AA 2520 PUBLISHED MAX LOADS with HORNADY 123 AMAX

[LRRPF52]

Whether you use AA's or Accurate's data, you still end up with the same starting loads for a 123gr Scenar or 123gr SMK, somewhere in the high 26._ grs. Explain the logic behind using one vs. another, other than a check to see that all are in the same area.

For example, what primers was Accurate using? What primer was Alexander Arms using? Acccurate used WSR. AA used CCI 450's. If you read the beginning chapters to any reloading manual, they will describe how components can change pressures significantly. WSR's are one of the thinner cupped primers that I don't use.

[LRRPF52]

Also, to say you recommend someone else's data over the company who brought the Grendel to market, who uses industry standard equipment (piezoelectric test instrumentation), what is the logic? Both Alexander Arms and Accurate powders, as well as Hodgdon's, Nosler, Hornady, and Lapua are using industry standard test equipment. That's where those pressure numbers and max load figures come from, using the SAAMI guidelines for Maximum Average Operating Pressures.

Alexander Arms follows very rigid industry engineering approaches associated with developing cartridges, and has untold time and investment into making this caliber the success that it is. Any loads that exceeded the specified maximum chamber pressure would not be published by someone with piezoelectric equipment.

I have reloading guides for other cartridges like the .270 Winchester, .260 Remington, with data from all the major bullet and powder makers, and you will find considerable variance in maximum loads sometimes, especially with high-pressure cases like the .270 Win. and .260 Rem....which has me going back to:

Start low, work up in sensible increments while watching your chronograph, brass, and primers. Reloading is not a simple hobby. It is a discipline with very dangerous potential if basic guidelines are ignored.

[lrgrendel]

Whether you use AA's or Accurate's data, you still end up with the same starting loads for a 123gr Scenar or 123gr SMK, somewhere in the high 26._ grs. Explain the logic behind using one vs. another, other than a check to see that all are in the same area.

For example, what primers was Accurate using? What primer was Alexander Arms using? Acccurate used WSR. AA used CCI 450's. If you read the beginning chapters to any reloading manual, they will describe how components can change pressures significantly. WSR's are one of the thinner cupped primers that I don't use.

LRRPF52

So I am using the CCI 450 which has one of thickest cups. This helps correct?

Now here is ALL of the relevant info.

24" AA OVERWATCH

AA2520

CCI 450

LAPUA BRASS ( 3 times fired and full resized )

HORNADY 123 g bullet

Sea level. 80deg F. 65% humidity.

I am the guy who started this. Apologies to those who are bored!
Right now I am at 29.4 g giving me 2572 FPS which I want to increase.

Looking at chrono erratic numbers please give me an example based on the above info.

Thanks

[XcountryRider]

Also, to say you recommend someone else's data over the company who brought the Grendel to market, who uses industry standard equipment (piezoelectric test instrumentation), what is the logic? Both Alexander Arms and Accurate powders, as well as Hodgdon's, Nosler, Hornady, and Lapua are using industry standard test equipment. That's where those pressure numbers and max load figures come from, using the SAAMI guidelines for Maximum Average Operating Pressures.

Alexander Arms follows very rigid industry engineering approaches associated with developing cartridges, and has untold time and investment into making this caliber the success that it is. Any loads that exceeded the specified maximum chamber pressure would not be published by someone with piezoelectric equipment.

I have reloading guides for other cartridges like the .270 Winchester, .260 Remington, with data from all the major bullet and powder makers, and you will find considerable variance in maximum loads sometimes, especially with high-pressure cases like the .270 Win. and .260 Rem....which has me going back to:

Start low, work up in sensible increments while watching your chronograph, brass, and primers. Reloading is not a simple hobby. It is a discipline with very dangerous potential if basic guidelines are ignored.

Use Alexander and i'll use Hornady and Accurate Power they aren't promoting a cartridge and have no real dog in the fight other than creating quality bullets and powders for us shooters. If the Grendel went away they'd be doing just fine. As Bill Waites has said theirs a chance AA2520 has evolved so better use the newer data than potentially outdated data.

[LRRPF52]

LRRPF52

So I am using the CCI 450 which has one of thickest cups. This helps correct?

Now here is ALL of the relevant info.

24" AA OVERWATCH

AA2520

CCI 450

LAPUA BRASS ( 3 times fired and full resized )

HORNADY 123 g bullet

Sea level. 80deg F. 65% humidity.

I am the guy who started this. Apologies to those who are bored!
Right now I am at 29.4 g giving me 2572 FPS which I want to increase.

Looking at chrono erratic numbers please give me an example based on the above info.

Thanks

The thicker cupped primers are more resilient to slam-fires in a floating firing pin system like the AR15.

If I were you, and there are no case head swelling signs in your brass, I would continue a pressure ladder in small increments of .2gr, taking note of what my pressure increases were up to the 29.4gr/2572fps point.

