.308 / SMK / Benchmark Ladder

[Adli]

Wanted to share my initial ladder testing with my first hand load attempt.

Shooting my .308 Savage 10 FP, 24" Barrel
Bullet: 150gr Sierra Match King HPBT
Powder: Hodgdon Benchmark
Brass: Once Fired ZQI 7.62x51

Powder Charge Ladder:
38/38.5/39.0/39.5/40/40.5 gr

Bench shooting, sandbags and tripod, 5 rounds/target
Adjusted my scope between 39.5 / 40 groups (should have done it to start)
1 bad primer strike on the 40.5gr group
39-40gr seemed to shoot the best, sub MOA

loaded another 20 at 40gr to try and collect a larger sample size.

Target Photo attached
Any suggestions are appreciated!

[NiMiK]

39 to 40 looks good. How close are you seating the bullet to the lands?

[baih777]

where did you get your starting information from ?
Sierra book shows max at 42.5
keep going higher. BUT you should reduce your loads to .3 increments from now on. when you get near the 42.5 max reduce your increments to .2
READ your primers.
if you keep going higher in that big of increments ( .5 ) you will get a real nice blown primer or a stuck case.
for my Savage FCP-K I load SMK 168 with benchmark at 42.2 with surplus brass.

[JMP]

The picture is sideways. Assuming the target was right side up, the 40.5 looks to have the least vertical dispersion. I'd take a closer look at that and keep going up in charge, assuming you do not have pressure issues.

[liber]

The odd thing I will say is that on the Hodgdon site they give 39.9 gr of Benchmark as a starting load for a 150 gr. bullet, and 43.9 max.

It seems like you would have been better starting your ladder from 40 gr. and going to 42.5 rather than how you started at 38 and went to 40.5.

[bazineta]

If the 7.62 cases are military, starting low is typically the right thing.

[liber]

If the 7.62 cases are military, starting low is typically the right thing.

Actually that's a good point, the title of this thread is 308/SMK/Benchmark

But the top post says ZQI brass in 7.62x51, and that is most likely NATO and would demand about 2 gr. less per case, so his 38 - 40.5 could be right if it is NATO.

[Adli]

Actually that's a good point, the title of this thread is 308/SMK/Benchmark

But the top post says ZQI brass in 7.62x51, and that is most likely NATO and would demand about 2 gr. less per case, so his 38 - 40.5 could be right if it is NATO.

Yes - Nice catch - I actually mixed it up, i only have ~40 .308 brass from Herters, but the other 500 i will be loading is in the NATO brass. Do you recommend re-running the ladder?

The odd thing I will say is that on the Hodgdon site they give 39.9 gr of Benchmark as a starting load for a 150 gr. bullet, and 43.9 max.

It seems like you would have been better starting your ladder from 40 gr. and going to 42.5 rather than how you started at 38 and went to 40.5.

I used the Sierra data, where they noted the max at 42.5 with the benchmark, and wanted to be safe. I wasn't sure if the 40.5 was a bad spread because of the charge or the trigger operator - but i can't imagine it could get better with more powder?

The picture is sideways. Assuming the target was right side up, the 40.5 looks to have the least vertical dispersion. I'd take a closer look at that and keep going up in charge, assuming you do not have pressure issues.

Yes sir, sorry about that - shot vertically. Reading your post, it seems like it maybe trigger operator error . Thanks

where did you get your starting information from ?
Sierra book shows max at 42.5
keep going higher. BUT you should reduce your loads to .3 increments from now on. when you get near the 42.5 max reduce your increments to .2
READ your primers.
if you keep going higher in that big of increments ( .5 ) you will get a real nice blown primer or a stuck case.
for my Savage FCP-K I load SMK 168 with benchmark at 42.2 with surplus brass.

Yes sir, Sierra. I will try some higher loads in those increments. I will need to do some reading on understanding what the spent cases are telling me - any recommendations?

39 to 40 looks good. How close are you seating the bullet to the lands?

I didn't measure that specifically, i was only measuring case length (2.015) and total length (2.810). I will do some reading on that before my next loads.

Thanks for the information.
To Do:
Learn about reading primers and pressure warnings
Case Land measurement
Run the ladder higher with .2-.3 increments.

[liber]

Yes - Nice catch - I actually mixed it up, i only have ~40 .308 brass from Herters, but the other 500 i will be loading is in the NATO brass. Do you recommend re-running the ladder?

You need to use the same brass for your ladder, so if you use 308 for the ladder, you really can't use that data with NATO. Match cases are similar to NATO in that the walls of the brass are thicker.

I would think you need to separate out the 308 and NATO cases and run different ladder tests for each, at least that is what I would do.

I used the Sierra data, where they noted the max at 42.5 with the benchmark, and wanted to be safe. I wasn't sure if the 40.5 was a bad spread because of the charge or the trigger operator - but i can't imagine it could get better with more powder?

It could. Keep in mind that your best group for vertical was at your top load. So it's hard to say.

[baih777]

all good info from everybody.
try Google " Primer Pressure Signs "
read a few articles. I cant explain it any better.

if you get a blown primer. don't panic. smoke will come out of your rifle.
when this happens I consider .2 below that load as max.

if you get a stuck case . if your at a range, another reloader will usually assist you in getting the stuck case out. well at least I never say no. you don't want to pull on the bolt handle that you rip off the rim of the case. I have one of those one piece Tipton cleaning rods to push the case out.

there's always help here.

which range do you shoot at ?

[baih777]

if you are only shooting 100 yards and your happy with 40.5 that's ok. but if you plan on shooting farther you will want that little but extra. your bullet wont drop as much.