Author Topic: Newbie question on pellets  (Read 2244 times)

  • Guest
Newbie question on pellets
« on: August 17, 2006, 12:16:06 PM »
I've noticed that if I sight in my scope with one brand of pellet and I try another similar styled, say pointed, pellet that the sights are wrong.  Do you guys resight you scope everytime you use a new pellet?  I have a Shadow 1000 with about 500 shots thru it.  I do have a new trigger on the way (thank you Charlie).
Thanks

Offline vinceb

  • Hero Member
  • *****
  • Posts: 1943
    • http://
Your best bet....
« Reply #1 on: August 17, 2006, 12:32:51 PM »
...is to settle on a pellet that works well, and by that I mean that it groups consistently (all shots very close together). You can then sight in your gun using those, and then stick with those pellets.

Different pellets will almost always have different POI's (Point of Impact), depending on too many variables to list. The difference gets magnified with increasing range.

Personally, I've found that ALL my rifles like Crosman Premier 7.9's (in the cardboard box). While most rifles (my Powerline, Quest, Gamo's and others) required minor sight adjustments when switching to this pellet, my B20 required about 20 clicks to the right! But once the windage was dialed in like that, it shoots them well.

BTW - generally speaking, pointed pellets don't tend to be the most accurate.

Offline Gene_SC

  • Hero Member
  • *****
  • Posts: 11378
    • http://www.airguntoys.com
Re: Newbie question on pellets
« Reply #2 on: August 17, 2006, 12:33:29 PM »
Couchflyer, I also have a Shadow 1000 and I know exactly what you mean. It is a newbie thingy...:) I went through it also. Here is how I managed it..  :) I shot different pellets and re sighted with each brand. I looked for the one with the tightest groups at around 30 to 40 yards and stayed with that one. Just so happens that the RWS Superdomes work for me. Every gun is different. Just because my shadow likes RWS Superdomes does not mean that yours will.

It is trial and error. Buy a sampler pack and work on it. That was the cheapest way to go when I am testing pellets with different air rifles.

Good Luck

Gene
THE ONES I SLEEP WITH: BSA Lightning XL, AA TX-200, AA ProSport, BSA Ultra, HW-97K, Crosman NPSS .177, FX Cyclone, HW-30 Nicle Plated, AA-S200, Crosman Marauder, CZ-634, R-9 DG, Webley/Scott UK Tomahawk, Benji Kantana, Benji Marauder, Benji Discovery.....
....

Gene\'s Tunz n Toyz
Springer Tunin

  • Guest
RE: Some information on pellets
« Reply #3 on: August 17, 2006, 06:26:41 PM »
couchflyer,

Welcome to the friendliest airgun bulletin board on the 'Net!


Here's some information on pellets for you to mull over.........

It come from a fellow whose primary interest in airguns is hunting, so some of it will be biased in that direction.  It also comes from a guy who has some very specific ideas about what works and what doesn't.  In other words, I'm an opinionated little prat.

Airgun pellets have their distictive wasp-waisted shape for a couple of reasons.  First, the shape make it possible for the pellet to be elogate in form but still light in weight.  This allows it to act like it has more sectional density than it does.  Second, it minimizes friction in the bore because the bearing surface on the skirt is fairly small, so you get good velocity with fairly low pressure pushing the thing out the barrel.

Airgun pellets come in four basic point or head types: flat or "wadcutter," hollow point,  pointed and dome.

Flat points work great for 10 meter match shooting.  The are desireable for this because the flat heads make a good "hole punch" that punches "clean," round, and easily scored holes in target paper.  They have fairly low ballastic coeffecients normally around the .009 to .011 range.  This means they shed velocity quickly because they have a lot of aerodynamic drag.  That isn't a big deal when your target is a dark circle on a piece of paper that is only 33 feet away.  It can be a huge deal if your target is a living thing that is five times farther out from the muzzle.

