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Old November 12, 2016, 08:51 AM   #1
oneshotone
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Join Date: November 11, 2016
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small rifle magnum primer

Hi Guys,
My first time on forum, please forgive this newbe.
Bought an H&R handi sb1 in 357 magnum, too good to be true $150.00 like new put some 125 gn factory loads thru it, would not stay in a 12" circle @ 50 ' no foolin! I throw stones bettet than that. Did some reading, bought a 0.381" reamer and proceded to create a 357 maximum from this distaster.Bought brass , loaded up to 24 grains of 1680 under my own 180gn jacketed RNHP(have swage press). Shoots 1.5" 3 shot groups from rest at 100 yd . All day long like grandma's chicken&biscuits!
Using standard small rifle primers. Would like to use small rifle magnum primers but the sb1 will not ignite them.
Anyone have info on a heaftier firing pin or pin spring for this rig?
Would really like to take it to full potential
Thanks, oneshotone
PS if you are looking for custom bullets, have .357,9mm,10mm,and .452 dies could make free samples, just about any bullet weight. Jacket or naked.
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Old November 12, 2016, 01:24 PM   #2
T. O'Heir
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Hi. Magnum primers have nothing whatever to do with the cartridge or its name. They're about the powder used, only.
However, if the rifle won't make magnum primers go bang, there's something wrong with the rifle. Despite what you might see on the internet, magnum primer cups are not any harder than standard primers. Difference is in the priming compound.
Anyway, Wolff Springs sells extra powder hammer springs for H&R Toppers/Handi-Rifles. https://www.gunsprings.com/H%20&%20R/cID2/mID27/dID131
The .357 Mag and Maximum use Small Pistol primers regardless of what they're fired out of.
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Old November 12, 2016, 10:19 PM   #3
Clark
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As I have said here before
I have come to the conclusion that reaming out to 357 MAX does not help much.
The full solution is to ream to 357 MAX, and throat out to where the bullet is just hanging on with the mouth of the case.
Take pointy bullets with boat tails and maybe I can lob one in on a deer at 400 yards with fast killing power. The 200 gr Nosler Accubond comes to mind.
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Old November 13, 2016, 03:46 PM   #4
Unclenick
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Oneshotone,

Welcome to the forum.

Smokeless gunpowder supplies its own oxygen, but not enough for 100% combustion. That's why there's carbon left in your bore. Because of the oxygen deficiency, if it isn't ignited properly and particularly if the powder is slow and has a lot of deterrent coating, it can actually extinguish if the there isn't enough starting pressure. That initial pressure comes from the gases from the primer. As you can imagine, in a large capacity case, like a magnum cartridge case, it takes more gas to reach that pressure than is required for a smaller capacity case. This is what the magnum primer provides. Extra starting gas for higher starting pressure. Additionally, over time, magnum primers have been made to generate hotter sparks for older spherical propellant formulations which are extra hard to ignite.

In your case, however, you don't have a case volume that is large for a rifle so you don't need a large volume of primer gas. All you need is something that produces enough gas for a magnum pistol case, and that turns out to be about the same as a small rifle standard primer produces. Indeed, either here or on the shooter's forum one member called CCI and asked them the difference between their magnum pistol and standard rifle and was told they contained the same amount of priming mix and so could be interchanged.

So, it turns out, you already have what you need. Going to a still hotter magnum rifle primer may actually deteriorate performance by unseating the bullets prematurely and irregularly with respect to the powder burn. It amy force you to use a little less powder to avoid excess pressure, and the resulting additional empty space in the case may hurt accuracy. They could also raise pressure by moving the bullet to the lands before the powder burns much, which can increase it by 20% or so. Moreover, unlike large primers, the small rifle magnum primers do have thicker cups and are harder to ignite, as you've discovered, though, I don't think a HR should have a problem with that. I would check the headspace. If that's fine, it is more likely you aren't seating the primer deeply enough to set the cup and anvil gap (bridge) properly because the thicker cups are harder to press into place (see this primer article).
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Old November 16, 2016, 04:33 PM   #5
oneshotone
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Join Date: November 11, 2016
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little primer,big subject

Hi guys,
Want to thank you for all the input! The more l read, the more apparent it is that I must learn a lot more. Am studying the info you suggested.
Found one more thing to check out, my H&R 357 MAXIMUM has a hammer induced firing pin travel of 0.040" all my other small primer rifles have 0.050" to 0.060" travel. I'm considering adding 0.015" travel to the H&R. The firing pin itself has a maximum stroke of 0.080" so I don't think it will do any harm and after installing the correct wolf spring it may like the cci magnum small rifle primer.what do you think?
Also I promise not to put any large diameter primers in my small primer pockets.
Thanks again, one shotone
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