What would happen to a load if a person primed cases with Mag Primers with a load that recommended standard primers? I know you shouldn't interchange them, but what would happen?
For example, a person loaded a 7mm mag with 62.8grs (max) of IMR4350 behind a Nosler Partition and used a Winchester Large Mag Primer instead of a winchester Large rifle primer.

This hasn't happened to me because I use a different brand of mag primers than my standard primers and double check everytime I prime cases.

I would probably use the Magnum primer behind the load you used as an example. Unless one is at or nearly at the maximum published load a magnum primer should not put put him over the top. In really cold weather I'd recommend magnum primers for consistant ignition, as the magnum primer will offset the lower pressure caused by the extreme cold. A word of CAUTION here though, deviating from published load data is not for the beginner and should not be done unless you start at the lower end of the load range and ladder back up watching for pressure signs.

As far as I know, and somestimes it aint much, a mag primer is about equivalent of 1 grain of powder! If you use them in a standard cartrige, work your loads up, dont start at or near max!

Careful now.....I'm not saying there is no difference.....just that I haven't seen the difference in my reloading.....

It depends on the load/powder & the brand of primer. I have found some magnum primers offer less vel. than certain match primers. You can't always equate vel. increases w/ pressure increases, but that's my exp. I reserve mag. primers for large loads of slow powder or maybe if hunting well below zero. If you are off the max. load for your rifle, probably not much diff.
The A-Square manual has a good article on component substitution.

I use CCI 200 large rifle primers with 64 gr of RL22 in the 7mag up here in the frozen tundra of Mt. Haven't had a single problem and until I do, I see no reason to change.

I noticed a difference in Winchester Mag primers and CCI Mag primers. The Winchester Mag primer would crater slightly and the CCI Mag primer did not crater. The identical powder charge with the Winchester Mag primer also hit slightly higher on the target. My assumption was the Winchester Mag primer was hotter than the CCI Mag primer. The CCI Mag primer gave me a tighter group also.

You can see a 5000 psi difference when switching from one type or brand of primer to another. This was documented in a recent book, might have been Gun Digest or Handloader's Digest, I can't remember off the top of my head.

I personally have seen 2000 - 3000 psi increases when switching from standard to magnum primers, as measured by a strain gage.

My procedure for testing primers is to calculate the velocity standard deviation for at least 10 shots with each type of primer. Whichever primer has the lowest standard deviation gets the nod.

I've always used standard CCI or Federal primers for IMR4350. Ball powders like WW760, Ramshot Big Game, and Ramshot Hunter prefer magnum primers.

mag primers, to the point of exclusion, are hotter than standard primers.

hotter means more starting energy

a hot day also means more starting energy

sure, you might burn a higher precentage of powder in the barrel with either...


but switching willie - nillie is going to make you a "bold" reloader... and their aint no OLD bold reloaders

I generally use federal 215s for powder charges over 90gr.. winchester mags for over 50gr ....

and winchester large rifle for those under

jeffe

For some reason unknown to me, readers of Accuratereloading seem not to go to the FAQ pages and read them.

Saeed did primer tests some time ago and has an entire section devoted to this question. If you go to the FAQ section, you will find a file on this topic.

Saeed isn't God, but he's a very good gun and shooting expert, so it would seem that we, as his guests, should at least learn what he has to teach us!

Here's the URL for his results:

http://www.accuratereloading.com/primer.html

________________

I have seen little change in FPS MAG vs Non mag primers and when I say little i'm talking 50FPS or less 90% of the time, where I have seen changes is in group size.

example my 22-250 24" barrel Kimber shooting a 50 gr Nosler BT using 38grs of H-380 fps will run 3720fps with a Fed. non mag primer and group size will be 0.825@100 same load with a Fed. match mag primer will run 3744fps but my groups shrink to 0.423.

I have had same in a 7mm-08 by switching to a match mag primer using RL-15 but have found groups in my 270 to get larger using match mag vs Rem. 9.5 standard with H-4831.

To me it's just trial and error as far as mixing and matching primers powder bullets & cases.

I tried my own experiment with standard and magprimers from CCI in my 7mm mag back in September. MagPro as a powder, Frontier once-fired cases, air temp 70degrees. The firearm is a T/C Encore with factory heavy barrel and a Trekker 3-12x40mm scope. I do not have a Chornograph (on my Christmas list) so the speeds are unknown.

Load #1
71grains of MagPro
CCI Large Rifle Primer
139grain Hornady SST
Load #1 had a distinctly slower ignition and of the 5 rounds I fired, 1 was a complete hangfires. There was no signs of pressure on the primer or case. The group was near 1MOA at 100yards.

