FX How vital is extreme spread ??

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Trucker3573

Trucker3573

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Feb 23, 2021
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I admit I get a little obsessive about it especially when I know the gun is capable. However how important really is it ? I ask as I’m struggling with a 700 mm .30 mk2 to get it better than 870-890. With a 18-20 fps spread it still will make one ragged hole at 55 yards. For general hunting purposes how far out do you think I can shoot before that really starts making a significant difference? Still making small tweaks. My M3 and Maverick are much tighter spreads but I think I may be worrying more than needed ?
 
Dr. Kralenstein said:
20 fps is the golden rule I thought, for a shot string curve. Now if you're having 20 fps variance all over through a shot string, that would be an issue. Bit a climb up and slow fall back for 20 fps is typical for an unregulated gun.

Regulated it should vary much at all while on the reg.
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It’s an impact mk2. Most shots stay within a 10 fps but there are always a few that stray to make it 20 fps. A bit frustrating probably just needs some fine tuning. My M3 is 100000000 times easier and faster.
 
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Airgunmann said:
I've found if 20 fps is in your on extreme spread usually it's fine unless it's getting stretched beyond 100 yards weight and messed up skirts can also along with size can change the fps
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Yeah I don’t shoot beyond 100. Rarely that far so I don’t think it’s a huge thing.
 
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Trucker3573 said:
It’s an impact mk2. Most shots stay within a 10 fps but there are always a few that stray to make it 20 fps. A bit frustrating probably just needs some fine tuning. My M3 is 100000000 times easier and faster.
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Like others have pointed out, likely a weight difference in the ammo.
 
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I think very well it might be a pellet thing. I don’t have a lot of experience with .30. Today I tweaked the hammer spring ever so slightly up and down. Did a 16 shot string with standard deviation of 6.4. Did another 21 shot string with it tweaked slightly the other way and got a standard deviation of 6.5. Pretty much is what it is. Stellar accuracy at 52 yards.
 
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Trucker3573 said:
I think very well it might be a pellet thing. I don’t have a lot of experience with .30. Today I tweaked the hammer spring ever so slightly up and down. Did a 16 shot string with standard deviation of 6.4. Did another 21 shot string with it tweaked slightly the other way and got a standard deviation of 6.5. Pretty much is what it is. Stellar accuracy at 52 yards.
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You'll be pleasantly surprised if you weight sort them. It's a bit of work, but it will eliminate flier's and tighten up the spread.
 
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Trucker3573 said:
It’s an impact mk2. Most shots stay within a 10 fps but there are always a few that stray to make it 20 fps. A bit frustrating probably just needs some fine tuning. My M3 is 100000000 times easier and faster.
Click to expand...
That could just be down to projectile irregularities, weight, size, deformity....

Fwiw, most of my experience with wide es means changes in elevation and drift on poi. But I do have a .25 and two barrels for it, short and long that behave the same. Massive variance in velocity due to an obscenely air hungry valve and a tiny air reservoir, but only result is a small amount of elevation shift at poi dictated by power level. Which is entirely predictable. More power hits higher. Not by much. Ymmv.
 
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I think for 100Y I'd agree with Keith, anything under 10 fps for a 25 shot string is very good, and an SD under 3 fps. For shooting long range out to 300 yards, under 5 ES and under 2 SD would be better...
For long range with my .25 Panthera 600mm and 49.5 grain Altaros ATP Smooth slugs, I get an ES of 1 fps and an SD of 0.5 fps from a 15-shot magazine. Thats in part due to a very good tune, and also due to the slugs being identical in weight and diameter.

25 Panthera STATs with 49.5 Altaros png.png
 
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