Load developement , Finding max velocity first , then what ?

[hounddawg]

@MetalGod - here is a thread on another forum regarding that bullet and load development, it may have some info for you. Seems like both Varget and N - 140 will net you over 2600 FPS

http://forum.accurateshooter.com/thr...-n140.3964852/

[Metal god]

Yep my research came up with a lot of the same info . Lots of guys using Varget and N-140 . Both are supposed to be at the top of the food chain in the 308 cartridge . I've never used either, Varget because it never seemed available when I was looking for it and N-140 because I have powders that work at a better price as well as it's availability .

For years there was only one LGS that sold powder in any good variety that would have something I "may" want . How ever there prices were high , like IMR powders being $40 a pound and the VV in the $50's . Because of that I had been forced IMO to buy online resulting in me staying with powders that I already knew worked . Many of the powders that I would have liked to try over the years , I was hesitant to buy do to the availability to me .

This has changed in the last few years . I found another LGS that sells powder at ok prices and more powder types are generally more available then they had been . This has helped me get out of my own way and buy new powders but I still have issues with trying new stuff . I really don't want 10 different bullets and 20 different powders I'm using for the same cartridge . Right now I have 3 bullets and 3 powders I use most in 308 .

I'm going to add another combo of the 200.20x bullet or 195gr ELD and what ever powder works with either . If I have problems with both I'll likely just go to the 190gr SMK because I already have data on that bullet and loads that work quite well .

[Metal god]

I went and tested the loads today . To recap , I loaded one round at minimum charge and continue loading one round in .5gr increments until I was .5gr over published max or so . That said as stated before there is no actual specific data for this bullet powder combo in 308 .

LOAD
308 cartridge
30cal 200.20x Berger hybrid match bullet http://www.bergerbullets.com/200-20x...t-bullet-f-tr/
N-550 powder
Lapua brass ( Virgin )
Fed 210 match primers

I concluded through my research that my start load should be 39gr and my max should be 46gr . I loaded 15 rounds in .5gr increments from 39gr through 46gr . I then fired each round over a chrono looking to get 2350fps or more .

these were my velocities
39gr - error
39.5gr -2103fps
40gr-2215fps
40.5gr-2263fps
41gr-2291fps
So far looking good and looking like I'll easily get to 2350fps but it was here my numbers started being inconsistent for lack of a better word .
41.5gr-2388fps
42gr-2495fps
42.5gr-2381fps
43gr2516fps
43.5gr-2541fps kinda flat primer with what might be the start of primer cratering . I'll post a pic later

At that point with the numbers all over the place as well as having velocities over 2500fps well below the charge rate one might expect those velocities , I stopped the testing .

FWIW I went ahead and shot 3 rounds of another load I had with me through the chrono to see what those numbers would be . that load was 168gr smk and 43gr IMR 4064 . those clocked in at 2694, 2672, 2707 . From a 20" barrel I'd say those numbers are close to 100fps faster then they should be .

Which leads me to my next question . Do you think my chrono was likely off by 50 to 100fps the whole time ? Meaning that other load clocking in at 2541fps was likely closer to 2441fps ?

For you quick loads guys

308 cartridge
30cal 200.20x Berger hybrid match bullet http://www.bergerbullets.com/200-20x...t-bullet-f-tr/
N-550 powder
Lapua brass ( Virgin ) - case volume 55.56gr
Fed 210 match primers
COAL 3.020 right at the lands , may be a few thou off but pretty much right there

The other load
168gr smk
43gr IMR-4064
LC-10 case ( once fired w/.002 shoulder bump ) case volume = 54.85gr
CCI LR primer
COAL-2.805 - .025 off the lands

Where my velocities on that first load anywhere close to what they should be per charge , I guess the same question for that other load as well ?

Thanks MG

P.S. as the title asks , now what ???

[hounddawg]

P.S. as the title asks , now what ???

if you are happy with the grouping then nothing. If not play with seating depths and primer brand/types

[Metal god]

Since there was only i shot fired at each charge , im pretty happy with the 0.000 moa group i got with every charge haha

[hounddawg]

im pretty happy with the 0.000 moa group i got with every charge haha

dayumm that's some good shootin' lol

seriously I do a pressure test run, then work on seating depth using a random safe charge that gets me the velocity I am looking for. Then test for grouping using seating depth adjustments, adjust charge to adjust for any horizontal or vertical tendencies, then adjust charge and primer to get flat SD's if it is to be a mid or long range load

[Metal god]

Yeah , thinking 41.5gr to 42.5gr is where I'll start and see if that's a goo area to play with . I'm having a hard time understanding the huge velocity swings though , I've not seen that before . My velocities generally go up pretty consitantly as the charge weight goes up .

