Another 10mm question

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Intel6
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Re: Another 10mm question

#16

Post by Intel6 »

I swear I commented on this specific question? Was it on another forum?

Usually LP magnum primers are used when you have a large case full of slow burning powder that you need to get ignited. We are talking large cases like .44 Mag and .45 Colt and larger. When you have those cases filled with slow burning pistol powder like Win 296 or Lil'gun you need the Magnum LP to get it going. The 10mm case does not have the large case volume of the magnum revolver rounds and I don't see why anyone would think they need a LPM primer for the round? I think some people just assume "it has to be better/needed" without any real evidence. In this case more isn't always better.

Many people do not realize that sometimes using primers that are too powerful for the case volume can cause problems. This happens in small capacity rifle rounds like the .22 Hornet. SR primers are made to ignite 20+ grain charges of powder so when they are used in a small cased (small case volume) rounds (around 10 grains of powder) the initial blast unseats the bullet before the powder has been ignited and then the powder ignites. So the bullet gets popped out of the case neck, slows down when it hits the rifling lead and then gets hit by the pressure of the burning powder. So rather than the pressure building and gradually pushing the bullet out of the case, into the rifling and down the barrel it slams into the slowing bullet and has to get it going again. This causes problems with the pressure curve and spikes it. Many people who load small cases like the Hornet have found that using small pistol primers (less powerful) results in much better accuracy. Remington actually makes a small rifle primer (Rem 6 1/2) that is less powerful just for small cased rifle rounds. That is all I use in my small cased rounds like .22 Hornet, .218 Mashbrun Bee and .17 Ackley Hornet.

Anyways, to get back on track:

In the case of the 10mm a lot of experienced 10mm reloaders have found that the CCI LPM primers have caused pressure spikes/problems when working with the high end 10mm loads. As a result it is common practice to use the regular CCI 300. I have standardized on the CCI 300 LP primer for all my 10mm loads and while I do have CCI 350 LPM primers I only use them for my .458 SOCOM loads.


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Intel6
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Re: Another 10mm question

#17

Post by Intel6 »

Also wanted to comment on the drilling out of flash holes in cases. The inference is that drilling the flash hole bigger helps with ignition or makes a loaded round more powerful?

I will put this out on its own line to make it clear DO NOT USE CASES WITH DRILLED OUT FLASH HOLES FOR LOADING REGULAR FULL PRESSURE ROUNDS.

Drilling out flash holes is only used in loading extremely low pressure rounds like blanks, wax bullet loads or what are commonly known as "cat sneeze" loads. In these types of rounds the primer backs out because it is trying to get all its combustion pressure out the small flash hole and the back pressure in the primer pocket pushes back on the primer and there is no reward pressure of the cartridge to re-seat it (see below). The primer backing out causes problems with the function of the firearm so you don't want that. The easy solution for these rounds is to drill out the flash hole so the primer pressure flows into the case with no backpressure on the primer and it stays fully seated.

When a loaded round is fired the pressure in the case not only pushes the bullet out the barrel but it also tries to push the case rearwards. Pressure follows the path of least resistance and flows back through the flash hole and tries to push the primer out. Because of the high pressure the whole case pushes back against the breach face sealing against the pressure and the primer stays seated. Realize that the brass case and brass primer are a "system" designed to seal that pressure from going rearward. The primer is sealing against the pressure and that is helped by the small flash hole restricting the pressure it has to deal with. If you open up that flash hole it lets more pressure back through to the primer and that small thin brass cup is the weakest spot in that case/primer "system" so it will be the first to let go.
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Boriqua
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Re: Another 10mm question

#18

Post by Boriqua »

Hey Intel6 .. I swear it wasnt me who asked!!
Having said that .. thank you for chiming in! You are one of the guys I always hope to hear from when the subject of making your own ammunition comes up.

I have pulled back from the local boards for the most part because the ratio of Stupid stuff to good useful gun talk and information is skewed the wrong way for me and I will admit to some times being sucked into the stupid void!

Keep posting though as I love to follow along!
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Intel6
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Re: Another 10mm question

#19

Post by Intel6 »

I would have sworn it was you, it was the same question, 10mm & magnum primers? Anyway, I am always willing to help out with questions. Especially when someone like you with a genuine interest asks. I have been reloading for 30+ years now and always say if I can cut down someone's learning curve and/or keep them from hurting themselves then I need to do what I can to help.
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Flash
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Re: Another 10mm question

#20

Post by Flash »

Only 30+ years? You're a newcomer.

At this point I'm at 65 years.

Seriously though, you are one of the few knowledgeable ones. There are a lot of experienced reloaders, been at it a long time, but very few knowledgeable ones.

Boriqua will end up being a knowledgeable one.

BTW, I didn't feel moved to do a complete primer (pun intended) of primers as I've encountered some hostility in the past when doing things like that, but I'm sure some here will end up reading and learning from what you wrote.
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ex462
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Re: Another 10mm question

#21

Post by ex462 »

I have a new sealed box of Nosler 135 grain 10mm hollow point.to whoever can use them.Located in east Mesa Send a PM and you can pick up.Had them for years and will never use them.
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Re: Another 10mm question

#22

Post by Viperdisorder »

Good info, the cci primers are far better, seem to have better shelf life as well
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