Reloading questions: low pressure

[bobcat93]

I made up some reloads for a 221 fireball. When I ejected the brass there was alot of carbon on the case body, and primers did have signs of high pressure, cratering...but I used a light charge and was .010" off the rifling
This was new 221 lapua brass..
I started thinking maybe I need to rework my load and increase the powder charge.
Then I started to wonder if to light of charge could give the same ( looking fired case) as an over charged case..if I was trying to read pressure signs by chronograph speed based upon what the reloading manual said speed should be. So if my brass, bullet, primer, powder charge, COL. , And barrel length and twist was the same as in the manual..my speed should be comparative correct?
So a flattened, cratered primer and carbon all over the case body could be from the case not having enough pressure to seal the chamber, and the primer could be from the case being forced against the bolt face..
I realize this is a dangerous topic and there are many variables involved. I would just like to discuss this topic .
Thanks.

 

[Homerange]

Reloading manuals list "Starting" or "Minimum" loads for good reason: to stay within safe pressures for the cartridge.
It's that simple.

 

[XBBR Shooter]

I made up some reloads for a 221 fireball. When I ejected the brass there was alot of carbon on the case body, and primers did have signs of high pressure, cratering...but I used a light charge and was .010" off the rifling
This was new 221 lapua brass..
I started thinking maybe I need to rework my load and increase the powder charge.
Then I started to wonder if to light of charge could give the same ( looking fired case) as an over charged case..if I was trying to read pressure signs by chronograph speed based upon what the reloading manual said speed should be. So if my brass, bullet, primer, powder charge, COL. , And barrel length and twist was the same as in the manual..my speed should be comparative correct?
So a flattened, cratered primer and carbon all over the case body could be from the case not having enough pressure to seal the chamber, and the primer could be from the case being forced against the bolt face..
I realize this is a dangerous topic and there are many variables involved. I would just like to discuss this topic .
Thanks.

If you are going to ask a question about reloads, you should give all of the reloading data.... and rifle. Some rifles show cratering when there are no pressure problems.

"And barrel length and twist was the same as in the manual..my speed should be comparative correct?"

No.

 

[bobcat93]

I'm not trying to have a debate about my reloads ..but interested in the possibility of high pressure signs from a cartridge with a light load from a reloading manual ..has anyone ever experienced this. I do not have my data in front of me but will post it later when I get home..I believe it was a mid. range charge..

 

[jlow]

Generally known in reloading cycles that light loads (below minimum) are in fact dangerous. Do a search and I am sure you will find lot of info on this.

 

[bobcat93]

If you are going to ask a question about reloads, you should give all of the reloading data.... and rifle. Some rifles show cratering when there are no pressure problems.

"And barrel length and twist was the same as in the manual..my speed should be comparative correct?"

No.

What is the cause of the cratering? Long firing pin?
I've been reloading for quite awhile, and for many different guns and have never seen this..that is why the topic in the first place..

 

[nvbroncrider]

Generally known in reloading cycles that light loads (below minimum) are in fact dangerous. Do a search and I am sure you will find lot of info on this.

Look up about the weatherby's or the 25-06. They were notorious for this especially with light loads of slow burning powders. They got a bad wrap from people not knowing what they were doing and having a secondary explosion that ruined many rifles and hurt a lot of people. Both the Hornady and Norma manuals go over this in great detail as well as some articles in magazines and forums.

You can see "excessive" pressure signs from light loads causes are from the neck not expanding to seal chamber black soot on case body and shoulder. Primer is not pressed back into pocket gas leaks around primer or bolt face can be gas cut and cratering can occur.

 

[Homerange]

What is the cause of the cratering? Long firing pin?
I've been reloading for quite awhile, and for many different guns and have never seen this.

Can be attributed to 2 common causes if pressure is not the cause.
Thin/soft primer cups.
Excessive bolt face clearances around the firing pin.

 

[bobcat93]

This is odd ..I have a CZ 527 American 221 fireball.. my load is:
221 fireball lapua brass 7× reloaded.. have been annealed a few times..primer pockets still tight like new..by the way this brass is not cheap, but man is the extra money worth it
Primer: rem. 7 1/2 BR.
Powder: alliance reloder #7- 17.8 gr.
Bullet: Sierra # 1385 - 40 gr.HP.
COL. : 1.880" that's .010" of the rifling in my rifle..
This load was pretty accurate , I could cover 5shot group with a quarter @100 yrds ..
I forget what my chony was reading because like a full I didn't write it down..but remember thinking I thought it should have been faster..
As you can see in the pic there isn't really pressure signs yet in my opinion..the primer is not flat at all but there is a slight ring around the primer, and the case had carbon past the shoulder..
Maybe I ran it to long in the tumbler, and that caused the case to be driven back hard against the bolt face ..but I was just wanting to discuss the possibility of over pressure signs on moderate charged reloads..( not lower then manual says/ not hotter either) right in the middle of the suggested charge weight..does it happen and why.
Thanks guys..I'm having a hard time explaining , conveying what I'm thinking..

