??Fine tune .308 load ??

[agent88]

How much makes a difference in acuuracy @ 300 yards and less? Tenth of a gn, half a gn, 1gn ?

Just wanted to hear your experiences

[BigBronco]

There is a lot more to improving accuracy than simply adding or subtracting a fraction of a grain of powder to your loads. Leading to your rifle with the proper distance to the lands and grooves using fire formed brass. Then adjust your charges for the best group. Read up on barrel harmonics. This is what adjusting the powder charge is all about.

[Witch Hunter]

Bronco nailed it, lots of things may affect accuracy more than powder weight.

[huckberry668]

There are other factors to accurate load but just answering your questions of charge weight affecting accuracy.... I've not tested loads in 1 tenth of a grain differences but the general answer is yes and no. My experience is that an accurate load has to have uniformed charge.

'Ladder test' is the way to find the sweet spots where slight variation of charge weights matters little to nothing. A ladder test is where you load each round in slight increments of charges (like .2 grains) from low to high. Shoot them in sequence at the same POA. Carefully document each POI and figure out where several consecutive rounds landed in the same POIs. those are your 'sweet spots' for that combo (brass, primer, bullet, powder and seating depth).

So, from the ladder test results (if done right) you'll have not as accurate rounds if your load charge differences just happened to be in the non-sweet-spots zones.

Use my recent ladder test below for example (provided I did it right), it wouldn't be an 'accurate load' if the charge differences falls between shots 12, 13, 14 and 15. But shots 7, 8, 9, 10 or higher ends 15, 16, 17 or 17, 18, 19 would be great loads.

[J-cat]

There are several theories floating out there:

One involves the use of fireformed brass with the bullet seated out to touch the rifling.

Another involves finding the optimum charge weight (ocw) where .2 grains higher or lower does not affect group size or location in relation to the point of aim.

Still another involves loading the bullet to exit the muzzle at the optimum barrel time (obt) using a chronograph and QuickLoad software.

I can tell you the OCW method works.

Sometimes, ocw jives with obt.

Loading into the lands doesn't work all the time. For every load you can concoct that way I can match or beat with conventionally loaded ammo.

[agent88]

Thanks For the replies.

I had just fired my first reloads at 100 yards tried 3 different powders all with seirra 168 hpbt.

Used min loads from lyman manual.

All went 1 moa or better. I was trying for .020 off lands COAL and was thinking of trying .010.

Most loads shot 3 -4" lower than hornaday factory match grade ammo I use.

I was thinking of going up 1gn for next batch

[J-cat]

But what were the loads? How long is your barrel?

[agent88]

But what were the loads? How long is your barrel?

24" barrel

Varget. 41gn
Imr 4064 40gn
Win748 40gn
Benchmark 37g


I'll have to double check those numbers tonite when I get home to be certain

I also did some .223

Sent from my SPH-L720 using Tapatalk

[J-cat]

What make of brass?

[agent88]

What make of brass?

Ok that I didn't keep track of.

It was all fire formed. Some federal match. Hornaday match and range brass

[J-cat]

There you go.

U need to sort your brass. They all have different capacities. Winchester has the most, LC the least. This affects the load.

[NorCalFocus]

Yes all your brass needs to be one head stamp.

POI is not as important as vertical spread is. If your gun like a lower charge and groups all the rounds really nice, all you have to do is adjust your scope to change POI.

Most guys do .2 grain jumps when doing ladder loads. .1 of a grain doesn't show a huge difference in my opinion.

[J-cat]

I did some figuring, using theories 2 and 3:

Optimum barrel time for a 24" barrel is 1.228 milliseconds. the following will get you there without approaching max pressure.

Assemble some test rounds at an OAL of 2.800". Load 5 batches of three rounds, .2grs apart, using the data below as the middle load.

For 748 and Varget in Hornady cases raise the charge to 43grs. Use 42.4grs in FC brass.

For 4064, reduce the above charges by .6grs

Use 39.7grs of Benchmark in FC cases and 40.2grs in Hornady cases.

[agent88]

I did some figuring, using theories 2 and 3:

Optimum barrel time for a 24" barrel is 1.228 milliseconds. the following will get you there without approaching max pressure.

Assemble some test rounds at an OAL of 2.800". Load 5 batches of three rounds, .2grs apart, using the data below as the middle load.

For 748 and Varget in Hornady cases raise the charge to 43grs. Use 42.4grs in FC brass.

For 4064, reduce the above charges by .6grs

Use 39.7grs of Benchmark in FC cases and 40.2grs in Hornady cases.

Thanks for taking the time. .. really appreciate it

Sent from my SPH-L720 using Tapatalk

[Motor Man]

I did some figuring, using theories 2 and 3:

Optimum barrel time for a 24" barrel is 1.228 milliseconds. the following will get you there without approaching max pressure.

Assemble some test rounds at an OAL of 2.800". Load 5 batches of three rounds, .2grs apart, using the data below as the middle load.

For 748 and Varget in Hornady cases raise the charge to 43grs. Use 42.4grs in FC brass.

For 4064, reduce the above charges by .6grs

Use 39.7grs of Benchmark in FC cases and 40.2grs in Hornady cases.

Does barrel twist rate make a difference on these figures? How about bullet weight? Does Quickload give different results depending on the brand of brass your using or is the info you posted from your testing? Is the Quickload program difficult to use? I was looking at their website the other day.

Would you mind running through a calculation for me? Below is the combination I plan on using:

308 cal, 175 grain sierra match King BTHP
24" barrel, 1 in 11.25 twist
Varget powder
Lake city LR brass