Gentlemen, hopefully this won't be too complicated a question but are there general rules of thumb for deciding what primer to use with what powder (based on load size or bullet weight or whatever)?

My dad used to get a 2" group to drop to 3/4" by using a magnum primer in his .270 (same powder/charge). It seemed like a fluke to stumble across such a result but maybe there is a sensible reason? Anyone know of any?

The free-for-all method of trying everything with everything seems like such a waste of time.
(obviously you need to follow the books but you get my point)

Thanks, Barry

quote:

Originally posted by BarryG:
Gentlemen, hopefully this won't be too complicated a question but are there general rules of thumb for deciding what primer to use with what powder (based on load size or bullet weight or whatever)?

Some say >70 grains of powder, use a magnum primer. Less than 70 grains, use a standard primer.

I've been using the "what the manual recommends for primers" approach. That seems to work pretty well.

I have noticed that I always end up using mag primers for spherical powders (usually under compressed powder situations).

I have always heard that you should use magnum primers for a 65 gr. or higher powder charge.

i use mag type primer with 65 grs. or higher. and also with ball type powder in the 30-06 class cases. everything else is WLR..

I have no rules of thumb for using primers except the large one go in the large holes and the small ones in the small holes and the large cartridges (based on the full length 300 H&H Magnum case) get magnum primers.

I've found that the particular type of prime frequently makes a significant difference in the accuracy department and that good accuracy doesn't always go along with the magnum primers with ball powder dictum or vice versa. If you aren't happy with a load, try different primers and sometimes it will make a difference.

For the most part I have always used Win-WLR primers for my loads. They have seemed to do the job on loads up to the belted mag sized cases. Even with some of the belted cases for the smaller calibers they have worked just fine and even better than some of the Mag primers.

If I worked up through a particular powers charge weights and didn't find the groups I was looking for, I sometimes would swap out the primer to another brand, but hardly ever went with a mag type.

The WIn's as a general rule always seemed to be a tad hotter than the rest, so that might be why they worked so well with so many different loads.

quote:

The free-for-all method of trying everything with everything seems like such a waste of time.
(obviously you need to follow the books but you get my point)

Yeah, we get your point. In fact, we all wish there was some secret way to make things work good without us having to. But ....

quote:

What Powder w/what Primer? Rules of thumb? Hopefully not too complex.

Interesting replies so far and I'd consider all of them valid.....or at least worthy of emulating.

Just one thing....always record what you used so you can reproduce it and always work up.

from there you're on your own.

I don't NEED a mag primer until my powder charge tops 70gr or is ball powder. You may work a load up, then swap a mag rpimer & see if groups tighten up (if near max, back off 5% & work back up). I have often found mag primers in smaller, medium burn rate powder charges decrease accuracy. In slower powders, increase accuracy. Your rifle will tell you.

quote:

Originally posted by BarryG:
...are there general rules of thumb for deciding what primer to use with what powder (based on load size or bullet weight or whatever)? ...

I use the old, Once I develop a Load with a Primer(or any component) continue using them from the same Lot until they are gone. Then re-develop the Load, or verify it with any New Lot.

Sometimes the Pressure goes down, sometimes up and occasionally it will actually remain close to the same when a Lot changes.

Best of luck to you.

If it's got a belt, I use a mag primer. If not, and it has a big hole, I use a large primer. If it has a small hole, I use a small primer.
I have tried using mag primers with standard loads and bench rest primers with standard loads and have, on occassion gotten small increases in accuracy. Sometimes, especially in hunting situations, not worth the extra expense. But I have never been fortunate enough to have a change of primers turn a pray and spray load into a barn-burning, one-holer.
IMO, it's kinda like adjusting your bullet jump. It may fine tune an already good load and make it slightly better (or worse), but it ain't gonna do a lot for a bad one.
Lets not forget, when we start jimmin' around, the new stuff ain't always gonna makes things better.

Rules of thumb

All ball powder - magnum primers
65gr + in 30'06 case - magnum primers
Reduce charge by 1 gr if trying magnum primer in a load that normally uses standard primers
I only use Fed 210 primers for all large rifles & F215 mag for large loads.

The idea that ball powder is hard to light, ergo, magnum primers, does not seem to hold true in the real world IMO. I've shot tons (slight exaggerateion for emphasis) of ball powder w/o a mag primer w/o a problem. Also, I have loaded up ammo in 90+ Okla temps that was fired in below 0 temps in Wy w/o mag primers that lit off and killed stuff okay. Maybe that's not cold enough to make a difference but if it's too cold, I ain't gonna be out there.