Is there any reason why you shouldn't use magnum primers?

I have been reloading rifle cartridges for a few years. I have used both small rifle and small rifle magnum primers in 223, 6mmbr, 30 carbine, and 300BLK. I have been using large rifle primers for .308 and 30-06 using "stick" powders like varget and 4895 and so on. I recent loaded up some 308 using w748 which is a ball powder. I had some minor hang fires. maybe 6 out of 50 rounds hade a quick delay.
The internets say you gotta use magnum primers with ball powder. I can confirm this to be true in larger cartridges.

So there are some circumstances when you need magnum primers. Is there circumstances when you have to use non magnum primers?

For SD numbers, with large primers, I've experienced better performance with 'softer' primers (cups and fire) such as Wolf or PMC large rifle primers.  Very good standard deviations in velocity...  Magnum primers have 'harder' fire and cups that can be beneficial igniting harder to start powders or running in semiautos with floating firing pins, and can help deter slamfires.

I use regular primers with large rifle primer cartridges, and use magnum or military primers in semiautos.  Small rifle primers I use CCI 450s exclusively, just because I got a deal on a million of them, and they work great.

Main thing is work up the load with that given primer and don't switch unless you work back up.

Thanks.
Naturally I work up a load with the chosen primer. I just wanted to make sure there isn't any circumstance where I shouldn't use LRM primers.   I think you told me what I needed to know. All my larger rifles are military PTR91, FAL, M1 Garand.

I plan to get a precision 308 rifle but I think I may use Lapua palma brass. If the primer pockets stay tight like the 6mmbr brass, the value would be hard to beat.

once again, thank you Heavies

Thanks.
Naturally I work up a load with the chosen primer. I just wanted to make sure there isn't any circumstance where I shouldn't use LRM primers.   I think you told me what I needed to know. All my larger rifles are military PTR91, FAL, M1 Garand.

I plan to get a precision 308 rifle but I think I may use Lapua palma brass. If the primer pockets stay tight like the 6mmbr brass, the value would be hard to beat.

once again, thank you Heavies

+1 on Lapua palma brass!  Been using those for a long time with CCI450s. They can take a lot.  Tight primer pockets on hot loads, in match chamber, with over 10x reloaded. Just need to anneal necks for long long life.


I found, however, I needed to ream out the flash hole for reliable ignition with 8208xbr.  Other powders may not need. Didnt affect SD numbers or accuracy by doing that. 


Another note, you 'll have to file down decapping pin diameter if you leave the palma flash hole laupa factory size.  Can't remeber if 6BR brass was the same way ...   

Thanks for the advise. Lapua 6br does infact have the small flash hole and I have a few of the special decapping pins. I believe that Redding dies came with both.

For SD numbers, with large primers, I've experienced better performance with 'softer' primers (cups and fire) such as Wolf or PMC large rifle primers.  Very good standard deviations in velocity...  Magnum primers have 'harder' fire and cups that can be beneficial igniting harder to start powders or running in semiautos with floating firing pins, and can help deter slamfires.

I use regular primers with large rifle primer cartridges, and use magnum or military primers in semiautos.  Small rifle primers I use CCI 450s exclusively, just because I got a deal on a million of them, and they work great.

Main thing is work up the load with that given primer and don't switch unless you work back up.

Interesting. I haven't had good luck with softer SRP like 400s. They heavily flatten and crater with the lighter loads. I use BR4s pretty much exclusively for my precision stuff. I use 400s and 41s for my carbine stuff. I did have 1 slamfire with a 400 but that is like several thousands of rounds of 400s. I can live with that.

You look look at SDs over ESs? I usually look at ES over at least a 10 shot string as a 8 is not acceptable for me.

Interesting. I haven't had good luck with softer SRP like 400s. They heavily flatten and crater with the lighter loads. I use BR4s pretty much exclusively for my precision stuff. I use 400s and 41s for my carbine stuff. I did have 1 slamfire with a 400 but that is like several thousands of rounds of 400s. I can live with that.

You look look at SDs over ESs? I usually look at ES over at least a 10 shot string as a 8 is not acceptable for me.

You should try cci450s I've had better consistency with 450s over br4s and 400s. They have a thicker cup than 400s and are cheaper than br4s and 41s too.

Interesting. I haven't had good luck with softer SRP like 400s. They heavily flatten and crater with the lighter loads. I use BR4s pretty much exclusively for my precision stuff. I use 400s and 41s for my carbine stuff. I did have 1 slamfire with a 400 but that is like several thousands of rounds of 400s. I can live with that.

You look look at SDs over ESs? I usually look at ES over at least a 10 shot string as a 8 is not acceptable for me.

Better to look at SD, statistically its the average of velocity dispersion across all rounds. The more shots in the series the better.  Still I dont discount ES, that could indicate problems in loading process or some other issue.  Single digits in both indicate a real good load. 

Velocity issues dont matter at 100 yards,  out to range it matters.   

You should try cci450s I've had better consistency with 450s over br4s and 400s. They have a thicker cup than 400s and are cheaper than br4s and 41s too.

+1

Is there any particular reason why you chose to use w748 for 308?? I'm going to guess either you have some already or your reloading progressively? As far as if you "need" to use a magnum primer, I would say if you need to use a magnum primer for proper ignition in any short action cartridge with powder fill <50grains, you probably need to re-examine some other factors such as the type of powder you are using. H4350, Varget, IMR 4350, R15 are all great options. The trend in the PRS and long range shooting community has been to switch to SRP as much as possible (hence companies such as Peterson and Alpha coming out with SRP 6.5 creed brass). Im no scientist, but it seems with the smaller/tamer ignitions with SRP, it helps with consistency vs. the violent ignition of a LRP or magnum primer. Other issues you can look at for hang fires are primer seating depth, if your powder has "clumped" or absorbed moisture, firing pin protrusion (usually not an issue), or if there are any obstructions within the flash hole prior to seating a primer.