load development question, need some advice.

[Shadow9mm]

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

So I ran some testing today. but I m not sure where to go from here. There was one small flat spot un the curve but It seemed too small to rely on. I had a really good SD on the low end and am considering moving down but am not sure. I feel more testing is needed, however I am not sure if I should tinker around in the 46.1 to 46.4 range the small semi flat spot in the curve. Or work down further from 44.9 since it had the single digit SD in the hopes it might flatten out.

Also the bolt was pretty stiff at 47.0g with no pressure signs on the primers or heads. 46.7 felt ok no pressure signs.

So the loads I am working up are for a 308 using the following.

Hornady 168g OTM loaded to hornady COL 2.800.
BL-c(2) Powder
CCI Large magnum rifle primers
LC brass
outside temp of 55f

5 shots per test group

44.9g, avg 2690, sd 9.04
45.2g, avg 2718, sd 16.66
45.5g, avg 2726, sd 13.44
45.8g, avg 2747, sd 10.18
46.1g, avg 2772, sd 14.02
46.4g, avg 2781, sd 11.46
46.7g, avg 2811, sd 13.41
47.0g, avg 2821, sd 22.61

Average Velocity

SD and ES

 

[sako2]

I would go with 46.4 and adjust seating depth.

 

[HiBC]

I can't give you any answer from the info I have,but I'll give you a general impression.

I give "stiff bolt lift" pretty good status as a "pressure sign" I might step down a touch more than 0.3 gr, myself.

Sure,I look at primers and case heads, but I do not consider them calibrated pressure test instruments. SOME magnum primers may have thicker/harder cups. Reading "sign" on primers,etc,I might see a red light or a yellow light.
But I generally do NOT get my green light there.

You are testing at 55 deg IF you should decide to load 0.3 gr under a stiff bolt lift
What will you get when its 88 deg F by the 4th of July? Or when that cartridge dwells a while in a hot chamber?

I'm not telling you what to do or not do. Just offering something to think about.

 

[Shadow9mm]

That's one of the things I was considering. I need to drop down, the question is how much. Honestly my first reaction would be -1.0g. But that eliminates the main flat spot on my curve. And of feel like a knee jerk reaction.

 

[MarkCO]

Try 1 round each of 45.0, 45.2, 45.4, 45.6, 45.8, 46.0, 46.2, 46.4 and see what it tells you. I'd pick a charge weight after that and look for the length node next.

 

[Metal god]

What rifle ?

Approximate weight ?

How are you holding it ?

A lot of guys don’t think how you hold your rifle effects your ES/SD but I’ve run test showing it does . Ever wonder why benchrest guys get such great ES/SD , that’s because they’re basically not even really interacting with the rifle . While us Joe Schmoe‘s hold the rifle and pull it in tight to the shoulder which really affects how the rifle shoots . Believe it or not that matters a lot .

 

[MarkCO]

A lot of guys don’t think how you hold your rifle effects your ES/SD but I’ve run test showing it does . Ever wonder why benchrest guys get such great ES/SD , that’s because they’re basically not even really interacting with the rifle . While us Joe Schmoe‘s hold the rifle and pull it in tight to the shoulder which really affects how the rifle shoots . Believe it or not that matters a lot .

Yep, consistency is key! While I assume, on forums and such, that the shooter has a keen grasp of, and applies the fundamentals correctly. I know it is much less than half do so. I was trying to help a guy out with a 10 shot load development and he was all over the place. I asked him to do it again and load 2 batches. His data from his 10 produced no nodes. I got two, predictable nodes shooting the same gun, but the sister set of loads. I think a lot of load development issues are shooter error, but it is a very hard think to extract without being there to see what is going on.

 

[kilotanker22]

Shadow, I am experimenting with same bullet weight and powder right now in my 308. I settled on 46.5 grains of BLC-(2), with Winchester Large Rifle Magnum Primers.

That is for preliminary results. I intend to shoot some more and test this load several times. and doing a seating depth test. I will PM you with my results.

 

[kilotanker22]

Also 44.5-45 grains of Varget yielded excellent results with 165 grain bullets. I am looking for consistent velocity before worrying about accuracy.

 

[hounddawg]

45.2g, avg 2718, sd 16.66
45.5g, avg 2726, sd 13.44

don't get too hung up on SD's, they change. With these two charges there is 8 FPS difference in the ES. Looks like a flat spot. What I would do is this.

Load up 50 at 45.3 and at whatever the longest seating depth I feel comfortable using.

Head to the range on the calmest day you can find and take a seating die, portable press, wind flags (unless the wind is 0 - 3 mph) and calipers to the range. Shoot 3 rounds at the max length. If the first two or three shots touch I adjust another then shoot it. If you can get seven in a row you are happy with the load development is finished. If not try .025 - .030 jump I have found most Sierras, Noslers, and Barnes seem to like to be in that zone.

