Fx Impact Fix & Mods for more FPS / FPE


Every carbide burr that I have used likes to grab brass material violently. Might be fine in a proper endmill and vise to lock the workpeice, but it's not worth the risks in a Dremel.

Ya gotta work on that grip strength. 💪

I never noticed any grabbing. I use a tight grip and light pressure with the carbide burrs. Lower speed helps control when your getting close to the final shape.
 


heavy-impact

If I understand you well it is important that inside hole in the brass port where pellet slides to barrel must stay the same to avoid jam issue?

Airgun-hobbyist 

The picture I found on the internet, if it is yours you did a excellent job

Where the pellet slides can not be wider or you will have feeding problems. Longer is Fine.

The picture you found on the internet is mine.
 

Damn I had the same idea! I should really get a proper end mill
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The dual port has a difference of 40fps from the standard port. so if you end up with an elongated port it makes no difference.


 
Is not only about getting more power, is about having 2 settings in one barrel. 

It might have some good uses in fpe restricted competition. Changes on site.

Dual can be elongated too (original vs elongated). 

One more tool for more tweaking

Each weapon needs to be assigned its own pellet or slug.

I only use slugs, and I adjust everything by one parameter.

I choose the best BC and accuracy I always use one slug.

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I don't think there will be any gain going above bore size on the port.

I think the gain is also from the pellet or slug not dropping off nose first into the port. So with the center supporting the projectile you can get an even bigger port area on either side of that, essentially making the ports the perfect size for the air volume needed and also contour shaping the port's exit into the barrel for optimal flow.
 
I don't think there will be any gain going above bore size on the port.

I think the gain is also from the pellet or slug not dropping off nose first into the port. So with the center supporting the projectile you can get an even bigger port area on either side of that, essentially making the ports the perfect size for the air volume needed and also contour shaping the port's exit into the barrel for optimal flow.

I agree. I have held back and been far more conservative with port enlargement due to jamming / loading issues (especially 30 cal). I also like this design better for deflecting the brunt of shot pressure on my hand made pellet (slug) pins. I'm also being conservative with the pin diameters, I'm just not sure how much pressure they can take (I'm sure there's math to ballpark that, but meh).
 

I think the gain is also from the pellet or slug not dropping off nose first into the port. So with the center supporting the projectile you can get an even bigger port area on either side of that, essentially making the ports the perfect size for the air volume needed and also contour shaping the port's exit into the barrel for optimal flow.

I explained in another thread but it's impossible for a projectile to tip into the port if the job was done correctly. FX made the port as wide as it can be reliable so it should never be made wider. You only need to flare the entry, lengthen slightly to match barrel area, radius the short turn and finish by blending all the cuts together for smooth airflow.
 

I think the gain is also from the pellet or slug not dropping off nose first into the port. So with the center supporting the projectile you can get an even bigger port area on either side of that, essentially making the ports the perfect size for the air volume needed and also contour shaping the port's exit into the barrel for optimal flow.

I explained in another thread but it's impossible for a projectile to tip into the port if the job was done correctly. FX made the port as wide as it can be reliable so it should never be made wider. You only need to flare the entry, lengthen slightly to match barrel area, radius the short turn and finish by blending all the cuts together for smooth airflow.

In a perfect world, maybe. There's been two inlets on different barrel kits that I bought that had undersized TPs drilled in them. Most recent was the 30 cal kit that had bought from UA, the inlet had to have been meant for a 17 cal. It was under 5mm and looked obscenely small.

An observation that I made - in terms of velocity, I never saw a performance hit by inadvertently going a little wider than the block's port. I'm also fairly certain that I have widened every inlet that I have modified unintentionally lol

@edosan - yep! That takes some stress off of modifying them 😂 
 
I’ve been following this thread for a while and I thought I would add my results from my Crown Continuum.

I ported both 380mm and 700mm barrels as well as the probe.

STOCK GUN FACTORY SET AT 150 bar. 

•380mm PW-Max 850-855 with 25.4gr

•700mm PW-Max 995 with 25.4gr

•700mm PW-Max 900-905 with 34gr

I just finished porting both barrels and the probe this afternoon and re-power tuned with the 700mm slug barrel and the 34gr. Reg pressure set to 155 bar. I didn’t mess around much above 155 seemed like it was about tapped out with stock internals.

•Ported 380mm PW-Max 875 with 25.4gr.

•Ported 700mm PW-Max 1040 with 25.4gr.

•Ported 700mm PW-Max 935-940 with 34gr.

I actually had the 380 barrel ported prior to this power tune and I was able to get the 25.4gr going 875. I’m sure it will go up a little bit with the current tune but I really don’t think it pays to port the 380 mm barrel. 

I want to shoot slugs at some point and was looking for a little bit of headroom. With limited time I did shoot a few groups 700mm 34gr and found that the gun was actually shooting best backed down to PW4 at 908. I didn’t try slower but I would imagine PW3 would also be great as it shot them great at 875 prior to the tune.

Definitely picked up some good FPS and a pretty easy mod to do. No problems with loading pellets.



12/15/19 Update.

I put the 380mm barrel on and ran it over the Crony.

25.4gr JSB’s 34gr 28.25 H&N

Max 890 795 850

PW5 883

PW4 880

PWC 867

PW3 855

PWD 825

PW2 808

Makes me wonder if I can shoot FX Hybrid slugs from the 380mm.