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You know a gun has gotten under your skin

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dan_house

Member
Feb 4, 2019
1,023
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Bozeman, Montana, United States
when you realize you have a Love/Hate relationship with it :)

After the bent cocking arm incident on the TX200, back to chrony work and setting up ballistic data for the gun

had been shooting 8.64's at 860ish..... which is 2-ish ft lbs over the WFTF 12 ft lb limit. some head scratching ensued, then remembered last time I shot the gun in FT competition I shot it in Open Piston, so that didnt matter..... Brain fart and too much time since Ive competed kinda blended memories and I thought I was OK for Worlds power levels

The 8.64's shoot well from that gun, at that speed. So now Im shooting 10.65's at 715 giving 12.11 ft lbs...

Have some 9 grain pellets havnt chronied yet, no idea what they'll do. Issue for me is, the 8.64's are well understood, have a bunch of them. Have no experience with the 10.65's or the 9 grain one..... Did try some 13 gr pels, High 500's for pellet speed....

One thing Ive thought of..... cocking the thing and leaving it a couple days to get it to take a set.

SO I'll ask an old question....Heavy pellet going slow, or lighter pellet going fast?

One thing I did notice, it takes several shots for the gun to settle into a "zone" of acceptable speeds.... the 10.65's started at 738 then another 8 - 10 shots to get it consistently into the 710's. Havent seen that behavior before. for a few minutes was thinking my seal or spring (12 lb kit...) was toast.

Yea... Love /Hate... :)
 
Just a thought: if I was entertaining a different pellet, I’d test to see which one has the best real-world ballistic coefficient. For field target I’ll tolerate a lot of things but wind deflection and general accuracy are non-negotiable.

Last week I did some BC testing (estimated from drop out to 50y - I didn't bring my labradar) and the 13.4's had about the same drop at 50y at the 10.3's, which given the lower velocity, meant much higher BC and wind resistance. While that was approaching 20ft-lb the testing method is universal.
 
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I have also been working up a TX200 for worlds the last couple of months, late night sessions, bumbling through tweaks and "performance" upgrades, band aids on fingers to prove it.

Definitely a two steps forward, one step backwards progress. Tonight's work is replace sheared lever pin, shim shoe, and replace breach seals... test... curse...
 
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One thing to check if your first few shots are a little hot is the spring and seal. It may be the seal takes a few shots to expand properly due to age or lubrication or it could be lube migration causing dieseling. Or it could be something else - see "EFFIN SRPINGERS".
I would pop it open, re-lube, check the seal for nicks and remove any power washers that may be in there. Then try the 8.64s again and see if they are at 12 fpe. If it's still hot, I would replace the seal with an unsized seal and size the seal until the chrony is where you want it.

Bear in mind that tuning the seal is going to introduce temperature as a variable. The seal will contract in cooler weather and shoot hotter.
 
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scotton said:
The seal will contract in cooler weather and shoot hotter.
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Yep... should have mentioned its still winter here in Montana, so its cool in the shop. Its a new-ish seal
gonzav71 said:
I recommend staying at 11 FPE to be safe.
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Ran another string Friday night w/10.65's. Avg'ing around 11.3-11.5

Have noticed its more consistent FPS-wise now that Ive only been shooting the 10.65 pels
 
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dan_house said:
Yep... should have mentioned its still winter here in Montana, so its cool in the shop. Its a new-ish seal

Ran another string Friday night w/10.65's. Avg'ing around 11.3-11.5

Have noticed its more consistent FPS-wise now that Ive only been shooting the 10.65 pels
Click to expand...
The downside to shooting 10.65 pellets for WFTF is your long rangefinding is going to have to be on point. Past your zero, that pellet is going to be falling off a cliff, but hopefully a higher BC will help compensate in the wind. If you are going to stick with the heavy pellets, I would raise your scope to flatten out the farther target dope.
 
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