Early Pressure Signs - 260AI Nosler Brass

[APGE]

Hi Folks,

I'm in the process of working up a load for a 260AI shooting 130 Norma diamonds (factory moly coat), h4350 and nosler brass. I have used quickload as a starting point and I should be on an obt node at around 46gr, with the projectile jammed at 56k psi (roughly).

Shooting groups this afternoon, I started 0.9gr below the predicted node and worked up in 0.3gr increments. This has been my go to load development for years and has never failed me. At 46.1gr I got a light ejector swipe, and stopped testing at 46.4gr due to a significant ejector swipe.

Could I have a fast batch of powder? Is the long bearing surface of the Norma diamond raising pressure? Is it true that nosler brass is really soft?

Looking for any advice here. Sadly I did not have a chrony with me, so I cannot report on expected vs actual muzzle velocity.

Alex

 

[dolek]

Did you check the volume of the Norma brass compared to the brass you had been using ?

 

[DaveTooley]

As you know powder varies from lot to lot
Brass toughness also varies from lot to lot. Mfg. to Mfg.
The yield point of the brass controls how much powder you can use.
No approximation by Quickload can change that.

 

[ALK]

Hi Folks,

I'm in the process of working up a load for a 260AI shooting 130 Norma diamonds (factory moly coat), h4350 and nosler brass. I have used quickload as a starting point and I should be on an obt node at around 46gr, with the projectile jammed at 56k psi (roughly).

Shooting groups this afternoon, I started 0.9gr below the predicted node and worked up in 0.3gr increments. This has been my go to load development for years and has never failed me. At 46.1gr I got a light ejector swipe, and stopped testing at 46.4gr due to a significant ejector swipe.

Could I have a fast batch of powder? Is the long bearing surface of the Norma diamond raising pressure? Is it true that nosler brass is really soft?

Looking for any advice here. Sadly I did not have a chrony with me, so I cannot report on expected vs actual muzzle velocity.

Alex

Had the same experience. Was fireforming 257AI Roberts. 20 cases of nosler brass & 20 R-P. Using Nosler reloading manual-Nosler recommended fireforming load with their bullet. Nosler brass had stif bolt lift.Only tried 2 rounds. R-P brass formed great-no problems. Also had this problem with 25-05. Called Nosler and they said I used to much powder--NO I USED the WRONG BRASS! ALK

 

[dolek]

Had the same experience. Was fireforming 257AI Roberts. 20 cases of nosler brass & 20 R-P. Using Nosler reloading manual-Nosler recommended fireforming load with their bullet. Nosler brass had stif bolt lift.Only tried 2 rounds. R-P brass formed great-no problems. Also had this problem with 25-05. Called Nosler and they said I used to much powder--NO I USED the WRONG BRASS! ALK

Did you check the volume on the Nosler and R-P brass ?

 

[BCBRAD]

Did you reconcile your start pressure.

Into the lands is 10,825 psi, subtract 29psi for every 0.001" off the lands, this will be your start pressure.

 

[Zero333]

Reloading is funny like that.

Worked up a load with cci-250 with velocity at 3,000 fps. no pressure signs. Changed to 215-m primers, group size was reduced in half !, but average velocity dropped -30 fps and got signs of pressure.
That was in a 300winmag.

 

[ALK]

Did you check the volume on the Nosler and R-P brass ?

 

[ALK]

No I did not check volume in either piece of brass. After going to AI that's going to change anyway. I have used Norma & R-P brass with no problems. Also, the Nosler brass being shorter than min. -after fireforming it's 20 to 30 thou. shorter. I just quit using nosler brass.

 

[dolek]

No I did not check volume in either piece of brass. After going to AI that's going to change anyway. I have used Norma & R-P brass with no problems. Also, the Nosler brass being shorter than min. -after fireforming it's 20 to 30 thou. shorter. I just quit using nosler brass.

Correct,it will change the volume going to AI but Norma,R-P, and Nosler formed to AI will still have different volumes even if the outside dimensions are the same . My guess would be that the Nosler volume is smaller than the other two.

 

[APGE]

Did you check the volume of the Norma brass compared to the brass you had been using ?

Yep - I'm measuring 56.2gr h20 capacity on a fireformed case

 

[APGE]

Did you reconcile your start pressure.

Into the lands is 10,825 psi, subtract 29psi for every 0.001" off the lands, this will be your start pressure.

Norma Diamonds are factory moly coated. I've been using 7145psi as the shot start pressure with a 15 thou jam.

 

[rhovee]

Was your velocity the same as quickload predicted for powder weight? A lot of time powder burn needs to be tuned to what your seeing in real life. Speeds will match but amount of powder to get you there won’t.

