Magnum primers?

BHuij

Active Member
When working up LV loads with 30 cal cartridges like .308, .303 Brit, 7.62x54R, etc., one of the problems to overcome is what to do with all the case volume you're not filling with powder. Using a slow rifle powder like you would for a regular-velocity jacketed bullet tends to give uneven, dirty burns because those powders are more likely to perform inconsistently at low pressures, and are often more position sensitive.

I'm assuming this is why most accurate LV loads use faster-burning shotgun, pistol, and magnum pistol powders (i.e. Unique, Bullseye, 2400, 4227, Red Dot, etc.). They burn fast, clean, and efficient in lower quantities compared to a slow rifle powder, and they tend to be less position sensitive.

My question is... how much does it buy you to use a magnum primer instead of a standard one? Magnum primers are hotter and higher pressure, so in theory you might be able to use a slightly slower powder without getting an uneven burn, right? Mind you, this is still for a LV load. But let's say in a .308 casing, instead of using 4227, could you use something like 4198 if you switched from a CCI 200 primer to a 250? Theoretically the slower burn of 4198 might be able to give you the same velocity for less pressure and/or a smaller charge, potentially increasing both accuracy and economy for LV loads.

Just thinking out loud here. If someone detects inconsistencies in my reasoning, I'd love to learn.
 

JWFilips

Well-Known Member
I have always found the use of Large pistol or Small pistol primers give you better consistancy with Low velocity load with fast powders
 

fiver

Well-Known Member
with my 'medium velocity' [1800-2,000 fps] loads I have seen enough of a difference between a rifle and pistol primer to try both.
I have also seen I could duplicate accuracy with either one but at a different powder volume.

at 100 yds it's been a toss up and no advantage to one or the other.
now maybe at 2 or 300yds I could see something different.

I think you'd be looking at maybe a mag primer helping with some of the too slow/low for them pressure powders, I have seen it help with some mediocre loads in almost magnum revolver loads.
any advantage it could have provided was totally negated by simply adding another grain of powder and it showed on the paper.

as far as why the fast powders for the low velocities.
it's simply a matter of that's the best, most efficient, lowest cost way to get there.
if you try using a tooo slow powder such as 50 BMG or H-860 your not going slow any more, it just doesn't work like that.
try 3031/1680 whatever and yu run into too many ignition problems even with a hot primer.
it isn't the primers fault your just killing the powder with not enough pressure and your not igniting any of the powder efficiently.
you could position the [fast rifle/slow pistol] powder against the primer like you do with a medium burn speed rifle powder [shrug] which would help any velocity variations the ignition problems caused, but then your back in the position of why bother?, a pound of red-dot is 20$.
 

Chris

Well-Known Member
Fiver pretty much laid it out. In my experience avoid mag primers with cast unless you need them, typically for slow powders and special circumstances. Some experimentation required.
 

BHuij

Active Member
Pretty much lines up with what I understood. Thanks for the clarification.

Main reason why I asked is way back when I first got into casting and loading for rifles, I only had one rifle, my Mosin. I got a little overzealous and ended up accidentally buying a bunch of CCI 250s instead of regular 200s for it, since I didn't fully understand the difference at the time. I still have like 600 of them and I wondered if I could turn a mistake into an advantage.
 

462

California's Central Coast Amid The Insanity
Frugalness forbids me to use a large amount of a slow powder, to achieve and satisfy my rifles' low velocity wants and needs, when a third of the amount of a fast powder is all that is required. Thus, other than with handguns, have not experimented with magnum powders.
 

BHuij

Active Member
Well the hope was that I could get a little more accuracy by achieving the same 1400-1500ish velocity with less pressure (and theoretically less deformation as a result). Besides that it seemed like a slower powder would get to the same velocity with less powder than a fast one, but that seems to be the opposite of what people are finding.
 

fiver

Well-Known Member
you can get kind of down there with a medium speed rifle powder but it will need a filler to be worth a hoot.
good news is H-322 needs a filler to do well either way but has the potential to make 1600 fps and be consistent.
try like 23grs of that and 1.5grs of Dacron with a mag primer and a gas check bullet.
you'll have a little fat powder column to work with.
 

BHuij

Active Member
Good to know. 1600 FPS isn't a velocity target that offers me anything over shooting slower for non HV loads, so it doesn't really make any sense to spend more on 23ish grains of H322, when 13 grains of Red Dot puts a hole in the paper just as well at 100 yards ;) Like you said, Red Dot is cheap and gets the job done for LV.
 

fiver

Well-Known Member
yep kind of a waste when you use less than that for a good accurate 223 varmint load.