Information about GD 600 Air Rifle

[bennedose]

Pellet drop is always a factor unless you shoot a pellet in outer space outside the influence of gravity

If a rifle shoots at 600 fps - here are some rough indicators

Muzzle velocity: 600 fps.(assuming zero air resistance - which is actually false)
Time to target at 30 feet (no air resistance) - 0.05 sec - pellet drop 0.5 inches
Time to target at 60 feet (no air resistance) - 0.1 sec - pellet drop 1.8 inches
Time to target at 90 feet (no air resistance) - 0.15 sec - pellet drop 4 inches
Time to target at 120 feet (no air resistance) - 0.2 sec - pellet drop 7.25 inches
Time to target at 150 feet (no air resistance) - 0.25 sec - pellet drop 11.3inches

30 meters is over 90 feet and air resistance is sure to slow the pellet down so the pellet that starts at 600 fps will take about 0.2 seconds to reach 30 meters and should have dropped more than 7 inches

At 50 meters the pellet will have dropped more than one foot. But even if the velocity has dropped to half - i.e 300 feet per second, it will penetrate small game - which is why air rifles can be used at 50 meters for small game in countries where hunting is legal.

But if one has to aim "two inches" above a target at 30 or 50 meters - that is the type of approximate "rule of thumb/guesstimate" aiming that plinkers do. Not for championship shooting.

The other point is that a target that is 1 x 1 inch at 10 meters will appear the same size as a 2 x 2 inch target at 20 meters or a 4 x 4 inch target at 40 meters. Hitting a 1 foot square target at 40 meters is the same as hitting a 3 x 3 inch tin can at 10 meters. You pellet will punch through the can at 10 meters but will merely dent the target at 40 meters and unless it makes a sound you won't even know you have hit the target.

[brihacharan]

The subject of grouping at various distances has been the 'Achilles Heel' for Air Gunners in general....
This is followed by the question 'At what point / distance' should the scope be zeroed?
With the variance present among air gun power, pellet shapes & weights & distances shot at, it appears that there is no one standard formula to solve this problem...
However, here's an extract of an article written by AR Guru BB Pelletier aka Tom Gaylord which should give us an overview on the subject.....



At what range should you zero your scope?
Posted on June 1, 2005 by B.B. Pelletier

Where to zero a scope is a question that always starts a friendly conversation among air-gunners & I’ll tell what your options are and leave the final choice to you.

PELLETS START TO FALL THE MINUTE THEY LEAVE THE MUZZLE
The moment a pellet (or bullet) leaves the muzzle, it begins falling toward the ground. It falls at the same rate it would if you dropped it from the height of the bore – assuming the bore is parallel to the ground! And that’s where the scope adjustment comes in.

Because a scope looks straight out and because it is mounted above the bore, it can only be made to intersect the trajectory of the pellet if it points down through the ballistic path the pellet takes. And, that is how scopes are sighted-in.

They are adjusted to look straight through the downward arcing trajectory of the pellet at a point close to the muzzle. When the pellet arrives at the spot where the downward-looking scope is pointing, the crosshairs will be exactly where the pellet is and the scope will be zeroed at that distance.

Beyond this point, the scope will actually be looking UNDER THE PELLET’S FLIGHT for a certain distance after the first point of intersection. Then the falling pellet will cross back through the scope’s line of sight once more, intersecting the pellet a second time and creating a second zero point.

HOW WE CORRECT THE PICTURE!
Nobody likes to think about their pellet falling, so we elevate the barrel so the pellet is actually going slightly up when it leaves the gun. Now, the whole thing makes more sense.

The pellet SEEMS to be rising when, in fact, it is only doing so because the barrel is tilted slightly up at the muzzle. The downward-looking scope intersects the pellet at some distance downrange, then the pellet SEEMS TO RISE above the straight line of the scope and intersect a second time further downrange.

WHAT’S A GOOD DISTANCE TO SIGHT-IN A SCOPE?

Now that we understand how it works, we need to find the right distance to sight-in. You now understand that the scope will actually be zeroed for TWO DISTANCES instead of one.

