How far should i push my luck?

[ScreaminEagle]

So, I loaded up a strings of rounds for my 257 Ackley last night. I headed out to the range to do a quick ladder test. Quickload stated that 49.9 gr of IMR4350 was dangerous and that I should not load. Well I shot a string from 47gr-53gr in .5 grain increments. At 53gr I still had no pressure signs at all. Easy bolt lift, no flattened primers, no shiny marks of any kind. My question is, how far should I push it? How far would you push it? Could everything be great with one load then go kaboom a 1/2 grain later? If it helps, I always start load development with the bullet jammed .015" into the lands.
Steve

 

[SJB358]

SE, is that the information I sent you? Resend your H20 capacity and let me re run it. Something doesn't feel right. If your running 3-4 grains over what QL is calling max, your either reading from 55K data or something else is monkeyed up. I have seen QL off with the WBY and RUM's but it is usually pretty spot on for the standard cartridges throated normal.

 

[kraky]

Sometimes quickload misses a bit on a certain powder. A generous chamber and lots of freebore can make a diff too.
What I do in cases like this is set the top pressure limit I want to load to and ask quickload what powders work best. I then take the top velocity as the ABSOLUTE Max speed I want to see on the chrono
So, lets say quickload says something like ramshot hunter is the fastest powder in a 06 with a 165 bullet hitting 2975 fps. Well...I'm pretty confident I Better NOT see 2975 with any other powder.

 

[nvbroncrider]

If I remember right on that thread I think the QL data was set at 55K so I think your fine if you look up that thread and look it will give you a column for PSI I think it's the 2nd one after the velocity. In a good modern action 63-65k is the so called standard operating pressure. It's what all modern cartridges are loaded to.

I stand corrected. I looked the thread up and I don't know what to say. Scotty updated the data at 62-63k. Did you run it over a graph did you see your velocities plateau?

 

[ScreaminEagle]

I did not shoot it over a chrono. I hit a sweet spot around 49-50gr. Maybe I'll just stick with that and see what velocity im getting

 

[SJB358]

Without a chrono it is really tough to see what is happening. Ackleys can hide PSI signs pretty easily till they are extreme.

 

[joelkdouglas]

I agree the velocity is a better indicator of pressure than the charge weight. I have loaded up to 4 grains over the Nosler max for my 25-06 with 110 Accubonds with no pressure signs. But the max charge lists a velocity of 3130 fps, a better indicator than the charge weight. I haven't gotten to 3130 yet.

 

[Elkman]

Could everything be great with one load then go kaboom a 1/2 grain later? If it helps, I always start load development with the bullet jammed .015" into the lands.
Steve

A 1/2 grain addition to my STW resulted in moderate bolt resistance, and 1 grain made it hard to open. So yes it can, even with larger capacity cartridges. I was in the QL, dangerous category.

 

[Vince]

What weight bullet?
I didn't see that in my perusal of this topic. I will note that you're loaded over my load, by a good bit, for the 100 Grain Partition in my 25-06. I'm suspecting something is off.

 

[ScreaminEagle]

What weight bullet?
I didn't see that in my perusal of this topic. I will note that you're loaded over my load, by a good bit, for the 100 Grain Partition in my 25-06. I'm suspecting something is off.

Ladder test was done with 100gr BT. I'm going to redo the top end of the ladder test, and shoot it over the chrono this time. I just expected to hit pressure signs around 51gr at least, but nothing showed up. I'm really confused. What should I be looking for when I shoot over the chrono? I think with everyone's help we can diagnose this thing

 

[SJB358]

Give me your H20 specs again SE, along with barrel length. I will run QL for your bullet.

Also, include your COAL.

 

[ScreaminEagle]

Scotty, I weighed 6 cases with an average of 60.6gr of water, my barrel length is 26", COAL was 2.985", 100gr Nosler BT, IMR4350, Bullets were jammed .015" into the lands. I should see pressure signs before I have a dangerous situation. I'm confused
Steve

 

[DrMike]

Steve,

Was the water deoxygenated? Did you fill to a convex meniscus? Your Maximum Case Capacity, overflow appears to be smaller than it should. Projection with the data provided is as follows:

Cartridge : .257 Roberts Imp.
Bullet : .257, 100, Nosler BalTip 25100
Useable Case Capaci: 56.003 grain H2O = 3.636 cm³
Cartridge O.A.L. L6: 2.985 inch = 75.82 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : IMR 4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 74 38.00 2522 1412 27475 7613 87.0 1.577
-18.0 76 38.95 2581 1479 29179 7863 88.2 1.541
-16.0 78 39.90 2640 1548 30984 8108 89.4 1.505
-14.0 80 40.85 2700 1618 32897 8348 90.6 1.471
-12.0 81 41.80 2759 1690 34922 8582 91.7 1.437
-10.0 83 42.75 2818 1763 37050 8809 92.7 1.404
-08.0 85 43.70 2877 1838 39282 9028 93.7 1.366
-06.0 87 44.65 2936 1914 41639 9240 94.6 1.329
-04.0 89 45.60 2995 1992 44134 9442 95.4 1.293 ! Near Maximum !
-02.0 91 46.55 3054 2071 46774 9634 96.2 1.259 ! Near Maximum !
+00.0 93 47.50 3112 2151 49569 9816 96.9 1.226 ! Near Maximum !
+02.0 94 48.45 3171 2232 52529 9986 97.5 1.194 !DANGEROUS LOAD-DO NOT USE!
+04.0 96 49.40 3229 2315 55665 10146 98.1 1.163 !DANGEROUS LOAD-DO NOT USE!
+06.0 98 50.35 3287 2399 58988 10292 98.6 1.133 !DANGEROUS LOAD-DO NOT USE!
+08.0 100 51.30 3344 2483 62511 10426 99.0 1.105 !DANGEROUS LOAD-DO NOT USE!
+10.0 102 52.25 3402 2569 66250 10546 99.4 1.077 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 93 47.50 3257 2356 58181 9804 99.8 1.141 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 93 47.50 2925 1900 41105 9392 90.4 1.335

 

[ScreaminEagle]

DrMike, I let a bottle of water sit overnight with the cap off. Also, it's been awhile since I have had chemistry class, but a convex meniscus is when there is a bubble at the top of the case neck, correct?
Is there any other way to deoxygenate water? I'm sure its me who is messing up the results, just don't know why.
Steve

 

[DrMike]

Sitting overnight will permit oxygen levels to equilibrate; you did right. You are correct on the meniscus. I just would have expected more case capacity. The absence of case capacity gives a lower projection.

 

[ScreaminEagle]

What would you do in this situation? Would you keep going at it in .5 grain intervals until you see pressure signs? I plan on doing in again over the chrono. Will I hit a point where there are no velocity gains? I've never had this happen before.
Steve

 

[DrMike]

I would do as you suggest, watching for pressure signs. Half grain increments will keep you from trouble, though one grain increments will get you there much more quickly. Each grain will be ~2% increments which are not excessive with this powder. I would back off a full grain when I encounter pressure signs.

 

[ScreaminEagle]

Ok, I'll give that a try. I'll post my results with the corresponding velocities, then maybe we can figure out what is going on.

 

[SJB358]

I think your probably going to see what you should when you pull the chrono out SE. Mike's data is ran for 50K PSI, so you have some room to work up. I would actually be very comfortable working into the 60-62K range of the presented data. Looking at that, your speeds should be in the 3300 range for the 100BT's.

Good luck, post up your results!