on velocity, LRM can drive 50-80 fps faster than LR, both for 300wm and 300wsm.
 
Similar story during "the great shortage" I bought 2k small pistol magnum primers. Velocity and impact point seemed unaffected in 9mm
 
A few years ago I was priming some 270 brass for load development. I went into my primer drawer and looked for some started sleeves before I grab a full one. There were 2 started ones of my primer of choice, cci 200s or so I thought. Poured them both into my hand primer tray and thats when I noticed I had poured 20 cci 250s into 50 or so cci 200s. First and only time to date I've committed such a blunder. I poured them aside and took a fresh sleeve od of 200s.

Proceded with load developed. X bolt stainless stalker, reloader 19(magic powder at times), 130 gr speer hot cores and cci 200s. Ended up at around 59 gr and they were shooting in the .4s. Just for kicks I went and made 3 more with the magnum 250 primers. Went back out to the bench and shot them at the same .4 group I had just shot with 200s. They opened my group up to .5 so........no chrony data for this though.

Did load work recently on a t3 lite in 204. 40 gr noslers and h4895. Once I achieved my desired 3800 fps I shot groups with cci 450s, fed 205m, and rem 7.5s. The federal got the most speed, the remingtons 60 fps slower with the cci somewhere I'm the middle. The cci cut group sizes in half so that's what I went with there.
 
remington jim said:
Really ? Please elaborate . Thxs RJ
Click to expand...
when I was developing loads for brass 410 shells, I was using large pistol primers and H110
one very cold day I went out to try some more loads and got quite a few squibs
Next outing I had loaded magnums and the problem went away (that day was even colder)

edit: needless to say the powder charges were the same and the action was devoid of oil
 
Magnum primers have a Longer Burn time to ignite larger amounts of slow burning powder and also even in cartridges of small amounts of certain shaped powders that are hard to ignite . Weather temp should have no bearing on igniting powder and I have never found a problem of cold weather ignition in any of the plus 100000 loads I have shot off . RJ
 
RJ, I've had "cold temperature" ignition issues with some powders. Not failures to ignite but inconsistent velocities.

I've tested velocities as -35C and +20C with IMR3031, H4831, and W760 using Standard primers and Magnum primers.

I didn't bother with any others, as this is a fairly decent range of powder speeds I generally use.

Our old friend Albert Forsland was interested as well and we did the tests together.

After the tests were finished, we both started using Magnum primers for everything, other than our HBR loads which we used CCI BR type primers, whose flame rate is somewhere in between Standard and Magnum primers.

Most shooters won't go to the range or hunt when it's that cold, some of us do or at least did when we were younger.

Some of the recently released powders are supposedly not temperature sensitive. I haven't checked.

If a person is a fair weather shooter hunter, they likely will not have ignition issues.

Overpriming is a fallacy IMHO, lots of people disagree with me. That's fine.

Magnum primers give me confidence in my loads under all conditions I'm likely to use them in.

Like you, I load for accuracy, velocity is nice, but it comes in second after accuracy.

Inconsistent ignition equals poor accuracy and magnum primers just eliminate a potential issue.
 
You must log in or register to reply here.
Back
Top Bottom