For a pellet gun that shoots around 800 fps. I like to sight in at 20 yards for the near distance. The second distance will be around 30 yards, and the pellet will not rise by as much as one pellet diameter at the in-between distances (between 20 and 30 yards). If you sight in at 15 yards with the same gun, the pellet will be back to the intersection of the crosshairs around 40 yards, and it will rise more than an inch in between.

For a gun that shoots 950 fps., I would still sight-in at 20 yards as the near distance but the far distance is now 37 yards or so. For both guns (800 and 950), the pellet will be about one inch below the aim point at 10 yards and will rise to the crosshairs as it approaches 20 yards. At the muzzle, the pellet will be as far below the crosshairs as the bore is below the optical path of the scope, which could be as much as three inches or more!

What if I only want ONE sight-in distance?
It IS POSSIBLE to sight a scope to intersect the pellet only once, but why would you want to? You align the scope to graze the pellet’s trajectory, and after that it’s all downhill!

IMHO - Its advisable to zero your scope at 2 distances - say 20yds & 35yds - then see the grouping....
Then shoot at longer distances eg. 45yds / 50yds / 70yds & see the drop, this will give an idea of the 'hold over' you need to hit the target...make a note of this & depending on the actual distance you're shooting you can adjust your hold accordingly..

Try it out & you'll be amazed at the groups you score
Briha

[kshitij]

@bennedose, I have some how have had the a completely different experience than what is mentioned by you.
For example, say i perfectly zero my rifle at 10m. If i then shoot out to 50m, the point of impact is not more than 6 inches below the point of aim, not 10.8 inches as per the calculations given by you.
Also, the pellet pretty easily punctures a beer can out at 50m.
I am saying this about the precihole scorpious.

Plus in my earlier post, when i said that pellet drop is not a factor, i meant it should not be factor at 50m that cannot be compensated for by adjusting the scope. So in my rifles case i have already adjusted the scope close to its upper limit to zero it at 10m, hence i am unable to zero at 50. The only reason here can be barrel droop because the said scope works fine at 50m on my other rifle.

[kshitij]

@brihaji, theory lesson done sir, lets go out and get on with the practicals

[Strong_Gun]

Every shooter has to be a beginner once in his life. I too acquired a scope and a top class air rifle at a time when I was a relative beginner and discovered all my mistakes after many years - because there was no internet to help me at that time.

You will need a special "springer rated" scope because ordinary telescopes suitable for regular firearms get damaged due to severe vibration when mounted on spring powered air rifles. You wil probably need to spend as much on the scope as you spend on the rifle - probably more. A cheap scope will rapidly move out of position and get damaged internally as happened to my scope.

The other thing is that it is very easy to get frustrated as a shooter if you keep on missing targets. With an air rifle - shooting at 30 meters - you will not even know if you have hit or missed the target unless you walk up to the target after every shot or have a powerful scope just for that. Even that may not help if you have missed the target altogether. Apart from that scopes make your air gun "top heavy" so that the rifle tends to roll over to an upside down position. Finally - when you look at a target via a scope at 30 meters - it is still not easy to aim at one point and shoot - especially if the rifle is not rested in one position. Holding the cross hairs over one point will show that the cross hairs are continuously moving wildly around like a child swinging a sparkler to draw patterns in the air during diwali. Only in the movies and in Horvath brother's videos are cross hairs dead steady.

As a beginner you will find it much better to discover that you are really capable of hitting a 3 inch by 3 inch target at 10 meters. It is not as easy as it sounds. Three things can go wrong
1. Your aim
2. The quality of the rifle
3. the quality of pellets.

if you are buying an "unknown" rifle like GD 600 and you are a beginner the above 3 points will affect your success greatly.

Buy the rifle. Start shooting at 10 meters and then increase to 30 meters. You will find that if your aim is really good at 10 meters, it will remain good at 30 meters because it is the same things that affect your aim.

