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Your thoughts on my ladder test results?

heytonyman

Full Member
Full Member
Minuteman
Jul 5, 2010
305
187
Franklin, PA
Hey Fellas, I took to the range for the first time with my recently acquired Surgeon Scalpel in .308. After a few rounds of 168FGMM I had it zero'd and was happy to see it cutting one ragged hole at 100 yards. Showing right at 2700fps average with this ammo thru the 24" Kreiger barrel.

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We moved out to 500 yards and setup 3 targets for a ladder test. I loaded up 3 - 11 shot strings of 178 A-Max's over Varget in Lapua Brass with CCI primers. Charge increased from 43.2g to 46.2g in .3 grain increments. Brass and bullets are weight-sorted to the best of my scales abilities, and I allowed 2-3 minutes between shots to keep barrel heat from becoming a factor. OAL was set by ogive to be consistent at .005" off the lands. Interestingly enough this is exactly 2.800" COAL with 178's. Pretty short throat!

First target I tried the color-coded bullet method but they all just left black holes in the cardboard so it was a fail. I'll post it just for comparison purposes. Wind was 4-6mph from 7 o'clock. Dial'd .2mils for wind, 3.2mils for elevation and had at it.

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Second target I decided to setup the go-pro to record the hits. Wind was again 4-6 from 7 o'clock. Increased wind hold to .3 mils and I felt comfortable when breaking these shots.

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For the third target the wind shifted from the 10 o'clock direction and decreased to about 3-4mph. I felt rushed on these shots as the battery in the go-pro was taking a crap. Still allowed cool-down time but didn't mess around breaking the shots. I didnt feel as comfortable on this series.

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In going thru the strings, I started to see pressure signs on the brass over the 45.3-45.6 mark. But no charged showed extreme over-pressure on the primer cups. It was my first time shooting at this particular range and I was not well-equipped so I did not get to chrono these loads at 500 yards.

I'd like to get your input on my results and advise where to go from here. From my findings there's a node down around 43.5 and again around 44.5 but this is my first attempt at the Audette Ladder so all input is appreciated! Thanks fellas.

Tony P.
 
Re: Your thoughts on my ladder test results?

I'd say you have something good going from 44.5 to 45.5. That doesn't look like more than a couple inches vertical dispersion, and at 500 yards, I think you are in the ballpark. If you are not seeing pressure at 45 grains, I would be tempted to load up a dozen or so and shoot them at 500 yards. Seems like a lot of people have settled on that charge for the AMAXs and the SMKs as well.

I am using a the OCW method for a custom 700 with a 20 Kreiger and getting similar results. I have settled on 45.4 grains of Varget under the 178 AMAX at 2.805 OAL. I think my Winchester cases may have a little more capacity than the Lapuas, as I am seeing no pressure signs.

I will post my results after my next range trip.

-Shaky
 
Re: Your thoughts on my ladder test results?

Thanks for the input Shaky. I have read into Dan Newberry's OCW method in depth and think I will eventually move in that direction for my next session as my local range (10 minutes down the road) is only out to 100 yards. This was our first trip to this particular range up in PA and I decided on the ladder for first go-around. Not only can you see the "clusters" as they appear on the board, but you can also measure the deviation from vertical point of aim on similar charges and, in a round-about-way, cross this information over to Dan's OCW type of development.

Interesting note about pressure, the load I found for my FN SPR was just shy of 46 grains behind 178's in Lapua brass. Extremely high I thought but in that rifle I didn't hit the lands until 2.915 COAL so I am definitely seeing the effects of differences in chamber size in relation to pressure.

I found out the hard way just how short the throat is in this Surgeon. Simply function-testing some 168 FGMM thru it, I had a bullet stick in the rifling and put out of the case on extraction. What a freakin' mess...
 
Re: Your thoughts on my ladder test results?

+1 the horizontal does not matter on this test. You are looking for the vertical dispersion.

On target #2 the results are different from #3.

#3, 44.1 to 44.7 is a good looking trio - 44.44 in the middle.

That same grouping on Target #2 is not so pretty.

I would try it again, focusing on the hold and aim-point and let the wind do what it is going to do.

Jeffvn
 
Re: Your thoughts on my ladder test results?

Correct guys I have been disregarding the horizontal. The difference between the two targets is what has me scratching head. I wish I would have gotten the results from the first target to factor in. On both targets 44.4 and 44.7 are pretty consistent. Going down 44.1 has spread and going up 45.0 has spread. Seems like a pretty narrow node if 44.4-44.7 is the optimal charge. Maybe I will have to do it again. Sucks the range is a 3 hour drive.
 
Re: Your thoughts on my ladder test results?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: heytonyman</div><div class="ubbcode-body">Correct guys I have been disregarding the horizontal. The difference between the two targets is what has me scratching head. I wish I would have gotten the results from the first target to factor in. On both targets 44.4 and 44.7 are pretty consistent. Going down 44.1 has spread and going up 45.0 has spread. Seems like a pretty narrow node if 44.4-44.7 is the optimal charge. Maybe I will have to do it again. Sucks the range is a 3 hour drive. </div></div>

Instead off doing another ladder it'd be a good idea to find the best seating depth and after that try 44.4-44.5-44.6-44.7 to find the lowest SD.
 
