Overpressure?

[Necroman99]

Hi folks. I think i know the answer but...
Made my first 30-30 loads and fired them in my win 94. They group really nice but...overpressure based on popped primers? Cases look good otherwise.
Recipe was off of leverevolution bottle. 35.5gr of that powder under a 160gr ftx bullet...i used fed primers though.
Thoughts?
Obviously the pics show cases before and after firing.

 

[1-trident-1]

not over pressured, measure your chamber headspace and then your sized brass. my guess is it is over 5 thou difference.

 

[todbartell]

looks underpressure if anything, due to the primer backing out of the pocket

 

[yomomma]

Definitely not overpressure

 

[time4t]

……..

 

[Necroman99]

Can i keep going as is? Just keep shooting these? Ive been reloading 308 223 270 for about 5 years...never seen an issue like this. I dont know how to check headspace. I can google. Brass should be right at trim to length cause i just trimmed it all. Gun is new to me. Could buy some factory and try that.

 

[Snider shooter]

So you tried a max load for your first test is what I understand. This load is safe in all of my 30-30's. If it was over pressure your primers would be flattened not popped out. 30-30 brass is thin,any over pressure loads will easily stretch the case and slam it back to the bolt face pushing the primer back in and flattening it. I have had this happen. Is your brass stretching. Primers backing out with no deformation is a sigh of low pressure or excessive head space problems. Your load according to Lyman #50 is max. You are not showing a low pressure sign. I assume you used a scale and not a scoop for charge weight

Check your rifle for excessive head space.
Check your charge weights on a scale.
If using a scoop you could be way under.

 

[Necroman99]

All loads weighed on a reliable scale.

 

[bigedp51]

The rated chamber pressure of the 30-30 is 38,000 cup or 43,000 psi and even at max pressure the primers will always back out.

My 30-30 Winchester 94 Trapper Model always has the primers protruding even when I load a little above max loads. The last time I went shooting at the range with my oldest son he had his Marlin 30-30, and I had my Winchester 94 30-30 and both rifles had the primers protruding with factory Remington and Federal ammunition.

This is because the chamber pressure is not great enough to push the case to the rear and contact the bolt face.

The amount the primer backs out if added to your rim thickness is your rifles actual headspace.

Below a example using .303 British case and a fired spent primer.

Measure the case from the base to the case mouth and write it down.

Next using a fired spent primer and a new unfired case seat the spent primer using just your fingers.

Now chamber the case and let the bolt face seat the primer and remove the case.

Now measure the case again from the base of the primer to the case mouth and write it down.

Now subtract the first case measurement from the second and this is your head clearance.

Now add your head clearance to your rim thickness and this is your rifles actual headspace.

Below a example of head clearance, this is normally the amount shoulder bump on a full length resized case. And a neck sized only case if resistance is felt closing the bolt has no head clearance. Meaning head clearance is the "air space" between the rear of the case and the bolt face.

NOTE, A British .303 Enfield rifle at max military headspace of .074 and a case with a rime thickness of .058 can have .016 head clearance.

And a 30-30 rifle at max headspace of .070 and a rim thickness of .063 can have the primer back out .007 and be perfectly safe and normal.

 

[Snider shooter]

Fire a factory round through it. See how that case looks. Do you have another rifle you can try your loads in. Firing it in a known rifle that is good would eliminate one it being your reloads. Someone could have over stressed the gun with hot loads sometime in its life. The 94 is not an overly strong action. Used correctly they will last many years. I have 94's pre WW1 that work excellent.

 

[bigedp51]

Any rifle if you make a workup load starting at the suggested starting load will have the primers protruding. And when the primers become flush with the base of the case it simply means the chamber pressure was great enough to make the brass to stretch and contact the bolt face.

And the head clearance and this stretching if excessive is what causes case head seperations.

Below because the .303 British is loaded to higher chamber pressure than the 30-30, the .303 British cases can stretch excessively and cause case head separations.

Bottom line, as long as the primers are protruding on your 30-30 cases it means the case is not stretching and thinning. And normally 30-30 cases die of split necks and not case head seperations.

 

[Necroman99]

Based on these comments and the bit ive read i think im gonna keep shooting the pricks. F it i dont think theyre dangerous.

 

[Ganderite]

What you see is common in any rifle load that is a bit low pressure. If you like the accuracy with that load, keep using it. Your brass will last longer.

For hunting, you might try 2 gr more.

 

[Mikey01]

Heres an easy way to chk headspace. Take a a factory or resized round and put a piece of elec tape on the bottom slide it in to your gun and close the bolt. If it closes all the way your headspace is to great.

 

[bigedp51]

If you look at the SAAMI cartridge and chamber drawing below you will see the manufacturing tolerance for rim thickness on the 30-30 is .063 to .053.

The Headspace is .063 to .070 giving you .007 to play with and .010 variation in rim thickness. So at the maximum headspace of .070 and a rim thickness of .053 you could have .017 head clearance.

Electrical tape comes in 7 mil and 10 mil thicknesses or .007 and .010 thickness and it is soft and stretches. Meaning using electrical for checking headspace is not a good idea.

 

[Mikey01]

It's not ideal no but better than thinking you may have an issue and just shooting till you have a failure to confirm. My elec tape is 12mm or.012 use two pieces if your is thinner if the OP is reloading he has micrometer. Not exact but good enough to know where your problem lies. The load he uses is the same I use in mine and should not be underpressered.