Let me put down a minor challenge for you:

Buy an air rifle wthout a scope. Aim at a paper target at 7 meters (about 20 feet) and shoot 5 pellets and try and get all 5 pellet holes grouped together in an area that is about the size of a 1 Rupee coin. It is more difficult than you might think. If that works, move back to 10 meters and later 15 meters.

bennedose

Hello bennedose,

Thank you for you valuable advice to me. I will surely remember all the things you have said. I have understand the things you have said, just i have some small confusions. let me ask you about them.
As, you have mentioned in your post, about shooting a target of 3" * 3" at 30 metre is not going to be so easy as it seems to be. Now my point is how 3 inch* 3 inch is related to 30 mtr? Are you talking about a target of 3cm* 3cm?? Because both the unit method is different( one is CGS unit/SI unit and another is FPS unit). Please make me clear about this.

I am happily accepting your challenge of shooting a paper target of size about a one rupee coin from a distance of 7 mtr(23.041 ft) with a new and unknown gun( to me also ) like GD 600. I will surely let you know about the result.

As, per you valuable advice I am not going to buy a scope right now and I am keeping the option of buying a strong scope in my mind for future.

You have also mentioned that any low level scope can be severely damaged due to the vibrations or recoils of a springer rifles. In that case to prevent this incident from happening or to stop the scopes to move back and forth on the spring tube, what if I use any type of "SCOPE STOPS"?? please let me know..

Regards,

Strong_Gun

[Strong_Gun]

> Suggest you go in for a good "AR Rated Scope" - Cost depends on your affordability
> Recommended brands are:
1. Center point 2-7 x 32
2. Bushnell 2-7 x 32
3. Hawke 2-7 x 32
> I own 1 & 2 and am happy with their performance & stability....
Briha

Hello Brihaji,

I have got the points of yours' and bennedose's in my mind. Thank you so much for suggesting some brands for me. But the thing is in Kolkata tactical scopes are not available in most of the gun shops. All are saying that the production or the supply is very less these days, though I know the situation is not the same as they mentioned, the reason is something else(that i dont know). Only one shop that is D.N. Biswas had shown me some scopes, but with respective of quality the cost is higher( it was a 4x28 scope, price= Rs. 2000, in my view ). So, please show me the way, by which I can order some good quality scopes when I do need them( shop name, place or online).

Another thing, that I already asked to bennedose, I want to ask to you too, that to prevent the problem of scope damaging or movement on the spring tube, whether the use of any type of "SCOPE STOPS" are good or not?? Please let me know my queries.

Thanks & Regards,

Strong_Gun

[Strong_Gun]

So you mean that the impact energy beyond 30mtrs is negligible from most indian air rifles. Interesting.

Just curious, how come there are so many local air rifle brands in kolkata? Some one has listed about 5 local brands available/originating there. In other parts of the country, i guess the choices available are restricted to ihp and precihole. Are these brands any good?

kshitij

Hello kshitij,

I have read last a few post of yours here. See, though I am beginner in this section, but I have some view to share with you. As per my discussions with some IfGians, shooters and shop personals, most of them want to keep the other indian made air rifles to a class and the Precihole products in another class. according to all of them, Precihole offers an accuracy which is unquestionable up to nearly 45 m-50 m. I believe you better know about that as you own one of them . Now, most of all air rifles beyond 35 mtr is not so accurate due to their spring power or barrel rifling. And it is quite surprising that in Kolkata a number of local made air rifles are available. The number of types are available here are more than 10. I have also seen a product here which has customized thumbhole in the stock But as I have said most of them are not exactly accurate beyond a limit, because in most of the cases they are used for plinking.

Regards,

Strong_Gun

[brihacharan]

@brihaji, theory lesson done sir, lets go out and get on with the practicals

Well Said
Let's Get On with it...
A good opportunity to bridge the gap between "Theory & Practicals"
Briha

[bennedose]

Thank you for you valuable advice to me. I will surely remember all the things you have said. I have understand the things you have said, just i have some small confusions. let me ask you about them.
As, you have mentioned in your post, about shooting a target of 3" * 3" at 30 metre is not going to be so easy as it seems to be. Now my point is how 3 inch* 3 inch is related to 30 mtr? Are you talking about a target of 3cm* 3cm?? Because both the unit method is different( one is CGS unit/SI unit and another is FPS unit). Please make me clear about this.

