Sorryifthis has come up recently here, but has anyone seen any noticeable difference (in FPS) in using magnum primers? I reload for .204, .243, .270, & 45-70 & would like to know if it will make any velocity difference if i switch to mag primers? I know it may cause a change in accuracy (good or bad), but i can work on that. Thanks -

Ben

Almost always I have seen an increase using mag primers. But I have sometimes seen a accuracy increase using std primers even in guns like the 300Win mag or RUM.

I tried some mag primers in my 308 once cause I ran out and accuracy was horrible but velocity up.

Generally, you want mag primers for powders slower than 4831 and regular for things below that IMO. I have never had good luck shooting mag primers for powders like 4064 or varget or even 4350

I think you will generally find that accuracy is the best with the proper primer for the case capacity of the caliber. I use Remington 9 1/2's (coldest primer) for small calibers like .22-250 and .243, Winchester and Federal standard primers for medium cases, and Federal 215's for calibers that hold more than 80 grains of powder. There are exceptions, though. Only problem with using a "cooler" primer with a large capacity case is that, even though it may turn in a good group on a warm day, cold weather ignition could be an issue at a most inopportune time.

Follow the data provided in the loading manual and you can't go wrong. Switching to magnum primers may increase pressures to unsafe levels with established loads using standard primers. Most manuals recommend magnum primers for use with spherical powders such as h380, 748, etc.

use what the powder manufacturer recommends for the powder... I used to use them for anything slower than say,H414 or 760, RL15, etc... but the case capacity or bullet weight does not always demand it... and I found I had better accuracy results in a couple rifles without them..

if you are dead set on using them, don't switch once you have a load worked up.. work up the load with them..

I use magnum primers in standard calibers when my velocity does not encrease with increased charges, I am going to hunt in very cold weather, or using ball powder. Good luck

I have seen velocity increases, decreases, and no changes at all due to the use of magnum vs standard primers. The effects of one over the other seem to depend on case capacities and powder type.

So far, the only round I have used magnum primers in exclusively has been the .416 Rigby, due to its huge cavernous case capacity. Perhaps some day I'll chronograph some loads in the .416 with standard primers, but I'm a little leery of hangfires with large charges of slow ball powders like AA8700....

I was out at the range yesterday watching a buddy of mine shoot a 300 Ultra Mag. Hewas shootingsome hand loads, using a healthy charge of Retumbo, that he decided toload withsome CCI regular large rifle primers. Got a bunch of hang fires. Almost got to be funny after awhile. After checking the bolt assembly, I suggestedhe try some other loads. Both factory ammo and handloads loaded with theFederal 215's gave 100% reliability.

Another use for them in medium sized cartridges is with ball powders which are more difficult to ignite.

No. Regards, Rick.