velocity seems a bit high

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gunlaker
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velocity seems a bit high

Post by gunlaker » Wed May 15, 2019 6:43 pm

What do you think of this muzzle velocity? Taken by my Magnetospeed. The Swiss number seems a little high to me.

.45-70
532gr Money bullet
65gr Swiss 1.5
14 shot average vel 1245 fps.

by comparison here is a load in the same rifle, but with plain Goex FFFg also taken today right after checking the Swiss numbers.
538gr PJ Creedmoor
65gr Goex FFFg
8 shot average vel 1190 fps.

I expected the Swiss 1.5 load to read about 50 fps slower so I wonder if the Magnetospeed is a bit wonky. It seems to shoot pretty well on the turkey line, and reasonably well at the rams, although with a bit more vertical than I'd like.

Chris.

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art ruggiero
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Re: velocity seems a bit high

Post by art ruggiero » Thu May 16, 2019 9:08 am

the swiss number is to high my 45/70 load with 70 gr swiss 1.5 and 540 gr. creedmoor runs 1220 art

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Lumpy Grits
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Re: velocity seems a bit high

Post by Lumpy Grits » Thu May 16, 2019 10:44 am

What's your BBL length?
Did you 'tune' the sensor as per instructions?
FWIW: I get pretty much the same FPS with Old 'E' 2 F.
Gary
"Hav'n you along, is like loose'n two good men"

gunlaker
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Re: velocity seems a bit high

Post by gunlaker » Thu May 16, 2019 2:24 pm

Thanks Art, that's what I thought.

Gary mine has no facility for tuning the sensors and definitely nothing in the instructions about it. Mine is a V.3 what version is yours? I haven't ever updated the software on it, so maybe the newer ones have that feature?

The barrel length is only 30".

I could run some .22's over it, but I don't know what sort of velocities to expect with a 28" barrel vs. velocity data printed on the box.

Chris.

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Lumpy Grits
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Re: velocity seems a bit high

Post by Lumpy Grits » Thu May 16, 2019 4:00 pm

I don't have one-I related what a friend did when he had the same issue.
Also-are you using a 'full' battery each session?
G.
"Hav'n you along, is like loose'n two good men"

gunlaker
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Re: velocity seems a bit high

Post by gunlaker » Thu May 16, 2019 4:22 pm

Yeah batteries have lots of juice :-).

Chris.

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Lumpy Grits
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Re: velocity seems a bit high

Post by Lumpy Grits » Thu May 16, 2019 6:29 pm

My PACT crono gets fresh batteries for each session.
Chris-Does yours use rechargeable or throw away type?
G.
"Hav'n you along, is like loose'n two good men"

gunlaker
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Re: velocity seems a bit high

Post by gunlaker » Fri May 17, 2019 6:55 am

Gary mine uses two of the CR123 batteries ( throw away ). It claims 50 hours of run time which is a pile. It also has a battery status in the menu system somewhere. They are definitely good. These days low if low batteries are causing a device to malfunction then it is just cheapness on the part of the manufacturer. It's super easy for any of these devices to include a low battery indicator on them.

Chris.

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Lumpy Grits
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Re: velocity seems a bit high

Post by Lumpy Grits » Fri May 17, 2019 9:50 am

Did not recall they used 123 batteries. Good long lasting batteries.
You can get a really good price on 123's from Sure-Fire.
My 20 yo PACT uses 1, 9volt.
G
"Hav'n you along, is like loose'n two good men"

gunlaker
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Re: velocity seems a bit high

Post by gunlaker » Tue May 21, 2019 11:27 am

Ok I believe I have an idea as to what it might be. I think all of the powder residue has sandblasted the heck out of my Magnetospeed :lol:

I have shot an awful lot of rounds over it so I can't really complain.

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Lumpy Grits
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Re: velocity seems a bit high

Post by Lumpy Grits » Tue May 21, 2019 12:26 pm

I would think either black or white powder would cut that. :?
G.
"Hav'n you along, is like loose'n two good men"

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desert deuce
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Re: velocity seems a bit high

Post by desert deuce » Tue May 21, 2019 8:06 pm

Good evening Chris in beautiful British Colombia. Couple of things concerning a 45-70 with Black Powder.

Do you have or have access to another chronograph to verify the readings that are questionable?

When I want velocities down in the 1145 range it is easier to switch to Goex than add enough wads in a swiss height powder column to get there. Don't discount the ability of a 540 grain bullet leaving the muzzle at 1145 until you try it, especially under tricky conditions on silhouette.

Being somewhat reliant on a chronograph what I look for is ES. Anything less than ten is good at LR target. 3-5 is wonderful. A pursuit where less truly is more.

For silhouette you can endure a bit more ES where 10-15 is probably OK. But again, less is better.

That said, the group shown on the Turkey is very acceptable. Remember, if the bird goes off the rail it is an X.
Sometimes you get the chicken, and sometimes you get the feathers!

gunlaker
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Re: velocity seems a bit high

Post by gunlaker » Tue May 21, 2019 8:32 pm

Zack I sold my optical chronograph shortly after buying this one unfortunately. My goal at the moment is to pit these two silhouette rifles ( Shiloh .40-65 vs Meacham .45-70 and use the one most likely to do best for our silhouette match next month.

So far, the Shiloh is winning, at least out to the turkey targets. I believe that the .45-70 is a little easier to shoot in shifting winds at the rams, but this load won't hold vertical quite as well at the rams as the .40-65 will.

I do have some .459" 540gr Money bullets sitting on the bench that I could try next week. Unfortunately I won't be able to shoot past 300 until the match ( cows grazing on the range :-), so without the chronograph I'll have to rely only on 300 yard groups which is a bit of a bummer.

I might just load for both rifles and make my decision based on the wind forecast.

I agree on the velocity spread. I certainly wouldn't want anything over 15 fps ES that's for sure, especially on a slow load.

Chris.

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