boisepaw
boisepaw
If I can't find regular Federal large rifle primers, is there any downside to using the magnum primers? What might be the problem with doing that?
Don’t know the answer, but I accidentally purchased 4 magnum rifle primers. Will sell at 1/2 price
If I can't find regular Federal large rifle primers, is there any downside to using the magnum primers? What might be the problem with doing that?
The only time this is really necessary is if you're already running on the hot side (eg, close to max). If you're running the more tepid loads most reloaders favor, it's unlikely that magnum primers are going to make much of a difference at all.You can use them but should start load development over to be on the safe side.
You can use them but should start load development over to be on the safe side.
A magnum primer ensures that slower burning powder (widely used in magnum loads) will burn more efficiently. There is a measurement called "brisance" which is basically how much fire comes out of the primer...more for magnum to set the slower powder to burn better.
Secondary is the harder or tougher primer cup to allow a bit higher pressure before blowing a primer which adds about 3 to 5 more grains to your load. So if you use a 30 grain load for example you need to subtract 3-5 grains from your load. I use to have a chart chart that laid out the brisance and psi ratings for small and large pistol and rifle by manufacturers. I will see if I can find it.
The only time this is really necessary is if you're already running on the hot side (eg, close to max). If you're running the more tepid loads most reloaders favor, it's unlikely that magnum primers are going to make much of a difference at all.
I don't believe it without a link. The only ST article I could find on the subject didn't say anything resembling any of this.But that also means it could.
There was an article online, IIRC from Shooting Times, that did pressure testing on exactly the same load, with just different brands of primers and both Standard and Magnum.
For lowest to highest pressure, but just changing primers, was something neat 15,000 psi.
It's almost certainly fine unless you're at or near max. Even then, you're probably fine given how conservative most loading manuals are. That was literally my first answer. Run a small test batch, verify, and then move on.Say for instance someone is using near max loads developed for a firearm that is already at the design limits for controlling pressure. A small increase in pressure that stems from the use of a magnum primer could yield catastrophic results to the user or wreck and damage the firearm without taking the correct precautionary measures.
You understand small magnum pistol primers are a thing, right? Ironically, my box of large pistol primers says explicitly "good for magnum or standard loads".I don't know anyone who is using a large rifle primers in a 9mm cartridge which is out of the realm of the op's initial question.
You understand small magnum pistol primers are a thing, right? Ironically, my box of large pistol primers says explicitly "good for magnum or standard loads".
I don't believe it without a link. The only ST article I could find on the subject didn't say anything resembling any of this.
Most people get a 50fps or so velocity boost from a magnum primer. There is no way that's 15k psi. Otherwise you'd have the entire USPSA community shooting 9mm major using SPMs.
I'm not saying don't run a small test batch to check for pressure signs, but starting from scratch is an extreme reaction to a primer change.
We heard a number of requests to add a primer chart in the Speer manuals I wrote showing what the various primer makers call their primer types. Note that there are no such charts in my books. Why? First, switching primer brands from what we used in the manual could create an unsafe condition.
We have a classic case study in the .22 Hornet. For years Speer used Small Rifle primers in the Hornet. When I shot some of the data for Speer Reloading Manual Number 12, I found too many propellants that were so rangy they would not meet my standards for publishable loads. As a result, we did not show very many propellants for the Hornet, and the velocities were rather modest.
While I was developing the .22 Hornet 33-grain TNT HP bullet, I tried Small Pistol primers, knowing from the 9mm experience above that such a light bullet could be unseated by primer power alone. I'd talked to a number of handloaders who were getting better accuracy with Small Pistol primers, and I wanted a look at the concept in a lab setting. Sure enough, switching to Small Pistol primers reduced the variations in pressure and velocity and also reduced average pressure. The latter let us safely run the charge weights a little higher for velocities more appropriate to the Hornet. Manual Number 14 shows many more Hornet loads with better velocities, thanks to Small Pistol primers.
As I said, the one I was talking about, I have not been able to find.
But this from another thread:
https://www.shootingtimes.com/editorial/ammunition_st_mamotaip_200909/100079
Here we have a situation where lower pressures gave higher velocities.
You could have higher pressure spikes, but lower average pressure, so not see major changes in velocity.
We have a classic case study in the .22 Hornet. For years Speer used Small Rifle primers in the Hornet. When I shot some of the data for Speer Reloading Manual Number 12, I found too many propellants that were so rangy they would not meet my standards for publishable loads. As a result, we did not show very many propellants for the Hornet, and the velocities were rather modest.
While I was developing the .22 Hornet 33-grain TNT HP bullet, I tried Small Pistol primers, knowing from the 9mm experience above that such a light bullet could be unseated by primer power alone. I'd talked to a number of handloaders who were getting better accuracy with Small Pistol primers, and I wanted a look at the concept in a lab setting. Sure enough, switching to Small Pistol primers reduced the variations in pressure and velocity and also reduced average pressure. The latter let us safely run the charge weights a little higher for velocities more appropriate to the Hornet. Manual Number 14 shows many more Hornet loads with better velocities, thanks to Small Pistol primers.
This perhaps? Goes back a ways.
I remember this article in relation to what can prove to be BIG swings given component changes. And however otherwise helpful, a chronograph can't show them, any more than an X-ray measures heart rate.
http://kwk.us/chronographs.html