Opinions on this ladder test, .308 208 amax over 2000MR powder

matt2143

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  • Dec 4, 2009
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    So I took from some info on here and set up a ladder test using My .308 AIAX 20" barrel that shoots mil M118LR at 2650 consistently.

    Load is as follows:

    Hornady 208gr AMAX
    Aliant PP2000MR powder
    Once Fired LC 04 Brass that has been slightly resized to just fit the chamber on my rifle

    I loaded from 42 grains to 46 grains in .5 grain increments with a target OGIVE overall length of 2.222" and overall of 2.960" (Magazine ID is 2.974 in the AX magazines and for reliability I found I needed at least 0.024"). Each load was hand weighed and is within .1 gr of target weight.

    I loaded two rounds of each weight and also measured the OGIVE for each round before firing.

    #1 - 42gr 2.218" - 2359 fps
    #2 - 42gr 2.218" - 2322 fps
    #3 - 42.5gr 2.222" - 2374 fps
    #4 - 42.5gr 2.215" - 2407 fps
    #5 - 43gr 2.222" - 2434 fps
    #6 - 43gr 2.222" - 2458 fps
    #7 - 43.5gr 2.222" - 2523 fps
    *#15 - 43.5gr 2.219" - 2489 fps
    #8 - 44gr 2.221" - 2504 fps
    #9 - 44gr 2.220" - 2497 fps
    #10 - 44.5gr 2.222" - 2538 fps
    *#16 - 44.5gr 2.222" - 2538 fps
    #11 - 45gr - 2.222" - 2547 fps
    #12 - 45gr - 2.222" - 2550 fps
    #13 - 45.5gr 2.218" - 2547 fps
    #14 - 45.5gr - 2.221" - 2590 fps
    #17 - 46gr - 2.220" - 2603 fps
    #18 - 46gr - 2.220" - 2621 fps



    So I found that 3 rounds had some resistance when chambering so I believe I need to resize further since I would run the case into the die a little at a time and chamber check it and stopped when the cases began to chamber without resistance, maybe they are a little tight so I have some once fired brass from this gun I will use next time. The once fired brass from this test was fired through a Sako TRG NOT this rifle which would explain the chamber size difference.

    Now every round from 42 grains to 46 grains had the same level of resistance on extraction! Pretty tough in fact, enough to require a hard bump from my hand to unlock the action. This caused me to focus on the case heads for pressure signs.

    Here are photos of the spent brass. FIRST PICTURE top right is 42 grains to the top left which is 43 grains, remember 2 cases for each weight, then second row right is 43 again and the left one is 44 grains. SECOND PICTURE is overlapping so disregard the top row, second row right is 44.5 and left is 45.5, Third row right is 45.5 and finishes at 46. The last case is a standard M118LR round with 175 smk @ 2650 fps and notice the cratering of the primer.

    Another note is the 42 grain cases although were tough to open the action the primers had zero flow back like normal M118LR which is why I continued the ladder test and disregarded that method of testing pressure signs.





    What really gets confusing is that some of these rounds have extractor marks even at 43.5 grains and not seen again until 45/46 grains. Below is a picture of two identical rounds, 45 grains, Ogive measured @ 2.222 and one was 2547 and the other 2550 fps.... Any guess why one would shows these signs and the other not?



    The last picture shows M118LR on the left and 46 #1, 46 #2, 45.5 #1 and 45.5 #2 cases, notice all have the same amount of primer flow.




    My end goal here is not to blow something up but to produce good velocities that are CONSISTENT in the 2450 fps to 2650 fps range (wherever the accuracy and pressure is safe!) Velocity is not as important as accuracy for what I am doing, fighting the wind with good barrel life.

    Also the target below was at 300 yards and each round is marked with number and powder charge. 45.5 and 45 grains produced a group of three rounds touching at 300 yards!

    I will run the ladder test again at 400 yards and fire only 1 round of each weight with 0.2 grain increments from 44 grains to 46 grains. Also loading once fired brass from this rifle to hopefully eliminate the heavy bolt lift problem unless it truly is from pressure.




