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Need for Speed? The FPS Checklist

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Need for Speed? The FPS Checklist!

FPS on the mind? This is a reference for all of those who feel like their BASR (Bolt-action Sniper Rifle) is missing FPS or for those who simply want more BANG out of their sniping machine.

Table of Contents

A. Accessories
B. BB's
C. Bucking
D. Chronograph
E. Cylinder
F. Cylinder head
G. Hop-up Chamber + Adjustment
H. Inner barrel (spacers included)
I. Nub
J. Piston body
K. Piston head/o-ring
L. Spring
M. Spring guide
N. Spring guide stopper
O. Stock Body

A. Accessories

1. Flash hiders/ mock suppressors/ barrel extensions

  • Sometimes these muzzle accessories are not properly aligned or poorly made and FPS can be lowered without the user knowing. I find it very important to chronograph a rifle with and without the accessory.
  • If the FPS is decreased with an accessory attached by ~5-10FPS or more, then the accessory is altering the BB's flight in some way.
2. Proper Alignment

  • Make sure that all available threading is secured properly and the inner barrel is aligned straight so the accessory does not touch the BB.

B. BB's

1. Washing/Cleaning
  • <- This entire thread discusses techniques and experiences with washing BB's. This method does not improve FPS dramatically, but it evens out and cleans the surface of certain BB's for more consistent and slightly better FPS/accuracy.
2. BB brand quality

  • Certain brands are known for having bad BB polish, uneven internal bubbles, varying weight, and varying sizes. All of these components are important for consistent FPS as well as creating higher or lower FPS readings in a chronograph. Sometimes bad quality BB's will create low FPS readings as mentioned in the next point.
3. For chronograph readings

  • Using a different brand of 0.20g BB's will alter your FPS reading for better or for worse. If you suspect your rifle is shooting lower than expected, try a different brand of high quality BB's. I have noticed as much as a 20FPS difference just from switching to a different BB brand.
C. Bucking

1. Thorough Cleaning

2. Simple Cleaning

  • A dirty bucking can ruin your FPS consistency, FPS output, and accuracy. For a simple clean, remove the bucking from the barrel and wash it with soap and warm water (inside & out) until you believe it is fully cleansed. Allow the wet bucking to air dry and re-install. You can apply grease on the outside of the bucking to assist the installation of any nubs (i.e. PSC/SCS nub.) Avoid any grease/lube/oil from contacting the inside of a bucking. It causes the BB to slip and contact the bucking in unpredictable ways which will cause inconsistent FPS.
3. Proper Installation

  • Make sure that the bucking is properly aligned with your inner barrel so the bucking maintains a proper seal. Some people install the bucking improperly and experience a lower FPS reading because of air loss.
4. Type of Bucking

  • Hard buckings and soft buckings effect FPS depending on the expected FPS output. Harder buckings are recommended for higher FPS setups.
5. Brand of Bucking

  • Certain brands work better than others when sealing for compression. Nine-ball, Prometheus, Firefly, Systema, TM, and PDI are all known to have great air sealing reputations.
6. ABB Rings

  • These rings were specifically made for VSR/Bar-10 rifles by a user named Noobie. Until I can gain more information regarding where to purchase these rings, I will leave this section incomplete for the moment.

7. Dental Floss Mod

  • This mod apparently works just as well as ABB rings, but the biggest downside is the potential of damaging your bucking if tightened too much or if very thin floss is used. This link will demonstrate installation:
10. Damaged Bucking

  • A damaged bucking will almost always decrease FPS. If there are holes or tears in your bucking then it's time to replace it. These holes and tears will not only effect your FPS output, but also your FPS consistency and accuracy.

D. Chronograph

1. Chronograph Brand

  • Xcortech is a highly recommended chronograph because it gives the closest approximation to a BB's REAL FPS.
  • Madbull is known to have an average deviation of +/-30 FPS and sometimes as much as 100FPS in several occurences.
  • If you believe your FPS is lower than expected and you've done all that you could with internal parts, try a different chronograph and re-test your FPS. I've personally experienced a difference of 35 FPS when going from a Madbull to an Xcortech.
2. Aiming consistency/angle

  • When chronoing, make sure to aim exactly the same for each shot. The sensors on most chronographs capture speeds differently when the BB is traveling at different angles. Consistent aiming will ensure proper readings.
3. Distance when chronoing

  • The distance of the muzzle to the chronograph's sensors can effect FPS readings. I usually remove the muzzle adapter for chronographs that include this option. You must be more careful when aiming through the chronograph opening, but this will allow more accurate FPS readings.
4. Vibration

  • Make sure to not contact the chronograph or vibrate the chronograph in any way, otherwise FPS readings may show much lower readings than expected.

5. BB brand

  • Please refer to section #3 of BB's
6. Battery Life

  • Low battery life sometimes affects FPS readings. Some people claim to get high readings while others get low readings. Just make sure the chronograph being used is properly charged.

