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Old October 23, 2012, 01:07 PM   #1
rebs
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a little confused about 5.56 hand loads

I have been loading LC 5.56 cases with 55 gr Hornady spire points and 55 gr Hornady FMJBT. The powder I am using is H335 and primers CCI # 400.

I loaded 20 of each bullet with 24.0 grs H335 and OAL of 2.200 and 20 of each bullet with 24.9 of H335 with OAL of 2.250.
They all grouped about the same, how could they all group about the same with that much difference in powder and OAL ?
There seems to be a slight edge to the ones with OAL of 2.200.
I am shooting these in a 16" barrel with 1 in 8 twist.
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Old October 23, 2012, 01:42 PM   #2
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I would guess you (the shooter) are the biggest variable here. That being said how meticulous is your shooting method?
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Old October 23, 2012, 02:09 PM   #3
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What distance is your target?
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Old October 23, 2012, 03:04 PM   #4
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A couple of thoughts. Loading the lesser powder charge at a shorter OAL will slightly increase the pressure, so that may contribute to evening out the difference.

Also, I found that H335 was significantly more even in groups and POI across a broader range of powder weights than other powders such as H4895, BLC2 and Varget. So for that specific powder it does not surprise me much. I was testing loads at 100 yds.

Could just be the harmonics on the particular barrel you have, too. It would be interesting to see how groups and POI compare for you on charge weights between 24.0 and .24.9 gr.
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Old October 23, 2012, 03:38 PM   #5
brokenanew
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Sounds like your shooting an AR. Those are interesting beasts. The top bullets like A-Max and some SMKs were grouping the same (not good groups though) but then tried the 77gr SMK and got nearly .25" group
Rifles are like therapy, takes some times to figure each one and what works best for it.

For me, if the groups aren't that great, all the loads tend to group that smae sorry group until I find that magic spot.
Ive had loads that within a grain, the groups would widen out then close up and then widen out again drastically... within a single grain of charge! Charges tend to go in that cycle. Wide-close-wide through out the chargin range. You could be one 2 wide slots.

H335 is a good powder for mid to small weight bullets.

I would try 5 shots of ever .3 grain. Not 20 shots of 2 different charges. Take your smallest group then adjust with 5 shots of .1 grains till you find the magic spot. Keep you OAL the same for all. After you have nailed down the best charge then you can play with the OAL. The OAL will not change pressure in the case enough to make a difference unless its a huge gap like 2.26 vs 2.22. Even then the pressure differences will be nominal.

Start your charge low then work up every .3 gr...same bullet, same cases, would even wieght the case, same OAL. Find your charge first.
Methodology is important. But you didn't say whether or not the groups were good.
Pilgrim is right your harmonics could play a role as well.
Good luck.
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Old October 23, 2012, 04:34 PM   #6
rebs
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I am shooting a Smith and Wesson Sport with 16" barrel 1 in 8 twist, R5 rifling, melonite. Shot from a bench resting one elbow on the bench using a nikon 3-9 x 40 scope at 100 yds. I did have a couple flyers.


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Old October 23, 2012, 07:24 PM   #7
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It does not seem to me that your shooting position, "one elbow on the bench" would lend itself to load evaluation. Proper use of front rest and a bag on the back will allow you to evaluate loads. It sounds like your positioning does not eliminate the shooter. Still, with that said, some powders will shoot to the same point over a pretty wide range of weights.
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Old October 23, 2012, 07:37 PM   #8
rebs
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Quote:
It does not seem to me that your shooting position, "one elbow on the bench" would lend itself to load evaluation. Proper use of front rest and a bag on the back will allow you to evaluate loads. It sounds like your positioning does not eliminate the shooter. Still, with that said, some powders will shoot to the same point over a pretty wide range of weights.
I will try a front rest and a bag on the stock and see what happens.
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Old October 23, 2012, 07:43 PM   #9
CrustyFN
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Quote:
I loaded 20 of each bullet with 24.0 grs H335 and OAL of 2.200 and 20 of each bullet with 24.9 of H335 with OAL of 2.250.
They all grouped about the same, how could they all group about the same with that much difference in powder and OAL ?
Not that my way is the best way but when doing load work up I only make one change at a time. I will load a few different powder charges all with the same OAL. Then when I find the most accurate I will play with the OAL to see if I can improve it even more. When making more than one change at a time you won't know which one affected the change when there is one. Have fun and nice groups.
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Old October 23, 2012, 07:49 PM   #10
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I think that's pretty darn good shooting without a bag or rest (other than your elbow).
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Old October 23, 2012, 08:20 PM   #11
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You're changing two things at once which makes it harder to figure out. First try different powder loads. Once you get good groups stick with that load and then change the COL.
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Old October 24, 2012, 09:15 AM   #12
Jimro
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The simple answer is "dumb luck" in that two different bullets with two different powder charges shot to the same POI in your rifle.

But there are a number of considerations you should think about.

The gas port in your barrel that cycles the action, it provides a sort of "buffer" effect on powder weight charges. One of the things you have to take into account when loading for an AR.

Your COAL is either going to be limited by your magazine or by your chamber. Since you have a stock factory rifle (as far as the chamber is concerned), just load to the magazine (you won't be able to get a 55gr bullet anywhere near the lands from the magazine).

Some powders "plateau" in velocity and more powder is just more powder and not a meaningful gain in velocity.

But, it looks like your rifle is liking the loads you put together. 55gr pills are generally not noted for sub MOA accuracy. From a 16" barrel I'd maybe try a few more loads to see if I could tighten the groups some, but not very much as it looks like you have acceptable accuracy from anything I'd use a 16" barreled AR for.

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Old October 24, 2012, 09:45 AM   #13
rebs
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The reason for the 2.200 coal is because thats just where it fell when seating to the canalure, so I tried it. Normally I would have a coal of 2.250 which is just short of the max of 2.260, just to allow for any variance when seating.
Thank you all for the help and advice, I believe I am going to start over with lowest powder charge and work up in .3 gr increments with everything else being the same and when I get the tightest group then I will vary the coal.
That was great advice not to change 2 things at the same time, I guess I should have known that but didn't.
It is a terrific hobby loading your own loads and then a trip to the range to see how they work out. Being retired I needed a hobby to fill in some time especially during the winter. I used to reload and shoot a lot 30 years ago but just recently got back into it.
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