Load #2
71grains of Magpro
CCI Large Magnum Rifle Primer
139grain Hornady SST

Load #2 had quicker ignition with a louder report. Of the 5 rounds fired, none had ignition problems. The group shot a tighter group at slightly large than 1/2MOA at 100yards. The primers had no noticeable pressure signs.

Load #2 was a moderate to hot load and the one I chose to hunt with this year. My books state that MagPrimers were recommended for this load. As for the hangfire in Load #1, I don't have a clue why it did that it could have been a bad primer or the anvil in the primer may not have touch the compound completely. All loads were measured with a scale.

I actualy did this with my 9mm loads for my KEL TEC sub 2000. I loaded 500 rnds and By accident (stupid) I have 30 rounds loaded with Win mag pistol primers mixed in them. I havnt dared to shoot them and I hate to waste the 470 properly loaded rounds. It is by the way -10F at my house right now, maybe they might be safe in that temp range?

According to published data, switching primers can get you into trouble. This is the data from the A-Square manual, from a 7 RM:

                fps     psi

Win WLRM        3045    67600
Win WLR         3024    64400
Fed 215         3036    61400
CCI 250         3039    61500
Rem 9.5M        3041    59300
CCI 200         3011    54800

That's a 23% increase in pressure, bottom to top. If you're using a published load based on the WLR, you might not be too bad off with the WLRM. (Of course, if the data had been developed with CUP, the crusher might not have captured the spikey nature of the true pressure curve.)

Worse, the rise in fps is only 1.1%, well within the error band of a basic chronograph. Even if your chrono. is spot on, backing off on the charge may not correct the pressure problem. Dropping fps by dropping charge weight drops pressure at about 2.5 times the rate of drop in fps, but this primer substitution caused a change in pressure about 20 times as great in pressure as in fps. This makes me question whether a chronograph can really keep you safe.

As has probably been covered before, magnum primers do not always produce higher velocities than standard primers.

In a specific large statistical test done on the 300 Win Mag using two different brands of standard and magnum primers and including both ball and extruded powders, the standard primer produced higher velocities than the magnum ones in both brands.

Elmer Keith also found this in some tests he ran.

This is not a blanket statement concerning all ammunition, but just to say it has been seen and repeated.

Hammer

Considering that chart, I'll stick to CCI200 primers for the 7. Less than 40fps but more than 7000 psi, is a very convincing argument in my eyes.

Looking at that chart and after looking at my 7mm loads, I will switch down to my CCI200 primers. I also have decided to experiment with IMR4350. I still haven't developed a load because it has been a high of 0 or lower for the last 2 weeks and I really don't want to discover that my loads are too hot. Maybe this weekend it will be above freezing, and I can get rid of some of those hot loads in the cold weather.

WLRM primers have corrected delayed ignition problems I've had with some very large capacity cartriges with cast and jacketed bullets.

The hot primers have also yielded more consistant velocities when using some ball powders. roger

I have no doubt the WLRM are useful, else Winchester would not have developed them. I must believe, though, they are a specialty tool, and should be used only when specified with piezo tested load data, such as that available from Winchester on-line. To quote Win's load data: "use only where magnum primers are specified," and in the copy of their data I have, they recommend WLR for the 7 RM. I should note that using too "soft" a primer can raise pressures, for the very reason bartsche mentioned: too soft a primer can cause delayed ignition in some cartridges.

When I first started reloading I worried myself sick over what was the best primer with which powder. Then discovered my best accuracy and most consistent loads came with the Federal primers. For the last ten years they are all I use and don't look back. I shoot 3000 plus rounds per year in a normal year, more when special projects are more numerous. The 210M and 215M in my opinion cannot be beat, if speed and accuracy are your game. Good shooting.

Like Federal 215 magnum primers in large African-size cases.

My experience with several calibers, specifically .223 and .375 H&H, was that magnum primers produced worse accuracy than standard ones. I tested CCI small rifle regular and magnum in the .223, and Federal 215 vs. regular WLR in the .375 H&H. (But if the chart given above is correct, then maybe the WLR is actually "hotter" than the Federal 215.)

quote:

Originally posted by asdf:
...This makes me question whether a chronograph can really keep you safe.

Excellent observation by asdf.

How do all the folks that say it is impossible to Reload without a chronograph account for such variances? Funny you never see them mention it when they are recommending the Ohlers and Cronys.

By the way, good old CHE & PRE would catch the Pressure differences with their First-Hand info coming directly from the Cases. (Seems I've heard that somewhere before. )