308 bullet how far off the lands?

tigrr

tigrr

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I am loading 155gr Match grade Bergers and the bullet touching the lands is 2.862 long. So if I back it off to 2.860, that should be a good place to start. .002 off the lands or should I back it off more to .005?
What is jumping the lands?
This is for my single shot 12F/TR.
 
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If you are feeding from the mag, set the OAL based on best functioning.

Tune the powder amounts in very small increments to get the best accuracy.

Just off the lands is a good place to start.

Send some Bergers down range to see how it does.

Jerry
 
If you are having contact with the lands and then seat 2 thou deeper I doubt you can measure it that accurately... 2 thou is not much difference. 10 thou is.

If you are working a load up for a .308 and you are lightly jamming the bullet into the rifling, it is a good place to start for accuracy... but if it is too long to feed out of the magazine it is no good.

"jumping the lands" isn't a term I am familiar with... how much bullet jump to the lands is a reference term...
 
I'm assuming this is for your f/TR... I agree with Dennis seat them 5 thou past where the lands and jacket first make contact with each other and use that as a starting point. genereally speaking, secant ogives and VLD bullets like to be solidly in contact with the lands, whereas tangent ogives/non VLDs tend to like jump. There are exceptions to this rule, like everything
 
tigrr said:
I am loading 155gr Match grade Bergers and the bullet touching the lands is 2.862 long. So if I back it off to 2.860, that should be a good place to start. .002 off the lands or should I back it off more to .005?
What is jumping the lands?
This is for my single shot 12F/TR.
Click to expand...

I think that this is a little long for your 12 F/TR. You may have trouble closing the bolt. Take an unprimed case and seat a bullet at this length, put it in the chamber and close the bolt.

Remove and re measure.
 
X2 Bob

I'm loading for a 6BR but what I did was lenghen them till I "just" felt pressure closing the bolt and then mesured and made notes and locked the dies in place.

Mike.
 
tigrr,

I just checked my 12 F/TR OAL and with Sierra 155 SMK the OAL is 2.2285 with a resulting COL of 2.810.

Sierra's tolerance on match bullets is +/- .020

I believe the published COL for the .308 is indeed 2.810.

Unfortunately I do not have any Bergers to do an apple to apple comparison but maybe some of the other guys have.

Cheers
 
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I loaded up 30 Berger rounds with an OAL of 2.857 5 thou off the lands. They start at 45 grains of Varget and proceed up in .1 gr increments to 46 grains. A friend gave me a box of Sierra Palma match 155grn so I loaded up 10 of them for the final sighting in of the scope!!
I have sighted it in roughly at 100yrds. What increments should I set the targets with the final goal of 1000 yards. Say 100, 300, 500, 700, 1000, what do you suggest?
Just did the math these bullets drop 291 inches at 1000 yrds, wow!
 
Can you shoot through a chronograph?

That will give you an idea of your velocity and the SD and ES numbers for the load you think is the most accurate at 100 yards.

A better indication of how well your load will work is too shoot it at 300 or 500 yards if you can.
 
I am not sure what distances they shoot in matches out in Alberta. Here in Ontario we shoot 300 yards or 300 meters depending on where you shoot. 500 and 600 yards takes care of the short ranges. Long range starts at 800 yards or 700 meters, again depending on where you are (Borden or Ottawa) with 900 yards/800m and 1000 yards/900m.

Instead of thinking 291 inches of drop at 1000 yards, think of it as 29 minutes of elevation, give or take a couple minutes. Elevations are the easy part, wind is another story.
 
I wasn't going to do much crono work till I find out which bullet my gun likes best.
I want to try out my Berger Match grade, the Lapua scenars, the Nosler CCs, the Sierra MKs and the Barnes TSXs.
The info I recieved from other people owning this same gun say its 3000-3100fps with the load I'm using.
I will likely start with the target at 300 then move to 500 then to 800 and lastly to 1000 yards.. I still have another 760 yards of space to go, 1760 yard shooting. reality check..
I wonder what the MOA drop is on that one?
 
