Hft 500

[shw]

I have an Hft 500 and I sent it back to the factory because it was low on power as it’s still in manufactures warranty .(.my local aa dealer chrono’d at 10.9 ftlbs and the grouping wasn’t spectacularly consistent)
so when it was returned to me from AA they Chrono’d and tested it so the average is now 778.8 FPS with a ftlbs of 11.32 which I’m led to believe is about right ?
However I still seem to be getting a few flyers every 10 shots which isn’t right for this type of gun I’m sure !
So after some reading I’m wondering if my gun needs a strip down and de gunk ,polish / tune etc ... have I got much to gain by doing this and are there any step by step guides as I’ve never stripped a gun before ?
So if their are any hft500 gurus out there Your thoughts will be greatly appreciated as I’m new to the sport...and enjoying it

[cooper_dan]

What pellets are you using? Are you shooting from a knee/bag/bipod etc?
To be honest there isn't much to be gained from stripping these down except for cleaning the barrel. The only things that effect the pellets are the amount of air pushing it, the barrel it's going down, and the silencer or air stripper at the end.

[shw]

I’m using AA Diablo fields 452. This is what airarms use and test with

[Archer50]

I’m using AA Diablo fields 452. This is what airarms use and test with

Are your 'flyers' actually 'droppers'? If so, I have the same problem and it is the reason I'm not using my HFT 500 for competitions at the moment.

I have cleaned everything that needs cleaning, degreased everything that needs degreasing, examined all the seals and surfaces, regged it, then deregged it again (because it didn't make any difference) and tried just about every size and weight of pellet there is. I still get about one pellet in 30 go 2 to 3 inches low at 25 yards. I have even tried shooting pellets backwards which is not as silly as it might sound given my eyesight! Even they didn't go as low as the random 'droppers' (and, incidentally, grouped surprisingly well ). I don't get this problem on any other gun including my S400, which has a more or less identical mechanism.

I'm not giving up as I have spent too much money and effort on the gun and like it a lot in every other respect. Any suggestions beyond the usual good advice about cleaning, polishing etc gratefully received. My current suspicion is that the problem is something to do with the barrel.

Happy New Year to you all.

Alan

[shw]

Yes I think droppers is the right word .. I’m not sure what to do next

[cooper_dan]

Have you tried washing/lubricating/weighing/sorting pellets? I use them straight from the tin but always check the skirts before loading. Over a hft shoot I'll probably throw away 2 or 3 pellets that don't look right

[Bezzer]

Have you checked the firing valve? anything other than a perfect sealing surface can cause problems even if it looks like a miniscule depression/ridge. I'm just in the middle of turning my 400 classic into a carbine and regging it. Before I started I was getting the odd dropped pellet and running test strings it dipped FPS every now and again, couldn't find the cause. Didn't use the gun for a few weeks before I started the carbine project, chopped the barrel and fitted the carbine cylinder and ran a string to get a baseline for the reg fitting work and it was running 660 fps instead of the usual 780fps, I know shortening a PCP barrel drops the velocity but over 100fps
Stripped it down again and this was the firing valve



New one costs £10-£12 so made a new one from delrin with a stainless shaft.


Everything went back together, done a load of test strings setting the reg up, back up to 780fps/11.3fpe no problem and not had a single dip like before. I'm thinking the odd dip was down to the firing valve starting to deform causing an intermittent problem then when I left it unused for a few weeks it finished it off and was permanently down.
Worth a check on your 500s as a similar/same valve is used.

[Archer50]

Thanks. I checked the valve and could see no problems, but I replaced it anyway and it made no difference.

Just to put a 2 inch drop at 27 yards into perspective, all other things being equal, it represents a 200+ fps loss of velocity for an AADF or a 17 grain pellet at 11.2 ft-lb.

I think my next test will be to shoot as many pellets as it takes over a Caldwell chrono (a Combro would change the barrel dynamics) and see if the drop in POI really is associated with a drop in velocity. That should help to narrow the problem down.

[poth]

Got rid of mine for the same reason flyers every 5 or 6 shots had the gun serviced etc bought a walther lg300 in the end never looked back

[Roger5]

This is beginning to look like a serious problem, the HFT500 is not that cheap, as Alan says he has other S series rifles that don't have this fault, I myself have 4 at present, and none of them are like this, I reckon Alan might be on to something with thinking that the barrel might have something to do with it, the firing valve would normally be my first port of call, but stumped at the moment, just wondering how many others are like this. Rog