Need to better understand

[PedroS]

One thing that I can't really understand is what my 24J rifle (regulated) is doing.

Charged at 200bar it shoots at 304m/s and is spot on the target, and I do mean spot on, 5 shots or more, in the same hole.
Somewhere after 10 shots it starts to open up, but still continues to shoot strongly at 304m/s. At this stage the pressure indicator has dropped to around 180bar (approximately as the scale is far from being easy to read).
Continuing to shoot, meaning more 30~40 shots (pressure around 100bar) it will never can regroup as before, but, and here's the puzzle, it continues to shoot at 304m/s.
Charged again to the max 200bar, et voila, the super tight group comes again, but only for 10 more shots... after that it spreads again.

Any light on this?

 

[Boomer_Mikey]

Barrel Condition

Try cleaning the barrel with VFG brass impregnated felt pellets for 10-15 strokes after the first card. This is a dry process so the barrel will only need a couple of shots to return to normal POI.

Mike Aber

 

[michaelthomas]

I would agree that it probably has nothing to do with your fill pressure. You can test that by simply tethering a large tank set to 200bar to your gun. If it is truly the fill pressure......the gun should group forever.

For what it's worth.....shooting 1000fps is not a good idea for accuracy. It's quite likely that your pellets are no more wind resistant at 1000fps (and quite likely, less), than they are at 850. The additional 150fps will only foul your barrel faster.....at the minimum.

Mike

 

[PedroS]

Try cleaning the barrel with VFG brass impregnated felt pellets for 10-15 strokes after the first card. This is a dry process so the barrel will only need a couple of shots to return to normal POI.

Mike Aber

Thanks for the tip. but I have done it already and didn't show much improvement.
One thing is certain this barrel gets dirty quicker and stronger than others I have.

 

[PedroS]

I would agree that it probably has nothing to do with your fill pressure. You can test that by simply tethering a large tank set to 200bar to your gun. If it is truly the fill pressure......the gun should group forever.

For what it's worth.....shooting 1000fps is not a good idea for accuracy. It's quite likely that your pellets are no more wind resistant at 1000fps (and quite likely, less), than they are at 850. The additional 150fps will only foul your barrel faster.....at the minimum.

Mike

Thanks.
I have looked some of your videos and... uau... that's shooting and wind reading capacity. A lot to be learned by me.
I'll try to decrease the speed of the pellets.
Post here later the results.

 

[KevinHarris]

Try cleaning the barrel with VFG brass impregnated felt pellets for 10-15 strokes after the first card. This is a dry process so the barrel will only need a couple of shots to return to normal POI. gun safe dehumidifier

Mike Aber

he is absolutely right you just need to follow the instructions.

 

[Jonnyh]

Seen this quite a few times of various rifles over the years.
Could be so many things to list but first areas to check are:-
Bedding in, or lack of.
Flex, air cylinders may veer off diagonally due to pressure and bare on something.

Last rifle free floating and bedded in the right place at only 25 yards just backing off the cylinder not touching anything would alter zero to drop 3/8" plus windage, subsequent backing off 1/16 of a rev saw zero move left to right 1 1/4" x 3/8" low by half a rev out. As said that's free floated and baffled me for 10 years.

 

[PedroS]

I would agree that it probably has nothing to do with your fill pressure. You can test that by simply tethering a large tank set to 200bar to your gun. If it is truly the fill pressure......the gun should group forever.

For what it's worth.....shooting 1000fps is not a good idea for accuracy. It's quite likely that your pellets are no more wind resistant at 1000fps (and quite likely, less), than they are at 850. The additional 150fps will only foul your barrel faster.....at the minimum.

Mike

You nailed it.
Decrease (heavier pellets and a bit less of energy) the pellet speed to around 800fps and voila!

Many thanks to all