405gr cast boolit velocity?

[jagdkampf]

I have cast some RCBS 405 gr boolits for my 45/70 sized them to .459 with blue angel bullet lube and gas checks. They ended up weighing 433 grs. I would suppose this is due to the lube and gas check. I started working up an accuracy load for my 45/70 Marlin 1895SS. I ended up with best accuracy with 50gr of Surplus 4895. It shoots this load very well, 1.5 inch groups at 125 yds. Finally got around to chronographing them and was very surprised. They chronographed at 2015fps +/- 30fps. I rechecked the chronograph with a couple different loads and it checks out OK, but this seems like a higher velocity than I would have expected. I shot a deer with it last year and got good expansion and penetration so I'm not complaining. Just wondering about the higher than expected velocity.
Randy

[Larry Gibson]

Something definately amiss there. I use 50 gr of milsurp 4895 under a 400 gr GC bullet and regularly get 1720-1760 fps depending on lot out of my 24" barrel. That's also the velocity range most manuals put such a load in. There's not that much difference that your slightly heavier bullet should make. I'd suggest a retest making sure the start screen is 15' from the muzzle. Many times if the screens are closer you can get faster readings with one cartridge but not another. Minimal distance to start screen is sometimes said to be 10' but 15' is getting to be the accepted distance. I don't know what your test condition/parameters were but having the start screen too close to the muzzle is the most common cause of abnormally high velocity readings.

Larry Gibson

[runfiverun]

is this one of those "chrony" set ups?
i have had them read 150 fps off from my pact digital, and off from the books a bit too.
i like to keep a box [500 same lot] of good [eley] 22 ammo on hand.
and shoot the same rifle over the screens just to check.
i also have a string tied to the front screen that i use to keep the distance from the bench consistant.
and i keep a piece of white corrugated plastic [like those campaign signs are made of]
mounted on top of the screens to help diffuse light.
all this helps get consistent readings with cast boolits.

[x101airborne]

Well, i didnt see anyone list a primer. Anyone using a magnum? Just asking. I have seen 400 fps between 30-06's with the same load. That is why it is important to use YOUR gun to develope loads. That is also why some here do not like to disclose load data. If it works for you, then good on ya!! Take the money and RUN!

[JJC]

I use 48.8 gr of H4895 and average 1735 fps with the RCBS 405, out of a Marlin 22" barrel. Federal GM 210 M large rifle primer. I chrone 10' from muzzle. I use a shooting chrony and always aim inbetween the brass fitting on the rods. I have gotten funny readings shooting higher up. 26-2700 fps with a 300 gr bullet.

[jagdkampf]

The chronograph is a "Chrony". I doubt the reading that I am getting off this particular bullet. Every other rifle have checked coincides with what I would expect for a given load. No biggie. I'll just call it an anomaly and figure the velocity is somewhere around 1700 - 1800fps. I am using Fed Mag Rifle primer and chrony set at 15 feet from muzzle. Thanks guys.
Randy

[HangFireW8]

While Shooting Chrony's are sensitive to muzzle blast, bad muzzle blast readings are all over the map. Loads with a lot of unburnt powder afterburning can cause false readings. Snub nose magnum's can also give them fits.

Moving the cronograph further away from the muzzle fixes the problem.

Looking at Hodgdon's reloading manual, top loads for "Modern Rifles" with a 400 gr j-bullet yield over 2100 fps. So, there is no reason to disbelieve your Chrony, especially if the readings are consistent.

-HF

[Mavrick]

FWIW- if you weigh your boolits before lube-sizing, you'll find that the extra weight doesn't come from the lube. Your alloy has too much lead. Since you are happy with the results, I wouldn't change anything. The boolits are only heavy in relation to what the manufacturer used to designate the mold. If you change the alloy to bring the weight in line, it'll only make the boolit harder, and it will expand less and slower.
I've had a bit of trouble from my chronograph when the angle of the sun got too radical, either too low, of too high( if I leave the diffusers off. I use an Oehler M33 with 5' split. My first screen is set at 5', therefore, my reading is a 7 1/2' instrumental. I've only been doing this for 30 years, as you can see...it's an old instrument.
Have fun,
Gene

[Larry Gibson]

Maverick

I started out with the Oehler m33 back in '75. I still have it. It was damaged in '90 when my car was rear ended on my way to the range. Had the screens, also on a 5' spacing, in the back of my Firebird with the rifles and other stuff. A barrel was driven through the one of the screens. The insurance adjuster had me call Oehler about repair. Dr. Oehler said the M33 was out of production but they might be able to fix it. The adjuster said to just get a new one and do what I wanted with the M33. I think he was just happy I wasn't claiming injury. Any ways i ended up with a new M35P and the M33 rebuilt. I still have both and they both still work fine.

I also had the low light problems but Oehler had a "fix" for it which I had done to my SkyScreens. I also took to moving the center of the Skyscreens back to 15' sot the start screen was 12.5" away from the muzzle. That got rid of the occasional high reading or no reading that I would get. I also have the Skyscreens on a board with a block in front of them with a 5/8" steel plate at a 45* angle to deflect any bullets that are low as the older Skyscreens had all the electronics out in the screen boxes. I drilled 2 holes the width of the "screen" window and stick 1/4" dowels 12" long in them. I also mark 4" up on them with black marker and then I can keep the cross hairs at or above the mark and shoot beteen the dowels. It's easy to line them up that way for shooting across both screens. The nice thing about the older M33 was having to take the time to twist the dial for the time reading and then converting it with the table to fps. That kept the barrel cool between shots. With the 35P it is too easy to shoot to fast. Alas the M33 didn't give all the data that the newer chronographs do but ES and average velcoity was easy to figure. The M33 is older technology but is still works. About once a year a line up the screens from the M33, the M35P and the m43 and shoot across them as a "check". Amazing how close all three machines concistently read.

Larry Gibson