barrel leading velocity

[prs]

With lead projectiles, at what velocity would one begin to worry about leading? My inquiry is really deeper than just that, you see, I am concerned about such in an "air rifle" (pellet gun). I just picked-up one of the Gamo Hunter Extreme rifles. With swaged lead pellets I believe it tops out at about 1,300FPS and with the lightweight special alloy pellets it is supposed to clip along at about 1,600fps. I never really thought about leading in an air rifle before. My intuition is that it shoud not be a problem with this rifle either, but.........

[felix]

Spring for the high quality euro target pellets. They contain bismuth, an antimony replacement. Bismuth is just as hard as antimony but heavier than lead, a distinct asset in keeping twist requirements in check. ... felix

[jonk]

Remember too that a lot of the problems with leading occur from gas etching with HOT plasma generated by the powder burn. I would suspect that with compressed air this would be far less an issue, as air expanding rapidly would actually have a cooling affect.

In any case it isn't moving any faster than a .22 so I don't see it woudl cause any issue.

The real question is rifling twist rate and projectile weight/dimensions and whether it will 'jump' the rifling and 'strip' the bullet- and I don't think this will happen if you stick with the projectiles Gamo recommends.

[mooman76]

It may move fast but you won't have near the pressure of a regular gun. I don't see there being a leading issue.

[deltaenterprizes]

Spring for the high quality euro target pellets. They contain bismuth, an antimony replacement. Bismuth is just as hard as antimony but heavier than lead, a distinct asset in keeping twist requirements in check. ... felix


Felix,I hate to disagree bismuth has 93% the density of lead.

[jack19512]

With swaged lead pellets I believe it tops out at about 1,300FPS and with the lightweight special alloy pellets it is supposed to clip along at about 1,600fps.









I am a long way from being a pellet gun expert but I have read that the lightweight pellets can be bad for some pellet guns, unless of course the particular manufacture recommends them. Also very few actually go the advertised velocity. I could be wrong about this though.

[Shiloh]

It may move fast but you won't have near the pressure of a regular gun. I don't see there being a leading issue.

And no gas plasma as stated in a previous post of this thread.

I would like to know the actual operating pressure, but I think that it is less than a .22 CB or BB cap. Any one know what they operate at??

Shiloh

[Larry Gibson]

prs

As mentioned few spring air rifles actually produce the advertised velocity with regular lead pellets. Then only if the lightest of pellets are used. The really high speeds advertised are with plastic saboted pellets or the that of a plated ballistic alloy such as the "Raptor". These generally weigh about 60-70% as much as a regular pellet of a given caliber. Unless the springer air rifle is made especially for these light weight pellets damage will occur, most often a broken spring. This is because the pellet does not offer enough resitance and the piston slams forward to hard. Other serious damage can also occur. The .22 cal Raptor weighs 9.8 gr and most who use them soon go back to a quality lead pellet of 12-15 gr weight. The .17s weigh 5.2 gr.

PCP air rifles are a different story.

BTW; most all quality pellets for use in the faster air rifless have a lube on them. Many who use such pellets at higher velocities in PCP air rifles also additionally lube the pellets. My "high speed" air rifle is a RWS M54 .22 cal. With the lightweight pellets it attains velocities over 900 fps as advertised. However accuracy sucks as compared to Crosman CPs at 14.3 gr. I recently picked up a tin of domed HPs from Cabella's and they shoot really well also. This M54 will shoot 1" at 50 yards or better. Velocity with the 14.3 gr CPs or HPs is right at 800 fps. It is a very deadly air rifle and has several hundred varmints (crows, rabbits, rats, feral cats, ground squirrels and oposums) to its credit along with an untold number of Starlings (miserable little bas**rds!). If I want more power than that I go to the .22LR or the .22 Hornet with cast bullets.

Larry Gibson

[felix]

Felix,I hate to disagree bismuth has 93% the density of lead. <--- true statement.

In lead boolits, however, the weight difference between a boolit with antimony, and one with bismuth as antimony's alternate, the final weight of the boolit is enhanced considerably. That was the intent of the memo above, but stated incorrectly as was pointed out. ... felix

[Meatco1]

Wow, and here I be thinking my RWS Dianna was a fast pellet gun!!!

Richard

[warf73]

In any case it isn't moving any faster than a .22 so I don't see it woudl cause any issue.
This statement is false:
22 CB runs on average at 720fps, 22 short is around 1000fps, 22 Long is around 1200fps, and a 22 long rifle is around 1400fps this is all average there are some companys that make all of these run faster and slower.
But the fastest 22lr I know is only running 1630fps.
So saying this pellet rifle isn't running as fast as a 22 isn't really a true a statement.
It's running faster than most all 22 ammo made.

[prs]

Thanks for all great info. Gamo's web site says leading should not be problem and that pellet guns do not requite as much cleaning as do firearms; but, I gotta tell ya, this sucker does lead-up with either Gamo Match pellets, or Beeman Silver Arrows. With the recommended Gamo Raptor-Special Gold Alloy pellets it does not. The claimed velocity with that special pellet is 1660fps -- I may have to run it over my speed trap one of these days. I have shot this gun on three seperate occasions and the day one was very discouraging, but then it dawned on me that I was using a scope with my very strong bifocal eyewear. Day two went much better, just using the Match type pellet and plinking black walnuts off of the backyard tree. Yesterday, from the bench -- it is no match for my iron sighted 5mm Benjamin/Sheridan Blue Streak I have owned for 43 years. It is going back to Gamo for inspection and replacement of the scope which appears to have a flawed lens internally and a poorly coated on on the front objective. Its a fine looking rifle and I hope it can perform.

prs

[Larry Gibson]

prs

The match pellets and Silver Arrows were not intended for such velocity. For regular pellets I'd suggest a domed one of medium weight for caliber. I'm assuming you have the .177 caliber Gamo because of the 1600+ fps claim. Cabella's domed pellets are lubed and are very good quality. I have been getting excellent results with them in my M54.

Larry Gibson

[prs]

prs

The match pellets and Silver Arrows were not intended for such velocity. For regular pellets I'd suggest a domed one of medium weight for caliber. I'm assuming you have the .177 caliber Gamo because of the 1600+ fps claim. Cabella's domed pellets are lubed and are very good quality. I have been getting excellent results with them in my M54.

Larry Gibson

Larry your are correct, it is the Hunter Extreme model. Gamo strongly warns to NOT get any oil or lube in the barrel. They do not come right out and say so, but maybe they are worried about creating excess pressure or even dieseling in this gun. So lubed pellets may be out. I will be talking with their customer service and I will put that in my "to ask" notes. I will probably ship it back early next week.

prs

[Larry Gibson]

prs

Dieseling is always a possibility but the lubes used have a very high flash point and don't diesel. Otherwise the pellet companies wouldn't sell them that way. You might go to one of the air rifle forums and discuss the subject there. Those boys are pretty knowledgeable about it.

Larry Gibson

[xpshooter]

I would recommend getting a bunch of different pellets and test your gun to see which pellet it likes the best. There are a few places that offer pellet samplers the best I have found is
http://www.airgunsusa.com/pellets.html
It's amazing what just changing pellets will do for group size.