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Finding the sweet spot - need help to understand the routine

paul73

paul73

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I continue reading/watching and have a very noob question, i guess. in most articles it is somehow not truly covered.
if we go, for an example, based on this article - Finding the Sweet Spot

he speaks there about measuring with oal gauge, then playing with sitting depth from max of 2.820" down. i get it - it is not rocket science.

what i do not get - how does this process correlate or should be correlated with choosing the most optimal powder load amount?

So what i ask is this - should this seating process be repeated, essentially, from a scratch for an every different powder amount or powder/primer combination? or is the deviation caused by seating depth expected to be completely irrelevant from the amount or type of the powder used in the load?

i am trying to see how many parameters this game of chasing a single hole group has. :)

PS. speaking specifically of the groups in the article is it difficult to understand the first set of 2 groups - as one was tight and second was out of whack. and rest of groups also pretty much inconsistent. odd. but all i care of is to understand the approach to this routine.
 
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i hope i asked it in the way that makes at least some sense - and if not, pls explain anyway. any info provided would be truly appreciated.
 
Are you wondering how many variables there are to get the best accuracy possible? Or are you asking how to determine what to test first or in what order -optimal charge weight, seating depth, primer choice etc.
 
TrashcanDan said:
May or may not help
Click to expand...
i looked at those briefly and he goes round and round but not about what i need to understand.

to cut it shorter.

before powder test to be done - you need to set the initial seating length to _something_.
i am not doing it for the AR10 rifle - that is limited by its mag max size of 2.8".

the AICS mag in bergara takes up to 2.9" C.O.L. i already did a barrel seating test - it jams bullet into the shell and makes a 2.865" C.O.L. it is typical for bergaras from what i did read.

that is my max. so, as it is prescribed - the seating testing would need to be done starting from 0.010" of that - at 2.855" , then .040, then .0.80, then 0.120 making the smallest size at 2.745" C.O.L. ok, marvellous. i will get to it. the idea from other video was that you need to settle on your powder charge first before doing all that.

i am lost completely, again, what length you supposed to set for the initial powder charge test. am i asking a wrong question? as all you guys are trying to help, i sense it, but i do not get it - am i thinking about it all in a wrong way?
or should i just set the first set of rounds to the prescribed by the book C.O.L. of 2.8" and use that length for powder load and pressure tests, settle on the powder load and then start testing seating depth?
 
paul73 said:
for the AR10 rifle....
Click to expand...
chasing a one hole group with a semi auto rifle? pretty optimistic, ya think. he's talking about a bolt gun, not a semi auto. what he's talking about has been hotly debated for decades. you need to reload for an ar10 by setting your depth for reliable feeding, not chasing the lands. just my opinion.
 
TrashcanDan said:
You may-

want to start .015-.020 off the lands first, just to use as a baseline for powder charge nodes and get a good burn/ smallest e.s./s.d. possible, then move on to seating depth node testing-

Is that what your asking?
Click to expand...
i guess.

i just spent all evening trying and playing with powder measure. i think i have it tuned and setup correctly - it is not much that can be done on the dillon 750 anyway, but, chasing a 42gr load size i do see that it mostly deviates 1-2gr back and forth, but, sometime it may produce 42.3gr and sometime - 41.7gr.

i would think it is a bit too much? i spent about an hour doing it just now, as i am still learning the process. will try to google now if i missed something or if it is how the stock powder bar operates. i also have a double alpha short powder bar, but it was doing same deviation. which is odd as the .223 set was i think more accurate in dispensing the required load.
 
paul73 said:
i guess.

i just spent all evening trying and playing with powder measure. i think i have it tuned and setup correctly - it is not much that can be done on the dillon 750 anyway, but, chasing a 42gr load size i do see that it mostly deviates 1-2gr back and forth, but, sometime it may produce 42.3gr and sometime - 41.7gr.

i would think it is a bit too much? i spent about an hour doing it just now, as i am still learning the process. will try to google now if i missed something or if it is how the stock powder bar operates. i also have a double alpha short powder bar, but it was doing same deviation. which is odd as the .223 set was i think more accurate in dispensing the required load.
Click to expand...

Probably good for getting you to a certain point, but you'll want to trickle in the final number.
 
paul73 said:
it is not much that can be done on the dillon 750 anyway, but, chasing a 42gr load size i do see that it mostly deviates 1-2gr back and forth, but, sometime it may produce 42.3gr and sometime - 41.7gr.
Click to expand...
That's way too much variation. For testing, it's better to weigh each charge. Get an RCBS Chargemaster if you want to make load development easier.