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If you can get a chronograph something around 2950 fps will get 155's to make the trip 1000 yards. 3000-3100 fps is really pushing the pressures and is detrimental to accuracy and brass life. Speed does not equal accuracy.
Berger's and Lapua's use about 2moa less elevation than SMK's and Nosler J4 Competition bullets at 1000 yards. Don't waste your money on Barnes bullets, you need a match bullet to hit targets way out there.
 
Newby long range shooter.
3 shot groups in inches at 100yrds .269, .371, .375, .376, .470, .530, .548, .564, .657 and .718
So now I take the best 4 groups and reload 6 of each and do it again?
This is fun even with it snowing and blowing.
Had ice rain for a few minutes.
All this is in preparation for shooting 1000 yrd targets.
I hope I don't run out of Bergers before I get this all figured out.
 
Whatever you powder spacing was, start two steps LOWER and go up to the
0.376 load unless you know you pulled the larger grouping load.

Test at 200yds and look for the group that is smallest AND flatest. The group should look round but if not, like a football on its side not on its tip.

Getting rid of vertical dispersion is critical to any LR success.

Sounds like you got another Savage shooter on your hands.

Don't worry about the Bergers, there will be more to offer you.

Jerry
 
When I am working up loads for my target guns I begin with the bullet in firm contact with the lands. When I find the maximum load, I work back down to find the best accuracy, and once there I play with the seating depth of the bullet if I need to. Mostly I don't.

Rather than worrying about how many thou off the lands, adjust your seating stem a quarter of a turn per adjustment. If you have a calibrated seating stem like the competition seating dies have, you can do the same and have an index to refer to. The more common bullet seaters adjust as follows: Redding uses 20 TPI and adjusts .012" per quarter turn, RCBS uses 28 TPI and adjusts .009" per quarter turn, Forster uses 32 TPI on 6mm and smaller and adjusts .008" per quarter turn, and 28 TPI for 25 caliber and larger and adjusts .012" per quarter turn, and Hornady use 18 TPI and adjusts .014" per quarter turn. I don't have data for the Lee seaters.
 
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I'm using Redding Delux dies and I rechecked the distance from the lands, 5 thou off. I'm all set to do some shooting. I have a 100 - 275 - 500 and 1000 yard targets set up, time to do some shooting. Time to do some calculating, how many clicks from 100 to 1000? Night Force 5.5-22X56 RP-N1 ret. Should have read instructions!!!
 
Depending on your load, a .308 must often be sighted 30 minutes higher than your 100 yard zero to get on paper at 1000. If you have 1/4 minute adjustments, that equals an additional 120 clicks, 1/8 minute adjustments equals an additional 240 clicks, and 1 cm adjustments equals an additional 75 clicks.
 
tigrr said:
I am loading 155gr Match grade Bergers and the bullet touching the lands is 2.862 long. So if I back it off to 2.860, that should be a good place to start. .002 off the lands or should I back it off more to .005?
What is jumping the lands?
This is for my single shot 12F/TR.
Click to expand...

I think you're talking about freebore. I keep all my .308 loads well below 2.810max cartridge length. You get more pressure as you back it off. How do you know the lands are touching at 2.862? Reamers work to get more. What are your groupings like at 200M?
 
Something is working right!
3 shot group at 1000 yrds under 12 inches, bottom 3. Top one is first shot at 1000. For this old-timer that’s a great start. Considering the wobbly bench I was shooting off.
IM001843.jpg

Now its time to settle down and fine tune everything.
I'm having a blast, literally!
:dancingbanana:
 
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Hey Boomer you were pretty close, it was 29 MOA from the 100yd to the 1000yd, with my load. I have an assorment of bullets to try and then I will choose the most accurate at the long range stuff. Right now its fun trigger time..
I shoot at a 24"w X 72"h piece of 1/4 inch thick steel plate 1000 yards away, its at a 30 degree angle so the bullets just splatter down into the ground.
I still have 760 yards of field left.. :sniper:
Jamie the 275 yard 3 shot groups were under an inch. The 500 were inside 4 inches. The 1000 yrd for the benefit of the doubt was probably around 10 (Actually was 11 inches)inches. The best 100 was .269.
All I'm shooting is 155gr Bergers pushed with Varget.
 
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