TX200 MKIII FAC power level

[moranmiket]

I have had an FAC TX200 in .177 for about a year or so. Today out of curiosity I shot some rounds over the chronograph. It seems my rifle is making on average about 13.5ftlbs. This seems a little low for an FAC rated rifle. I'm curious what other TX200 owners see their rifles performing at.
8.64gr HN Field Target Trophy, average around 825fps.
The rifle shoots accurately at this power level with these pellets and heavier up to about 10.3gr. So I'm not sure I would be looking to tune it up to a higher level. It just seems lower in power than what I was expecting, which was more in the 15 to 16ftlb range.

Thanks in advance for your insights.

[subscriber]

Michael,

The .22 version is likely 20% more potent.  As in 16.2 FPE.   Rated power is often given for the configuration that flatters the results.

That said, PA rate the .22 as 755 FPS with 11.9 grain pellets; so 15 FPE:
https://www.pyramydair.com/product/air-arms-tx200-mkiii-air-rifle?m=174#517

PA rate the .177 at 930 FPS, without giving pellet weight; but I bet it is the lightest lead pellet, at 7 grain.  That would be 13.4 FPE:
https://www.pyramydair.com/product/air-arms-tx200-mkiii-air-rifle?m=174#517

So, I suspect your TZ200 is operating to spec.  It is just not up to a probably unfounded expectation for the .177.

[Jim-in-UK]

The export spring is rated at 46.36 lbf/in and, assuming a 96mm stroke and 11mm of preload, should give circa 13.5 ft. lb. if the energy efficiency is the same as UK TX200s. Another 6mm of preload should take ME nearer 15 ft. lb. but, as the rifle is shooting accurately as is, I wouldn't change anything.

[MartyMcFly]

When my TX200 was brand new it was doing close to 16 fpe with JSB 8.4. However, after settling in and probably burning off some lube it shoots around 13.5. The longer I own this rifle the more I believe that it’s best at around 12 fpe.

In your quest for max power I would consider trying other pellets. The heaviest pellet doesn’t alway give the highest output. Furthermore, the same weight pellets from different brands can produce different power levels. Take for example the JSB 8.44 and QYS 8.48, in my gun there is a 30 FPS difference with equal accuracy.

-Marty

[subscriber]

The heaviest pellet doesn’t always give the highest output.

Yes.  That heavy pellet phenomena is a PCP thing.  Medium power springers usually produce peak output with medium weight pellets.  Low power springers, produce highest output with lighter pellets.  Magnum springers produce highest output with heavy pellets.  By light, medium and heavy, I mean 7 to 8; 8 to 9 and 9 to 10+ grains for .177, respectively. 

[moranmiket]

Thank you all! Sounds like 13.5ftlb is about right. I'm not dissatisfied with the rifle's performance, it's actually fun to shoot. I think I was confused about how close to 12ftlb the FAC rated gun is. I wonder if the sub 12 model shoots closer to 10-11ftlb.

[Frank in Fairfield]

I bought my TX200 in 2014.
I was told to shoot 8.64g H&N FTT, 4.52mm
It shot at 915fps for a bunch of years for around 15fpe.
Scott (Motorhead) made a DELRIN spring follower for it.
Last year it’s started slowing down.
In February of this year I rebuilt it using the AA factory (export) kit.
I noticed the original tophat was installed backwards increasing spring load and speed.
During the rebuild I put in Scott’s follower and corrected the installation of the tophat.
I used the original tophat and cocking shoe.
After about 500 rounds, the spring settled in and these are my speeds:

[Jim-in-UK]

I wonder if the sub 12 model shoots closer to 10-11ftlb.

From the factory they tend to be nearer 12 ft. lb. than 11 ft. lb., but most seem to settle nearer 11 ft. lb. than 12 ft. lb. as the mainspring reaches its settled length.

Most HFT shooters are happy with 770-780fps (11 ft. lb. to 11.4 ft. lb.) with 8.4gn pellets.