E. Cylinder

1. Cleaning

  • Too much dirt, grease, or oil can effect FPS. Use soap and water and/or rubbing alcohol to clean all the dirt/grease inside the cylinder. Allow to air-dry or use lint-free cloth.
2. Re-greasing

3. Teflon and other coated Cylinders

  • These cylinders allow for smoother bolt operation (push+pull), but they do not necessarily increase FPS like one would expect. In fact from my experience, the FPS readings from a non-coated cylinder is the same as a coated one.
4. Bore-up Cylinder for VSR/Bar-10 platforms

  • There are bore-up cylinders available for these platforms which increase the cylinder volume. The volume increase is not tremendously larger, but they can increase FPS just enough to make a difference.

F. Cylinder head

1. Taper/bevel mod

2. Teflon tape mod

3. Nozzle polishing mod

  • This modification may increase FPS by 10-30 FPS. This involves applying at least 2 coats of clear nail polish (or any hard + chip resistance substance) onto the cylinder head nozzle. This allows for better air seal between the cylinder head nozzle and the bucking lips. This picture I rendered should give a better idea:

4. Nozzle boring mod

  • It is possible to bore out (increase the inner diameter) of the cylinder head's nozzle a little more. This will enlarge the passage that air can flow through which enables more air to accelerate the BB.
  • Please note: It is possible to permanently ruin your cylinder head so perform this mod at your own discretion.
  • To bore out the nozzle, you can use a rotating tool of some sort (drill, dremel, etc.) and carefully sand the inside of the nozzle until you are content with the diameter increase.
  • Boring out the nozzle does indeed increase FPS, by a fair amount if your not shy with the drill size..... combine this with a deep ported and polished cylinder head and you can gain around 60 fps if done right and you get the port shape right. -Vindicareassassin
5. O-ring replacement

  • If your o-ring is severely damaged then simply find an o-ring replacement at your nearest hardware store. Although requiring a cylinder o-ring replacement is not too common, finding a replacement is at the utmost importance.

G. Hop-up Chamber + Adjustment

1. O-ring replacement for PDI Chambers

  • The o-rings for the PDI hop up chambers were designed for a better air seal. They act similar to teflon taping both ends of the bucking to your inner barrel. If you are suspecting FPS loss somewhere and all else fails, you may need to change your o-rings.
2. Adjusting hop-up level for FPS

  • It's commonly known that adjusting the hop up too high or too low can effect FPS dramatically. Adjusting to find your maximum FPS can be tedious depending on your hop up chamber, but this is necessary to determine the maximum output on the current spring installed.
3. Upgraded hop-Up chambers

  • In particular, PDI hop up chambers include air seal o-rings for better compression and this chamber also allows the use of AEG barrels and AEG buckings- all of which can potentially increase FPS significantly.
4. TDC Mod

  • This modification is primarily for VSR/Bar-10 platforms. TDC, or Top-Dead-Center, virtually removes all hop-up arm foul play. Adjustments will become more consistent and therefore FPS will become more consistent. If you feel that your hop-up arm may be causing FPS inconsistencies or accuracy issues contact username: Cheeseman ... He can answer your questions and has the capability of installing a TDC Mod.

5. Aps2/Type96 PDI Hop-up Chamber Booster Spring

  • The booster spring included with the hop-up chamber is designated to perform the same way as the O-ring which goes around the lever arms. The booster spring prevents the lever arms from jumping up when a BB passes from inside the inner barrel. This keeps the lever arms consistently in place and therefore increases FPS consistency.
  • The spring is not required, but if you need more consistent hop up or more consistent FPS, I would recommend it.

H. Inner barrel (spacers included)

1. Cleaning

  • A dirty barrel can undoubtedly decrease your FPS output so keeping it clean is required from time to time.

  • Rubbing alcohol and a lint-free cloth (or some people use teflon tape) is all you really need to clean the barrel. Run a few cloths saturated with rubbing alcohol a few times down the barrel from bucking end to muzzle end with the bucking taken off. Once there is no more dirt residue on the cloths, run a couple of dry cloths until you are satisfied.
2. Polishing

3. Barrel Spacers

  • Barrel spacers will reduce vibration of the inner barrel and this has been proven to increase FPS slightly for various people (myself included)
  • Electrical/Duct Tape Spacer: Simply wrap several rounds of tape in at least 3 places on the inner barrel. The more spacers, the better. When placing the inner barrel back into the outer barrel, it should be a very snug fit to eliminate vibration.
  • One-piece Paper Spacer:
  • Wax Barrel Spacer:
Please feel free to leave suggestions or criticize any part of this post.
This thread is intended to be updated so this is not the final version.

It's quite late where I'm located and I'm going to knock out soon. I will probably revise and/or add more sections or information at a later time.
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If you learned about FPS, you should also knowledge about bbs Size because size have matter about his FPS, speed, velocity etc. Check the first how to know about BBs size :
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