    Please offer suggestions, advice, or warnings. I am new to reloading and just trying to work this one up.
     

    JGorski

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    I absolutely hate ladder tests, but from this target Id take 45grs and load up 15 and shoot 3, 5 shot groups at 300 and see what you get.
     

    matt2143

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  • Dec 4, 2009
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    i also forgot to mention it was windy and I was holding the same POA for the duration. After case prep with a waxy type lube I only hand wiped them with a rag, I don't know if that makes a difference on the variations in the case heads on the fired brass above. Next time I will post process tumble them for 20 minutes to ensure the prep lube has been completely removed.

    I just measured the ring that becomes shiny at the back of the case where it hangs in the chamber due to size is .270" from the base.

    Diameter of unfired M118LR 0.466", once fired 0.469

    Diameter of sized cases from another rifle but fits and was the same lot used for the test 0.4695, the once fired and 'sticky' brass is 0.4705
    i am guessing the brass did not spring back and .0015" was enough to make the bolt stick some???
     
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    jwp6114

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    i only do lader testing at 600 and beyond... just my preference.
     
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    matt2143

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    I am in Fairfax, VA. This rifle only has a 20" barrel and is set up around Precision Rifle and Sniper Comps with a maximum range for me of about 1100 yards. I have never shot an F/TR match and do not really have any plans to do so at this time.
     

    jwp6114

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    20" at 1100 yards... Good luck my friend... You most likely will stop at 800ish yards. Unless your skills are quite high in wind calling... Depending on your target size at distance...
     

    matt2143

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  • Dec 4, 2009
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    I have shot my Sako TRG 22 20" .308 pushing M118LR @ 2600 fps to 1000 yards without much trouble. Shooting these heavies to 1100 should be the same with a good bit less wind correction. I have done a number of first round hits at 950 in comps and still have a good bit to learn about wind correction.

    And yes this AX 20" barrel is shooting 60 - 80 fps faster than my Sako was. Also I have around 200 rounds through it so I do not think it is still breaking in, most people have said velocities drop some in the first 150 rounds. I did see a couple rounds of M118LR fly at 2750 in the first 50 but is has leveled out to a pretty consistent 2650 with suppressor attached (TBAC 30BA).

    Thanks,

    Matt
     
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    Sterling Shooter

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    OP.

    Your pseudo science is not going to get you to your destination, or any discovery other than learning your rifle can indeed rupture when pushed as you are pushing it. What you want is supersonic velocity to the desired distance; but, with your length barrel, most any load will be an overload for LR; and, overloads generally produce erratic velocity. You might want to consider mid range shooting. Also consider, the most important aspect of LR ammunition, other than getting to the distance nose-on, is getting there to the dialed elevation. Loading to single digit ES and SD will effectively make your target bigger if it's a bullseye type; and thus, not countering for wind just right may not have a consequence. Judging from your post, which places emphasis on stuff which you think is important but is not, as well as attempting LR with a mid range concept, I doubt you have ever though about the tip I just gave you, or anything else which is really important to LR shooting, if hitting the target is what's important. I don't mean to be doggin ya; but, you might want to step back and do a little reading on the subject from a credentialed author; and then, re-start.
     
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    matt2143

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    I do not take your post as "doggin me." I will try to give you some insight as to what I am thinking, and you are probably right, I may be looking at this equation the wrong way and I definitely have a lot more to learn! Also most shots are 800 and in with a few out there pretty far. Honestly I love my 20" even if it handicaps me (I am hard headed I know).

