What difference does 50 feet per second really make in .177?.

[barrel]

This quite surprised me with .177 AA Field pellets at 8.44 grains

750 fps = 10.54 ft/lbs
800 fps = 11.99 ft/lbs

zeroed at 40 yards the difference in impact point between a gun shooting at 800 fps and one shooting at 750 fps would be as follows. At 10 yards 2.54 mm, at 20 yards 3.5 mm, at 30 yards 2.54 mm, and at 50 yards 4.82 mm.

Sort of puts things in perspective a little and makes you realise being too close to the limit does not make that much sense, just me thinking out loud really.

Kindest regards

Barrel

[rabbitwrecker]

A very good point - but people are so fixated on power that you've likely wasted your time posting the above...

[TonyL]

Excellent post and agrees with what many experienced shooters have been saying for years.

As a compromise, you'd be thinking 765 to 770 fps would be perfect, but as you demonstrate, would make minimal difference to trajectory / impact.

[riku]

There's not that much difference from 800 to 950 fps either, about 7 yards extra range if we stay within 1" arc. Of course with modern PCPs and pellets that is extra range where you can actually hit things.

[rogb]

This quite surprised me with .177 AA Field pellets at 8.44 grains

750 fps = 10.54 ft/lbs
800 fps = 11.99 ft/lbs

zeroed at 40 yards the difference in impact point between a gun shooting at 800 fps and one shooting at 750 fps would be as follows. At 10 yards 2.54 mm, at 20 yards 3.5 mm, at 30 yards 2.54 mm, and at 50 yards 4.82 mm.

Sort of puts things in perspective a little and makes you realise being too close to the limit does not make that much sense, just me thinking out loud really.

Kindest regards

Barrel

D id you shoot that on paper or using Chairgun?

[barrel]

D id you shoot that on paper or using Chairgun?

Hi rogb, I would like to say that I am so sure of my aim that I can tell when I shoot 3mm low, but sadly not.

Kindest regards

Barrel

[boozybloke]

Ok, that's not a lot of difference, but it is still a difference. I get the feeling that a lot of power chasing isn't necessarily down to the difference in poi but wanting to get as close to what we are 'allowed' cos it just seems a waste of a whole ftlb if you're 'only' shooting 10.99 ftlb*



*yes I know you want a bigger margin than 0.01 ftlb in reality

[rogb]

Hi rogb, I would like to say that I am so sure of my aim that I can tell when I shoot 3mm low, but sadly not.

Kindest regards

Barrel

Fair enough mate. Chairgun will give you a rough idea but different head sizes, different batches and different barrels (NPI) will all have slightly different trajectories and wind behaviour. Many HFT/FTers have found this out during testing on paper range cards. I will take the 3mm to the good any day
The ones I am using at the minute seem a little (mm's) flatter than some others I was using. Reason? they go through 8-10fps quicker. I will take that as it means a little less chance of clipping 25mm's at 40 yards at 6 or 12 o'clock.
I also try to have fun when shooting too... sometimes

[Jesim1]

This quite surprised me with .177 AA Field pellets at 8.44 grains

750 fps = 10.54 ft/lbs
800 fps = 11.99 ft/lbs

zeroed at 40 yards the difference in impact point between a gun shooting at 800 fps and one shooting at 750 fps would be as follows. At 10 yards 2.54 mm, at 20 yards 3.5 mm, at 30 yards 2.54 mm, and at 50 yards 4.82 mm.

Sort of puts things in perspective a little and makes you realise being too close to the limit does not make that much sense, just me thinking out loud really.

Kindest regards

Barrel

You have to remember also that if your shooting at 750fps roughly with every pellet then there is no actual difference in perceived accuracy pellet to pellet. Your scenario would only be a problem if it was 750fps on one pellet and then say 800fps on the next, causing your POI to be moving due to the difference in velocities.

So consistence is the key, not power.

James

[Shed tuner]

yeah, I set mine to around 11 FP, job done

[Amac]

In answer to the original post, b-----r all.

Andy

[Protegimus]

Does this become more important when not killing paper or steels and when there may be some wind?