Some people like hollow point pellets but I'll admit right up front that I am not one of them.  The idea is that the hollow cavity in the head of the pellet will allow it to expand and "dump" more energy into the target.  I don't personally put any faith in "shock value" or "energy transfer" applied to the take of game, so I don't have much use for pellets of this type.  Even if they do work as advertised, they still suffer from a low ballistic coeffecient that is about the same as that of a wadcutter -usually in the .009-.011 class.  As with wadcutters, these holllow points will tend to shed velocity quickly and since velocity is squared when calcuating impact energy, they won't carry as much energy as other types of pellet will.  I personally think the main reason why people who love these things and praise them for remaining in the critter and eliminating pass-through is because of their low BC, more than anything else.

Here's a "for example"........

If I shoot Crosman Premier Lights, which are a domed head pellet, out of my tuned .177 Beeman R-9, they will carry around 9 ft/lb of energy to the target.  They will do this because their relatively high ballistic coeffecient of .027 allows them to retain velocity and thus energy over distance.

If I switch to Crow-Magnums, which are a hollow point pellet that some swear by, the remaining energy at 50 yards will be a little over half of what I get from the CPL's -somewhere around 5 ft/lb.  This is because they have a much lower BC and don't retain as much velocity downrange.  If I shoot a chukar partridge in the chest (legal with air rifles here in CA) with a CPL, I'll get complete pass through penetration all the way out to 50 yards and even a tick farther.  I won't with hollow points.  Again, I believe that the reason for this has more to do with the hollow point pellet's exterior ballistics than their terminal ballistics.  In other words, they don't penetrate as much because they aren't going as fast and don't have as much energy.

Next, we have pointed pellets.  I don't think there is much of a "point" to using these.  The problem with pointed pellets is that the pointed shape isn't really all that aerodynamic, either.  These do slip through the atmosphere a little better than flat points do and will have ballistic coeffecients in the .011 to .017 range.  They won't carry as much energy downrange as a domed pellet will.  Another problem is that they tend to be the least accurate of all pellet types. It is very difficult to make the tip of the point of these concentric with the axis of roation, and even if you can, it is tough to keep those pointy ends factroy fresh during shipping and handling.

I saved the best for last -the dome-head pellet.  Examples of dome-heads are Crosman Premiers, Beeman Field Target Specials, and Beeman Kodiaks, among others.

When done right, these are the domed head will be the most aerodynamic pellet and will have the highest ballistic coeffecient.  The will thus carry the most energy and most velocity downrange.

Note I used the words "done right".  There are some domed pellets that don't have very high ballistic coeffecients, and RWS Superdomes are a prime example of a pellet that could be better than it is.

Yeah, they don't look very aerodynamic.  I mean, when you compare them to the 180 grain Barnes X Bullets I shoot out of my .30-'06, they don't look very aerodynamic.  And they aren't, in comparision.  But the reason why you want a pointy bullet in an "ought-six" is that they'll exit the muzzle at 2800 ft/s (well, they will out my CZ 550, anyhow) which is well above the average 1080 ft/s speed of sound.

Think of the shape of a raindrop, and you'll see why domed is where it is at for subsonic projectiles.

Pellets come in different weights.  The unit of measure used is the "grain," an old English unit still utilized in the gun trade.  If memory serves, there are something like 3,000 grains to a pound.  You can, for example, get Crosman Premiers in two different weights in .177, with the lighter ones advertised at 7.9 grains and the heavier ones advertised at 10.5 grains.

In general, spring-piston rifles will tend to be more effecient with "mid-weight" pellets or pellets that are near the middle of the range of weights available in a particular caliber.  Thsi has to do with the way these rifles function, and is a matter best reserved for a future discussion.

PCP's and pump pneumatics will tend to be more effecient with the heaviest pellets in a given caliber.

In .177, I like Crosman Premier Lights (7.9 gr.), Crosman Copperhead Pointed (7.9 gr. and not really pointed), Premier Heavy (10.5) and Kodiak (10.6).

The Crosman Copperhead Pointed is my favorite because they shoot really flat out of my wife's Shadow and my tuned .177 R-9 due to their .028 BC, which is about as high as it gets in pellets suited for mid-magnum springers.  My R-9 develops the most energy at the muzzle and thumps with the most energy at the 50 yard line with this pellet, and it groups them tight enough to hit 1" kill zones out to 50 yards.

The other pellets listed above all have BC's in the .024 to .027 range in most guns.

