Pellets Producing Different Ftpds Results

[PJWmids 35]

I tuned my rifle recently, and purchased a couple of tins of crossman premier ultra magnum .22 cal 14.3 gr. when I shoot with these i got an average of 599.2 fps which equates to 11.40 ftpds. they are quite a tight fit.

 

i had a tin of rws superdomes 14.5gr lying around so i put them over my chrono and got a reading of 629.66 thats 12.77 ftpds and are quite a loose fit.

 

is it normal to achieve such a massive difference in power just by using a different brand pellet?

I dont want my rifle to be illegal so will have to bring the power down so the rws are firing within the legal limit, but this will mean that my first choice off pellet the crossman premier will be firing at alot less fps. or should I start to use a lighter pellet to increase the fps? but I personally prefer the crossman for accuracy? I'm a bit confused as to what is the best thing to do. any advice welcome.

 

[darkdd81 36]

Best thing to do bud is de-tune it to get the power down to mid 11's with the superdomes, and then just stick to the crossmans. If there pushing 10 that's will do just fine.

[DenBell 149]

i have the same problem at the minute pal, my scorpion is shooting at 11.8 fpe with air arms field but but 12.4 fpe with bisley mags so my plan is to get it down a bit. i dont know how true it is but a lad at my local shooting range told me that if the police wanted to take your rifle and test it they will put a few different grains through it. not worth from my view point.

[PJWmids 35]

If such variables can can be achieved from using different pellets it's any wonder anyone is a 100 percent sure what there rifle is at. The end of the day my rifle is consistent at 11.4 with crossman, if I hadn't used any other pellets I'd have been none the wiser. Surely you can't be prosecuted if the pellets you are personally using are firing at a legal limit. It all seems a bit of grey area to me.

[Skot Ruthless Teale 1,701]

aye it is a grey area.

 

and a massive pain in the arse!

[PJWmids 35]

Lol aye it just!

[DenBell 149]

If such variables can can be achieved from using different pellets it's any wonder anyone is a 100 percent sure what there rifle is at. The end of the day my rifle is consistent at 11.4 with crossman, if I hadn't used any other pellets I'd have been none the wiser. Surely you can't be prosecuted if the pellets you are personally using are firing at a legal limit. It all seems a bit of grey area to me.

 

good point mate, but when its as close as mine to the limit you kind of know its a possibility. i think i would rather try and do something about it than have some jobsworth trying to take my rifle off me.

[ghillies 209]

the rule of thumb is tune a pcp with heavey pellets and tune a springer with light..thats the narm, lol but just incase try some others.

 

allow about a 1/3 to 1/2 a foot pound for the silencer not being on too...

 

its all about the fit and the barrel lands and how they 'drag up the barrel' some run sweet, some loiter and faff about, so higher and lower foot pounds.

 

the weight issue, its an equasion, basicaly the velosty and weight and a few other numbers, increase the weight for the same gun set up the velosity reduces because its heavier, lighten a pellet in the same gun (the same chamber of air volume) and it'll go faster... but, the diference after the equasion is roughly the same..faster time lighter or slower times heavier..about the same bar the difference in the barrel and the airodynamics of the pellet.

 

the rest is drag up yu barrell and the BC (balistic coificient), the BC is how well the pellet flies basicaly, if it flies really well it retains power further, adding weight carries the power/energy better, but, it all depends on the pellet shape and barrel fit.

 

10.5 to 11.5 is usually about safe in legal turms, in a springer especially the 10.5 end is a lot smoother running than 11.5, in a pcp its noticable if you know what your looking for lol.

 

edit in......btw, the diference between 10.5 and 11.5 is the shape of the tragectry arc (assuming you have a good bc etc) if the gun,the barrel and the pellets are boggo standard and that...you'll be looking for 11.5 to do what 10.5 will do down range, i.e. the furthest 'safe' distance to shoot live targets, if your into real distance plenking and target stuff...forget the cheap end it just wont group at -100 yards...some really bad end stuff has a job to group at 30 yards, no matter the power.

i'll go out on a limb and say most the average stuff today from the better companies will see 50 yards if your practiced enough...

Edited September 30, 2013 by ghillies

[AirgunGuy 362]

It's not really a grey area at all mate. To the best of my knowledge the law can use any commercially available pellet to test your rifle and if it goes over with any then you're done. RWS Hobbys at 11.5gr are the lightest in .22 i think so if you're going over with a pellet at 14.5gr then a pellet at 11.5gr should in theory take you well over. Its your responsability, no one elses. Set it at 11.5FPE with RWS Hobbys and you should be fine

 

Have a look on a site like the BASC. All the laws and info should be on there

Edited September 30, 2013 by AirgunGuy

[PJWmids 35]

well if thats the case then wouldnt it be sensible for the police to have stated in the public domain that they will use rws hobbys to test fire spring air rifles, so then all spring air rifle owners could then put their rifles over a chrono with those pellets and then be safe in the knowledge everyone knows where they stand. and then the heaviest type in a pcp if thats the way it works with them.

 

my intial concern was was it possible for one 14.3 gr pellet to shoot at 11.4 and another 14.5gr pellet shoot at 12.7 which obviously is cause its doing it through my rifle. but i presume its more to do with the fit in the barrel first tight and later loose.

 

I dont remember there being such a difference firing both pellets before the rifle was tuned, but the recent crossman pellets are from the new tins I recently purchased. I wonder if they have made these new pellets slightly bigger resulting in the reduced fps.

 

Do pellets vary alot from one batch to another?

[AirgunGuy 362]

Again mate...it's not their responsability...it's the responsability of the individual to make sure they keep within the law...as with any law.

 

As for your rifle going over with a different pellet but of similar weight. Sounds as thought the tighter pellet is leaving the barrel slower than the slacker pellet...hence the reading. A pellet at 14.5gr is in the middle of the weight range for most .22 pellets so if yours is running at 11.4 with that weight of pellet then i would lower the power as there are several pellets that could take your rifle over.

 

I don't know much about ballistics or the laws but i made sure i learned enough to keep me and my wee fella right and avoid a possible jail sentence. I've had several conversations with RFD's in the Glasgow area and they say that the cops are in their shops regularly asking about airgun owners. They're itching to catch people up here as they're has been 1 young child killed by an air rifle and plenty other incidents. The Scottish government are trying to get all air rifles on a license. It may seem a load of shite to you, me and everyone else but that's the way it is and for peace of mind it's best to keep within the law with air rifles. 1FPE isn't going to make a huge difference down range.

 

As for pellet batches...yes they can vary to the best of my knowledge

[PJWmids 35]

Looks like I need to get some of these hobbys then lol

[AirgunGuy 362]

Looks like I need to get some of these hobbys then lol

Aye mate. Worth trying them through your rifle. I'm sure they're the lightest "commercially available". Keeps you right

Edited September 30, 2013 by AirgunGuy

[ghillies 209]

the whole things a grey area...subject to whim i think.......................................

[AirgunGuy 362]

the whole things a grey area...subject to whim i think.......................................

Not really mate. If you do enough searchin, it's all there. If you're gonna get into air rifles then you need to know where you stand imho.