How many "sweet spots?"

[223copperhead]

Worked up a load 223rem. RE15/Hornady 68BTHP
Started at 22.7grains in 0.2 increments to 23.3 .
23.3 gave best group at 0.400". The rest were about .75" to 0.80".
Made up some more rounds to confirm, and got great results, 4 five shot groups well under 0.50". When I checked drop at 200yards the calculated speed was 2550 ft/second (based on 5.1" drop). The group at 200 yards was 2.75".
Keep in mind I do not shoot alot out to 200 yards so the size may be me.
I was wondering if I should work up a little hotter load to increase velocity and possibly accuracy. My question is can I expect to hit another "sweet spot" if I go hotter?
Thanks!!

 

[Hondo 60]

Because the harmonics of every barrel is different, I don't believe there's a definitive answer.
For some "yes", for others "no"

Good Luck

 

[Ifishsum]

Often the answer is yes..but you don't really know until you try. Be safe of course.

I've started to consider it a bonus when I find an accuracy node at the low end of the range, because I can use that for short range matches and save powder + wear and tear on the gun. I generally limit the top end stuff for the long line (over 300) because the velocity difference really is not much of a factor at shorter ranges. For anything less I will take accuracy over velocity 100% of the time.

 

[GooseGestapo]

FWIW; I use 25.0gr of RL15 with either 65gr Sierra GK, 68gr Hornady BTHP, 69gr Sierra MK, or 70gr Berger VLD. It "simplifies" things.
Also, 26.0gr with 60gr bullets, 25.5 with 63gr.

All are incredibly accurate from two 1/9" twist bbls .223's. I don't really see "accuracy nodes" once you pass a point. It's where you find a "node" when you approach maximums that matters.

My Rem. Mod-7 has 1/12"twist and I've only tried the 65gr GK, which is 1.5moa, or about what the rifle shoots with ANYTHING, 40gr or heavier. (never tried anything heavier than 65gr from it as 60gr V-max Hornady's won't group (tumbling and yawing bullets at 100yds).

Also there is the matter of "sample size". Have you shot enough of a given load to determine the "true" accuracy potential, or just a single or pair of 3 or 5shot groups.
"Accuracy node" may be just a random sampling, rather than an "absolute" characteristic.

 

[FROGO207]

When I do a workup for a rifle I usually find two good nodes with a particular load that will group better than the rest of loads tried, Then one of those two when tested head to head will prove better at distance. I say usually with the cavat that some barrels will never be good shooters or you only find one node that is "OK" but not really that accurate.

 

[Walkalong]

It just might, work up slowly and see. But for punching paper at 100 yards, you have a nice on there. Velocity helps more at longer distances. Less flight time is always good.

 

[joem1945]

Sometimes I'll hit 2 or 3 sweet spots on a given load. Mostly they seem to fall between 92% to 98% of the maximum load data. It depends on the gun. Everytime I think I got a handle on ballistics something throws me a curve. Moatly it's trial and error.

 

[spitballer]

For me dialing in a load as the barrel gets warmer is a dynamic process and I can count on the bullets to start dropping (at higher velocity!) when the barrel warms and is no longer tight enough to hold them to a good seal. Sometimes simply waiting a few minutes for the barrel to cool off is enough, but lately I've been trying to load hot enough to balance fouling build-up with bore dilation, giving me a few extra shots before having to clean. This is for soft varmint bullets in an old-fashioned long gun, harder bullets I'm not too familiar with. Not sure if you're actually using a chrony but I would definitely recommend it for load development, it may reveal some surprises like the aforementioned bullets that are dropping lower but traveling faster! FWIW published load data appears to be based on the first shot from a clean, cold barrel and I've learned to use this first shot as a reference for future adjustments.

 

[Andrew Leigh]

I am a proponent of the OBT theory. With all my work doing loads for myself and others the average 22 to 24" barrel will have about 7 or 8 accuracy nodes. There are nodes that are simply too slow and nodes that are too fast that come with the commensurate pressure problems. My observations are that in reality there are two and at best three "sweet spots" for common calibres. The third is often too slow and will result in underutilisation of the calibre.

 

[kerreckt]

You can creep up a bit and find out. There is no other way given that each rifle is different. Even the same model from the same manufacturer. I have found that some of my most accurate loads in .223 are at, or slightly over published data, so I will carefully try it. It seems it is often with a grain or so, of someones published max. One that comes to mind are some of my IMR4198 loads.

 

[223copperhead]

I did four 5 shot groups which were:
0.43"
0.75"
0.50"
0.75"
Should I expect better?
My 200 yard group was 2.50".
I will work up a little more just to see.
Is there room for improvement with this load?

Thanks for the replies!!

 

[spitballer]

My 200 yard group was 2.50"...

I never expect to shoot less than 1 moa 2" groups at 200 yards so I'm pleasantly surprised when it happens. but with a 12' twist I almost always use the 55 grainers and they drift a lot when any kind of breeze is blowing. On truly calm days I might do 1/2 moa. Frankly I'm surprised that the heavier 68 grainers you're using aren't doing better at 200: with RE 15 you must be using a shorter barrel, is this an AR platform rifle we're talking about? What about twist rate?

post script: my bad, copperhead. I'm thinking of 10x. You may be right on the money with 15

 

[ArchAngelCD]

I did four 5 shot groups which were:
0.43"
0.75"
0.50"
0.75"
Should I expect better?
My 200 yard group was 2.50".
I will work up a little more just to see.
Is there room for improvement with this load?

Thanks for the replies!!

If you are getting an average of .5" 5 shot groups @100 yards that is a very good load. The groups opening up to 2.5" @200 yards IMO is not the fault of the load but the shooter. If I had a load that accurate I wouldn't be looking for a better load but more quality trigger time with that load.

 

[joem1945]

One of the best reloads for .30-06 and a 150 FMJFB chrono'd at 2000 FPS. Under 1" @ 100 yds. It wouldn't operate a M1 Garand, darn it.

 

[223copperhead]

Thanks for all the advise!
I think based on the advise here, I'll just keep loading
This charge and use it for a target round.

I will spend more time at 200 yards and see if I can achieve better
groups with practice. Actually, thinking back, this is my first time shooting past 100 yards.

Thanks again for all the advise!
Great forum btw.