500 Mag Large Rifle vs Large Rifle Mag Primers

Black Sunshine · Mar 23, 2019

I'm getting ready to load up another batch of 500mag. I'm loading 350gr Sierra, 460gr RN, and 700gr WC. The 460 and 700gr are from Matt's Bullets. Matt recommended I use magnum rifle primers. The same powder and charge is listed on a popular listing of 500 mag loads....except the popular page recommends a large rifle primer, not the magnum.

My prior 2 batches have used the magnum.

I'm interested in input regarding what the expected difference should be, assuming the same powder charge and bullet.

ruggyh · Mar 23, 2019

Use what the published load data calls for.

While you may not notice any difference you don't know the impact on peak pressure.

Contrary to what most think velocity is not an indicator of peak pressure, but is the result of total pressure under the pressure curve.

The closer you are loading to max published data the greater the odds the peak pressure has moved up.

Most would argue their guns has show no ill effect, I would preface that any damage done by marginal over pressure condition is additive (and unseen by visual inspection) and your gun is now simply not as strong as it was before, with continual over pressure will eventually lead to catastrophic failure.

In the end the choose is with the reloader as are the risk.

be safe
Ruggy

AManWearingAHat · Mar 24, 2019

I would stick to the manual. As the poster before me said, You have no idea what a magnum primer is doing for peak pressures.

I let the people who write the books for a living tell me what to do, rather than experiment on my own. In the end it’s up to you, but good load practice dictates we stay within the published data and components.

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iouri · Mar 24, 2019

CCI LRM is all I've been using in my 500 (about 1200 rds) and 460 (about 800 rds). I don't load to max; haven't had sticky extraction or flattened primers. YMMV.

buck460XVR · Mar 29, 2019

Contrary to many beliefs, whether or not one uses "magnum" primers, is usually determined by the powder, not the caliber. You do not tell us what powder you are using. Also, many times in very large straight walled cases with large volumes of powder capacity, a magnum primer is not as needed as in smaller straight walled cases like .357.

Hard to tell what the actual difference may be as there is a variance in power in primers also. One magnum primer may be a tad hotter than another. For most of us, substituting a magnum primer for a listed standard primer in a tested load is not going to matter much. It may give a tad more velocity, or a tad more consistency. In some cases it can do the opposite. If I was not a a max load, I wouldn't be afraid to use a mag primer instead of a standard primer if I had nuttin' else. If I was at max, and in the same situation, I'd probably back down my powder charge a hair. If I had standard primers as listed in the recipe, that's what I would use. You and others are free to feel and do differently.

Black Sunshine · Mar 29, 2019

The powder used in all loads in question is H110. Hogden, along with Matt's Bullets, recommends a Magnum Large Rifle Primer. Hogden only has info for the 350gr bullet (among those I listed). The "popular" listing recommends the non mag version of LRP for all 3 bullets/powder/charge I noted in OP.

Research shows that many say the magnum primer has the effect of 1 to 1.5 additional grains of powder...of course, there's no hard fast rule. Also there is discussion that large volumes of powder (seems like it was somewhere around 40 grains and up) may need the magnum primer to fully ignite the powder charge.

Thanks to all for the responses.

ruggyh · Mar 29, 2019

I use Winchester Large Rifle Primers (LRP) with H110 and have yet to have any ignition problems. That roughly 5000 rounds of 460 S&W a year and 1000 rounds of 500 S&W a year. (note I load another 1000 to 1500 rounds of 460 a year with other powders)

Don't try to down load H110 and you won't have ignition problems.

You can look a Hornady data and others and see the use standard primer- they also follow H110 powder rule don't load below 80% case fill.

If you insist on using Magnum primers work your loads up from the bottom and stop if extraction gets stick and back off.

As an aside you will find Magnum primers give poorer results in large volume large cross sectional area cases as the burn rate of the powder slows down.

I have yet to get good results in testing them with 4227 or 4198 in 500 S&W.

be safe
Ruggy

500 Mag Large Rifle vs Large Rifle Mag Primers

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Black Sunshine

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