This BC thing varies, though.  In my .20 R-9, the flat-shooting champion is the Beeman FTS with a BC of .027 when fired out of that rifle.  If I fire them out of the more powerful .20 R-1, they have a BC of .019.  As a result, the amount of energy that both rifles deliver at 50 yards with those pellets is about the same.  So is the trajectory, even though the R-1 has a full 100 ft/s advanatge in muzzle velocity when shooting these.  In my .20 R-1, the most effecient pellet is the Kodiak.

When I select a pellet for a new rifle, I am interested in choosing only from those that are going to carry enough energy downrange at the 50 yard line to kill a jackrabbit dead (or turkey if we're talking .20 or larger) and that means I need 8 ft/lbs or more at impact.  So I select from those with the highest ballistic coeffecients of .025+  and then use the most accurate ones in that partiuclar gun, most of the time.  I say "most of the time" because on paper, my R-9 shoots Kodiaks better than Copperheads but in the real world, the flatter trajectory due to the increased velocity of the lighter pellet makes a huge difference, and they are "accurate enough."

Once I decide on a pellet, I stick with it for a particular gun.  With my .20 R-9, for example, that pellet is Beeman FTS.  With my .20 R-1, that pellet is the Kodiak.  With my .177 R-9, that pellet is the Copperhead.  With my Benjamin 397 pumper, that pellet is the Kodiak.  I also buy enough so that I never run out and have to settle for using something else as a substitue and then have to sight in my rifle over again on account of the new ammo.

In closing, I am anal about BC becase I believe that the two most important things that determine killing effect in hunting are placement and penetration.  I feel that way when I pack my .375 H&H off to Africa with round-nosed "solid" non-expanding bullets.  I also use solids in my .30-'06 over there (220 gr. .308 Barnes).  I feel that way when I hunt pigs, deer, elk, and so forth here with the '06, but since I can't legally use solids, I use Barnes 180 gr. X bullets instead, which are renowned for their ability to "wade in deep".  I feel that way when I hunt small game with air rifles, too.  While I prefer .20 caliber for most general hunting use, I could get by with .177 for everything but turkey and pefer it for some specialized situations because of the penetration and flat tarejctory which helps with placement.

Too little penetration can cause problems of its own.  I've never had a critter complain yet about getting killed with too much.  Too much allows you to do things you can't get done with too little in the field.  In the field, things don't always work out like we plan with the first shot, for a variety of reasons.  If I do a head shot on a bunny at long range, and put the pellet too low or too far forward, too much penetration allows me to concentrate on anchoring the wounded critter by busting the near side front shoulder AND the off-side one.  Bunnies have a hard time running with two busted front shoulder bones.  They can run pretty fast on three legs.  With this kind of penetration, though, what normally happens is that I get a complete pass through on a brain-pan shot that punches two holes in the hopper's noggin, rather than just one, resulting in the same instant death I'd witness if I hit the critter in the same spot with a shot from my .22 LR CZ 452-2E.  Since I am hitting bone, energy transfer is probably pretty good, and I have enough in reserve to hit the bone twice.

Opinions obviously vary, but shooting pellets with high BC works for me, while shooting those with lower BC hasn't worked so hot.

-JP
http://www.uplandhunter.net

  • Guest
Re: Newbie question on pellets
« Reply #4 on: August 17, 2006, 08:56:58 PM »
yup, it does seem to change.
 
If you want to try out a different pellet, then yes I would suggest re-sighting it in when you do so.

Of course, then the original pellets you sighted in for won't be quite right any longer.

To me experimenting with different pellets is part of the fun of airgunning and I wouldn't let resighting in stop me from doing it =D

Different pellets really do have different feels and I love seeing all the nuances that the hobby can offer.

I just have to remember the last pellet I used in case I actually have to shoot at a ground hog or something.

  • Guest
Re: Newbie question on pellets
« Reply #5 on: August 20, 2006, 02:23:26 PM »
Thanks guys, how does one find out the ballistic coeffecients on the pelletgs?

Offline daved

  • Hero Member
  • *****
  • Posts: 2093
    • http://
Re: Newbie question on pellets
« Reply #6 on: August 20, 2006, 05:06:40 PM »