I am happily accepting your challenge of shooting a paper target of size about a one rupee coin from a distance of 7 mtr(23.041 ft) with a new and unknown gun( to me also ) like GD 600. I will surely let you know about the result.

As, per you valuable advice I am not going to buy a scope right now and I am keeping the option of buying a strong scope in my mind for future.

You have also mentioned that any low level scope can be severely damaged due to the vibrations or recoils of a springer rifles. In that case to prevent this incident from happening or to stop the scopes to move back and forth on the spring tube, what if I use any type of "SCOPE STOPS"?? please let me know..

Regards,

Strong_Gun

Sorry about the units confusion.. Actually I detest using fps, fpe and feet. I would prefer using the standard in India and the rest of the world other than US and UK - that is meters, cm, Joules, m/sec etc.

However since most English language gun info comes to us from UK or US we have a huge gunner community that continues to use outmoded units. I think militaries have moved out of this and at least one American space probe missed the target because of units confusion.

But rest assured that where I have written 30 m I mean meters, and where I have written 3 inches I mean 3 inches/7.5 cm. I grew up (in school) wit those idiotic feet/pound units but grew out of them in college in the 1970s.

A scope stop will not save a scope that cannot with stand the severe "backwards-forwards" double recoil of spring powered air rifles. I had one such lousy scope. As long as I used it without a scope stop - I had to re adjust it after every 5 or 10 shots. After I installed a stop, the cross hairs moved out of position and started rotating with every shot

[bennedose]

@bennedose, I have some how have had the a completely different experience than what is mentioned by you.
For example, say i perfectly zero my rifle at 10m. If i then shoot out to 50m, the point of impact is not more than 6 inches below the point of aim, not 10.8 inches as per the calculations given by you.
Also, the pellet pretty easily punctures a beer can out at 50m.
I am saying this about the precihole scorpious.

Actually that is not "my experience". It is simply a calculation

Acceleration due to gravity is 32 feet per sec squared (9.8 meters per sec squared)

The formula for drop due to gravity is

Drop of pellet (in feet) = 1/2 x A x (T^2) where A = 32 and T = time of pellet flight in seconds

The exact figures will vary depending on muzzle velocity. If the barrel is pointing slightly up as occurs when the sights are adjusted to longer ranges, the pellet can fall 2 feet and still appear that it has fallen only 6 inches below the spot aimed. The calculation is totally useless if you do not know the muzzzle velocity or whether the pellet is shot slightly upwards.

Beer cans are made of thin aluminium and are easy to pierce even with a pin in your hand. I usually use thicker tin cans such as those that contain "Asian Paints" or "Dulux" paints or Rossogolla/Amul cheese or Baked beans tins.

At short distances the pellet will go through both sides. At longer distances - only one side. At 50 meters I would be surprised if the Scorpius pierces even one side of the thicker tins.

[kshitij]

@Bennedose, buddy hats off to the amount of thought and analysis you put in.
Like other lesser mortals, i tend to go with the feel and learning from past experiences to build on my shooting ability. So my corrections and compensations are mostly from learnings of previous hits and misses.

As far as penetrating targets is concerned, i am happy splitting beer cans and bottles at 50m with the preci. For eveything else, even upto 100m, i use the diana to stunning effect

[moulindu]

Hi Basu,

Can you elaborate what you mean by effective range? Does it mean pellets shot from Indian air rifles do not travel beyond 30mtrs or are they not accurate after that range?

In either case, i use a precihole upto at about 45-50mtrs and i get one inch group easily(any flyers clearly being on my part and not the rifles). The only problem i faced is that i am unable to zero the rifle and scope while shooting at that distance and i assume it to be because of the barrel droop, which i have been advised can be corrected at the precihole works. For now i just tend to place the crosshair about two inches higher than where i want the pellet to hit...

