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> 243 105 A-Max w/Superformance
243 105 A-Max w/Superformance
@ 09:46 am (GMT) |
Jim MoseleyHas anyone tried the 243 shooting the 105 A-Max loading the new Superformance powder? I called Hornady and they don't even have a suggestion for a starting point. I was thinking that there may be another powder with a simular burn rate that would give me a starting point. Any ideas from you guys??Thanks |
Replies
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@ 11:05 am (GMT) |
Nathan FosterRe: 243 105 A-Max w/SuperformanceHi Jim, the charge weights are similar (near identical to) H4831sc (ADI 2213sc), though the results will be different. Start with 39gr and work up in half grain increments to 42gr. If you are confident at reading pressure signs and find 42gr to be mild, you may be able to work up loads past 42gr. This will of course depend on your individual chamber and bore dimensions. 42gr of Superformance will yield immensely high velocities in comparison to traditional powders so be safe.Great to hear about your Doe hunt, yes that A-Max is a great bullet. |
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@ 02:20 pm (GMT) |
Jim MoseleyRe: 243 105 A-Max w/SuperformanceStarted my test yesterday beginning by loading one round each from 40grs to 43.5 in 1/2gr increments just to fine where the pressure signs begin. 43.5 showed signs of a ring around the firing pin indent. MV started at 2733 to 2977 fps. Today a loaded 4 rounds each at 42, 42.5, and 43. Groups were only around 1 inch, but shows horizontal stringing. Bullets are seated .010 off the lands. Don't know if I should seat closer to the lands or back off and allow a little more jump. Hornady guy says to bullet should be seated near the lands. I think these are pretty good MV's for a 22" sporter barrel. Not really sure which direction to go and how to deal with the horizontal stringing. Barrel is floating fine. The savage has 3 screws for the stock. I wonder if there is a particular order when tightening these screws. Feel free to chime if you have any suggestions!! |
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@ 06:05 pm (GMT) |
Nathan FosterRe: 243 105 A-Max w/SuperformanceHi Jim, Ok, I want to start by discussing how to read primers. I am very sorry if this is covering factors you are already aware of.
In the above pic, primer 1 is showing signs of high pressure, seen as the flattening of the outer edge. Please see the bump, marked (A). If loads are increased, the primer will keep flowing out into the chamfer of the primer pocket. Looking down at a fired case, the edge will appear square. Cases 2 and 3 have nice rounded edges, showing low pressures. Case 3 has a ring of protruding material marked (B). This is not caused by high pressure, instead, it is caused by excessive firing pin protrusion. In most instances, this should be ignored. Excessive firing pin protrusion seems to be a common occurance these days, better this than a hang fire. 
In the image above, we see an extractor scuff mark, the shiny mark at the left. This can also be a sign of high pressure and is something to watch for. That said, there are occasions when this reading is misleading. In the above case for example, the scuff mark is due to the brass being extremely soft, flowing into the extractor groove. How can we tell? by looking at the edge of the primer, its still nice and round and along with this, the primer pocket are still tight. In other instances, scuffing can come about after repeated neck sizing, the case is simply cramped in the chamber, regardless of whether it is fired or not, it will come out of the chamber scuffed. So its something that requires a a degree of patience and careful observation. Next factor, seating depths. As a rule, I start at 40 thou jump (1mm) for all load work. I don't want this as yet another variable so I have my 1mm jump and thats it. If however, the rifle is say a .308 Winchester with nearly a quarter inch bullet jump dictated by the magazine (or a WSM or RUM), then I focus solely on bullet to bore concentricity and good case grip. Another issue arises with Berger VLD bullets. These can display 7 thou differences at the ogive from bullet to bullet, so a 10 thou jump simply isn't an option with the VLD. The only time I will go down to 10 or 7 thou jump, is when a barrel has a vibrational stress problem. By this, I mean that the barrel isn't whipping to the same point with each shot and is instead, upredictable in the way it vibrates. By going to say 7-10 thou jump, my goal is to get that bullet out of the barrel before the powder charge pressure wave has a chance to fully effect barrel harmonics. In such instances, it can make a huge difference. I would rather unscrew and throw out a barrel that performs this way however, many folk would perhaps prefer to just work with it. Of course, you can go the other way. From 40 thou, the jump can be increased to 80 thou, resulting in different timing and this is what its all about, timing. In my experience, bullet seating depths really have nothing to do with the projectile and everything to do with barrel stresses. Drastically changing the timing via bullet jump and changes in powder burn rates can get groups down from 2-3" to under 1". The most difficult aspect, is being able to recognise the vibrational stress. Stringing can be attributed to many factors but there are three factors that are most common: Bedding, heat related barrel stress, vibrational stress in the barrel. As you increase recoil, other factors such as bipods can be added to the mix. You can draw on past experience to determine whether this stringing only occurs with this ammunition or whether it occurs will all ammunition. I always bed factory mass produced rifles out of habit. Occasionally I will hear about a rifle that shoots extremely well in its factory stock. Its great when this happens but it should not be expected and never viewed as the norm. The larger factories, especially in the current economic climate, simply don't have the time or funds to provide meticulous fitting. You have to remember, Savage would be proud of a 1" grouping rifle for X dollars. To get the rifle shooting to .5" lifts the game considerably. Generally speaking, a factory rifle that groups 1" is a great thing. More than likely, bedding will get it down that last half inch- unless there is a stress problem in the steel. All we can do is go through the steps in a methodical manner, narrowing down each variable. The three action screws you mention are relative to action stress, which is a less common problem but can be very trying. With some Savage rifles, one of the screws is simply a wood screw, designed to secure the trigger guard. Tension of wood screws does not matter a great deal. The more problematic systems are found on the likes of the M77 Ruger and M70 Winny, the middle screw can cause accuracy problems. You will have to check the set up of your rifle to see which system is in place. Cheers, Nathan. |
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@ 09:21 am (GMT) |
Jim MoseleyRe: 243 105 A-Max w/SuperformanceHow do I post a pic?? Thought I could copy and paste...would not work. |
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@ 09:25 am (GMT) |
Nathan FosterRe: 243 105 A-Max w/SuperformanceI put up a post in the rifles general discussion section yesterday titled how to post a pic. If you get stuck, skype me (terminal-ballistics-research) or email me or respond to the post so I can help. |
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@ 02:29 am (GMT) |
Jim MoseleyRe: 243 105 A-Max w/SuperformanceThanks for posting the photos of the primers. Its seems that the more I read, the less I know. When I compared my spent primer to yours, it is a pin protrusion and not pressure. I used a 8x photographer lupe to see the detail. As for my groups, the hottest round is the most accurate, but all groups put one round that would cut the 1/4" bull eye @ 100yds. That leads to the belief that a bedding job is needed, as you suggested, so I ordered an Acraglas Gel kit which will arrive on Wed. This will my first attempt on bedding, should be interesting?! Wish I had the money to come to UZ to hunt with you. Anyway I'll let you how the bedding job goes and if the accuracy improves. Thanks for all the info!! |
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@ 10:03 am (GMT) |
Nathan FosterRe: 243 105 A-Max w/SuperformanceOh you break my heart, buying bedding compound from the competition LOL.No problems Jim. If you get stuck or want help during the project, just email or skype me. Skype is pretty handy with the web cam, I can look at your job and see how you're going. Point is, there is no need to go it alone. |
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