If not adjust in or out .003 - .005 and shoot another two or three. Keep playing with the seating depth til it made me grin. Sometimes I adjust only 2 rounds at each depth, if they are a inch apart no use wasting components on a third. If the first three are .5 MOA I adjust a fourth fifth etc until I get a flyer. After doing this enough times you will be able to look at the first couple of groups and know whether you are headed in the right direction by the way the group shape changes.

An alternative is use the Berger jump test, google it if you have never tried it. I have found several great loads using it. Just for record I have seen Sierras that like to be touching and Bergers that like .075 off so seating depth is a crapshoot

 

[Nick_C_S]

My advice is worth every penny you paid.

I'm a pistol guy; but have done a fair amount of load development with lever rifles and AR-15. My experience with pistol development is far more extensive. Anyway:

Thanks for the data and chart. If it was me (and I know it's not) I would do more experimenting in the 45.8 to 46.4 range. It looks like your "sweet spot" resides somewhere in there. This is assuming corresponding accuracy.

It has been my experience that low SD's usually means good accuracy (but not always); and high SD's almost always means poor accuracy.

 

[Shadow9mm]

What rifle ?

Approximate weight ?

How are you holding it ?

A lot of guys don’t think how you hold your rifle effects your ES/SD but I’ve run test showing it does . Ever wonder why benchrest guys get such great ES/SD , that’s because they’re basically not even really interacting with the rifle . While us Joe Schmoe‘s hold the rifle and pull it in tight to the shoulder which really affects how the rifle shoots . Believe it or not that matters a lot .

Mossberg patriot

8.5lb

with basic front and rear sand bag on concrete bench.

chronograph about 9ft from the muzzle

basic caldwell chronograph.

I am also wondering if, to some degree, the equipment or setup I have to measure with is is not adequate to measure to the degree that I need. The chronograph seems accurate enough at +/- 0.25% of stated velocity. but getting the gun lined up over the unit at the same height and angle is the tricky part.

 

[hounddawg]

you can always get a Labradar....ohhh wait

https://www.youtube.com/watch?v=6PdWZMJ5Jnw

people put way too much faith in chrono numbers imho

three groups on this target, only difference was the far right group was not annealed. Oddly enough that group had a lower ES/SD than the far left group but more flyers. Only difference between far left group and center group was how they were pulled from ammo box but the numbers are radically different

edited because I still cannot tell my left from my right lol

 

[Unclenick]

Shadow9mm,

I am assuming you have the 22" barrel most common to the versions of the Mossberg rifle you mentioned in your earlier posts asking about load increments. The Hodgdon test barrel is the standard 24". Yet the velocity they report for 47-grains of BL-(C)2 with the Sierra version of the 168-grain match bullet is about what you are reporting from 1.2 grains less powder. At 22" your top velocity should be about 50 fps slower than their 24" barrel produces, or about 2704 fps with that powder. So you may be starting out ner book max peak pressure with your component combination.

The reasons that could happen are several. Your Lake City brass most likely has a grain or two less water capacity than the Winchester brass that Hodgdon used for their load data. Your magnum primer may be raising pressure above that produced using the Federal 210M primer Hodgdon employed in their data. You could also have a faster lot of the powder. Your bullet could be a little harder or seat a little deeper than the Sierra. Your barrel could be a little tighter than Hodgdon's was. You could have some combination of all of the above, or your chronograph could be off. Your tight bolt lift suggests the problem is probably not the chronograph, or at least, not just the chronograph. All the other pressure signs being absent is not as reliable an indicator as tight bolt lift saying that pressure is high. LC brass has harder heads than most, and primer hardness has considerable variation, too, so they may not tell you where your pressure is.

It looks like your results are performing with the equivalent of what 1.2 grains of extra powder would do in the Hodgdon test barrel as compared to the Hodgdon data. That would tend to explain the hard bolt lift, and I would nudge all your charges down by that much as a starting point. In other words, use 42.8 to start and 45.8 as maximum until you know better.

The other issue is your flat spots. IME, flat spots tend to be wider than you show, spaning at least two load increments. I would re-fire from 42.8 to 45.8. I would follow Dan Newberry's round-robin practice to tend to equalize for building gun fouling and condition changes during the shooting session. Newberry uses 3 strings of incremented loads in his round robins, but 5 is more if you have time to do it again. I would also plot each string of shots separately rather than the average in case we can spot a flat spot that is being averaged out by fouling and condition changes over time.

 

[Shadow9mm]

Shadow9mm,

I am assuming you have the 22" barrel most common to the versions of the Mossberg rifle you mentioned in your earlier posts asking about load increments. The Hodgdon test barrel is the standard 24". Yet the velocity they report for 47-grains of BL-(C)2 with the Sierra version of the 168-grain match bullet is about what you are reporting from 1.2 grains less powder. At 22" your top velocity should be about 50 fps slower than their 24" barrel produces, or about 2704 fps with that powder. So you may be starting out ner book max peak pressure with your component combination.

