Interestingly, all my airguns obey this general rule, except the 45 which makes a fairly consistent 5.25 ftlb with anything lead that is a good fit in the barrel whatever the weight! The FTT green (5.5gn) I bought for an experiment manage only 4.8 (at 628 ft/s) but these are a tight fit and are nowhere near as soft as lead based pellets.
JSB exacts and mosquito express do particularly well through the chrono and are a good fit for my barrel, as for accuracy I'm not a good enough shot with a pistol to tell the difference between the many brands of pellets I tend to put through them. RWS R10 produce extremely low variation shot to shot in the 45.
Forgot to add, if you are only using the 45 for plinking and informal target shooting the RWS Hobby and Geco flat heads are really cheap and surprisingly good. Only a tad over £4 from the site sponsor, JS Ramsbottom.
Last edited by sevorg; 07-02-2017 at 02:59 PM. Reason: Added cheap flathead info
Well I have just got myself a tin or two of hobbies so will push those through later this week.
I noticed the hw45 has two cocking points low / high power does anybody have any idea or figures what the differential is (in terminology a noob can understand)?
@Oling very intrigued by your comments on the "preferences", I understand the balance of weight / trajectory aspect of your argument re spring pistols but am curious as to why pcp / co2 add fpe? Is it due to power delivery, efficiency of delivery or what?
Hi oling, it's a 2010 dual power model. Originally it made 5.5 with Webley Express and Falcon Accuracy+ in the early dieselling days! I stripped it, made some minor changes and dry lubed it late last year, details here if you're interested
http://www.airgunbbs.com/showthread....ling-with-a-45
This reduced the power a bit with a new, resized seal and spring guide reversed but it is now much smoother to cock and very consistent shot to shot. I'm sure it would make 5.5+ if I fitted the spring guide back in the original position, inside the piston, but this just makes it graunchy to cock and not so nice shot cycle.
Anyway, I was a tad bored yesterday so put a whole load of pellets through it as I was surprised at the pellet energy v. weight results I had in the past. Results below:
RWS Hobby (6.94gn) 4.58 (slightly tight in barrel)
RWS Superdome (8.26gn) 4.27 (tight fit in barrel)
RWS Superfield 4.51 (8.35gn) 4.97
RWS Superfield 4.52 (8.52gn) 4.47
JSB Heavy (10.33gn) 4.56
JSB Exact 4.52 (8.45gn) 4.99
Webley Express (7.84gn) 5.17
Falcon Accuracy + (7.32gn) 5.28
Crosman Accupel (7.94gn) 4.99
H&N FTT (8.21gn) 4.73 (slightly tight fit)
These are average 10 shot figures, each pellet weighed to 0.02gn accuracy and shot though a Skan Pro 1 series 3 chrono.
I revise my earlier comment and now agree that it does make better power with the lighter pellets. My older results were taken using the manufacturers' stated weight for the ammo and were quite a bit out in many cases. Hope the results are useful to the GB2017
On my original pistol when new and it was still dieselling a little, the low power setting (the first point the pistol cocks at, at about 90 degrees) produced around 3.7 FPE. The second (full power) position made around 5.5 FPE. Both these figures drop as the oil disperses but this can take several tins of pellets.
Last edited by sevorg; 08-02-2017 at 01:04 PM. Reason: rubbish punctuation
I would probably do the whole thing injustice trying to explain it as I have only an elementary understanding of how it all works. Spring piston power plants are in essence compressing a very small volume of air very very fast. This small volume of air will produce more energy if it only has to push a lighter pellet than a heavier pellet as it decelerates less. Of course, this is subject to the balancing of the piston/spring etc. but this tends to hold.
With PCPs you're talking about a larger volume of air moving not so quickly (at sub 12 FPE at least). This larger volume doesn't get as affected by heavier pellets and actually tends to somewhat linearly increase the power with the pellet weight. Incidentally, a lot of modern PCPs running over 11 FPE will be over 12 FPE with a 30 grain piledriver in .22 (21 grain in .177).
Co2 on the other hand is a much larger molecule and travels slower than air but there is a lot 'more' of it. This therefore decelerates the least of all of the propellants so you tend to see the greatest gain in FPE with a heavy pellet (I've seen 50-100% increases in FPE moving from a very light pellet to a super heavyweight).
If you're interested in a more formal explanation, check out Tom Gaylord of Pyramyd Air who writes a regular blog in the US as he does a far better job than I will in explaining these things.
thanks to both oling and sevorg for the tests and explanations both extremely helpful, will certainly be following up on Toms blog later
177 Hobbies were an unpleasantly tight fit in my HW45 barrel.
Now I use German match pellets (R10, H&N) and get good results.
I agree with an earlier post about keeping oil off the aluminium action. It will result in faded patches. A clean dry cloth is all you need to wipe away the finger prints.
Arthur
I wish I was in the land of cotton.