29.6.....________
29.8.....________
30.0.....________

...and so forth. If you are within MAOP, the curve should be fairly linear, meaning the charge weights will produce consistent increases, like around 20fps. Once you get near or exceed max in your rifle, you will usually see a sudden spike or even drop in velocity along your pressure ladder. A 50fps+ increase will tell you something is going on different than your previous load increments.

I confirm this with at least 3 batches, so I know where I stand with my chamber and the load. You should be at 2620fps at 30.0gr. Also, what is your COL?

You might also run external ballistics comparisons to see what advantage you're getting with 2650fps vs. 2572fps.

[LRRPF52]

Here's a comparison for sea level using the 2572fps vs. 2650fps mv's with the 123gr A-MAX, and Brian Litz's adjusted G1 BC for it (.509 vs. .510)

       Range    Velocity    Energy     Trajectory         TOF          Drift
      (yards)     (fps)     (ft-lb)       (MILS)         (sec)         (MILS)
          0      [B]2572[/B]        1807           0.00         0.0000         0.00
        100      2404        1579          -0.00         0.1206        -0.20
        200      2243        1374          -0.49         0.2498        -0.41
        300      2088        1190          -1.29         0.3884        -0.63
        400      1939        1027          -2.25         0.5375        -0.87
        500      1798         883          -3.34         0.6982        -1.13
        600      1664         756          -4.56         0.8717        -1.40
        700      1539         647          -5.94         1.0592        -1.70
        800      1424         554          -7.48         1.2620        -2.01
        900      1321         477          -9.21         1.4808        -2.34
       [B]1000      1231         414         -11.14         1.7163        -2.69[/B]

       Range    Velocity    Energy     Trajectory         TOF          Drift
      (yards)     (fps)     (ft-lb)       (MILS)         (sec)         (MILS)
          0      [B]2650[/B]        1918           0.00         0.0000         0.00
        100      2479        1679          -0.00         0.1170        -0.19
        200      2315        1464          -0.44         0.2423        -0.39
        300      2157        1271          -1.19         0.3765        -0.60
        400      2005        1098          -2.08         0.5207        -0.83
        500      1861         945          -3.10         0.6760        -1.08
        600      1723         811          -4.24         0.8436        -1.34
        700      1594         694          -5.52         1.0246        -1.62
        800      1475         594          -6.96         1.2203        -1.92
        900      1366         510          -8.57         1.4318        -2.25
       [B]1000      1270         441         -10.38         1.6598        -2.58[/B]

You'll have to reference your local weather station data and figure out how close you are to the transonic barrier at your altitude and baro pressure:



Sea level speed of sound is 1116fps. As you descend into it, especially in thick air, strange things can happen. It's a difficult area of flight to document, and has baffled aerospace engineers for decades due to the erratic wave phenomena and vortices associated with transonic flight.

[LR1955]

LRRPF52

So I am using the CCI 450 which has one of thickest cups. This helps correct?

Now here is ALL of the relevant info.

24" AA OVERWATCH

AA2520

CCI 450

LAPUA BRASS ( 3 times fired and full resized )

HORNADY 123 g bullet

Sea level. 80deg F. 65% humidity.

I am the guy who started this. Apologies to those who are bored!
Right now I am at 29.4 g giving me 2572 FPS which I want to increase.

Looking at chrono erratic numbers please give me an example based on the above info.

Thanks

LRG:

2575 fps is a pretty decent velocity for your 24" barrel using a 123 and 2520. That is pretty much what most people, including me, have been able to get from that load.

What velocity do you want to hit and maybe one of us can offer some experienced advice?

LR1955

[lrgrendel]

The thicker cupped primers are more resilient to slam-fires in a floating firing pin system like the AR15.

If I were you, and there are no case head swelling signs in your brass, I would continue a pressure ladder in small increments of .2gr, taking note of what my pressure increases were up to the 29.4gr/2572fps point.

29.6.....________
29.8.....________
30.0.....________

...and so forth. If you are within MAOP, the curve should be fairly linear, meaning the charge weights will produce consistent increases, like around 20fps. Once you get near or exceed max in your rifle, you will usually see a sudden spike or even drop in velocity along your pressure ladder. A 50fps+ increase will tell you something is going on different than your previous load increments.

I confirm this with at least 3 batches, so I know where I stand with my chamber and the load. You should be at 2620fps at 30.0gr. Also, what is your COL?

You might also run external ballistics comparisons to see what advantage you're getting with 2650fps vs. 2572fps.

Ok. To answer your question. 2.25 COL up to now but I went to the range today........

[lrgrendel]

LRG:

2575 fps is a pretty decent velocity for your 24" barrel using a 123 and 2520. That is pretty much what most people, including me, have been able to get from that load.

What velocity do you want to hit and maybe one of us can offer some experienced advice?

LR1955

And to answer this question.

It is not so much as any particular velocity. This is where I am coming from.