I start with the bullet 0.020" off the lands, then either follow the OCW method, or if I'm in a hurry, make two rounds each at 90%, 92%, 94%, 96%, 98%, and 100% of the max charge weight, fire them over a chronograph, graph the results (velocity on the Y-axis and charge weight on the X) and pick the charge weight in the middle of the fastest flat spot on the graph. Then I start messing with seating depth while shooting groups.

If the results are inconsistent, repeat the test with the bullet 0.010" or 0.030" off the lands.

When you find the right load, replace your Dillon powder measure with a Hornady.
 
paul73 said:
i guess.

i just spent all evening trying and playing with powder measure. i think i have it tuned and setup correctly - it is not much that can be done on the dillon 750 anyway, but, chasing a 42gr load size i do see that it mostly deviates 1-2gr back and forth, but, sometime it may produce 42.3gr and sometime - 41.7gr.

i would think it is a bit too much? i spent about an hour doing it just now, as i am still learning the process. will try to google now if i missed something or if it is how the stock powder bar operates. i also have a double alpha short powder bar, but it was doing same deviation. which is odd as the .223 set was i think more accurate in dispensing the required load.
Click to expand...
You may want to get some kind of Gem scale. They are small relatively cheap electronic scales about 50 bucks and will get you accuracy to about a tenth of a grain instead of 1-2 grains.
I don't know what your caliber is but if it is something like 6.5 CM , I think your rifle should be capable of less than 1 MOA or much less at 100 yards.

Usually the starting point is a well known load for that caliber probably around 10 - 20 thou off the lands to start depending on the bullet you are using. Do the powder charge amount testing first, then do the jump testing. good luck
 
When I climbed out of this rabbit hole I settled on copying the 175gr GMM load as best I can, since I have multiple bolt guns in 308 I wanted a load I could use in any one of them. It's a compromise but at the distances I'm shooting it's really not that much of an issue. Now I have a shelf full of shit I never use, neck sizing bushings and dies, runout gauges, meplat trimmers, etc. I use an older Redding bench rest powder measure, that thing is never off more +/- 1/10 of a grain with ball powder.
 
EddieCoyle said:
That's way too much variation. For testing, it's better to weigh each charge. Get an RCBS Chargemaster if you want to make load development easier.

I start with the bullet 0.020" off the lands, then either follow the OCW method, or if I'm in a hurry, make two rounds each at 90%, 92%, 94%, 96%, 98%, and 100% of the max charge weight, fire them over a chronograph, graph the results (velocity on the Y-axis and charge weight on the X) and pick the charge weight in the middle of the fastest flat spot on the graph. Then I start messing with seating depth while shooting groups.

If the results are inconsistent, repeat the test with the bullet 0.010" or 0.030" off the lands.

When you find the right load, replace your Dillon powder measure with a Hornady.
Click to expand...
it was late in the evening and i did not realize during my testing that 42gn of long grain imr 4350 was filling up the 6.5CM case above the neck, so i think it was the reason of the inconsistent loads amount when i would pour it out on the scale for checking.
it was really odd - as the hornady manual says a maximum charge weight for the imr 4350 powder in the 6.5CM to be 43gn - well, it is actually the 40gn that the maximum possible amount of powder can be in that case, from what i checked this morning, in order to be able to put in the bullet at 2.8" COL.

i also think the powder bar of 750 dillon was not liking that long grain stick powder very much indeed. it would be cutting grains of that powder every other time as well then i would move the handle up, felt like operating a grinder.
accurate #2495 with the .223 test did not give me such a huge deviation from load to load when i worked on setting up that bar, nor felt like a grinder.
 
