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Had To Test Bullet Seating Pressure - 30-30

2K views 8 replies 6 participants last post by  yukondog 
#1 ·
Posted an article here called something like "Long Range 30-30". Some feedback questioned why I do not crimp bullets so they don't move during loading and during recoil in a Marlin 336. Without testing I replied there was no need to crimp as the tiny recoil of a 30-30 in a 336 and the magazine tube spring do not have the pressure to move normally reloaded bullets in properly fitted dies.

What WAS the pressure required to move a seated, non-crimped bullet? I had to test.

Isaac Newton talked of "objects at rest staying at rest". That is the issue with bullets pulling OUT of a case during recoil. The 30-30 has little recoil but what about the magazine tube spring and pressure loading a full tube? My guess is the spring is way too light to do much but there's a binding as you press shells into the tube that can seem high.

I just took 4 cases, deprimed, measured wall thickness and outside neck diameters before and after sizing. With that knowledge and some Sierra 150 gr. flat points I measured neck tension. The brass varied from .009" to .011" thick. Actually I think that's real thin but it is what it is. After sizing and doing the measurements, one Remington case would only have .003" of interference fit. Two others were at .004" and one at .005". What kind of pressure would that take to push those bullets in?


Bullets were seated .35" into the case necks. That's not all the way to the neck bottom but right at the cannelure on these bullets. First time on the bathroom scale and I could not push them in at all just holding the cases in my hand. Got to 30 lbs and my hand got sore.

Devised a holder with the shell holder inside a socket. Took the case with "only" .003" interference (the thin one) and pushed to 60 lbs and the bullet did go in.

I went OVER 70 lbs on the other three, could not push any harder, my hand hurts and none of the other three moved.


My conclusion is there's no reasonable way you are going to push those bullets farther into the case during magazine tube loading and certainly not going to get them to move OUT during shooting with such low recoil.

You don't need to crimp.
 
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#2 ·
Why dont you test the amount of force needed to pull the bullet from the case.

I did this at university with a tensile strength measuring device.

All you would need is some method of holding the bullet and another method for gripping the bullet and pulling it from the case.

I drilled holes in both to attach it to the machine.

This way you would get an idea of the ammount of force needed to jolt the bullet from the case under recoil.

Supprised me the SD on a number of bullets made at the same time.

Chris
 
#3 ·
My conclusion is there's no reasonable way you are going to push those bullets farther into the case during magazine tube loading and certainly not going to get them to move OUT during shooting with such low recoil.

You don't need to crimp.
Your entire premise is flawed...

It has nothing to do with 'pushing' the bullet in while loading, and 'out' under recoil...

It is slamming them IN under recoil...
 
#6 ·
I appreciate your write up. However, I disagree with your conclusion. That does not make you wrong...
 
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#7 ·
The inertia of the bullet keeps the bullet still at recoil. The case is attached to most guns, has less inertia and pulls back - away from the bullet during recoil. That means the bullet tries to move out. That issue is somewhat more common in revolvers where bullets back out in the cylinders. Don't know about stacked inside a magazine tube. In a 336 30-30 there is so little recoil I would doubt it amounts to much at all. Certainly not like the hard strike of an inertia bullet pullet. Not remotely like that.

I have no clue what the magazine spring tension in a magazine tube is. Doubt it is over 50 lbs. Probably more like 10-20 lbs and maybe less. All it has to do is hold the shells against the carrier. Getting a handle on pressures needed to pushing a bullet IN while loading was my test purpose.

Now why the smashed bullets on that cartridge??? Is that a 444 or some kind of 44? I don't know. Obviously I did not test that caliber and my conclusions are based only on the 336 in 30-30. To extrapolate that to other things begs many, many more issues and should not be considered valid and related to my findings.
 
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