FX Impact. Enough fpe for .30 slugs?

Jump to latest Follow Reply
As Bob mention is not about the cal, is about the weight of the slug in order to achieve a max output of 950fps and then tuning that down a bit (considering youtubers experiences), Bob has shown recently that 910 ish fps is also good shooting pretty good @ 170 y, but you need to consider that bob has some mods (not a big one) that gains (correct me bob if I am wrong) like 20-40 extra fps?. (hammer weight?)

With stock crowns or impact and just tuning max is like: (just a guess, is not exact, is only to have an idea +- with numbers)

0.22, 23gn (600mm) = 930 ish fps (this is the more tested slug liner so far)

0.25, 28gn +- (700mm)= 940 ish fps (starting to hit the market)

0.30, 38gn +- (700mm) = 930 ish fps (never saw anyone testing this ones)

Considering that, you need to find the slug that weight the same or less, if weight more (and they usually they weigh more than that) will take the fps down, unless you add mods (hammer weight) or others (like 700mm liner, probably add 10% more speed), how many fps down is good?...looks like bob has proven than 910 ish fps is good too, but we need to see (and probably will in the future) see more accuracy tests on slugs to know for sure, but so far is very promising. 

Why Heavier slugs are available? I think better BC that means straighter flight and less wind influence on long distances


 
Upvote 0
My all stock 25 cal FX Impact X 700mm, Gen 3, with the latest AMP Regulator, is only able to push the 34gr JSB MK2 to about 890fps, with settings all maxed out and regulator set at 148/150bar or so. Without power mods from Ernest, I don't see how it can push 25 cal slugs weighing more than 35gr into the 950fps range, even if i cranked up the reg to 160bar. 

So, until Ernest has some power mods that will enable the 25 cal FX Impact X 700mm to comfortably shoot 35-40gr slugs in the 950fps range, I, for one, wouldn't touch the 25 cal slug liners for now.

So, if the current stock 25 cal FX Impact X 700mm can't handle heavier slugs without mods from Ernest, it is hard to imagine how the FX Impact X 700mm in 30 cal can find the power to push heavier 30 cal slugs into the 925/950fps range, without substantial power mods first. 


 
Upvote 0
This guys RatSniperSlugs.com have a very nice slug on 0.25 that in paper sounds like it could do it, but donno if is the way to go (Lighter I mean...but for sure is easier than mods) .. and also I have read bad comments about they delivery (they just do not deliver after weeks). I have not see any slug similar to that one ... If I had the 0.25 SL I will definitely contact them and ask him for several hundreds of those to test and review. But only after I have got confirmation that they can deliver

​25 caliber

​26 grain Wicked Monster Hollowpoint

​Hybrid Pellet

​Also called the FX X-Treme Pellet

And in 30 cal;

34.5 gr Kryptonite Sledgehammer

​contains a 6mm airsoft BB

.360" long - Designed for the FX Impact

Definitely worth to test them. I have not seen any other brand of pellets or pellet maker with those lightweight pellets. 
 
Upvote 0
I have a theory, and I base this on evidence of my FX Impact MK2 .25, Cal 700 mm, using NSA 36.2 gr. slugs. When I got the MK in July I tuned it in for the Jumbo MK II JSB pellets, and it didn't take long before I was shooting with great accuracy... right around 915 FPS. Then came the slug liner, and from the get-go I had trouble tuning it in. But I will make a long story as short as I can. While FX had increased the capacity to move air, they did nothing for the hammer spring... it's the same hammer spring used on the old FX, the smaller calibers, etc... and that used to be fine. But, the slug liner creates more resistance, the slug has more surface area in contact, the slug does not squish, and the slug is heavier... all in all the amount or air to move this slug has dramatically increased as expected. What I found is there is a DP across the valve; one side is the regulator pressure, the other side is atmospheric. To open that valve, the hammer has to have enough velocity to overcome that DP on the valve. What I have found is to increase the regulator pressure you must also increase the hammer spring pressure; they go hand in hand. I can tell you with my impact, I am currently getting about 915 FPS with the hammer spring at .585 inches. The maximum I can go is .560 inches. So I don't have much room, nor do I want to sit on the tightest setting either. The current regulator pressure is 148 BAR. I walked that hammer spring from sloppy lose to .585, so I know that I only increased in speed... meaning that the valve did not open too much. Now I will tell you part II. Last week while trying to tune it in, I got some erratic behavior. I suspected too much hammer spring. At the end of the day I was at 165 BAR, with the hammer spring maxed out and only getting 400 FPS; I will re-type..not a typo... 4000 FPS. It was pitiful. The key came when I looked at the reservoir pressure. After 28 shots I only used 25 BAR. In other words, the valve was not opening very far, or for very long. The 165 Bar was too much pressure for the spring to overcome. It seems to me that the design of the MK2 failed in the strength of the hammer spring. Shooting slugs, or getting a slug liner should come with a beefier hammer spring.
 
Upvote 0
I have a theory, and I base this on evidence of my FX Impact MK2 .25, Cal 700 mm, using NSA 36.2 gr. slugs. When I got the MK in July I tuned it in for the Jumbo MK II JSB pellets, and it didn't take long before I was shooting with great accuracy... right around 915 FPS. Then came the slug liner, and from the get-go I had trouble tuning it in. But I will make a long story as short as I can. While FX had increased the capacity to move air, they did nothing for the hammer spring... it's the same hammer spring used on the old FX, the smaller calibers, etc... and that used to be fine. But, the slug liner creates more resistance, the slug has more surface area in contact, the slug does not squish, and the slug is heavier... all in all the amount or air to move this slug has dramatically increased as expected. What I found is there is a DP across the valve; one side is the regulator pressure, the other side is atmospheric. To open that valve, the hammer has to have enough velocity to overcome that DP on the valve. What I have found is to increase the regulator pressure you must also increase the hammer spring pressure; they go hand in hand. I can tell you with my impact, I am currently getting about 915 FPS with the hammer spring at .585 inches. The maximum I can go is .560 inches. So I don't have much room, nor do I want to sit on the tightest setting either. The current regulator pressure is 148 BAR. I walked that hammer spring from sloppy lose to .585, so I know that I only increased in speed... meaning that the valve did not open too much. Now I will tell you part II. Last week while trying to tune it in, I got some erratic behavior. I suspected too much hammer spring. At the end of the day I was at 165 BAR, with the hammer spring maxed out and only getting 400 FPS; I will re-type..not a typo... 4000 FPS. It was pitiful. The key came when I looked at the reservoir pressure. After 28 shots I only used 25 BAR. In other words, the valve was not opening very far, or for very long. The 165 Bar was too much pressure for the spring to overcome. It seems to me that the design of the MK2 failed in the strength of the hammer spring. Shooting slugs, or getting a slug liner should come with a beefier hammer spring.
Click to expand...

You can add a hammer weight instead of a stronger spring. Opens valve more at higher reg pressures
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu