My new U2 700, .25 was shooting JSB MK2 33.95 at 987fps. I just ordered some Zans, 38gr, .253 diameter. What velocity do you think the Zans will shoot at the exact same regulator setting?
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An educated guess, please
- Thread starter BBGunn
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Ohhhhhm, a guessing game, my favorite. Seeing as you're .003 larger than the bore I'd say ZERO. This'll be interesting.
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As I said, interesting, so what's the minor diameter of the barrel? I know that CZ's can shoot slugs but it's that friction air gap thing that is a variable. My guess is 935-945, I really want to say lower though. Out of my 600mm Maverick I'm getting 907fps with 26gr slugs and 869 with 33.95's the inverse of what you are doing.
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I understand what you are getting at. I don't know the land diameter. For that matter I don't know the diameter of the grooves on my particular barrel. These are non-choked barrels. I was quoted the average groove diameter of these AGT rifles at .254"-.255" from a conversation with the fellow who owns AVS Slugs. He claims these AGT .25 barrels shoot best with slug diameters of .253, .254, .255. I don't know this for a fact..., but I soon will once the slugs get here.
If I don't see impact on target after the first shot I'll be sure to check the bore!
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^^not mine, but my old shooting chrony I loaned to a friend came back with fabricated shade rods. I don’t know how he shot one of those, but he did.
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That ZAN slug will have a lot more surface friction than the JSB pellet, and weights 4 grains more. A respectable 930 fps and good long range accuracy is my guess.
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Here is my guess and reasoning for it:
The JSB is a pellet and the Zan is a slug: This should mean the pellet has an easier time molding to the inside of the barrel which in turn should mean less air leaking in front of the pellet.
The Zan is a slug and 0.003 larger than base .25 cal, now without knowing the inner diameters of the barrel it's hard to tell how it will affect it. If it was a perfect fit it should use 99.9% of the energy from the air to push the slug. If the slug is too tight it will slow down and if the barrel is too large it will lose energy. The Zan slug is also 10.65% heavier which slows down speed but it all depends on how efficient the use of energy is.
TLDR:
If JSB MK2 33.95 is shot at 987fps then I'm guessing the heavier slug will fly at around 935fps.
The JSB is a pellet and the Zan is a slug: This should mean the pellet has an easier time molding to the inside of the barrel which in turn should mean less air leaking in front of the pellet.
The Zan is a slug and 0.003 larger than base .25 cal, now without knowing the inner diameters of the barrel it's hard to tell how it will affect it. If it was a perfect fit it should use 99.9% of the energy from the air to push the slug. If the slug is too tight it will slow down and if the barrel is too large it will lose energy. The Zan slug is also 10.65% heavier which slows down speed but it all depends on how efficient the use of energy is.
TLDR:
If JSB MK2 33.95 is shot at 987fps then I'm guessing the heavier slug will fly at around 935fps.
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It's roughly 10fps per gr. I just checked my data from when I was testing Zans it is 10fps per gr. loss Plus the slug penalty. so I'm lowering my estimate to 900- 910, I'm going to also guess they'll be like a shotgun. Too much air behind the slug.
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I have seen and compared some power/velocity figures of testers who run both slugs and pellets with the same power settings.
And for slugs in .22cal I observed a loss of power of 2 to 4 FPE when compared to pellets.
A simple ballistic calculator will tell you what velocity that will be with the slugs you fancy.
Matthias
And for slugs in .22cal I observed a loss of power of 2 to 4 FPE when compared to pellets.
A simple ballistic calculator will tell you what velocity that will be with the slugs you fancy.
Matthias
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But that takes the fun of guessing out of the game. If you can just do everything on a calculator you will become dependent on them and not learn how to do the estimates yourself trough knowledge. You will simply not learn it because you just want the answer and not how to get the answer.A simple ballistic calculator will tell you what velocity that will be with the slugs you fancy.
Matthias
Kinda like how when I was a child I had memorized about 30 different phone numbers but today the only one I know is my own because all I do is click a name and the phone calls them.
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For SUB MOA accuracy use only .2553 diameter. Use 44 grain flat or dish base. Tune to a harmonic node somewhere around 960 fps depending on your on you location. I have not had anyone come back and tell me that .2553 was not shooting the best of any other diameter in the agt vulcan 3 25 calI understand what you are getting at. I don't know the land diameter. For that matter I don't know the diameter of the grooves on my particular barrel. These are non-choked barrels. I was quoted the average groove diameter of these AGT rifles at .254"-.255" from a conversation with the fellow who owns AVS Slugs. He claims these AGT .25 barrels shoot best with slug diameters of .253, .254, .255. I don't know this for a fact..., but I soon will once the slugs get here.
If I don't see impact on target after the first shot I'll be sure to check the bore!
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I received the ZAN 38gr (,253") a coupe days ago. Didn't get to test them right away because of the heavy snow storms we have this week. As I write this now we are in the middle of heavy snow and winds!
At any rate, yesterday was the one day we had that was fair and not blizzard like so I started to test the ZANs. I can't say for sure what the velocity was with the slugs at the factory reg. setting as I adjusted the reg. past the factory setting. Based on the guesses you folks shared with me, I decided to go +1/8-turn past the factory setting.
First shot showed velocity at about 545FPS!!! I fired a couple more to confirm that velocity and then assumed the rifle was in 'valve lock'. I turned the hammer in 2-turns and tested again. Velocity went up to an average of 1005FPS over 10-shots! 1005FPS was higher than what I was 'aiming' for but decided to fire a few groups to see how the Zans grouped. The slugs were grouping with no crazy flyers but overall group size not quite acceptable (for me anyway).
I'm looking for about 950FPS so another reg. adjustment is coming. I ran out of time yesterday so no conclusion out of this just yet. The Zan 38gr (.253") look like they have a chance of grouping well with the right velocity but still too early to say for sure.
Snow storm will conclude by Sunday morning and I'll likely get back to this slug testing Monday or Tuesday.
I would say that at the factory reg. setting..., those of you who guessed around 920FPS are pretty close???
At any rate, yesterday was the one day we had that was fair and not blizzard like so I started to test the ZANs. I can't say for sure what the velocity was with the slugs at the factory reg. setting as I adjusted the reg. past the factory setting. Based on the guesses you folks shared with me, I decided to go +1/8-turn past the factory setting.
First shot showed velocity at about 545FPS!!! I fired a couple more to confirm that velocity and then assumed the rifle was in 'valve lock'. I turned the hammer in 2-turns and tested again. Velocity went up to an average of 1005FPS over 10-shots! 1005FPS was higher than what I was 'aiming' for but decided to fire a few groups to see how the Zans grouped. The slugs were grouping with no crazy flyers but overall group size not quite acceptable (for me anyway).
I'm looking for about 950FPS so another reg. adjustment is coming. I ran out of time yesterday so no conclusion out of this just yet. The Zan 38gr (.253") look like they have a chance of grouping well with the right velocity but still too early to say for sure.
Snow storm will conclude by Sunday morning and I'll likely get back to this slug testing Monday or Tuesday.
I would say that at the factory reg. setting..., those of you who guessed around 920FPS are pretty close???
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