Advice needed: FX Impact X and JSB Pellets Optimal Speed

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edosan

edosan

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Apr 30, 2018
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Hello Guys, new member over here, need your help/advice of the experienced users of the impact or impact x (without mods) and JSB pellets.

In your experience the optimal speed in fps for best accuracy @ 50 yards:

Cal 0.22 

JSB Jumbo 0.22 15.89gn is:

JSB Jumbo Heavy 0.22 15.89gn is:

JSB Jumbo Monster Redesigned 0.22 25.39gn is:

Cal 0.25

JSB King 0.25 25.39gn is:

JSB King Heavy MKII 0.25 33.95gn is:

Cal 0.30 

JSB Exact 0.30 44.75gn is:

JSB Exact 0.30 50.15gn is:

Thanks in advance
 
That's alot to ask. I can start you with saying many of those were shot best out of LW barrels between 860-920fps.

I believe the STX is like a Polygonal barrel. Meant to be pushed fast.

Then there's variances in every barrel & pellet. Lube or not to lube? Are you going to sort, sixe, weigh them all for testing and continue, or want out of the tin accuracy? 

I'd say weigh & sort by head size. You can fire pellets on lowest setting into a 55 gallon drum of water. Measure with micrometer or caliper to see what marks your barrel is lewving. How deep are grooves? What's your size before & after going through barrel.

At 50 yards for accuracy, I'm betting 880fps for .25 Kings. For all of them at 50 yards I'd say start testing there, then go up & down & see what shrinks your groups.

If your guns aren't regulated, try to test while tethered & all is as consistent as possible.

That's how to win, eliminate your tolerance stacking to as low as possible. 
 
Upvote 0
That's alot to ask. I can start you with saying many of those were shot best out of LW barrels between 860-920fps.

I believe the STX is like a Polygonal barrel. Meant to be pushed fast.

Then there's variances in every barrel & pellet. Lube or not to lube? Are you going to sort, sixe, weigh them all for testing and continue, or want out of the tin accuracy? 

I'd say weigh & sort by head size. You can fire pellets on lowest setting into a 55 gallon drum of water. Measure with micrometer or caliper to see what marks your barrel is lewving. How deep are grooves? What's your size before & after going through barrel.

At 50 yards for accuracy, I'm betting 880fps for .25 Kings. For all of them at 50 yards I'd say start testing there, then go up & down & see what shrinks your groups.

If your guns aren't regulated, try to test while tethered & all is as consistent as possible.

That's how to win, eliminate your tolerance stacking to as low as possible.
Click to expand...

Thanks James!, is for the impact x, regulated. No need to weight and wash the pellets, just out of the tin. The idea is to compare data and answer what you can (I mean I do not expect you guys answer all!) for example

Cal 0.25

JSB King 0.25 25.39gn is: 840ish (IME is the best speed for accuracy on my impact x, I have tested from 700 to 950)

This can help a lot of newbies to save lots of pellets wasted just for test. I will make a final datasheet with all the info (stats), Thanks again for sharing!
 
Upvote 0
That's alot to ask. I can start you with saying many of those were shot best out of LW barrels between 860-920fps.

I believe the STX is like a Polygonal barrel. Meant to be pushed fast.

Then there's variances in every barrel & pellet. Lube or not to lube? Are you going to sort, sixe, weigh them all for testing and continue, or want out of the tin accuracy? 

I'd say weigh & sort by head size. You can fire pellets on lowest setting into a 55 gallon drum of water. Measure with micrometer or caliper to see what marks your barrel is lewving. How deep are grooves? What's your size before & after going through barrel.

At 50 yards for accuracy, I'm betting 880fps for .25 Kings. For all of them at 50 yards I'd say start testing there, then go up & down & see what shrinks your groups.

If your guns aren't regulated, try to test while tethered & all is as consistent as possible.

That's how to win, eliminate your tolerance stacking to as low as possible.
Click to expand...

thats some serious thought..how to win..can we hangout..I want to bend an ear/!
 
Upvote 0
Sorry to piggyback on this thread, but i have a situation along these lines:

.22 impact X

ive been shooting FT and the limit is 20FPE.

i have several tins of 18.16 so i tuned it down to ~700 fps to meet the limit. Probably not the Ideal solution.

looking at the jsb options, to be at 20FPE:

18.16g =705fps

15.89=755

14.3=795

13.43=820 

based on that, should i go with the 13.43?

any experience with those pellets?



thanks,

eric
 
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The best thing is to try accuracy at those speeds more than the speed itself, where I live I have no restrictions and I do not participate in FT events only Benchrest so no experience I can give you to share, try the Predators Lead Free, I have test them (not very much) with good results, and they weight only 11.75 gn, I have try those more in 0.25 cal, and they go supersonic easy (they weight 16.54 gn in 0.25), with my configuration on Mk2 34gn.

Anyway the point is, test for accuracy @ those speeds and tell us how it goes, so we all learn about sub 20 ;)
 
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Sorry for the thread revival. Just beginning what will turn into an expensive obsession.

I found a chart that has max fps to expect from specific cal and grain pellets but, max is not necessarily most accurate.

My google skills are pretty good (I think) but, I can't find the information requested by the OP. Anyone have any other suggestions?
 
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