Primers .... Magnum or Standard

Muttt

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I just realized that I used Magnum primers in my last batch of .308 reloads. I have 7mm Rem Mag so I use Magnum primers for those. And, I use standard large rifle primers in my Grendel and .308. My question is this. How much of a difference does it make in powder burn rate, pressure, velocity accuracy etc ...... when switching between standard and magnum primers??
 

lessthanfour

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Re: Primers .... Magnum or Standard

im not sure but my pops made a batch of 100 .223 using magnums that shot sub moa, didnt chrono them.
 

Beef82

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Re: Primers .... Magnum or Standard

Not much usually. Might make more in cold temps or with ball powders. Shouldn't cause problems unless the load is near the ragged edge pressure wise. Accuracy could go either way.
 

ChrisGarrett

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Re: Primers .... Magnum or Standard

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Muttt</div><div class="ubbcode-body">I just realized that I used Magnum primers in my last batch of .308 reloads. I have 7mm Rem Mag so I use Magnum primers for those. And, I use standard large rifle primers in my Grendel and .308. My question is this. How much of a difference does it make in powder burn rate, pressure, velocity accuracy etc ...... when switching between standard and magnum primers?? </div></div>

Speer and some other guides like to use magnum primers with ball powders, for even middle grade cartridges.

If you were already pushing redline with these loads, using standard primers, you might have an issue. If you're in the middle of the pack, I wouldn't worry about it. Shoot one and check for pressure signs.

Chris
 

Kinsman

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Re: Primers .... Magnum or Standard

The Sierra Ballistics Technicians tell me that magnum primers can make as much difference as one or two grains of powder. I use a lot of magnum primers, but I start with them and work up the load as usual.
I would not start with a load I had already worked up to it's max, and then go to magnum primers.
Otherwise, you got magnums, use them.
 

SpeedyR

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Re: Primers .... Magnum or Standard

without know the powder and load it's hard to say but as others have said, unless you are close to maximum loads, it shouldn't be a problem as far as safety goes. as for accuracy it's hard to tell. i play with some smaller centerfire rounds (22hornet and 218 bee) and it's funny how many options people run in primers. some run small rifle, some run small pistol (yes in the rifle cartridge) and some run SR mag primers. whatever works best for you but watch for pressure signs and go from there.
 

BuzzBoss915

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Re: Primers .... Magnum or Standard

I think that is a mistake that should never happen. We cannot be casual about ANY component; oops! wrong bullet, oops! different powder!

Unless, as mentioned, very cold conditions or really hard to ignite spherical powder. I have shot 300WinMag for many years and have always used the standard Win 120 8½ primer.

I agree with the slacker; start with mag primers for a special application, if you must, because switching at the last moment could cause serious and unexpected problems.

So, your question:

"How much of a difference does it make in powder burn rate, pressure, velocity accuracy etc ...... when switching between standard and magnum primers??"

A poor choice of words: "switching". If you have a reason to develop a load with mag primers, that's fine, but switching, as you did, is a no no. BB
 

MALLARD

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Re: Primers .... Magnum or Standard

+1 doesnt do much

i think it effects accuracy more then anything , the "events" recorded by my pressure trace machine looked better or worse with different primers ,but i didnt notice any huge change in exit times, pressures, or velocitie
 

Muttt

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Re: Primers .... Magnum or Standard

Well, it's not as bad as it sounds. I was working up a new load for my .308. I have a little bin with my large rifle primers in it. I grabbed one and loaded 100 brass. After I already loaded the cases, and I went to toss the empty box, I realized it was a box of magnum (how it got in the wrong container .... who knows) primers. Now, I wasn't about to go and tear down 100 rounds and then decap them all with live primers. So, I just went ahead and ran them through my rifle. My begining load was mininum and my end load was .5 gr from max. So, I wasn't pushing the edge or anything. And, it wasn't that I took a good known load which was hot and then put in the wrong primers. In that case I may have unloaded them.

I just wonder what difference it made in my loads. Since the min is 40 grains and the max is 44 grains ... and my most accurate loads came in between 40gr and 41.5gr, I was wondering what effect the primers actually had on my loads. Hope that helps explain it a little. If I were to use standard primers, would my better loads be with 41.5gr to 42.5gr????

Now, since my first batch was with magnum primers, all my other loads are using the magnum primers. So, there isn't an issue here. I'll just keep using magnums. But, I don't have alot of magnums to use (I know .... go buy more). So, if I were to go back to standard, how much would that effect the accuracy, velocity, etc ..... See where I was originally going with my question.
 

BuzzBoss915

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Re: Primers .... Magnum or Standard

I think so? What you should be aware of is the intensity of the primer discharge will affect, (somewhat) the burning rate of your powder, in most cases, the powder will burn faster than what it should, so, if you were using IMR 4350, it could burn like 3031, with a mag primer. I just made that up, and it is a way extreme example, but the trend will be faster and if that's okay, suits your purpose, then it doesn't matter much. But, it could result in degraded performance as far as velocity?

I'm trying to answer your hypothetical question. You never mention the powder, so who can say if the magnum primers would help or not hurt the performance? Primers are cheap, don't use them in a 308, if you don't have to because you might find very little data for that case, powder, bullet and a mag primer.

I know a few predator hunters, (thousands, actually) but some live in Canada, and they might have a large supply of H380 and hunt in subzero conditions. Hypothetical only, I don't know that, for a fact? Anyway,it would make sense to use magnum primers or suffer rather degraded performance/velocity, and there goes your ability to hit what you are aiming at, at far ranges. That is an example of why you would want to use magnum primers when they are not needed, in most applications. Unless, (of course) you are trying to light 100 grains of slow burning powder?

It's not that big of a deal, as you say, but I would end it at this point and use the data as comparative, and get back to a standard large rifle primer; were I you. BB
 

Smith44699

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Re: Primers .... Magnum or Standard

I sometimes work a load up with them. I find sometimes that give a better velocity deviation. So maybe a better pressure curve. Especially when a load has vertical stringing. I will back off 10 percent and work back up to the load. It has worked for me several times. So with my experience with them. If your are not max or over. You probably won't even notice. Groups may get better. They may get worse. I would shoot them and not look back. If you do a google search on this topic you will come up with a lot of good information. Just my .02.
 

Muttt

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Re: Primers .... Magnum or Standard

Well, I have to start over working up my load. So, I'll just go back to standard primers. Up till now, I kept using them since I didn't want to change anything mid test. But, since I'm starting over. I'll start over with standard primer. Once I find the right load, I may load some of each later on and compare and see how much of a difference it makes.