I recently purchased an M4 in 177. Ive only shot one mag so far and Im assuming thats it but I had a dev of 100fps. If I cut the two worst shots im at 56fps. Like up and down between 790 and 830ish throughout the whole mag. Is this normal? Thanks!
FX New M4 177
- Thread starter IndiAirgun
- Start date
Hi,
Not an expert on the M4, but have done a lot of tuning on other FX airguns. I expect you are way off a good tune. Depending on the pellet, you should have a desired range of velocities you want to reach. For instance, the folks shooting .177 13.4gr pellets (JSB, Air Arms, FX) on the 30yd Challange Thread here on AGN have found great accuracy with those pellets around 810-830 fps.
Th get to that point degas the rifle, turn the reg adjustment screw all the way closed, the back off 1 complete turn. Set the Power Wheel to something fairly low, like 10. Then set the quick tune to something like 2.0. Finally set the valve return spring adjuster to something like 3 three lines. Regas the rifle and bring the pressure up to about 89 bar. Then shoot a three or so shots to see what the velocity is. Try going up two clicks on the power wheel (a much bigger change than doing the adjustment on the QTS). If the velocity increased but not far enough then repeat. Keep repeating till you hit your target velocity, or the velocity increases very little, or you run out of clicks. In those cases you need to up the reg pressure. Keep repeating the process till you get 10-15 fps faster than your desired velocity. Now use the QTS to adjust in small increments till you are good. The close down the valve return spring adjuster until you notice the speed dropping. Open back up a bit.
That should get you to a spot where you can shoot groups or punch holes in targets like the 30yd Challange to check your accuracy. You may need to try several different velocities to find the one that gives you the most repeatable good results.
Cheers,
Greg
Here is a video from a Danish Guy who shoots .177 slugs out of an M3. He has a bunch of videos, but this one is on his tuning method.
Not an expert on the M4, but have done a lot of tuning on other FX airguns. I expect you are way off a good tune. Depending on the pellet, you should have a desired range of velocities you want to reach. For instance, the folks shooting .177 13.4gr pellets (JSB, Air Arms, FX) on the 30yd Challange Thread here on AGN have found great accuracy with those pellets around 810-830 fps.
Th get to that point degas the rifle, turn the reg adjustment screw all the way closed, the back off 1 complete turn. Set the Power Wheel to something fairly low, like 10. Then set the quick tune to something like 2.0. Finally set the valve return spring adjuster to something like 3 three lines. Regas the rifle and bring the pressure up to about 89 bar. Then shoot a three or so shots to see what the velocity is. Try going up two clicks on the power wheel (a much bigger change than doing the adjustment on the QTS). If the velocity increased but not far enough then repeat. Keep repeating till you hit your target velocity, or the velocity increases very little, or you run out of clicks. In those cases you need to up the reg pressure. Keep repeating the process till you get 10-15 fps faster than your desired velocity. Now use the QTS to adjust in small increments till you are good. The close down the valve return spring adjuster until you notice the speed dropping. Open back up a bit.
That should get you to a spot where you can shoot groups or punch holes in targets like the 30yd Challange to check your accuracy. You may need to try several different velocities to find the one that gives you the most repeatable good results.
Cheers,
Greg
Here is a video from a Danish Guy who shoots .177 slugs out of an M3. He has a bunch of videos, but this one is on his tuning method.
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