The reasons that could happen are several. Your Lake City brass most likely has a grain or two less water capacity than the Winchester brass that Hodgdon used for their load data. Your magnum primer may be raising pressure above that produced using the Federal 210M primer Hodgdon employed in their data. You could also have a faster lot of the powder. Your bullet could be a little harder or seat a little deeper than the Sierra. Your barrel could be a little tighter than Hodgdon's was. You could have some combination of all of the above, or your chronograph could be off. Your tight bolt lift suggests the problem is probably not the chronograph. All the other pressure signs being absent is not as reliable an indicator as tight bolt lift. LC brass has harder heads than most, and primer hardness has considerable variation, too, so they may not tell you where your pressure is.

It looks like your results are performing with the equivalent of what 1.2 grains of extra powder would do in the Hodgdon test barrel as compared to the Hodgdon data. That would tend to explain the hard bolt lift, and I would nudge all your charges down by that much as a starting point. In other words, use 42.8 to start and 45.8 as maximum until you know better.

The other issue is your flat spots. IME, flat spots tend to be wider than you show, spaning at least two load increments. I would re-fire from 42.8 to 45.8. I would follow Dan Newberry's round-robin practice to tend to equalize for building gun fouling and condition changes during the shooting session. Newberry uses 3 strings of incremented loads in his round robins, but 5 is more if you have time to do it again. I would also plot each string of shots separately rather than the average in case we can spot a flat spot that is being averaged out by fouling and condition changes over time.

yes a 22in barrel.

I am clear LC brass has a touch less capacity, however during my initial workup I had no issued going up to 47.0g on a warmer day. about 65F.

I attributed the extra velocity to the rather long jump of 0.065 that the bullets are making. Bullets are loaded to Hornady's spec of 2.800, which is also max mag length in my gun so I cannot seat them out any longer.

I agree completely, I was expecting the flat spot to be larger that is one of the reasons I decided to ask, it did not seem like what I was expecting to see.

here is the un averaged velocity data. I was trying to figure out how to work the the spread sheet for the multiple data points but have not figured it out as of yet.

44.9
2702
2679
2695
2684
2691

45.2
2748
2716
2710
2713
2707

45.5
2719
2730
2735
2708
2742

45.8
2758
2753
2749
2731
2748

46.1
2783
2784
2755
2780
2759

46.4
2794
2775
2785
2765
2788

46.7
2826
2793
2802
2819
2816

47.0
2787
2814
2834
2846
2828

 

[Shadow9mm]

Was able to get the 65guys excel sheet. here's how the graphs came out.

 

[Metal god]

IMHO your set up ( all the way around ) is not best to get into the SD single digits consistently. To light a rifle , pulled into the shoulder and standard bags is hard to get single digit SD’s . Id be happy with low teens with that set up . I agree with Nick C S that 45.5 through 46 is a good spot based on your numbers , maybe even 45.2 through 45.8 .

I also agree with Houndawg .

How far off the lands are these loads . As UN points out , you seem to be close to max allowable pressure . If you’re way off the lands and plan to seat closer to fine tune . I would use caution and creep up to the lands slowly . The closer you get to the lands the greater the chance of pressure spikes and if you’re already pushing max any spikes are not going to be well received by your rifle .

 

[Shadow9mm]

IMHO your set up ( all the way around ) is not best to get into the SD single digits consistently. To light a rifle , pulled into the shoulder and standard bags is hard to get single digit SD’s . Id be happy with low teens with that set up . I agree with Nick C S that 45.5 through 46 is a good spot based on your numbers , maybe even 45.2 through 45.8 .

I also agree with Houndawg .

How far off the lands are these loads . As UN points out , you seem to be close to max allowable pressure . If you’re way off the lands and plan to seat closer to fine tune . I would use caution and creep up to the lands slowly . The closer you get to the lands the greater the chance of pressure spikes and if you’re already pushing max any spikes are not going to be well received by your rifle .

Way far off the lands. My measurements have it at 0.065 off the lands and that is at max mag length of 2.800. I plan to seat deeper in 0.003 increments to test for seating as I am loaded out as far as I am able to at this point. That will be after I get powder figured out...

 

[Shadow9mm]

So I essentially have 2 options
1- New chronograph, something like the magneto speed or Labrador.

2- A lead sled, or something like it to lock the gun down and keep its placement consistent in relation to the chronograph.

 

[Metal god]

No you have one option go shoot some groups and pick a load . Once you get a $2k+ rig with the scope to match , thats when you start buying other/better equipment ;-) .