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EddieCoyle said:
replace your Dillon powder measure with a Hornady
Click to expand...
i did read about it, but i soooo did not want to do that... :(
is it really an only solution to get a perfectly accurate powder loads on the 750 machine? no way to get some improvement to the dillon contraption - an aftermarket bar, or, dunno, any mutilation of the measure itself? if it would vary in .2gn area it would not be an issue, but to see a 42gn, 41.7gn then a 42.3gn was way too odd. i will retest it today with a #2495 powder in that bar/measure to be sure.

do you mean this model?
www.hornady.com

Lock-N-Load® Powder Measure - Hornady Manufacturing, Inc

Lock-N-Load® Powder Measure Item #050069 The pioneering design of the quick change Lock-N-Load® Powder Measure has been copied by others but never replicated. Offering the most flexible operation and widest range of use, the Lock-N-Load® Powd...
www.hornady.com www.hornady.com


PS. i just did the re-test with #2495 - it is very accurate, set to 41gn it was going mostly at 40.9gn/41gn/41.1gn(less) with only once in a dozen pulls to show 41.3gn, and 2 41.2gn. but mostly it was closer to lower end, realistically a pretty stable .2gn deviation and no grinding/cutting powder sticks.
 
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1903Collector said:
Now I have a shelf full of shit I never use, neck sizing bushings and dies
Click to expand...
i kinda feel the type S die with a set of bushings - which was a $240 fun - is producing a marginally, very marginally better result than a basic FL die from this set i got:
www.midwayusa.com

Redding National Match 3-Die Set 6.5 Creedmoor

The Redding National Match Die Set combines three of Redding's most popular dies for shooters looking to get the most accurate rounds out of their gas...
www.midwayusa.com www.midwayusa.com

looking and measuring it i can see that neck is seated a bit deeper, true, looks better formed and more consistent, and overall sizing outcome with type S is more consistent, but, i am not positive of how much of an actual effect it would have on an accuracy. but i will keep it as the type s die is also better made and produces cases that fit AR10 better than that 'premium' FL die. it makes a .001 diff where it matters compared to other one.

but it just may be a result of quality deviation in redding dies also.

like, the best FL sizing die for the .223 ended up to be a cheapest one from RCBS. as long as it works - i do not care.
 
paul73 said:
i kinda feel the type S die with a set of bushings - which was a $240 fun - is producing a marginally, very marginally better result than a basic FL die from this set i got:
www.midwayusa.com

Redding National Match 3-Die Set 6.5 Creedmoor

The Redding National Match Die Set combines three of Redding's most popular dies for shooters looking to get the most accurate rounds out of their gas...
www.midwayusa.com www.midwayusa.com

looking and measuring it i can see that neck is seated a bit deeper, true, looks better formed and more consistent, and overall sizing outcome with type S is more consistent, but, i am not positive of how much of an actual effect it would have on an accuracy. but i will keep it as the type s die is also better made and produces cases that fit AR10 better than that 'premium' FL die. it makes a .001 diff where it matters compared to other one.

but it just may be a result of quality deviation in redding dies also.

like, the best FL sizing die for the .223 ended up to be a cheapest one from RCBS. as long as it works - i do not care.
Click to expand...
I have a lot of Redding equipment but most of it is older stuff, 10+ years or older, it's always been accurate and reliable. I have bushing dies for both 308 and 223...they sit, I never use them anymore, as I said earlier I have multiple guns in the same calibers and its just easier for me to full length size everything. Hey every manufacturer has f*** ups!...I once had a PPK (smith & Wesson) with half the barrel un-rifled.
 
paul73 said:
i guess.

i just spent all evening trying and playing with powder measure. i think i have it tuned and setup correctly - it is not much that can be done on the dillon 750 anyway, but, chasing a 42gr load size i do see that it mostly deviates 1-2gr back and forth, but, sometime it may produce 42.3gr and sometime - 41.7gr.

i would think it is a bit too much? i spent about an hour doing it just now, as i am still learning the process. will try to google now if i missed something or if it is how the stock powder bar operates. i also have a double alpha short powder bar, but it was doing same deviation. which is odd as the .223 set was i think more accurate in dispensing the required load.
Click to expand...
Sometimes you just have to stop running all over the place. Pick a powder/primer/bullet preferable the ones you have enough of to do testing and then have enough to shoot after.

Start somewhere. I will often start with the what the bullet manufacture recommends for COL a base point.

It took me several attempts to finally start to see OCW method.

What I learned from the OCW method is finding that node where your point of aim and point of impact does not have a large shift. Some rifles/loads this can be pretty broad range.
I then focused on finding which load in that range gave the best group. Then I messed with Bullet seating depth. Although 90% of my loads are for mag fed rifles I am restricted to that spec.

It can also depend on the bullet profile. S[ome of these VLD bullets loaded to mag length can be a long way from the lands.

Have you developed a base line with factory ammo/ skills with your rifle ?
 
