Accuracy loss in fired brass - 30 Nosler ?

[brentc]

Jeff, I've seen this happen and I've come to the conclusion that pressure safe and accurate loads worked up in fire formed cases will normally translate to virgin cases. The same type of loads worked up in virgin cases hardly ever translate to fire formed.

 

[Broz]

Jeff, I've seen this happen and I've come to the conclusion that pressure safe and accurate loads worked up in fire formed cases will normally translate to virgin cases. The same type of loads worked up in virgin cases hardly ever translate to fire formed.

Exactly!! I now think back of my old methods where I took 10 virgin cases. Broke in the barrel with them while watch for pressure as I increased the charge. I then at least had an Idea. Then used those ten fire formed cases to develop a load. Once I had it I loaded up the rest of the virgin and went to the longer distances. By the time I had 50 fire formed I had the rifle pretty much dialed in. I remember a 338 AI where I was at 1800 yards trying the fire formed , then virgin brass and all went into group. This gave me a false sense of security.

The problem I created was trying to take a short cut. As you stated, works one way but not the other. I agree.

Thanks
Jeff

 

[FURMAN]

I have developed loads for over 20 rifles, all .5moa capable, and NONE of them have shown any difference between fired and virgin brass and one of those rifles was a 20VT using necked down 221FB brass. Several of them have been wildcats involving necking down but no shoulder angle change. I have, however always seen a change in velocity at around 75-150 rounds which sometimes, but not always, required a powder change. I know the barrel speeding up is not Broz's issue because he can still get the good groups with virgin brass. 80.5 grains of Retumbo with the 215 seated -.010(2.790 at the ogive) seems to be getting me in the .2s-.3s. ES under 20, not great, but ok. I have not shot it at distance yet. This is in a CA Ridgeline 30 Nosler bedded in a Stocky's long range carbon fiber. This load is about 1.5 grains under the start of pressure and my velocities are around 2950fps(shooting chrony). I will have to validate that later with drops.

 

[Broz]

Ok I needed to confirm to leave no doubt in my mind. So I fine tuned the load in with a slight change of Charge weight. Same powder lot. Same primer lot, same bullet lot.

Went from 82 gr to 82.2 gr and it tightened up. If I don't blow it , it will shoot .25 moa. And first round from a cold barrel is dead nuts center aim point. So, after all this I called it done. Now I needed to revisit the chronograph to see what increase in velocity I got with an additional .2 gr. In fire formed brass, 82.2 gr is shooting 3100 fps again with single digit ES.

Bottom line.

Virgin brass with 84 gr = 3100 fps.

Fire formed brass with 82.2 gr = 3100 fps.

1.8 gr less charge, same velocity.

Velocity from a proven Magneto speed I have learned to trust.

Jeff

 

[Broz]

Thank you each and every one for the help and suggestions. The load work up for my 30 Nosler "#Executive Order" is done. Now to pit her up against my tried and true 300 win mag "Heart Breaker" and see if there is a real value in opting for a 30 Nosler over the ole 300 win mag.

This was the final zero check at 100 yards from a dead cold rifle.gun)

 

[dok7mm]

Jeff,
Glad you got it figured out. I had the exact same problem in a 6.5-284. I finally came around to the same solution, but it took me longer. I learned the hard way, to fire form my brass prior to doing any load workup. Sure hope your experiment works out as you stretch it out.

 

[brentc]

I have developed loads for over 20 rifles, all .5moa capable, and NONE of them have shown any difference between fired and virgin brass and one of those rifles was a 20VT using necked down 221FB brass. Several of them have been wildcats involving necking down but no shoulder angle change. I have, however always seen a change in velocity at around 75-150 rounds which sometimes, but not always, required a powder change. I know the barrel speeding up is not Broz's issue because he can still get the good groups with virgin brass. 80.5 grains of Retumbo with the 215 seated -.010(2.790 at the ogive) seems to be getting me in the .2s-.3s. ES under 20, not great, but ok. I have not shot it at distance yet. This is in a CA Ridgeline 30 Nosler bedded in a Stocky's long range carbon fiber. This load is about 1.5 grains under the start of pressure and my velocities are around 2950fps(shooting chrony). I will have to validate that later with drops.

When you pressure test, you will see signs much later with virgin cases than with fire formed cases. Whether you've experienced it or not, it happens. And there is ample explanation provided in this thread that discusses the "why". Jeff's example of a hydraulic accumulator was spot on.

 

[FURMAN]

I will not argue this theory nor was I in my previous post. The only rifles of mine that had the accuracy node near pressure max were my two 20BRs. So those were the only two I could have had a real chance to experience this. In all other rifles I have developed loads for the accuracy node was lower and no difference was seen in groups or drops at distance between virgin and fired brass. Broz's experience with this particular rifle has me wanting to do some more testing.

 

[cape cove]

Broz, this is a great thread.Real good info here. I hope you get all sorted out. I didn't know this could happen with virgin vs fire formed brass. Most of the loads I have developed have been with fire formed brass therefore I never noticed anything. The only time I developed a load with virgin brass was with my 30/378 Wea and ended up with the run out problem I mentioned,BUT when I look back at my notes on this I seen where I had to later reduce my initial max load by 1.5 grs. I assumed at the time that a different batch of powder was to blame, but mabey it was just this virgin brass thing. As I said great info.

 

[Lonewolf74]

So you guy's have experienced this load and pressure change between fire formed and Virgin brass even when full length resizing? But you don't seem to see the same effect going from loads developed in fired brass to virgin brass?

I'm curious cus I may change the way I was going to approach load development for my new 300 win mag. I'm starting from scratch with it and was gonna run through all 100 cases before reloading any but now maybe I'll use 20 or so to break in and load develop.

 

[Broz]

This was indeed the most extreme case of this I have ever seen. I credit that to the 30 Nosler and Nosler brass. Be it case design, coefficients between case and chamber wall ...... what ever. This was extreme. As I stated, I have seen much smaller raises in pressure and velocity appear in fire formed brass with a load coming from Virgin brass before. I expect it. But never like this.

Lonewolf74, The 300 win mag is a much more forgiving animal. But yes I would do the load work up in fired brass from the new chamber for sure.

Jeff

 

[Lonewolf74]

Thanks again for the help Broz

One last question, about where have you found the node for the 215 hybrid and H1000? You told me to start with 74 gr and work up but I'm just wanting an idea of about where it should be and avoid loading rounds too far over max.

 

[Broz]

Thanks again for the help Broz

One last question, about where have you found the node for the 215 hybrid and H1000? You told me to start with 74 gr and work up but I'm just wanting an idea of about where it should be and avoid loading rounds too far over max.

There is no clear answer to this because of brass, powder lot, chamber spec and some other variations. But I will try. Most will see pressure at 77 gr or just above. That said, I have seen some brass, lot , rifle combinations see pressure at 74. Then there are those few combinations that will go 78 or even 79 gr. No short cut here. Start at 73 or 74 and work up with your components in Fire formed brass.

Jeff

 

[brentc]

Thanks again for the help Broz

One last question, about where have you found the node for the 215 hybrid and H1000? You told me to start with 74 gr and work up but I'm just wanting an idea of about where it should be and avoid loading rounds too far over max.

30 Nosler or 300 Win?