[Steyr]

You have to remember also that if your shooting at 750fps roughly with every pellet then there is no actual difference in perceived accuracy pellet to pellet. Your scenario would only be a problem if it was 750fps on one pellet and then say 800fps on the next, causing your POI to be moving due to the difference in velocities.

So consistence is the key, not power.

James

But this is exactly the problem people have when they think their gun is sick because the shot to shot FPS figures stray into double figures.
Agreed a tight FPS is an indicator of a good rifle in terms of consistancy but its chasing dragons.
People cannot shoot as well as a 5 FPS variation.
even if the action is viced....the on paper hole at 35 yards is going to be negligble even with a 50 variation.
My Steyr had a wide FPS spread but it didnt really show at the target end.
FPS is a bit like Turnover. Turnover isnt the important figure. It is your net profit.

[bozzer]

I posted this yesterday but deleted it as it was quite boring and anal ...

... but I'll try again.

When you post it as per the original post it all seems negligible ... just a couple of pellet widths at 45 yards etc.

I've just done a quick check on Chairgun ( so not real life ).

Using a popular pellet like JSB Exact at 8.4gr.

If you zero at 35 yards with medium mounts. The difference in drop off at 45 yards is @ 6 or 7mm ish between 750fps and 800fps. That's poi UNDER your zero at 35 yards. At the mid point of about 25 yards ( tad less ) the difference is @ 3mm. That's poi OVER your zero at 35 yards.

So the difference in total, in the 'loop', up to your 45 yards ( max distance in HFT ) is more like 9 or 10mm ( 3 over and then 7 under ).

So again you may say ... so what ... it's a couple of pellet widths?

If you are target shooting like HFT you aren't dialling your scope. You are estimating range and holding over and under on aim.

You can get 15mm kills up to 25 yards away. So if you miss dead centre by 7.5mm you miss that target. The pellet is 4.5mm wide ( 0.177 ... most popular category ). So take half of that ( 4.5/2= 2.25mm ) away from that 7.5mm and you get 7.5-2.25=5.25mm. So if you miss a 15mm kill at 25 yards by 5.25mm you will split that kill and may miss that target ( the distance before the edge of the pellet will hit the plate ). That 5.25mm isn't a lot at 25 yards, especially in some wind. If you miss in a vertical manner then the distance to the edge of the kill gets less and less horizontally. So the closer you can get to dead centre, the more you can be out re the wind.

So you'll probably be grateful of those extra 3mm to play with.

Same applies at 45 yards. At that distance you can get 35mm kills. The difference between 800 and 750 from your 35 yard zero is @ 6/7mm. So let's say at that distance the accuracy of your kit plus your failings mean your average edge to edge group at that distance is 18mm ( @ 5p piece ... that's pretty good ). So you are already likely to be edge of pellet 9mm from dead centre. Add on the 7mm for difference in velocity, and you are now edge of pellet 16mm from dead centre. Dead centre to edge of kill is 35/2=17.5mm. So the edge of your pellet is now just 1.5mm from the bottom of the kill. At this point, the horizontal distance to the edge of kill is going to be very small. Drift from wind at 45 yards is at it's greatest. So again you will be grateful of those extra 7mm to avoid a split at edge of kill and a miss. A shot at the edge of your typical group and you've got the distance or wind slightly wrong, using the 750fps and you've missed. The 800fps gives you another 7mm to play with, and you may knock that target down.

People are spending £2k on rifles to gain just a few mm's of extra accuracy so they can steal a target or two over a season.

If you are going to do that then why would you give your opponents a 10mm advantage in 'loop' over the overall course distance by having your pellets slower than theirs?

This was always my argument about using the heavy Magnums at 10.6gr. They were the most accurate pellet in my rifle but at 700fps had a much greater loop than people using 7.9 or 8.4gr.

Also ( and this can blow my above load of b0ll0x to bits ) ... a number of target shooters find that their best pellet is more accurate out of their rifle at a certain Muzzle Velocity. For instance, a lot of target shooters using Exacts prefer to run them at 770fps when 800fps is still legal. It's not because they want to be a bit safer re the limit and the law ... it's because they have found they seem to give tighter groups at that speed as opposed to 800fps.