I shoot 308 WIN with many other shooters ( now before any one gets too excited I am NOT REPEAT NOT trying to compare the Grendel to a 308) out to a 1000 yds on a regular basis and we hit fairly consistently. The guys with the DTA's and AI's obviously do better. Now we all shoot in or around the same velocity and within the transonic range.
If there is such a thing I am trying to find that "window" in the Grendel.

Also I am not made of money and right now have no intention of going to a bigger case.

[lrgrendel]

Reloaded and tried again

I reloaded again with the following results:

29.6

2616
2621
2624
2668
2673 Spread of 57 and average of 2640

29.8

2620
2637
2641
2681
ERR. Spread of 61 and average of 2644

30.0

2614
2644
2664
2668
2671. Spread of 57 and average of 2652

30.2

2648
2652
2687
2691
ERR. Spread of 43 and average of 2670


29.4. 2612 2614 2634 2640 2640 2644 2649 2654 2666

Spread of 54 and average of 2639.


The 29.4 were loaded last week to a COL of 2.25.
I loaded all other 4 loads this morning to 2.26.

At the range to day I used a buddy's chrono and it gave a little higher results than mine but let's keep that for another day!

Only went half way between AA max and ACCURATE max today and had no issues.
I include a photo of the 29.6g cases and the 30.2g. There maybe a very slight flattening of the primers in the 30.2.

I inspected after every shot and saw nothing alarming.

I am a little disappointed there is only an increase of 31 FPS between 29.4 and 30.2.

29.4 continues to perform and 30.2 looks promising.

I have another 1000 yd shoot on Monday and am thinking of using 30.2 unless someone gives me a reason not to.

Also I am going to shoot somewhere between 600 and 1000 that I didn't do last time.

[drewzter]

May I ask what range the above target was shot at?

[lrgrendel]

May I ask what range the above target was shot at?

Sorry everything at 100 yds

[LRRPF52]

Nice results, except the erratic fliers in ES are what will screw you downrange often, while not showing up at 100yds in the groups. See if you can load out further to 2.275" or longer without jamming the lands. Your brass looks textbook, without any measurements on the case head and possible expansion. Are the primer pockets still tight?

I would do some really attentive loading of the 30.0gr load, checking your scale, and double-checking your loads to wring out that .2gr error most digital scales have. These extreme spreads don't give me a warm and fuzzy, especially when I see ES's in the single digits sometimes with my Grendel. The ES's in the 50+fps are probably telling you that you're close to the edge. 50fps ES can mean a lot at distance, which is why we long-range guys like as small of an ES as possible.

You can play around with the seating depth and other factors, but I think 600yds will be a better range to fine-tune a good load. Go for as low an ES as possible, with the most accurate load at 600yds. I'm interested to see what LR1955's advice is as well, but don't expect to get into .260 Rem velocities and have a bolt last long on you.

[lrgrendel]

Nice results, except the erratic fliers in ES are what will screw you downrange often, while not showing up at 100yds in the groups. See if you can load out further to 2.275" or longer without jamming the lands. Your brass looks textbook, without any measurements on the case head and possible expansion. Are the primer pockets still tight?

I would do some really attentive loading of the 30.0gr load, checking your scale, and double-checking your loads to wring out that .2gr error most digital scales have. These extreme spreads don't give me a warm and fuzzy, especially when I see ES's in the single digits sometimes with my Grendel. The ES's in the 50+fps are probably telling you that you're close to the edge. 50fps ES can mean a lot at distance, which is why we long-range guys like as small of an ES as possible.

You can play around with the seating depth and other factors, but I think 600yds will be a better range to fine-tune a good load. Go for as low an ES as possible, with the most accurate load at 600yds. I'm interested to see what LR1955's advice is as well, but don't expect to get into .260 Rem velocities and have a bolt last long on you.

LRRPF52

First of all I really appreciate the detailed advice.

Yes I can load longer than mag length but will be limited by the mag well as I single feed by just putting a single round into the mag. I am a little hesitant without knowing where my lands are but I will have a modified case and insert to use with my Hornady comparator in a few days.

How did you know I have a digital scale!! Yes I do, a RCBS Rangemaster 750 which I don't trust. I put the powder dish back on the scale after every powder charge to make sure it is zeroed. I may go back to a traditional scale.

I will certainly work with the 30.0g charge. I aim to shoot with it on Monday out to at least 700 to 800 and let you know.

[LRRPF52]

Every Grendel mag I have will accept 2.300" COL, whether CProducts or ASC, so bullets with more secant ogives can usually be loaded way long. I start with a 2.300" COL dummy cartridge (no primer), then drop it in my chamber to see where I'm at, using a marker on the bullet shank-to-ogive transition area. I then will turn the die down a little until the desired result is found with at least a 1/2 turn more to ensure bullet variance doesn't bite me.

If you take advantage of your chamber's leade, you can get a full case with minimal compression on the charge, giving a longer burn without erratic pressure/velocity behavior.