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  1. ackuric

    Internal and external ballistics spreadsheet

    I said I'd release this in May last year, just never said which year. Maybe its 2022? I built this all in 3-4 months during the beginning of the pandemic, but have kind of slept on it for the last year due to burning out on it, it is/was quite overwhelming. Its 98% complete and fully in beta...
  2. ackuric

    Backwards math to optimize energy output

    ...how minor changes may effect your energy output in a traditional pcp. For these simple solutions, you need to know some of your rifles specs. ***Port size Increase/Decrease*** Port OD / Bore OD .2 / .25 = .8 What is your energy output 80% of? Lets say this rifle is at 60 fpe. 60 fpe...
  3. ackuric

    Marauder valve lift limiter - Another approach

    There are many ways to skin this cat. I recently decided to approach this modification for my marauder with two ideas in mine, external adjust-ability, and simple modification. As they say, KISS (keep it simple sillygoose). This mod can apply to any air gun that has a machinable hammer, and...
  4. ackuric

    Portsize and 2 milliseconds, whats the connection?

    Port size and efficiency volume 2. What does Port size have to do with 2 milliseconds? Is this a punchline to a joke? Absolutely not. 2 Milliseconds is roughly the amount of time you have to expel as much air into an airguns barrel prior to the pellet out pacing any further air being...
  5. ackuric

    Portsize vs Efficiency. Why bigger is always better when regulated.

    ...adjust via hammer strike in a full/over bore condition. I hope this helps explain why bigger ports are ALWAYS better in a regulated air rifle. **Do note, one should never widen their barrel port beyond 75-85% of their bore diameter, to reduce risk of projectile damage upon loading...rather...
  6. ackuric

    Popular Ammo Spec/Data request!

    Simple request, if you have what you consider a popular pellets for your caliber in your stash, and a micrometer, please take the time to measure and provide me with said data as I would like to include it in my upcoming sheet for those that don't have the means (micrometers :P ) or knowledge...
  7. ackuric

    Popular Gun Specs/Data Request

    If you have a more common/popular air gun and the following data, please take the time to fill out as I'd like to include it in my upcoming spreadsheet. Only OEM data is needed right now, if you don't have OEM data (unmodified from manufacturer) then please don't proceed! This data may be used...
  8. ackuric

    Official Release Simple PCP Calculator / Mobile

    ...to edit and which to leave.) https://docs.google.com/spreadsheets/d/1Y7Boso1AgFxWk1ZiNoCStnT1K8hDpS4r_m73gSsj96Q/copy *the advanced version coming in a few weeks will have an incredible amount of more data, and functionality but will only be accessible via PC using...
  9. ackuric

    Robert Lane...very unprofessional

    I'm not a 'customer is always right' type of person, as I run my own business...but when I order something, twice, and between 4-8 weeks goes by without receiving anything, I simply start a case with paypal to protect my money, as I don't like to spend it on thin air...I inquired about...
  10. ackuric

    Simple PCP Performance Calculator

    ....177 caliber making 20 fpe to .50 caliber making 600+ FPE. External link: http://s000.tinyupload.com/?file_id=60686858958191045898 *edited new version includes units for each field to minimize confusion.* *added graphical data *added volumetric efficiency calculator (fpe/ci)...
  11. ackuric

    FX STX Pellet Liner A Outer Diameter

    Anyone with a FX Smooth twist X Pellet liner A in .22 cal know or can obtain the liners OD? Thanks! -Matt
  12. ackuric

    Explaining Free flight / Hammer gap

    Free flight / hammer gap is when there is a nominal distance (ideally at least 2/3 distance of valve lift) between the face of the hammer that strikes the valve stem when the rifle is left uncocked, and the valve stem itself. Why is it important to have this in place in modern pcp's you ask? To...
  13. ackuric

    Max Pellet Expansion / Deck of Cards test.

    Thought I'd welcome those with powerful airguns and a deck of cards laying around to a test to see what it takes, or if its even possible, to shoot through an entire deck of playing cards (Calling all .452 slayer owners hah). My attempt was at a mere 56 muzzle FPE @ a safe distance of 10 yards...
  14. ackuric

    How Plenum Volume Effects FPE Output

    ...loss, where as the higher power the rifle is the more energy loss would be seen @ 1/3 cc of plenum, still within acceptable margins I'd imagine. ***this graph reflects my setup but the rule of thumb for plenum volume availability being 1/3rd to 1 cc per FPE still stand for most pcp's***...
  15. ackuric

    60~ FPE For Medium Game Test

    I decided to do a little test replicating a real world hunting condition to see how powerful a 60 fpe shot really was and how effective it may be taking down bigger (medium) game. For this test I used an old leather wallet to replicate the hide of a larger animal, and then 3/4" particle board...
  16. ackuric

    Rubber mulch boxes, or any backstop, use caution!

    My .25 cal is tuned to shoot around 56 FPE but I also shoot it at 60 fpe. I use a 9" thick box packed TIGHT with rubber mulch and frequently shake/flip it to keep things uniform inside. First pic shows the thickness in the direction I shoot. Second shows a few exit paths...luckily for me behind...
  17. ackuric

    When you go to punch paper but you punch air instead.

    Gotta love 1 hole groups! No need to measure CTC :)
  18. ackuric

    90% Bore porting Revisted. Marauder @ .23"

    ...exit port and seat which should hold up great. That is at the edge, it increases in thickness gradually as the angle in the porting changes. ***Note porting to .23" with only .238~" throat requires a .04-.045" valve stem, do not modify a stock valve stem in attempt to copy this. Upgraded...
  19. ackuric

    The Quest to 90% Bore Porting.

    I do a lot of modifications to PCP rifles. And the following I will be presenting to you should NOT BE ATTEMPTED unless you have thorough knowledge of how pcp's work, inside and out, but mostly inside. The following was done with VERY limited set of tools : drill, dremel, clamps, peek/delrin...
  20. ackuric

    Measuring Internal Ballistics

    ...hammer momentum / closing force. That is with consideration of energy loss after lifting the valve off the seat which is pressure on the seat area * compression distance of poppet / 2. Closing force being (primarily) the cross sectional area of your poppet stem times the average pressure of...