Does the use of a magnum primer effect maximum velocity for a given bullet/powder combination? As I understand it, you will reach maximum pressures with less powder when using a magnum primer vs. large rifle primer. So with all else being equal, if you loaded to maximum pressures with a load using magnum primers and loaded to maximum pressures with a load using large rifle primers, which load should have a greater velocity?

I have only done a few comparisons of std and mag primers. From my limited experience, there really isn't much difference in velocity.

What is the issue, is what primer best ignites the powder you are using for the most consistant accuracy and velocity. There is also the issue of consistant ignition of some powders in low temperatures.

Personally, I use mag primers with ball powders, or large cases, ie those burning ~100 grs of powder. In cases using 60 gr or less of stick or flake powder, I use std primers. Everything goes bang and groups well, even in the dead of winter.

Basically what I'm saying is there are no free lunches in velocity, you have to raise pressure to raise velocity, and trying to fiddle around with primers to gain a minor improvement in velocity is a waste of time and money. If you really want more speed, get a longer barrel and/or a bigger case.

Paul H,
Thanks for the info. I suspected there wasn't enough difference to be noticible but thought I would get the opinions of others. The cartridge I am starting to experiment with is the 300 WSM. I'm thoroughly pleased with the cartridge so far but can't help tinkering around with it. A common afliction for us reloaders as I'm sure your familiar with. Case capacity is about 70 grains of extruded powder once you shove a bullet in it. Should a person be using a Large Rifle or Magnum primer with such a case?

In my 35 whelen ackley I set off 62 gr w/ a Federal 210, which is a standard primer. I don't know where the magic cutoff is in regards to going from a standard primer to a mag primer. Many folks use stds in the 375 H&H. When I had a 458 lott, I only used mag primers, but I was burning nearly 90 grs of powder in a long case with a large bore. Since the WSM is a shorter case with a small bore, I would expect it to ignite well with a standard primer.

There are so many things to fiddle and experiment with that it can drive you crazy. Primers are the last thing I fiddle with, and I've been so pleased with the Federal 210, that it is my standard rifle primer.

As a general statement, if I had a gun that was so finicky that it would require fiddling with primers to get it to shoot acceptably, I'd either sell the gun, or have it re-barrelled. Life is too short, and components too exspensive to justify that grief.

Since our graceous host has the opportunity and means to test all sorts of combinations, he has just such a primer test. I think its in the FAQ's, wander around here and you should find it.

In the days before I had access to such an illustrious hoard of knowledge as is present on this forum (brown nose over) I bought 1,000 federal magnum match primers for my 9.3x62 using no more than 60grs of extruded powder, but which might be slightly compressed. At present rate of use they'll last 5 years.

Seeing as the rifle is accurate and might get used somewhere cold I presume the worst I have done is to waste a small amount of money. The other cases I load for are 6.5x55 and 7x57 which I normaly use CCI LR BR and N150/N160 in. I'm about to run out of these, would it be silly to start using the fed mag matches in these? (reworking of course)

I occasionaly use rem 91/2s to distinguish between say 100gr and 120gr ballistic tips (CCI BRs and fed mag match - silver, rem91/2s - copper) I'm about to run out of 91/2s are there any better copper coloured primers for 6.5x55/7x57/9.3x62. I must admit I'm starting to get bored of reworking loads (my wife get's irritated too) so there would have to be a definate gain in changing anything. There have I answered my question?

[This message has been edited by 1894 (edited 05-31-2001).]

Jay,

I am loading the .300 WSM now and starting with Winchester's data: W760 powder and WLR (NOT the Magnum version) primer. I think given the length of the powder column a standard large rifle primer will be fine, and Winchester's are a little hotter than most anyway.

Pistol primers . . .

I buy the magnum primers (Federal) for all applications. Loading HS6 and H110 for 38 Spl. 357, 45 ACP, 44 mag. HS6 is bulky. Can't hurt to have a decent igniter for these loads.

You will get variations in pressure/velocity between mag and reg primers. That will affect accuracy, but it shouldn't drive pressures to dangerous levels, even in max. loads.

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PowderBurns Black Powder / Muzzle Loading Forum:

www.hotboards.com/plus/plus.mirage?who=powderburns

I shoot a bunch of 338's (surprise!!!) Best primers seem to be Federals. I've done a good bit of testing and shooting with 210's, 210M's, and both the 215's. The highest velocity I get is with the 210M's behind RL22, regardless of rifle. Not by much, 10 fps, but I've checked the same load, same gun, same day, one first then last, and 210M's not only give the higher velocity but the best accuracy with that powder in several guns.

There is too much variance in too many of the factors that influence ignition of the powder in a case. Sort of like a hammer blow. Some hit hard and some don't. Then some burn hotter, or longer, or different. I don't believe there is much predictability in what any combination will do. You just have to experiment and go with what works well. Bob

From my limited experience, I agree with Paul H that there's little difference in velocity. But I found that there is a substantial difference in accuracy when magnum primers are used in smaller cases where they aren't necessary, such as the .223 -- the magnum primers are considerably less accurate. I use regular -- non magnum -- Winchester WLR primers even for the 375 H&H, and this seems to give better results in terms of accuracy. For large capacity relative to bore size cases, such as the 300 Weatherby, magnum primers do seem to give better results.

My experience is fully in line with Paul H and LE270. There is little real difference between "standard" and "magnum" primers, but what little there is is usually in favor of the standards.

What little effect a magnum primer has is to make the powder act as if it has a faster burning rate. Think about it. The initial flash generates more heat and expanding gas and presumably starts the powder burning more quickly. The pressure curve must necessarily be a little sharper with magnum primers, and therefore the pressure-velocity ratio less favorable.

I even use standard force primers with WC 872, an extremely slow surplus ball powder, in a 7mm STW. Have never experienced anything but perfect ignition.

When cases start aproaching a compressed load, I find that a magnum primer is worth about one and a half grains extra with bullets of 150 grains and up. Lower loads with more airspace does not have this much of an effect.

Bob338,
What 338s do you have?

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Gerard Schultz
GS Custom Bullets

Having followed this thread so far let me change tack slightly; I've been advised to always use Match primers in stead of Large Rifle on the grounds that they're of better quality and will perform more consistently.

Any views on this please?

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By all means always use the match primers. Your contribution to the profit margin of the manufacturer will help keep the regular primers (which are identical to the match primers, but packaged in a different box) more affordable for the rest of us.