RNFP vs. SWC and detonation with a levergun

W

wiiawiwb

New member
I have a Rossi 92 levergun and have been reloading for it using MBC 255 gr SWC. I also have 250 gr RNFP that I could use.

I was wondering about various bullet profiles when loading a levergun. Since the bullets are loaded one behind the other in the tube, with a RNFP could there be a detonation of the primer in the bullet in front of it upon shooting recoil?

The SWC profile seems to have a wide enough flat nose for that not to happen. What about the RNFP profile, could that unexpected detonation occur?
 
You didn't ask, but sometimes SWC nose profile doesn't feed too good in a '92. I have used RNFP for years in my lever guns with no issues of feeding or magazine tube detonation.
 
Primer detonations ARE possible with a roundnose lead bullet.

The determining factor is HOW rounded.

If the tip's narrow enough to transmit energy inside the primer pocket diameter, then you may have a problem.

Helps to hold a candidate bullet against the primed case & see.
Denis
 
Here are the exact bullets I have. One is a SWC while the other a RNFP. The SWC feeds and ejects through my Rossi 92 without a hitch.

http://missouribullet.com/details.php?prodId=210&category=20&secondary=14&keywords= - The flat head is 8cm across.

http://missouribullet.com/details.php?prodId=246&category=20&secondary=14&keywords= - The flat head is 6cm across.

The primer pocket measures 5cm across.

Now that I've measured them, I don't see how the RNFP could never enter the primer pocket while horizontal in the tube.
 
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And that's what you need to do to determine safety.

If the nose of the bullet is too wide to strike the primer with enough energy to ignite, you should be good.

Denis
 
The old R-P 150gr PSP 35 REM load was a scary one to consider in a tube fed gun. I think Remington addressed this on their rifles with spiral impressed on the mag tube to keep the bullet point off of the primer. Never saw this on a 336 though. Our local Walmart would only stock this load for years, I don't think it's even offered anymore.
 
It helps to understand why it is possible for a round in a tubular magazine to be fired by the bullet point of another round. It does take a certain combination of bullet point, recoil and the number of rounds in the magazine.

When the rifle fires and moves back from recoil, Newton's law says that the cartridges in the magazine try to stay where they are, so if they can move forward, they do, compressing the magazine spring. Then, as the rifle stops moving, the rounds move backward. If the magazine is full, none of the cartridges will move enough to cause a problem. And if there is only one round in the magazine, there is no problem.

But if there are, say, three rounds in a six round magazine, the rounds move forward, then when recoil stops, they move back rapidly under the force of the magazine spring.* It is at that point, not during recoil, that there is the possibility of primer ignition. And, since the cartridges are moving somewhat freely, the bullet points will not be at the bottom of the tube due to gravity, but may be in a position to meet the primer of a round as it comes back.

Some who don't quite understand what happens believe that claims of a round firing in a tubular magazine are myths, and that a bullet point can't reach a primer. It is not a myth, and it can. That is why it is best to use flat point or round soft point bulllets in tubular magazine rifles.

*It is to slow that movement that some tubular magazines have raised spirals inside.

Jim
 
Any besides the Remington 14-141 pumps?
It is usually said that their tube flutes are deep enough and at the right pitch to keep the bullet point off the primer.

Then there was The French Solution for the Balle D in the Lebel.
 
They both look good to me and I wouldn't worry--but it probably wouldn't hurt to call the bullet manufacturers to be sure. I notice the RNFP is intended to be a cowboy action bullet (likely a low-powered cartridge formulation) and I'd be concerned about that suitability as well.
 
Gee, guys, the RNFP was designed FOR tube magazines as CAS became popular. They are pretty close to the shape that Won the Frontier.

Does the Internet make people timid about everything?
 
Gee, guys, the RNFP was designed FOR tube magazines as CAS became popular. They are pretty close to the shape that Won the Frontier.

Does the Internet make people timid about everything?
Click to expand...
I'm not familiar with the Missouri product--but it seems to me to be a specialty bullet designed for low-velocity applications--might have to watch that hardness vs velocity was my point.
 
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