Cheers!

hi kshitij not trying to confuse you but you must have heard about holdover & holdunder. it is used in HFT or FT tournaments. The technique to "dope the scope" is easy but laborious affair. take a measuring tape & mark different points so as to where you want to place your targets say from 10 to 50 yds at a difference of 5yds(as scopes are rating distance in yrds). Then after getting your zero try to find the POI with reference to the POA, there you will be able to find the mildot holdover & holdunder at different range. Note those points down in a table. First write down the elvation/windage grads at your zero. Then try to hit the POA by altering the elevation/ windage turrets untill you get a dead on POA=POI, write those datas as well. then you can make a chart & put it for your reference for shooting. In HFT once you have set the scope(parallax compensation) then one have to use only holdover/ under to make a hit. You will be amazed to see that the parallax adjustment in avg scope might not tally with the measuring tape (mine doesnot). So i made my own marking of yardage on my scope in reference to the measuring tape. You have take account of the wind as well as at certain days it mite be windy. Its same trial & error method. Try to take the angle of shooting into account as well. you can take the help of hawke chairgun pro (both for android /pc) to get a general idea of your drop of pellet at different distance, but fist you need to fill up all the datas as correctly as possible. its a boring but satisfying effort for accurate shooting at different distance.
i have used the same technique for range estimation of my scope & i am dead accurate at any unknown distance (30yds max available space)as all the probable factors are already fed into my chart/scope. I guess i could make my self as simple as possible.
regards Moulindu

[VishyB]

Dear Bennedose,

Thank you for sharing the most interesting book "The Airgun from Trigger to Target" by G.V.Cardew and G.M.Cardew.
It really puts many things in perspective.

Regards,
Vishwanath

[SamarjitSingh]

Hi
I have GD 600 air rifle for a month now bought from Aimco. Its a great buy if you can handle the weight, as for me personally i like a heavy gun but again it is hereditary [Punjabi {heavy gun, heavy bike(Bullet), heavy car(Scorpio, i could buy a tractor too only if i Wasn't a Delhi-ite)}]. Well! getting back to topic, here are some observations.

Pros:
Rifled barrel, aids in accuracy at 6+ meters.
Sound
Finishing is awesome (Best looking air rifle by far i know of)
Reasonable price

Cons
Heavy (dont mistake me i like to hold a heavy gun but after 10-15 shots its hard to carry on shooting)
Break barrel is very hard to load, unless you are muscle than fat dont buy it.
bit of working around with sight is required before it can be called accurate enough.
Butter/Ghee intake increases for additional strength you need

In all due seriousness GD 600 is a great gun for the money. but only buy it if you are strong enough.

[Strong_Gun]

Hi
I have GD 600 air rifle for a month now bought from Aimco. here are some observations.

Pros:
Rifled barrel, aids in accuracy at 6+ meters.
Sound
Finishing is awesome (Best looking air rifle by far i know of)
Reasonable price

Cons
Heavy (dont mistake me i like to hold a heavy gun but after 10-15 shots its hard to carry on shooting)
Break barrel is very hard to load, unless you are muscle than fat dont buy it.
bit of working around with sight is required before it can be called accurate enough.
Butter/Ghee intake increases for additional strength you need

In all due seriousness GD 600 is a great gun for the money. but only buy it if you are strong enough.

Hello Samarjit,

first of all congratulation on your new acquisition. Before buying air rifle I too had a strong fascination for this particular rifle but after advices from a number of senior IfGians like Basu sir, Brihacharan ji, bemnedose and others I changed my mind. I do completely respect your Punjabi sentiments and feelings but still I felt that after all shooting is all about accuracy and power. So, I didn't bought it but I am a proud owner of GD Rx 100 rifle. If you need info about that please visit
http://indiansforguns.com/viewtopic.php?f=2&t=22590 . Any way how much your rifle cost?? please let me know...

Regards,

Strong_Gun