RockyMtnMT
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One more. How is accuracy?
Interesting ladder test results. Ideas?
- Thread starter Nevrsummr
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Nevrsummr
Well-Known Member
79.6 bolt lift became difficult. H1000
Nevrsummr
Well-Known Member
Accuracy started out bad. By the 78.9 it was down to 1". Definitely some room for user error though due to very poor cheek weld on this rifle
Nevrsummr
Well-Known Member
Yes, brand new nosler brass
I learned this lesson the hard way when I switched brass in my 7RM. My #'s were all over the board with the new Peterson brass compared to my already developed load with RP brass. Once I retested with the fired brass low and behold my #'s fell right back inline with single digit SD. The Peterson brass actually took 2 firings before it was fully fireformed and settled in.
Lefty38-55
Well-Known Member
... shows why ladder tests can be useless as an "end all, be all" and that the Optimal Charge Weight method by Dan Newbury to be a superior mrthod ... if it is THE most accurate grouping that you want. Chase the nodes ... not the velocity ...
cabelasken
Well-Known Member
I think he is using H1000
RockyMtnMT
Official LRH Sponsor
Ok. I am not much of a node hunter, so I would go to 79g and work there. Load several and check your accuracy and speed. Accuracy is more important than low es. Es under 30 with good accuracy means you are good to very long range. If accuracy here is not as expected then there are a couple of things to work on. One at a time not both. Work on seating depth to find a sweet spot or neck tension / crimp to settle it down. You may have said. How far is the lands are you? I would start seating deeper 20 thou art a time and see if accuracy settles in. If you are 20 thou or closer to the lands we May see the velocity settle with a bit more jump.
Calvin45
Well-Known Member
Those numbers are interesting…
A few years back I worked up a load with imr 8133 in .300 win mag with 225 eld m bullets.
Settled on 78.5 grains. It was compressed but I was able to go higher but very oddly after this charge weight there was no appreciable gain in velocity even up to 82 grains of VERY compressed powder (Winchester brass, many brands wouldn't hold that much under a loooong bullet under any circumstances) 2760-2800 fps.
A few years back I worked up a load with imr 8133 in .300 win mag with 225 eld m bullets.
Settled on 78.5 grains. It was compressed but I was able to go higher but very oddly after this charge weight there was no appreciable gain in velocity even up to 82 grains of VERY compressed powder (Winchester brass, many brands wouldn't hold that much under a loooong bullet under any circumstances) 2760-2800 fps.
med358-boise
Well-Known Member
I would submit you know nothing about 78.2, 78.4, & 78.6. 1 data point tells you nothing.
For this reason, I find the ladder method close to useless.
Even if you are using a digital dispenser, the specification of that device is +/- .1 grain. That means what you think was a 78.9 load could have been a 78.8 load or a 79.0 load. An ES of less than 15 is pretty good. What if 78.2 @ 3299 was at the low end of the average and 78.4 for at 3315 was at the high-end so the actual averages for the those two charge weights is 3306 and 3308.
Neversummr this is not directed at you personally but I am always baffled by what I call the "Rules of Internet Statistics" where 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact.
If it were me, I would use the OCW method and for a case that big load in .6 increments starting around 75.8 and look for two consectuive loads that have similar POIs and similar group size.
For this reason, I find the ladder method close to useless.
Even if you are using a digital dispenser, the specification of that device is +/- .1 grain. That means what you think was a 78.9 load could have been a 78.8 load or a 79.0 load. An ES of less than 15 is pretty good. What if 78.2 @ 3299 was at the low end of the average and 78.4 for at 3315 was at the high-end so the actual averages for the those two charge weights is 3306 and 3308.
Neversummr this is not directed at you personally but I am always baffled by what I call the "Rules of Internet Statistics" where 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact.
If it were me, I would use the OCW method and for a case that big load in .6 increments starting around 75.8 and look for two consectuive loads that have similar POIs and similar group size.
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tesines
Well-Known Member
Now that your are that close, test different primers. I was very surprised how much it matters in my own testing…..
in short yes, generally you will see "higher" pressures or velocities in hot temps. For load dev in the heat of summer I would go back to the range in the fall or winter to check POI and grouping and velocities etc. and if anythings way off then fine tune another ladder test or seating depth.
Did you let the barrel adequately cool down before the different groups? Ive had odd velocity jumps in ladder tests when I was using only a cheap digital scale that went away when I bought an analog scale. Consistency in shoulder bumping, case trim, charge weight, seating depth, barrel temp are important. I also dont fully trust virgin brass until its at least fireformed once.
Huntnful
Well-Known Member
Yeah those micro ladder tests on the big cartridges really don't mean much. Shoot whatever is the most accurate IMO. I had the 155's at 3390 out of a 28 Nos with 26" barrel and 84gr. N570.
But a prime example I JUST shot, was a three shot group with an ES of 5 and SD of 2. I liked the group, so I continued to shoot it for another 10 or so rounds. Turned into an ES of 20 and SD of like 8. Still shot good though.
But looking at your info, I'd just shoot 79gr. and figure out what depth the bullet needs to be in order to be accurate and don't dwell too much on the numbers. That "drop" in velocity with the barely slightly higher charge rate really means nothing based on your ES spreads. Now if you were going in 1gr. increments, that'd be a different story.
But a prime example I JUST shot, was a three shot group with an ES of 5 and SD of 2. I liked the group, so I continued to shoot it for another 10 or so rounds. Turned into an ES of 20 and SD of like 8. Still shot good though.
But looking at your info, I'd just shoot 79gr. and figure out what depth the bullet needs to be in order to be accurate and don't dwell too much on the numbers. That "drop" in velocity with the barely slightly higher charge rate really means nothing based on your ES spreads. Now if you were going in 1gr. increments, that'd be a different story.