There is one thing that could explain it but I don't think it happened and if it did , it was the biggest screw up I've ever done . This cartridges are so long they don't fit in my standard 308 boxes ( they do but the lid is pushing down on the tips of the bullets when closed ). I decided to transfer the rounds to a 30-06 box and by doing so I may have mixed up the rounds . I don't believe I did but it would explain why 41.5gr through 42.5gr seem mixed up as far as velocities . That still does not explain the rather large jumps of 100fps then mellowing out to around 40fps jumps back to 100fps jumps I've just not seen that before in my testing .

No I've never done only one round at each charge weight before but I still have never seen 1 of the 5 rounds in a group be that far off from the rest in that group or one 5 shot average be 100fps fast then the next with only a .5gr increase in charge weight .

This leads me to think I may have mixed them up when moving from one box to the next . I forget which member brought it up but I was told recently that I should mark each round rather then marking just the box .

This is how they were placed in the box

[Dufus]

Get a package of Sharpies and color code each one. I usually color the primer. Then make a legend of what each color represents.

[Aguila Blanca]

Originally Posted by Metal god

It’s not so much that you are to exceed max pressure or charge but rather having those loads with you in case in your rifle the manuals max charge is not your max charge.

The only way you can really find the maximum load for your firearm is to keep increasing until you blow it up. Then you'll know what was too much, but it's too late to be of much use.

[Metal god]

The only way you can really find the maximum load for your firearm is to keep increasing until you blow it up.

Maybe I should say Max Allowable Pressure ( MAP ) or Max Allowable Velocity (MAV) This is not the first time I've not used the best terms or wording in this thread although I do believe you all understand the idea here .

[Metal god]

This was posted in another thread here at TFL by FrankenMauser . It is what my loads should have produced from a 20" barrel



These were my velocities .
39gr - error
39.5gr -2103fps
40gr-2215fps
40.5gr-2263fps
41gr-2291fps
So far looking good and looking like I'll easily get to 2350fps but it was here my numbers started being inconsistent for lack of a better word .
41.5gr-2388fps
42gr-2495fps
42.5gr-2381fps
43gr2516fps
43.5gr-2541fps kinda flat primer with what might be the start of primer cratering . I'll post a pic later

[cdoc42]

To prevent the problem experienced by 44AMP knocking his loads over, I have routinely used a set of "Magic Markers"to mark the primers, and making a "dot"of the same color on the label made that identifies the loads. I always use no color with a blank circle on my first labeled cartridge, then green, blue, black and finally red to identify the load closest to max. If I have more loads than colored markers, I'll make 2 vertical lines with two colors on each primer. My experience with this just happens to differ from 44AMP because I have been lucky never to have knocked a box of reloads over, probably just because Murphy left me alone to go through all the trouble for nothing.

[cptjack]

I suggest to turn off the music

[hounddawg]

I always like to go with the lowest charge that will get the job done, saves on barrel wear and powder. The deer or the target won't notice it was 25FPS slower

On the velocity jumps MG, I find those a lot. Go up two or three tenths of a grain and velocity is flat then go up .1 more a and a 75 or 100 FPS jump. A flat velocity node is pure gold for long range. I had a 4831SC charge that only varied 7FPS over a .5 grain spread then jumped over 50 the next .1

[Metal god]

Originally Posted by Me

Yeah , thinking 41.5gr to 42.5gr is where I'll start and see if that's a goo area to play with . I'm having a hard time understanding the huge velocity swings though , I've not seen that before . My velocities generally go up pretty consitantly as the charge weight goes up .

41.5gr-2388fps
42gr-2495fps
42.5gr-2381fps

So I went and shot 5rds of each of these charges . I shot them through a chrono and was very disappointed with the results . Basically they were 2100fps through 2210fps which was nowhere near what my first test showed . I'm well below the 2350fps I need . On the bright side all three groups where sub moa with 42.5gr being the best at 1/2 moa with three of the 5 all in one hole . Not all touching to make one hole at 1/2 moa but 3 of the shots in one .308 sized hole . I could barely tell more then one bullet went though that hole . All for not though because even that load is 140fps slower then what I'm looking for .

So it appears me trying to save components ultimately is going to cost me more because my theory finding the velocity first did not work .

[DaleA]

Captain Pollyanna here:
Well you went out and systematically tried something. You looked honestly at the results and they are not what you want. (So I imagine you are going to go try something different.)

Disclaimer: Lots of my personal reloading knowledge comes from stuff I've read, not stuff I've done. (But when I comment on stuff I do try to include whether or not I've done it.)

Now the next time this topic comes up you'll be able to talk about it from experience and not from just something you read somewhere.

That's got to count for something.

Good Luck.

[RC20]

I've been loading and shooting for over fifty years....news to me. Most shooters and hunters I've ever met are looking for accuracy as the primary goal, followed by safe pressure.

I would turn that around. Safe pressure is first, accuracy is not.

[Metal god]

I would turn that around. Safe pressure is first, accuracy is not.