    As an example, I shot in the ASC match last weekend. We engaged targets to 1246 yards, elevation around 4000ft, 75 degrees, 50% humidity and 30inhg. My factory loaded M118LR goes transonic at around 1200 yards. I am loading for the best ES and SD I can get, the 44.5 and 45gr loads above showed 3fps and 8fps spread and those are good numbers, loading more rounds will tell if the load and my abilities are up to the task. Some of these targets at those distances at matches get pretty big, I am not shooting MOA targets that far by any means.... Running factory ammo I have ES of almost 80fps on my ammo and IT IS causing me to have flat out high or low misses with follow ups using the same hold to hit POA which leads me to believe my chrono when I get those round regularly come it WAY off. I believe I was not clear above to state I am going after reloading with heavy bullets to assist me with velocity variations and helping to buck the wind more in more distant shots. I have been mindful of the bullet performance as it goes through it's transition from supersonic to subsonic velocities and I have heard the AMAX's fair quite well. I do agree with you I have more reading to do and may be looking at it from the wrong perspective but that is why I post here, to gather insight regardless if the feedback is positive or negative.

    After talking with Jared Joplin he advised me to take the once fired brass from this gun and give it another go. I also spoke with another AIAX owner shooting a .260 we compared notes and it appears the firing pin design possibly is causing the flow back in the primers and is likely a normal thing given we were both running factory ammo and saw it at various temps (25 degrees to 90 degrees).

    I am jumping about .060" IIRC and the 46gr loads were compressed. I could not really feel resistance when seating the bullet and it did not try to back itself out from too much pressure. However with 44.5gr I still can hear powder shake when I shake the loaded round.
     

    jwp6114

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    We are talking about 308 right,
    I'm not sure how much more dense 2000-mr is than 4064
    Bit at 41.5 with 4064 they are quite compressed... Can't hear kernels when shaking... And that was with .020 jump...

    Was your chamber specifically throated for 208's?

    I have 1lb of 2000-mr, its up next for testing.
     

    matt2143

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    The 2000MR powder is tiny flat dots. It sits very well in a case from what I have experienced. I will double check on the next set and make sure 44.5 is correct for the shake test. Yes this is .308 at mag length for AIAX mags, 2.960" OAL.

    **NOTE**

    I may have figured out the sticking case issue... I am using a pretty waxy case lube and was only wiping the case afterwards with a dry rag. I believe I need to clean them thoroughly next go around. I can understand wax on a case is a sticky bad thing, may also be why I saw pressure signs on that one case at 43.5gr, maybe I left more than the others...
     
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    jwp6114

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    Haven't opened the bottle to check it out... My gun tis throated for 178's so I can't seat them out long and have much jump, don't care about running in a mag...

    When I get time it's my next powder to try., did you find that the grouped best in your gun at .060 jump?

    But I look forward to shoot these ultra high bc pills (for 308)
     

    matt2143

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    Because of my requirements for the rifle (must run mag length). I am starting at 2.960" and if they group well (see above 3 rounds touching at 300 yards), then I will leave it, if they do not work then I will seat them a tad shorter but the bullet is so long and already seated in there far enough I do not really want to set them back any further. This is a dedicated Precision and Sniper competition gun and as such I must be able to crank out 10 rounds without stopping for mag feeding issues or anything like that.
     

    matt2143

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    Okay I went out today to a farm and did some shooting at 260 yards....

    Both my standard M118LR from the same lot was 50fps slower (2600 fps) and the 208 loads were running 50fps slower even though ambient was the same (90 degrees). I am thinking the ammo last go around had more sun exposure, today I was set back into the woods shooting across a field.

    I measured everything over again and found PP 2000MR powder fits 45 grains in the case and the 208 amax will fall in with gravity to 2.218 Ogive overall length. I seated the rounds to 2.222 to the ogive and they are jumping .015". Overall I saw velocity swings of 60 fps from 15 rounds!, crappy accruacy (I verified by shooting M118LR 5 round groups in the .2's! before and after shooting the 208 rounds).

    Given the signs of pressure even on rounds that read 2450 the 208 amax is not for me. I don't have a need for them if I can only safely run them at 2400fps. I have some 178 Amax's I will try next of the 2000MR and see what I can come up with.

    Bolt lift was a little stiff, no real pressure signs except for the outer edge of the case rim had a little wipe from the brass markings in the bolt face.
     

    jwp6114

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    Opinions on this ladder test, .308 208 amax over 2000MR powder

    So do u have a pile of 208's u don't want? PM me if so.

    They shoot great in both my bolt gun and ar-10 with pp2000mr