Effect of speed increase on an LW barrel without shock.

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Greetings.
    I’m doing my first shooting tests with the boat tail lime. 25, mold 253-51.
My Hatsan BT 65 with LW without shock and 60 cm in length, does not shoot well the bullet of this caliber, nor subcalibrated to 0.253 and to 0.251.
At 30 m the group is very poor and at 50m disastrous.
    The best result has been with the subcalibre 0.251. The boat tail of 51 grains slen to 231m x second. This is not a speed too high. And I thought the bad groupings were due to the low speed of exit of the bullet.
      But when reading your tickets I understood that it can be an excessive twist problem.
      If you increase the speed of these bullets from 51 grains to 260 or 270 m x second, the spin of the projectile will be greater and the scatter too?.

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[rsterneParticipant]

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Sorry, I don’t know what you mean by “without shock”…. I know that some shooters are having difficulty when shooting any bullet (not pellet) in a choked barrel, other find it just fine, once they find the proper diameter….

Bob

[thierryaudibert]

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Hello Bob, hello all
i suppose he want to say unchoked barrel

correct me if i’m wrong

Thierry

[enriquegarramiolaroblesParticipant]

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Hi.
   
Barrell “sin choque”(Spanish). I do not know the term in English: unchoked barrell.
Sorry,The google translator is very naughty. :'(
My question is if it will possibly improve the group by increasing the speed from 125 m / sg to 180 m / sg?
I’m not sure if it increases the speed of a single projectile in the barrel, it also increases the rotation of the bullet.
Thanks to both.

[rsterneParticipant]

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I have no experience with using bullets at less than 800 fps (240 m/s), nor have I seen anyone else doing that…. If you can’t get at least 200 m/s, I would suggest you need a lighter bullet/pellet for optimum performance….

Bob

[enriquegarramiolaroblesParticipant]

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Sorry Bob, I wrote wrong:
225 to 280 mxsg

[teemuParticipant]

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Only way find out is testing lowest speed

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> fastets which brings best results. But You need chrono…Or can you adjust speed?

[enriquegarramiolaroblesParticipant]

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Hi.
    I have my Hatsan BT 65 cal. 25 “in dry doc”.
It will be modified to achieve the maximum possible power:
-Rotate the volume of the internal chamber of the valve.
-The needle was thinned and the needle seat was enlarged to 6mm.
-The needle spring was removed and the valve cap was removed.
-A single air outlet hole was left at 6mm in front of the transfer and the others were plugged.
– A hammer spring will be placed harder and weight will be added to the hammer.
– Size will be removed from the block so that the valve can open more.
      Before I moved the Barracuda lime. 25 to 306m xsg (94 j). And the boat tail 41 g of Bob at 235 m x sg. I would like to move the boat tail from 51 g to 100 j or close.
The boat tail of the 253-41 and 253-51 molds do not go well: they disperse a lot at 30m and more at 50. Recalibrated at 251 improve a little, but do not group in an inch at 30m.
    I have already asked Noe for the 250-41 and 250-51 molds, to continue testing until reaching acceptable groups at 30m, and adjusting the rifle configuration to improve groups to the maximum.

[Author]

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