On the whole I'd agree with that and to a certain extent that was what I was trying . Find the max allowable pressure first and see if the subsequent velocities where what I wanted . The first test looked as if it was going to work , BUUUUUT it didn't poor MG

I should note that the temperature was 25* lower then it was on the first test . I don't think that's enough to cause that big a drop in velocity though , even with temp sensitive powders . I mean the first test said 41.5gr had a velocity of 2388fps and this test it was barely over 2100fps . That's just to big a swing . I clearly did something wrong and or different on that first test because I trust this recent 5 shot result way more then any single shot result .

[Rimfire5]

Metal God,

I'm afraid that you can't assume that because your chronograph provides a reading that it is necessarily always correct.

I presume you have a single sensor chronograph so you have no way of telling if the readings being taken are consistent.
My Oehler 35P has two sets of sensors in sequence and it reports if the two readings are significantly different and reports that the readings are potentially in error. Even then it can be fooled by the conditions during measurement.

That said, I have found that a chronograph can be fooled by the shock wave if the unit is positioned too close to the barrel.

Also, if the bullet path is not directly over the sensors or is too high above the sensors, you can get really strange readings like your getting. Some chronographs are more sensitive to that than others.

Chronographs also can get confused if there are shadows over the sensors or the diffusers.
At our range, in the early morning, the baffles at 10 yards shade my chronograph and I leave the diffusers off to get consistent readings.
When the sun moves and the shadows disappear, I have to put the diffusers back on to maintain consistent readings.

[GeauxTide]

I've been loading and shooting for over fifty years....news to me. Most shooters and hunters I've ever met are looking for accuracy as the primary goal, followed by safe pressure.

I'm at 45 years. When I started loading a 7mm Weatherby, I did just that. As I've manured, I'm persuaded that accuracy and high velocity are easily obtained.

[Metal god]

I'm persuaded that accuracy and high velocity are easily obtained.

Please elaborate what easy means to you .

I don't disagree that one can and should be able to find top velocity with good accuracy . I however don't find that to be all that easy . Sometimes I don't have the right combo of bullet and powder so I need to try something else . When I start needing to change components to get what I'm looking for , I no longer consider that load development an easy one . Easy to me means the bullet and powder combo gets you both top velocity and accuracy right away . I don't run into that very often . I use 8 different bullets and or weights in all 4 different 308's I shoot . As well as 6 different bullets in all 6 of my 223's and I've never found it easy to get both top velocity and accuracy together because each rifle likes it's own combo of components . I almost always find my best accuracy well before I max out on charge or velocity .

I've said this before , I've often excepted moa rather then sub moa to gain another 100fps with hunting loads . That's what I mean by looking for velocity rather then accuracy . The load is still plenty accurate , just not the best I've found with those components . I would never suggest an inaccurate load ( 3 moa+ ) is better just because it gets you more velocity .

But I've not been loading for 45+ years like you guys . If so , that would mean I started when I was 3 . Hmm maybe my grandson will be able to say that though . He's been helping me with little things in my reloading room since he was 3 . Cutest thing ever was when I showed him my calipers and asked can you say calipers , he replied caterpillars

[kilotanker22]

I agree that light conditions may have been the issue. I once had a prochrono that would read way high velocities when the sun wasn't straight over head or close to it. Recently I purchased a Magnetospeed. And that issue has seemed to disappear. Even with the Magnetospeed though. The bullet path needs to be withing certain parameters to read correctly. The nice thing about it though. Is that if you get an error. It will read out an error number and basically tell you the problem.

I also recently switched to the Satterlee ladder test method to try. Except I do it a bit different. Instead of starting 1.5 grains below your max load. I start 2.5-3.0 grains below and increase in .2 grain incriments. I don't always start at the higher end. Especially with a rifle and powder I don't know. I usually pick a bullet I want to use. Then target my ladder test in the general velocity range I want to be. With a powder that's available to me. Then load somewhere amidst a flat sport in the velocity curve I see. Then I load some to test for avg velocity, SD and how they group. With the last load development I ended up almost 100 fps above max listed velocity in the manual, yet I was over a grain below their max velocity with that bullet and powder. I also had no signs of pressure. Same thing with a lighter bullet.



I have developed several good loads using this method so far. And all of them took less than 40 shots fired total for each load development. It definitely works when executed properly. To keep track of what rounds are what as far as charge weight. I use a sharpie and write every charge on the case in which it is charged. Easy since I only start with 1 shot of each charge. Then I fire them in order recording the velocities. I do not get the rifle too hot. Nor do I allow the round to remain in the chamber for more than a few seconds before I fire it.

But I don't load to find my max load normally. As I said earlier. I pick a bullet and target velocity and powder. See where it takes me. Everyone likes super accurate rifles, but if I can shoot 1MOA, meet or exceed my targeted velocity and have 10fps or less SD I am happy. If I can make it happen firing the fewest number of shots possible is even better. Less load work up, more practice.