Bisley magnums and ft/lbs

[don1971]

I’ve seen it written several times that the pellet of choice for checking you are on the right side of the law is the Bisley magnum, as this is what the police/labs would use to check your gun. I think the suggestion is the heavier pellet can push ME over the limit, more in PCP’s?
I tested 4 guns tonight one of them a .22 P15 stayed about the same at 11.5, another .22 P15 dropped to just over 10, a .22 Hw95 also dropped to near 10, and a .177 wildacat did the same.

Based on what I have read I wouldn’t have expected that. Anyone else find similar?

Cheers

[Lavant_Lad]

Your findings were that they stayed the same or dropped !!!! but dropped from what ?
What readings were you getting before, on your normal pellet of choice?

[pruddasfinest]

Yeh.
Bis mags increase some of my guns but decrease in others.
Might be cos they’re tighter in the barrel.

[don1971]

Sorry, my mistake, the pellet I was comparing against was JSB Diablo 15.9 gr.

[rovercoupe]

In my testing I normally find the jsb,s or rws superdomes give the highest power levels but I test with a few different ones and tune to whatever gives the highest power.

If weight was the biggest influence they would be testing with rabbit magnums!

[angrybear]

Every barrel is unique which is why we have to pellet test for accuracy,
It is also why we need to pellet test for the most efficient in any given barrel, because it's the most efficient that will give the highest MV, it might be heavy, light or somewhere in the middle but it will suit your barrel.

[zephyr]

I too heard this. But also that it was not true.

I tested 10 different (make and type/weight) pellets in two sub 12ftlb air rifles. I found the data did not support that heavier weight pellets give higher ftlb, nor that Bisley Magnums (or any other make, type or weight of pellet) always gives the highest power. But, that was just two air rifles - MK4is and HW100.

[Rich]

With a fair degree of predictability, I find that JSB Exact Jumbo at 18+ grains are the pacesetters for power in 22 calibre, and Exact Heavy at 10+ grains in 177. This is for PCPs. If I am checking a PCP that is close to the limit these are the pellets of choice as in my experience they reliably give a shade more power in many rifles.

[rancidtom]

In a regulated .22 PCP you generally find JSB Jumbo Exact 15.9 grain or AA Field 15.9 grain give the best efficiency (highest M.E.)
With an unregulated .22 PCP sub12 gun you often find the JSB Jumbo Exact Heavy 18.1 grain pellets give the highest M.E.
Bisley Magnum/H&N Baracuda 21 grain are often less M.E but not always.
With .22 springers a light pellet will often give the peak M.E. for instance Flacon Accuracy Plus 13.4 grain or JSB Jumbo Exact RS 13.4 (basically the same pellet). Some springers will peak with RWS Hobby 12 grain, others may give more M.E with JSB Jumbo Exact Express 14.3 grain (Webley Mosquito Express).
.177 PCP's, regged or not, as a rule prefer the heavier pellets for higher M.E. such as JSB Exact Heavy 10.3 which generally are a little more efficient than Bisley Magnum/H&N Baracuda pellets (in most barrels but not always!)
.177 springers will again give peak energy with lighter pellets such as JSB Exact Express or RS and maybe even RWS Hobby.
These are general guidelines, not rules, there are plenty of exceptions, individual rifles do vary, I have in the past successfully managed to set up a .177 regged PCP to give peak power with JSB Exact RS rather than the heavier pellets.
It doesn't cost a huge amount to buy a tin of the "usual suspects" for your type/calibre of gun, try them and make sure you stay legal, if for example you have a gun that likes heavy pellets try a few other brands and weights in the range of the ones giving the best from the list above. It doesn't cost too much to stay legal, also you may well find a type of pellet that is more consistent and suitable for your individual barrel while testing, it's not always the most powerful that give the best grouping, small consistent groups are more important than another 0.1 or 0.2 FtLb.

[bozzer]

I too heard this ... but also that it was not true.

That's cleared that up then!