Powder charge and seating depth
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WildRose
Well-Known Member
Depending on the bullet you're certainly correct. VLD type bullets have a much more abrupt engagement to the lands than do more traditional bullets so they really don't like much jump at all.
The Secant Ogive bullets make that long transition easily on a long slow ride and are somewhat self aligning where the Tangent Ogive bullets just slam into it and may or may not self alight with a longer jump.
Secant vs Tangent Ogive.
WildRose
Well-Known Member
If I remember right he says find a charge to start and then tune it when you have good results that would be your final OAL and charge.
He says it's about combustion, so if I had to seat bullet let's say .040 away from from starting point to get good group that would change my combustion so would that effect my es
WildRose
Well-Known Member
It changes everything including peak pressures. The closer you are to the lands the more danger there is of serious pressure spikes with even very small increases in your load.
Personally I load just sort of mag length, work up the most accurate charge I can find and then tweak the seating depth to see if I can improve.
Mikecr
Well-Known Member
This is decades old perpetuated misinformation.
Hell, I knew the VLD needed seating declarations were hogwash back in the 80s..
It NEVER was true, as any of us doing actual full seating testing seen for ourselves.
WildRose
Well-Known Member
Misinformation? Berger is giving us misinformation along with everyone who's done those tests who tells us they get the best accuracy from their VLD's loading them closer to the lands rather than farther away or all of the other companies producing non VLD's that tell us their's do better seated farther out?
treeman59
Active Member
Coal is according to Sammi chamber or magazine length. Better to find the lands first and start .020" shorter than that. In my experience vlds like to be close to the lands and typical match bullets work better .025 - .040" off the lands.
Hugnot
Well-Known Member
Powder charge:
Some cartridges, like .300 WM are loaded to fit 3.34-inch magazine lengths when actually the cartridge would be best suited to be loaded at 3.6 inches and gain about 8% more powder capacity (powder charge increase). True magnum length actions intended for .300 H&H & .375 H&H would work. My rifle has no magazine being a single shot and has a chamber cut to conform to a sample 3.6-inch inert round. To a lesser extent, same for the .243 Win, a sample 2.825-inch COAL inert round, that fits inside the magazine, was provided for the chamber cutting. Berger 6mm, 95 grain VLD bullets are seated with COAL somewhat shorter than 2.8 COAL. Rounds feed real good & accuracy is good, in compliance with Berger directives in regard to seating depths. The 6mm 95 VLD has a real good form factor, lighter weight for higher velocities but has an abrupt ogive transition requiring seating depth adjustments.
Bullet type - tangent ogive bullets, as defined in the Berger manual, are more forgiving than the secant ogive variety in regard to seating depth ... Tangent - "smooth junction with bearing surface good for self-aligning, Secant - "abrupt juncture, not good for self-aligning... sensitive to seating depth". Apparently, this has led to the "hybrid" type bullet, in an effort to have similar form factors as a secant ogive bullet but with the self-aligning features as a tangent ogive bullet.
Looking at the Berger VLD bullets an abrupt ogive transition is easily observed. The transition is not as easily seen in Hornady bullets, also secant ogive types. I seat both brands deep enough for clearance & periodically adjust for throat erosion. Berger has made zillions of VLD bullets and there has to be validity in seating depth recommendations. Having a nice precise chamber also helps.
Some cartridges, like .300 WM are loaded to fit 3.34-inch magazine lengths when actually the cartridge would be best suited to be loaded at 3.6 inches and gain about 8% more powder capacity (powder charge increase). True magnum length actions intended for .300 H&H & .375 H&H would work. My rifle has no magazine being a single shot and has a chamber cut to conform to a sample 3.6-inch inert round. To a lesser extent, same for the .243 Win, a sample 2.825-inch COAL inert round, that fits inside the magazine, was provided for the chamber cutting. Berger 6mm, 95 grain VLD bullets are seated with COAL somewhat shorter than 2.8 COAL. Rounds feed real good & accuracy is good, in compliance with Berger directives in regard to seating depths. The 6mm 95 VLD has a real good form factor, lighter weight for higher velocities but has an abrupt ogive transition requiring seating depth adjustments.
Bullet type - tangent ogive bullets, as defined in the Berger manual, are more forgiving than the secant ogive variety in regard to seating depth ... Tangent - "smooth junction with bearing surface good for self-aligning, Secant - "abrupt juncture, not good for self-aligning... sensitive to seating depth". Apparently, this has led to the "hybrid" type bullet, in an effort to have similar form factors as a secant ogive bullet but with the self-aligning features as a tangent ogive bullet.
Looking at the Berger VLD bullets an abrupt ogive transition is easily observed. The transition is not as easily seen in Hornady bullets, also secant ogive types. I seat both brands deep enough for clearance & periodically adjust for throat erosion. Berger has made zillions of VLD bullets and there has to be validity in seating depth recommendations. Having a nice precise chamber also helps.
Kmccord
Well-Known Member
Well, depends on your rifle, the one I loaded for a 7mm Rem Mag with the 168 HVLD bullet, it liked it at .050 off the lands. I think all of them are going to be running several nodes on seating depth, you may get good at .010 off, then no good at .020 then better at .030 then better at .040 and start to open up again sort of like a powder charge. That is what I observed with the 7mag and a few other rifles.
@6paksak: don't confuse COAL (cartridge overall length, base to tip) with CBTO (case base to ogive) which has to be measured with something like the Hornady Bullet Comparator system.
I've learned from the folks here on the forum that CBTO is much more reliable.
QuietTexan
Well-Known Member
I agree with you, concentricity does make better groups. What I'm getting at is along the lines of one of Mike's points, if you want to test something get out of the node. So while a honed die is the best option long run, in the short run experimenting with the bushings and mandrels in a not-good place for concentricity is fine because you know you can tune out the effects induced by it because you've done it.
Let me try another way - accept worse groups while you're messing with the neck setting and deciding which spec to get a honed die for. The groups will get better when you start using the correctly spec'd die and runout gets better again. Or you might already have the spec, if you're happy with the bushing mandrel you have, order the die for that spec. But you just introduced annealing, so it might take a few loads to get to a consistent spec again.
One more anecdote - when testing a barrel tuner, you WANT bad groups so you can really see how the tuner moves them. So you have to find a bad load to test the one particular thing you're changing. If you shoot one hole at 100, there's no real way other than going really far away to see the changes. If you shoot 3" at 100 yards you can see the tuner swing the group around. You want to see the effects of seating depth, so pick a charge weight that makes bad groups so you can see the group size move with seating depth. When you bring the depth and charge node together, you should have a resilient, long lasting load going forward that doesn't need to be tweaked for a while.
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We've probably all seen the video in which EC is wearing a tee shirt with a target on it, and bullet holes scattered all over the place. Inscription: "I neck size"
