I've been reloading for a long time but I never claim to know everything. For my 260, I use CCI BR-2 primers, IMR4350 powder, regular Remington brass. I double weight EVERY charge EVERY time. I full length re-size my brass. I use Forster match dies. I trim the cases to length. I use a Forster device that measures off the ogive to determine jump. I double check base - ogive length. What I DON'T do is sort my brass or check the necks for concentricity. In short, I'm as careful as I can reasonably be. But I still get these 25+FPS - 50FPS variations in velocity. What am I doing wrong?
How do I eliminate velocity fluctuations?
- Thread starter RedRyder
- Start date
have you tried chamfering the inside of your flash holes? Most all regular brass that has stamped flash holes have a big burr on them and it is usually a lot bigger on one side than the other, so the flash does not come out even and the chamfer will make it come out even all of the way around.
What are you using to measure velocity? Is it one out of 50 that is way off or are they all evenly scattered? Are the variations befween days and sessions or between shots?
Factory barrel or custom? I think the necks are important. Specifically neck tension and how it varies from case to case. I do nothing to sort or prep brass beyond fl sizing and chamfering necks. I anneal frequently though, which for me cut the spreads in half.
Also, have you ever tried another powder? Might be worth a try.
Also, have you ever tried another powder? Might be worth a try.
I have an arbor press with a hydraulic pressure gauge. The reason this press exists is bullet release is responsible for ES. Depending on how you load your rounds, you may need different amounts of seating pressure. In my case it's around 90 PSI. I did a test where I tried 40 PSI, 60, 80, 90, 100+. My ES was anywhere from 13 to 50 depending on the seating pressure.
I think that light seating pressure is prolly best suited for loading into the lands. I jump my bullets so higher seating pressure works best, but not too high.
You should experiment with different amounts of neck tension. One will give you the lowest ES.
I think that light seating pressure is prolly best suited for loading into the lands. I jump my bullets so higher seating pressure works best, but not too high.
You should experiment with different amounts of neck tension. One will give you the lowest ES.
Primer change, neck tension change, a different velocity node that is more forgiving. Different seating depth. These are all things that I have found can change the ES of a load.
I'm shooting 42g I4350 - kind of the "uber" load for 260s. I'm getting around 2840 out of it. I have nice fast barrels. My 260 barrels are a 26" Krieger and a 25" Schneider, both low rd count. Both are Beanland rifles. After my wife, they're the two things I'd run back into a housefire to get.
I clean out the primer pocket but never have deburred.
918v, how do you experiment with neck tension? I just have a rockchucker but I use Forster comp dies. I will say that of all the factors mentioned, I think neck tension is the culprit. Especially in light of the fact that this 260 brass lasts FOREVER. Despite my best record keeping efforts, I've lost count of how many times these things have been reloaded. 10 - 12xs at least.
I use a Magneto Ver 2 for chrono work. Variations are between shots. I mean, I see guys with a ES of like...4 and I've never ever seen anything that low.
Thanks all.
I clean out the primer pocket but never have deburred.
918v, how do you experiment with neck tension? I just have a rockchucker but I use Forster comp dies. I will say that of all the factors mentioned, I think neck tension is the culprit. Especially in light of the fact that this 260 brass lasts FOREVER. Despite my best record keeping efforts, I've lost count of how many times these things have been reloaded. 10 - 12xs at least.
I use a Magneto Ver 2 for chrono work. Variations are between shots. I mean, I see guys with a ES of like...4 and I've never ever seen anything that low.
Thanks all.
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Good brass and you shouldn't have to deburr. Annealing is how you get down that low, sets the brass back to a fresh even slate reducing tension issues arising from within the brass material itself.
I play with neck tension by using a Lee collet neck die with different diameter decapping rods giving me anywhere from .001" to .003" neck tension. You can also use a bushing die with different size bushings to accomplish the same thing. Sounds like you are FL sizing and your neck tension is very high, prolly too high. But neck tension alone is not enough. It's neck tension plus neck hardness plus inner neck surface smoothness that affect seating pressure. Some people polish the neck with steel wool. Some people lube the neck. Some people are lubing the neck unintentionally without even realizing what they're doing. What initially looks like excessive neck tension actually works well due to the condition of the neck surface. I use .005" neck tension in some loads but only half the neck gets sized. So the resulting seating pressure is correct even though the neck tension is high.
You mentioned your brass has been fired 10x or more times. That many firing would have work hardened your necks to the point where your ES is huge. Low ES requires factory soft necks or 1x fired necks. On my 300WM the ES goes from 10 to 60 after several firings if I don't anneal.
When I eject a spent case, I often notice that there is blackening around the neck. Why is this occurring? Is it indicative of something going wrong? Is it indicative of excessive neck tension? Maybe I'll spring for some Lapua brass as Spife suggests.
If you're not using a collet or bushing die then you can try different madrel sizes to change neck tension. With that many firings annealing will make a major step in the direction of more consistent neck tension and release.
The harder the neck the slower it seals the chamber the more gas blow by the dirtier the neck.
Some soot is normal. A chamber neck that is on the large side can increase the soot also. Hard necks will make it worse
Reloading consistent, quality ammunition is the sum of the parts. In reading the steps and tools you use to reload, the one step missing, and others mentioned, is annealing. What neck tension are you running? You also don't mention how you clean your brass or whether or not you lubricate the inside of your necks. If you clean your brass with an ultrasonic cleaner or use the stainless, tumble method, you're getting the inside of the necks very clean and this translates to poor bullet release unless you apply some sort of lubricant like dry graphite. Annealing will help with brass life while providing more consistent neck tension which in turn should help reduce your numbers.
The fouling around the neck is a by-product of the firing process. Chambers are larger than your cases so cases can expand and contract allowing you to insert and then remove them after firing. The neck area of the chamber is also larger to allow expansion so the bullet can release. The fouling is only on the neck because the shoulder of the case seals the chamber as it expands.
