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Realize a couple things, long range hunting is a very deliberate type of hunting. The game generally has no idea that a pair of eyes is even upon them. The animals are calm, generally feeding or bedded and there is no hurry at all.
Also, you are set up in most cases at a position with rifle, ranging gear, drop charts, spotters and ammo sitting there ready to roll. You have plenty of time to set up, you have plenty of time to get ready for the shot and you have plenty of time to shoot.
By the time the trigger pulls on that first shot, everything is and has been in place generally for quite some time. Its getting prepared before hand that will make you successful more then anything. That has to do with practice on the rifle but also in being prepared for that second shot
I had cornmeal formed my brass and hunted with the cornmeal formed brass and like others before me had hunted successfully with that brass. It was very accurate. However all good things come to an end and nearly all of my cornmeal brass was shot up and I now had mostly fully formed brass. So I annealed the fully formed brass, full length sized it and loaded it up with the same powder charge and bullet and primer and went to the range today. I had just enough of the cornmeal formed loads left to run a side by side comparison. These are some of the things I found.
1. The fully formed brass shoots to a different point of impact than the cornmeal formed brass at 100 yards and 600 yards (0.5MOA).
2. The fully formed brass seems to have higher pressure with the same powder charge than the cornmeal formed brass.
3. Even with the higher pressures the fully formed brass seemed to have more drop at 600 yards than the cornmeal formed brass with the same powder charge.
4. I tested two rounds of 102.5 grains of H US 869 and two rouunds of 103 grains of H US 869 at 600 yards to see what the point of impact would be.
5. To match the drops of the cornmeal formed brass with a 102 grains of H US 869 it appears I would need about 103 grains of H US869. At 70+ degrees temperature 103 grains of H US is very, very touchy and you cannot let it sit in a hot chamber and heat up before pulling the trigger. I was very careful to keep my bullets in the cooler and not shoot faster than once in five minutes and still things got interesting.
The action I use is a Nesika M and it is smooth. I lubed the lugs. So when you start noticing bolt lift with it you have a good idea that pressures are different and it is time to quit and go home
I post this information so anybody else who has Kirby to build them a great elk rifle will know a few things about the transition from cornmeal brass to fully formed brass. While the difference is not great at the shorter ranges it is enough to cause problems past 1K.
The Smokin Fur Rifle Club
Last edited by Len Backus; 08-11-2007 at 09:11 PM.
Reason: Minor editorial changes
That is very good information and allows me to add another recommendation to my AM shooters.
If you do fireform with corn meal or any other low pressure forming technique, it is always important to hunt with the brass that you have performed the final sight in with.
By that I mean, if your going to use freshly formed cases for the big game season, make sure the cases you sight the rilfe in with are the same lot you shoot at game.
If you want to use cases that have one high pressure firing on them, make sure all your cases are on the same round firing when you take them to the field.
Not only does this make sure your loads will be consistant but also that you will be able to keep track of the number of firings on each lot of cases which I recommend.
I always recommend shooting up an entire lot of brass before reloading them. It is because of this that I generally form up either 50 or 100 cases and split them up into two groups of 25 or 50 cases.
That way I can finish up one batch and still have the second batch of the same lot to shoot. Then I can reload the first fired batch while finishing up the second half of the first batch. Sounds kind of confusing but it really is not.
Just a way to make sure that you do not have some cases that have one firing, some that have 4 firings and some that have 6 firings all in the same lot of brass.
Once a case has been fired under high pressure live fire, after that the difference will be very little but keeping track of your firings per case is always a good idea.
I do not think its a matter of the corn meal forming method causing the slight point of impact change compared to once fired cases. I think this is common with any "virgin" case what is high pressure fired for the first time.
Like all else, when you put a 200 gr 7mm bullet on top of +100 grains of powder everything you see from the bolt face to the target will be magnified. This is why it seems at times you are seeing things for the first time shooting these extreme rounds. that is really not the case, its just that in the extreme cases, it makes a difference you can actually see and realize its happening.
Good point also about letting US869 heat up. All ball powders or all powders to some degree will do this. If your shooting in hot temps, always keep your ammo out of direct sunlight and never let a round cook in a hot chamber.
Again, good report.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.