I'll re read that back soon and realise it was anal all over again and delete it again.

[Artfull-Bodger]

I posted this yesterday but deleted it as it was quite boring and anal ...

... but I'll try again.

When you post it as per the original post it all seems negligible ... just a couple of pellet widths at 45 yards etc.

I've just done a quick check on Chairgun ( so not real life ).

Using a popular pellet like JSB Exact at 8.4gr.

If you zero at 35 yards with medium mounts. The difference in drop off at 45 yards is @ 6 or 7mm ish between 750fps and 800fps. That's poi UNDER your zero at 35 yards. At the mid point of about 25 yards ( tad less ) the difference is @ 3mm. That's poi OVER your zero at 35 yards.

So the difference in total, in the 'loop', up to your 45 yards ( max distance in HFT ) is more like 9 or 10mm ( 3 over and then 7 under ).

So again you may say ... so what ... it's a couple of pellet widths?

If you are target shooting like HFT you aren't dialling your scope. You are estimating range and holding over and under on aim.

You can get 15mm kills up to 25 yards away. So if you miss dead centre by 7.5mm you miss that target. The pellet is 4.5mm wide ( 0.177 ... most popular category ). So take half of that ( 4.5/2= 2.25mm ) away from that 7.5mm and you get 7.5-2.25=5.25mm. So if you miss a 15mm kill at 25 yards by 5.25mm you will split that kill and may miss that target ( the distance before the edge of the pellet will hit the plate ). That 5.25mm isn't a lot at 25 yards, especially in some wind. If you miss in a vertical manner then the distance to the edge of the kill gets less and less horizontally. So the closer you can get to dead centre, the more you can be out re the wind.

So you'll probably be grateful of those extra 3mm to play with.

Same applies at 45 yards. At that distance you can get 35mm kills. The difference between 800 and 750 from your 35 yard zero is @ 6/7mm. So let's say at that distance the accuracy of your kit plus your failings mean your average edge to edge group at that distance is 18mm ( @ 5p piece ... that's pretty good ). So you are already likely to be edge of pellet 9mm from dead centre. Add on the 7mm for difference in velocity, and you are now edge of pellet 16mm from dead centre. Dead centre to edge of kill is 35/2=17.5mm. So the edge of your pellet is now just 1.5mm from the bottom of the kill. At this point, the horizontal distance to the edge of kill is going to be very small. Drift from wind at 45 yards is at it's greatest. So again you will be grateful of those extra 7mm to avoid a split at edge of kill and a miss. A shot at the edge of your typical group and you've got the distance or wind slightly wrong, using the 750fps and you've missed. The 800fps gives you another 7mm to play with, and you may knock that target down.

People are spending £2k on rifles to gain just a few mm's of extra accuracy so they can steal a target or two over a season.

If you are going to do that then why would you give your opponents a 10mm advantage in 'loop' over the overall course distance by having your pellets slower than theirs?

This was always my argument about using the heavy Magnums at 10.6gr. They were the most accurate pellet in my rifle but at 700fps had a much greater loop than people using 7.9 or 8.4gr.

Also ( and this can blow my above load of b0ll0x to bits ) ... a number of target shooters find that their best pellet is more accurate out of their rifle at a certain Muzzle Velocity. For instance, a lot of target shooters using Exacts prefer to run them at 770fps when 800fps is still legal. It's not because they want to be a bit safer re the limit and the law ... it's because they have found they seem to give tighter groups at that speed as opposed to 800fps.

I'll re read that back soon and realise it was anal all over again and delete it again.

In reality your not giving away anything to your competitors as you will have set up your equipment and plotted your drops for the relevant ranges, if you shoot at 750fps and your opponent shoots at 800 fps you will both be using drops for the velocity you are using, so if your setting is 45yds dot 2 at 9xmag, and your opponent is 45yds dot 2 at 10mag it won't make a blind bit of difference!

A batch of pellets or a different make can result in greater than a 10mm difference for the same weight, these tiny differences are irrelevant as you cannot hold steady enough to make a 3mm difference and neither will the wind!