Reloading: Something strange afoot

[johnf]

I reloaded 40 rounds of 243 shells keeping everything very uniform. I started with 38.5 gr. of IMR 4350 and going up to 42 gr. 5 bullets each at 1/2 gr. increments. Shooting all 100gr sierra game kings.

What just doesn't make any sense to me is the accuracy that I got. It was pretty bad at first but every load I put through it the group went up about an inch. at 100 yards. I was getting like 3-5 inch groups and then at 40 gr. it dropped to about 1", stayed the same for 40-41 then 41.5 I got a about a 1/2" 5 shot group. I was hoping that the group would tighten up more with the 42.0 gr. which is the hottest load I made, but they spread out to about a 4 inch group again.

Everything I've heard or read says that the differences would be very subtle.

Does this make any sense to anyone?

Should I just work up another 10-15 at 41.5 and see if I get the same results?

[bluelund79]

That is what I would do....and also when you go back to the range, try and see if you can go on a day with as close to the same weather as possible. Sounds like a pretty neat hobby. May I ask what your start up cost was? I have been interested in doing that as well. I do my shotshells for trap shooting, but making my own rounds for the centerfire rifles would be fun....

[johnf]

$90 for a Lee challenger press kit

$22 Set of lee 243 dies

$8 for a tricker (which I still haven't gotten)

$7 for 2 50 round shell boxes

$22 1lb of powder that will load around 175 243 shells

$23 100 bullets

$3 100 primers

$4 Spray on case lube.

$179 or $35.80 a box. This was enough to make 100 shells or 5 boxes. Not great, but the next batch will cost me $46 or 5 boxes $9.2 a box for premium bullets. If I want to buy cheaper bullets or buy powder in bulk it goes down a bunch.

The next thing I'll get will be a case trimming guide, then either be a tumber or caliper. Probably the caliper.

[OJR]

I would try loading the best accuracy again and see what happens.

Usually you will find one load that a rifle likes the best! Stay with it!

I am going to be selling a bunch of reloading equipment in the near future and I will list it later on!

[wtnhunt]

  OJR said:

I would try loading the best accuracy again and see what happens.

Usually you will find one load that a rifle likes the best! Stay with it!

Think if I was into reloading, that would be the advice I would follow. Makes good sense, when you find a load the rifle likes stick with it. Interesting though that there would be so much difference with that little of a powder variation.

[Texan_Til_I_Die]

I can't explain WHY, but I've seen similar results with my 220 Swift. A half grain variance in the charge and the groups open up an inch or more. I never worried about it, just went with the most accurate load and called it good.

BTW - A half inch group with that 243 is outstanding. I'd be very happy with that.

[Dubie]

I would go with the best load built up too, and stick with that unless you want to work up again. Half a grain could be a pretty big difference in the pressure on a smaller casing, giving you the drastic results. It seems pricey to reload at first, but once you get through the experimenting on a caliber, and into the mass production, you see some pretty big savings.

[tped]

I would work up around the 41.5 grain load in .2 increments to see what happens but you can't knock 5 in .500 no matter how you look at it. If you desire to play further use your 41.5 grain load and play with the bullet seating depth and distance off the lands in your rifle which may/may not make a difference also.

For simplicity and most of my shooting - I would load up 15 of the 41.5 loads exactly as you had them and see if the group is consistent - if so it would be a winner for me and I would stick with it.

[bowana]

You may want to weigh your cases to make sure they are uniform. Also double check your powder charges to ensure uniformity (the 4350 IMR and Hodgdon can be tricky to meter sometimes). With bullets weighing 100 grains, the 243 can be finicky. The 85 grain bullets seem more forgiving. But, there is no reason you should not be able to achieve 1/2 groups with the 243, especially with the bullet you chose.