Re: Your thoughts on my ladder test results?

To get your shots to show with marker- be sure to shoot only white paper. I realize each rifle is different but, I kissed the lands, found a node, then played with seating depth. Didn't find all that much diff with messing with seating after that. FWIW, I'm at 44.5 Varget, Lapua brass and 175 SMK's. Little toasty but, my GAP loves it. Good Luck!
 
Re: Your thoughts on my ladder test results?

I would pay a little more attention to your 2nd target since you know your weren't not perfect on the final target. The 45.0gr could have totally been you on the 3rd target. I would focus on 44.4 to 45.0. It's looking like 44.7 is strong. I'm with you the first target would have been some nice data. Just more reason to plan ahead and make the drive again. I'm new to loading so take my info with a grain of salt.
 
Re: Your thoughts on my ladder test results?

Steve, interesting you say to go right into seating depth tuning. Can I ask why? Won't optimal seating depth change with different charges and have me running in circles? Has going straight for seating depth yielded better results for you?

I though about staying at .005 off the lands and running 5-shot groups at 100 yards in the range of 44.2-45.0 in .2 increments looking for the best ES's, then progress into seating depth tuning.
 
Re: Your thoughts on my ladder test results?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: heytonyman</div><div class="ubbcode-body">Steve, interesting you say to go right into seating depth tuning. Can I ask why? Won't optimal seating depth change with different charges and have me running in circles? Has going straight for seating depth yielded better results for you?

I though about staying at .005 off the lands and running 5-shot groups at 100 yards in the range of 44.2-45.0 in .2 increments looking for the best ES's, then progress into seating depth tuning. </div></div>

Seating depth, powder charge weight, type of primer, amount of neck tension, consistency of neck tension, ES/SD, on and on, it's all a juggling act(circles)-+ with the intention of squeezing out max accuracy and consistency. One change of a variable will affect the rest.

Since you've already done the ladder 3 times with close results on 2 of the tests it's pretty clear to me that the middle of the node is in region of 44.3 up to 44.7(Maybe 30-40 fps difference ???)so there is no need to do it again.

I do ladders for 2 reasons. One is to find a velocity node window that the barrel shoots best at and two being able to stay within that node regardless of temperature swings. I like to use powders that are not temp sensitive so I don't have to worry about velocity weaving in and out of a node with temp or having to reduce the charge/increase the charge at different times of the year because of temp.

Yes, I go strait to seating depth at this point. little changes in seating depth won't affect velocity that much but usually helps tighten up groups. Also a few 10ths more powder either up and down will compensate for loss and gain in velocity from changing seating depth. You're just trying to produce the velocity in the middle of the node which should be determined by now.

It's entirely possible that the seating depth you are at right now is producing the most accuracy the rifle is capable of. This has happened to me before twice. I got lucky is all.

Really it all comes down to how much time you are willing to invest to find out how well the rifle is going to shoot. Lord knows I've stopped at "good enough" before a few times, LOL.

I like to shoot groups at 200Y. It's a little easier to see if a load is shooting really tight. I found the best seating depth for my 6x47L because one test group I shot had 4 shots through the same hole at 200Y, fifth opened up the group to 1", I think the last one was my fault. The other groups were 1"-1.25". I had all my loading gear with me and made up another five rounds the same as the group with 4 shots through the same hole. All 5 went into a half inch with 6 fps SD so I called it good.
 
Re: Your thoughts on my ladder test results?

Steve123, I did exactly what you suggested and loaded up groups of 44.4 at various seating depths, and also loaded up groups from 44.2 to 45.0 in .2 jumps to check SD's. The conditions were horrible so I let the seating depth set alone and went looking for the SD info instead. I could barely see impacts at 200 yards on the wet paper but the chrono numbers were looking nice. 44.2g ES 25 SD 13, 44.4g ES 6 SD 3 for 5 shot groups. The ES's started to open up from 44.6 upward as did the group size. Imagine my surprise when I walked down to the target at 200 yards and seen this!

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Needless to say, I am thrilled with the Surgeon so far. I'm going to shoot the seating depth loads next time out but I cannot imagine it getting any better than this. Thanks for your help!

Tony P.
 
Re: Your thoughts on my ladder test results?

On your color coding, use white butcher paper or buy a roll of blue print paper. I do this all the time. Works GREAT! I shoot 3 or 4 rounds and go mark the target with the color and charge so there is no confusion. I use colored sharpies. Some colors like brown, red and orange are hard to tell apart, so I try to shoot those colors in different batches in between marking the target.
 
Re: Your thoughts on my ladder test results?

Nice shootin really.. i would work around 44.4 like others r saying