 

[XBBR Shooter]

This is odd ..I have a CZ 527 American 221 fireball.. my load is:
221 fireball lapua brass 7× reloaded.. have been annealed a few times..primer pockets still tight like new..by the way this brass is not cheap, but man is the extra money worth it
Primer: rem. 7 1/2 BR.
Powder: alliance reloder #7- 17.8 gr.
Bullet: Sierra # 1385 - 40 gr.HP.
COL. : 1.880" that's .010" of the rifling in my rifle..
This load was pretty accurate , I could cover 5shot group with a quarter @100 yrds ..
I forget what my chony was reading because like a full I didn't write it down..but remember thinking I thought it should have been faster..
As you can see in the pic there isn't really pressure signs yet in my opinion..the primer is not flat at all but there is a slight ring around the primer, and the case had carbon past the shoulder..
Maybe I ran it to long in the tumbler, and that caused the case to be driven back hard against the bolt face ..but I was just wanting to discuss the possibility of over pressure signs on moderate charged reloads..( not lower then manual says/ not hotter either) right in the middle of the suggested charge weight..does it happen and why.
Thanks guys..I'm having a hard time explaining , conveying what I'm thinking..

I don't see any cratering - I see typical signs of LOW pressure. Your problems are from VERY low pressure that cannot seal the chamber at the neck.

THIS is cratering.

 

[Comrade Terry]

I don't see any cratering - I see typical signs of LOW pressure. Your problems are from VERY low pressure that cannot seal the chamber at the neck.

THIS is cratering.

View attachment 985263

^^^ +1

 

[XBBR Shooter]

What is the cause of the cratering? Long firing pin?
I've been reloading for quite awhile, and for many different guns and have never seen this..that is why the topic in the first place..

Not caused by a long firing pin - the firing pin and pin spring are part of the pressure containment system. - they are what holds the pressure back, from blowing out the back of the bolt.

When the pressure starts to exceed the force of the spring pushing the pin against the primer, the pin gets pushed back into the bolt - that leaves the primer with the normal "dent", being pushed out, and it looks like a tiny volcano.
Cratering can be caused by:
1 - excessive pressure, or
2 - Weak pin spring, allowing the pin to be pushed back into the bolt at a lower pressure (fix this with a new or stronger spring)

If the hole in the bolt for the pin, is much larger than the pin itself, you can get what is called, "Faux (fake) Cratering". It does not go away with lowering the load - and it is there with factory loads - it looks different than real cratering - the ridge has a soft, rounded look.

 

[bobcat93]

Ahhh thank you gentlemen..perfect..also thank you for pics..

 

[fourpower]

I made up some reloads for a 221 fireball. When I ejected the brass there was alot of carbon on the case body, and primers did have signs of high pressure, cratering...but I used a light charge and was .010" off the rifling
This was new 221 lapua brass..
I started thinking maybe I need to rework my load and increase the powder charge.
Then I started to wonder if to light of charge could give the same ( looking fired case) as an over charged case..if I was trying to read pressure signs by chronograph speed based upon what the reloading manual said speed should be. So if my brass, bullet, primer, powder charge, COL. , And barrel length and twist was the same as in the manual..my speed should be comparative correct?
So a flattened, cratered primer and carbon all over the case body could be from the case not having enough pressure to seal the chamber, and the primer could be from the case being forced against the bolt face..
I realize this is a dangerous topic and there are many variables involved. I would just like to discuss this topic .
Thanks.

I do a lot of reloading on 221 fireball and what you have is to light a load. you must work at top end of powder charge. if you ever see carbon on case body that is very bad and you are asking for trouble! I load all my bullets with Lil'Gun and get great speed & groups.

 

[bobcat93]

Thanks for the tip, from all the reading I've done it appears the general consensus is the 221, 20 VT, and 17 fireball all run best at close to max charge..I had some loads made up just to run to the gun club with my new rifle..I'll work it up in + .3 - +.5 grain increments...then work on tuning the load

 

[jlow]

I don't know anything about 221 fireball but ran your numbers through QL. At least as far as I can see with a big "grain of salt" (without knowing you case volume and MV for adjustment), you are at 35,470 psi Pmax and just getting into MAP 25% which IMHO is not low pressure. Max pressure is around 45,000 for reference. QL predicts MV= 3,146 fps for reference.

I also assume when you say "that's .010" of the rifling in my rifle.." you actually mean 0.010" off the rifling? If you are touching or seating into the lands, that number I quoted could be much higher so take care going higher.

 

[XBBR Shooter]

I don't know anything about 221 fireball but ran your numbers through QL. At least as far as I can see with a big "grain of salt" (without knowing you case volume and MV for adjustment), you are at 35,470 psi Pmax and just getting into MAP 25% which IMHO is not low pressure. Max pressure is around 45,000 for reference. QL predicts MV= 3,146 fps for reference.

I also assume when you say "that's .010" of the rifling in my rifle.." you actually mean 0.010" off the rifling? If you are touching or seating into the lands, that number I quoted could be much higher so take care going higher.

SAAMI MAP for the .221 Fireball is 60,000 psi... 35k is 1/2of the pressure.

 

[jlow]

SAAMI MAP for the .221 Fireball is 60,000 psi... 35k is 1/2of the pressure.

Just going by what is in QL and what MAP 25% is with my own experience.

 

[jlow]

SAAMI MAP for the .221 Fireball is 60,000 psi... 35k is 1/2of the pressure.

Just going by what is in QL and what MAP 25% is with my own experience i.e. it is not super low pressure. Again, this is not necessarily the final answer, just a piece of data that I offer to help.