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Secondary explosion effect

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Secondary Explosion Effect, or S.E.E. seems to occur when a "slow" powder is used and the powder charge reduced to below 15% of max. This will cause the powder to detonate rather that burn at the prescribed rate.

I get lots of phone calls about "IT". Everyone seems to have a different theory on its cause, but there is no doubt what the effect is if "IT" happens. Total destruction is the standard result. However, as I have stated many times; no one really knows why S.E.E. happens, and it cannot recreated upon demand.

File:Explosions.jpgThe most interesting call was from a powder company ballistics laboratory technician. He really only called to say that I was correct. All the possible reasons for S.E.E. are only "theories", just as I stated.

A few years ago, one of the major powder companies set about trying to create S.E.E. They loaded, and then loaded some more, and nothing happened. They tried up to 25% reduction in max loadings, and still nothing. They tried powder tipped forward in the case; they tried it tipped back to the rear of the case. They tried standard primers, and they tried magnum primers; and they still could not make "IT" happen.

Then, while they were doing the tests, they got a call from a customer who had just blown up his gun, with only an 11% reduction of powder. They tried the same identical recipe that he used to blow up his rifle, and nothing happened. The only conclusion drawn was that S.E.E. can happen, but there is just no way of knowing when or at what point it will happen.

He had another thing to add, and that was that S.E.E. does not just occur with "slow" powders, but can and does occur with fast powders as well. His experience has been with "Cowboy Action Shooters", who are loading small charges of fast powder.

Apparently, when even small charges are loaded into relatively large cases like the .45 Long Colt etc. these charges will "detonate". And that is what S.E.E. really is, "detonation" of the powder charge rather that burning.

Another thing that was causing guns to blow up was in those large cases with light charges, they could be "double-charged". There is enough room to get two charges in the case and not really know it. So, when seating the bullet, no undue problems are encountered in bullet seating. But when fired, the gun comes apart.

On a further reloading note, the reloading of METRIC cartridges should not be neglected. Metric designations are of European persuasion, and it is just how they name their cartridges.

There are a real host of them, but the most popular ones are, the 6.5 Jap. 7.7 Jap., 6.5x55 Swedish, 7x57 Mauser, 7.65 Argentine Mauser, and .303 British. Along with the ever-popular 8x57 Mauser, 8x60S, 8mm-06 (Wildcat), and several of 9.3 cartridges, there are plenty of metrics to work with.

The 6.5 (.264 dia.) and the 7mm (.284 dia.) are certainly the most popular. All the major bullet companies make a great selection of bullets for them. The new .260 Remington, which is a 6.5 (.264 dia.) bullet on a .308 case, has put even more light on the metric 6.5 calibers.

The 7mm group of cartridges is one of the worlds greatest. From the old 7x57 that Karamojo Bell shot elephants with clear up to the new 7mm STW. Just pick and choose the one you want, and load anything from 100gr. to 174gr. bullets. Our American 7mm Rem Mag and the 7mm-08 are direct descendents of the early 7mm cartridges.

The 7x64 Brenneke continues popularity to the point that now Speer Nitrex is even loading a 160gr. Grand Slam for it along with a Federal loading a 160gr. Nosler Partition. Also, our .280 Remington is a direct American version of the 7x64.

The 7.65 Argentine Mauser is on the 1909 Mauser Action, which is prized by many custom gun builders. I have shot the 7.65 possibly more, than any of the metrics, except maybe the 8x57.

In fact, I have one particular 7.65 that shoots so well and consistently, that I took it to Zimbabwe for use on plains game. It absolutely loves the Hornady 174gr. bullet, and I took impala, warthogs, and even kudu with it. That 174gr. bullet at 2,500 fps, worked just fine.

The .303 British uses the same .311 or .312 bullets and it is a very popular cartridge. Hornady loads it in their Custom Ammo and also loads it in a "Light Magnum" load. Federal Cartridge must agree, because they now load it in a "High Energy" 180gr. Bonded Bear Claw at 2590 fps.

The 8x57 Mauser is fun and easy to load as well, now that wee are finally getting some "good" bullets for it. Most of the original 170gr. round nose bullets offered for years are too fragile for anything bigger that a small antelopes, and the factory loads are really under loaded.

If you want to try something unusual, try some Remington 185gr. Pt SPCL bullets that are available from various mail order catalog companies. Load those in your 8x57, or 8x60S. They are made for the 8mm Rem Mag, but work perfectly at the slower non-magnum velocities. We have had particularly good success in the 8x60S on plains game.

The 8mm-06 is a very popular conversion, and really makes the 8mm into a fine hunting round. With the great bullets available now for it, like the 200gr. Speer, 200gr. Nosler, and the various Barnes X bullets, it will do anything the 30-06 will do and a bit more. If you want to make a short belted magnum out of it, try an 8mm bullet in a .338 Mag case. Remington is now loading a 200gr. Swift in their 8mm Rem Mag., which is exactly what that cartridge needed.

The 9.3‘s are a great BIG game round. You can shoot those .366 bullets in a 9.3x57, 9.3x62, 9.3x64, and the 9.3x74. Speer makes a 270gr. Semi Pointed Hot Core; Barnes makes a 250gr. and 286gr. X Bullet, and a 286gr. Solid Round Nose. Nosler must think that the 9.3 is the new hot ticket, because they just came out with a 286gr. Partition.

Getting dies is not a real problem, as RCBS and C-H Tool, seem to make them for about every caliber ever conceived. They are a bit expensive, but worth the fun you can have.

When loading ANY of the METRICS, be extra careful of the gun you are going to put it in. A lot of those are on old military actions, and you should not try to ring out the last little bit of velocity.

Really, you just load them just like any other common cartridge. They need nothing special except the proper dies and bullets. All of our common powders work just fine along with normal primers.

Terry Blauwkamp is a lifelong hunter and a veteran of many African safaris. His reloading expertise extends beyond the standard American calibers to metric and classic African calibers.

So if you come across a special gun, or a just want to load one you already have, don’t be timid… go for it just like any other cartridge.

Feel free to write to Terry at if you have any questions or comments.

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