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mac1911 said:
Have you developed a base line with factory ammo/ skills with your rifle ?
Click to expand...
i can say so, yes, as i had it all tested on various ammo and now it is set for the 6.5cm i got from cmp - so i know how they group, and i know what they are loaded with.
i will be able to see any significant deviation from how it is setup for stock ammo, of course. it shoots it pretty well, close to 1/2moa most of the time.
the challenge was to push it to 1/4 moa from 1/2 moa. :)
 
paul73 said:
i can say so, yes, as i had it all tested on various ammo and now it is set for the 6.5cm i got from cmp - so i know how they group, and i know what they are loaded with.
i will be able to see any significant deviation from how it is setup for stock ammo, of course. it shoots it pretty well, close to 1/2moa most of the time.
the challenge was to push it to 1/4 moa from 1/2 moa. :)
Click to expand...
Nice, which creedmoor variety did you get.
Love their lapua component based ammo
 
mac1911 said:
Nice, which creedmoor variety did you get.
Click to expand...
they only had nosler and hornady - 140gr BTHP. hornady one is better, and i stocked up on it, while it was barely above $1pr.
and also bought whole local supply :) of S&B 140gr packs while they were from $16 to $20 per pack, mostly at $16 per pack. then prices went bananas and still remain there.

S&B is using similar BTHP bullet and is very decently accurate. so i hope my loads will be at least not worse, after i sort it all out.

the most abismal 6.5CM i got were federal 123gr loads - those fly at 1-1.5MOA.
 
paul73 said:
they only had nosler and hornady - 140gr BTHP. hornady one is better, and i stocked up on it, while it was barely above $1pr.
and also bought whole local supply :) of S&B 140gr packs while they were from $16 to $20 per pack, mostly at $16 per pack. then prices went bananas and still remain there.

S&B is using similar BTHP bullet and is very decently accurate. so i hope my loads will be at least not worse, after i sort it all out.

the most abismal 6.5CM i got were federal 123gr loads - those fly at 1-1.5MOA.
Click to expand...
Thought tou might have picked up the creedmoor sport ammo cmp has been selling. The 308 and 30-06 assembled with lapua stuff is great.
I only have a 6.5 sweed made in 1913
It pukes on light bullets. Only way I can even get close to the lands is with round nose bullet,
Even that old rifle and iron sights and berger 140 I get under 2moa from a supported benched position
I run at mag length
 
mac1911 said:
Thought tou might have picked up the creedmoor sport ammo cmp has been selling. The 308 and 30-06 assembled with lapua stuff is great.
I only have a 6.5 sweed made in 1913
It pukes on light bullets. Only way I can even get close to the lands is with round nose bullet,
Even that old rifle and iron sights and berger 140 I get under 2moa from a supported benched position
I run at mag length
Click to expand...
i made an AR10 in 6.5CM that is shooting 1 to 3/4 MOA - a fun gun, but the Bergara LRP 2.0 is a gem. i have managed once to get 4 shots into a dime sized hole at 100yds, so, i know the barrel is capable.
it sucks of course that it is not going to last long that good - 2k to 5k shots lifespan, but, i just love the feel of the precision weapon. :) when i can handle it properly, the damn thing kicks.

AR10 in 6.5CM as a hunting rig is pretty neat. i got it with a 3-18x scope, it is not too heavy (nor light, of course) - but it shoots way, way better than a .308. I want to try different loads for that AR, may be i will find a load combination that will work well for its 18" barrel.
 
i have to share it as it is rather comical. :)
:(
well, the good thing is - i did not blow up my rifle, all the loads i made did fire, all worked fine. this target below was a test of the loads made at 2.265" seating, 41.8gn of AA2495.
all shots clocked from 2396 to 2433. wrong powder for .223, but i was curious. by the manual it was supposed to be at 2600fps with 21.8gn, but - no.

specifically group on the left clocked - 2425, 2396, 2399, 2420. 'group' on the right - 2433, 2412, 2381, 2433. chrono is accurate, i tested it before.
from what i can remember i was pulling handle steady and nothing was showing a deviation.
can it be my shooting? maybe, i WANT to hope it was me flinching - as i was shooting just from the bipod, so, will try to get a solid turret next time to mount the gun.
still, i find it rather ridiculous. no good logical explanation how 8 consequent rounds can produce such a thing.
#1_aa2495_2400fps.jpg
 
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