Tin bum short stroke for tx.

[seagate]

Just concluded some acuracy testing with aafield express 7.9, very happy with it. From seated I occasionally cought a glimpse of the pellet as whizzed through the focus, that's never been known before with this particular rifle, there's noticeabley less recoil or appears so to the shooter.Shooting at spinners at 40 yards I would have previously missed a few with the wobbles I had going , but I missed a few less than I usually would in similar circumstances, so in my book it's no more or less accurate but for most garden plinkers like myself it's noticeabley more consistently predictable.Easier to shoot.


Ran a few through the chroney before I packed up, hovering around 790 to 812 or so , not as half as consistent as it was with the standard spring but feels better to shoot and easier to hit the target so I don't really care at the moment.

[gary martin]

were the pellets weighed? i weighed a tin of AA fields 8.44g stated on tin last night. lowest was just over 8g highest was just over 8.7g. if you are shooting out of the tin, and had a spread like i had 0.7g it will make a difference. the rifle may also need to bed in a little.

[seagate]

I only ever weigh pellets when I get a fresh sleeve of them.

these are a sample of these particular express pellets being used at the moment, the same ones are stella in hw100 and hw30.

I am at sometime going to put the original spring back in with tb guide to to satisfy curiosity.

[seagate]

I've been thinking about the poor consistency all day at work racking my brains as to what I've got wrong .


This afternoon fired 10 falcon accuracy through the chroney, there was a spread of 18 fps and averaging 10.6ftlb,same sort of poor consistency with other pellets aswell so it's not the pellet.
I can't remember the last time I gave the barrel a clean,it could be years ago.Gave It a pull through with a fag filter and it came out like a chimney sweeps brush,so 6 more goes had it clean.

These are the numbers for jsb made pellets,after a thorough decoke. What a vast difference it makes.

Each over 12+ shots.
7.3grn high 812 low 802 10.5 ftlb -10fps spread. - slight power drop in these particular pellets after barrel cleaning.
7.9grn high 818 low 807 11.7 ftlb -11fps spread.
8.4grn high 797 low 793 11.9 ftlb - 4fps spread. - so it's likely been over the limit before the barrel clean.

After removing the remaining 2 power shims.

Each over 20shots.
7.3grn high 813 low 801 10.6ftlb -12 fps spread -removed 2 shims and the velocity remains the same.
7.9grn high 798 low 788 11.0ftlb -10 ftps spread.
8.4grn high 787 low 776 11.4ftlb -11 ftps spread.
Overall happy with the results though I wouldn't object to shaving off a little more velocity off.

Just a quick question for the tuners and fiddlers, what are the pros and cons of having a weaker longer spring like ive got now or say the standard aa mk3 spring with 12mm of power shims.What's the nature of springs allied to recoil, surge and things I've never heard of? Can you boil it down to a sentence or 2 for us thickies,please.

[Timmytree]

That's like trying to understand a woman!
All I know is that AA Fields are the most efficient pellet in my Prosport, no matter what I do to it they produce higher power than anything else.

[seagate]

I've had the same experience with aa fields in most rifles I've ever had,pcp or boingers.

[seagate]

Had another delve inside to experiment with reducing velocity for easy plinking,
In the tinbum kit, he supplies 2 washers of different thickness to experiment with under the top hat,it sort of equates to the standard top hat for 177 or the slightly shorter 22 version.
So swapped over the washers, thick one out -thin one in.Voila velocity down to around low 780-10.7 with the 7.9 express pellets and mid 740 10.4 ftlb with aa field 8.4. By some quirk,the lighter pellets make more power than the 8.4, just an observation....

Picked up new ammo supplies that I want to try out, rws r10 match at 8grn and rws supermags at 9grn. Both shoot very well for wadcutters out of hw98 and hw100,useable on unwelcome guests at near 30 yards.Not as yet tried them in tx.

Question-in theory which set up might shoot smoothest, shorter spring with power washers or longer lighter spring without? Any thoughts or musings on the subject?

[Sake-san]

Generally, longer, softer springs will give a more pleasing feel (not sure what you really mean by smooth), personally I prefer shorter and stiffer for a faster feel, snappy, like a good crocodile sandwich .

[seagate]

''(not sure what you really mean by smooth)'' neither do I when I think about it.


Here are some info comparing a the standard mk3 spring and a Titan no10.


Looking at the lengths when partially loaded with 18lb it looks like they're virtually the same stiffness,the titan being fractionally softer.
The arrangement that I prefer with the tb piston head on , is the titan spring on aa steel guide with the delrin top hat with without any added preload. The spring dry apart from the ends,not a hint of buzz or nastiness.Used the rifle regularly over the last week,after 500+shots it's sat at 770 780ish with 7.9 express. Very quiet muzzle report.

[seagate]

I've been using the gun last week ,and maybe gone through some 1000 shots since the rebuild, it's descretely crept up in to the region of 815 fps from around 780 ish .Chairgun says it's currently around 11.7ftlb ,it still shoots civilised, an all lovely lovely but it's abit mad for garden plinking. I might just put back in the original spring or my spare and see what that's doing now the seal has fully worn in.