 

[ShootDots]

I use Lapua "Palma" S/R brass for all my .260A.I.s.. This brass is about as strong as you will find anywhere. Now I don't want to get into bitch session, however, 46 grs of H4350 is a bit over the top for any "naked" 130 class bullet. With a Berger 140LRBT, which has a short bearing surface, 44.0grs is about tops and that MAY very well produce a sticky bolt lift! I know you are using a "MOLY" coated bullet, but 46+grs, especially for a "Non-Palma" brass, in my opinion, is asking for pressure signs.. My last .260A.I. using the 140LRBT load was 43.4grs of H4350! That produced 2930 and on a L-O-N-G shot string in the Arizona sun, caused a very stiff bolt lift! Remember, that is with necked down Palma brass. What would have happened with L/R primer brass?

 

[riflewoman]

Your “node” might be at 46 gr, but the max load probably won’t be there. The max load with H4350 listed in Nosler data is 43 ish. The increase in case volume is at best 10% or 5 grains water. That means a safe initial “max” to work toward would be 44.5, (for a safe guide halve the water increase for the increase in powder) You might get 45 depending on lot of the powder or other factors but still I wouldn’t push it.

 

[APGE]

I use Lapua "Palma" S/R brass for all my .260A.I.s.. This brass is about as strong as you will find anywhere. Now I don't want to get into bitch session, however, 46 grs of H4350 is a bit over the top for any "naked" 130 class bullet. With a Berger 140LRBT, which has a short bearing surface, 44.0grs is about tops and that MAY very well produce a sticky bolt lift! I know you are using a "MOLY" coated bullet, but 46+grs, especially for a "Non-Palma" brass, in my opinion, is asking for pressure signs.. My last .260A.I. using the 140LRBT load was 43.4grs of H4350! That produced 2930 and on a L-O-N-G shot string in the Arizona sun, caused a very stiff bolt lift! Remember, that is with necked down Palma brass. What would have happened with L/R primer brass?

Thanks for all the replies gents, and no fear about getting into a bitch session - I'm here asking for advice.

I've no doubt at all that I was loading too hot - that's why I abandoned the test. I'm curious as to how I've ended up with clearly far too much pressure using the same system I have used to develop good, safe loads for probably a dozen different calibres and a few dozen rifles. Usually by starting 1gr or so under the predicted node has given me a margin for change in burn rate and I've found the actual node somewhere either side. Not this time

This is the first time quickload had let me down so spectacularly. It tells me I should be at 56k psi, but I'm definitely well over that. Maybe I have a particularly fast batch of powder.

I'll revert to a ladder test now that I know what a practical maximum is for this combination based on bolt lift and ejector swipes.

No quickload shortcuts this time (unless someone has a good load they wish to share )

 

[dolek]

Yep - I'm measuring 56.2gr h20 capacity on a fireformed case

What do the other two makes of brass have for volume ?

 

[BCBRAD]

To get accurate results with QL:

All weights and measures inputted to the program as accurately as possible, this means

-Case volume in grains of water
-Bullet measured length, diameter, small diameter (BT), length of taper, and weight
-Powder charge weighed to 0.02 grains
-Cartridge overall length
-Distance to the lands (or jammed)
-Set start pressure (there is a factor for coated bullets in the drop down)
- Model several powders in the burn rate appropriate for application (H4350 is vg for 260ai)
-The OBT must be known for your barrel length
-The OCW (really great if it overlays the Pmax) must be very close to the Pmax. This is the Z1 line.
- The OBT will dictate the amount of powder to use. Sometimes you will not get to the next higher node as psi is over max.

Now load 5 rounds and chronograph them, optical chrono's can give erroneous velocities. The Labradar is the most accurate and user friendly. Magnetospeed is accurate but not user friendly to the degree the radar is.

Compare predicted velocity to actual.

If it does not jive (should be within 30 or so ft/s of predicted) adjust the Ba of the powder, only up to 5% though.

The powder adjustment, it may require adding or reducing powder charge to get back to the OBT.

Bullet weights can be tweaked up to 4%, this moderates the effect of a fast or slow rifle bore.

Weighting Factor, can be tweaked up to 10%, for a 260Rem it is 47, for the AI I would try 45 or 46. This does not jive with the QL default but is arrived at through calculation.

Also, input the temperature you will be testing in as this effects the Ba.

A load that is on or very close to the barrel time and the Pmax and Z1 lines overlayed will be a good load, a very good load.

QL works well for me. The user has to have knowledge of internal ballistics to fully realize what the program is capable of.

With out velocity been known , the QL program does not work!

 

[Dusty Stevens]

First off- .9 gr is not starting low.

 

[APGE]

First off- .9 gr is not starting low.

0.9gr lower than a quickload prediction of 56k psi (based on measurements, not QL defaults), not 0.9gr lower than a published max.