Yes yes I have read. I'm specifically asking about an fx impact m4. And I repeat from above must you tear down the entire barrel every time you want to rotate the barrel??
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I always wondered (while indexing my barrel) if it was possible to use a shooting bag and instead of doing all of that, would you be able to accomplish this by rotating your entire gun 90, 180, 270 degrees and using the crosshair axis to shoot at the same zero. I wonder if you could get a good idea of the barrel index by rotating the entire gun instead of removing/twisting the barrel.No, you do not need to tear down the shroud and liner in order to index. You do need to remove the shroud and the threaded tensioner (10mm open end wrench), mark the end of the muzzle with a sharpie, then shoot once all is back together.
Repeat, moving the sharpie mark position each time. You should be able to move it with your fingers but sometimes it will require a plier to do so. Just use something like a piece of leather to protect the liner sides from galling.
There is no need to remove the liner.
It's somewhat tedious but has a lot of value.
If you try this without reassembly, it won't work as there are different harmonics at play if the liner is not tensioned and shrouded.
mike
Maybe just rotate the targetI always wondered (while indexing my barrel) if it was possible to use a shooting bag and instead of doing all of that, would you be able to accomplish this by rotating your entire gun 90, 180, 270 degrees and using the crosshair axis to shoot at the same zero. I wonder if you could get a good idea of the barrel index by rotating the entire gun instead of removing/twisting the barrel.
It appears there is usually a black mark on the outside of the barrel that should be discernable once the barrel nut is removed. I would mark the position of the barrel nut so it can be retorqued to the same position each time. Mark the position of the black mark as if it were on a clock face for reference, if you can't see one make a black mark with a sharpie, say at 12 oclock high. Removal of the barrel is NOT necessary or recommended as getting the O-rings back in exact position is hit or miss at best. Make a large target with a single aimpoint and shoot 2 or 3 rounds to see where it groups and write the clock position that produced that group. REMOVE barrel nut, rotate the barrel in a one hour increment clockwise, retighten barrel nut then shoot another group. Your group will change in reference to the aimpoint and previous group, write the barrel position down and the group it produced for reference then repeat the process till you do a full rotation of the barrel, then observe the pattern that the barrel has produced, it will be roundish, or an oval in shape. The result you are looking for is to find the barrel position that produced the highest point in the circle or oval and then set that as the finished position you want to reassembly with. This will supposedly give you the best performance between point of aim and scope correction. If you need more detail reference indexing on the forums in a general internet search, there are much better descriptions of the process and it's advantages than mine, good luck and we'll try to answer any questions that we can.Can somebody here, please explain the process of indexing an fx impact. Can you see the red line on the liner without taking the whole damn thing apart? Just asking for a step by step, thank you to anyone who can answer this, in advance.
I just used a permanent marker to mark the outside of the barrel and carry the mark around the front of the barrel. It is visible from inside the lock nut viewing from the outside.Does anyone have a suggestion as to how to permanently mark the muzzle? After indexing years ago I scratched the index mark on the outside of the liner, but it’s not visible with the muzzle nut installed. I’ve used both paint and marker but they’re only good for one assembly. Since the liner rotates with muzzle nut installation I find it important to see the mark with the nut in place. Scratching the face of the muzzle would have to be a bad idea.
No sir, just rotate it a measurable amount and see how it changes point of impact. Find the highest possible point of impact and lock it down there.Yes yes I have read. I'm specifically asking about an fx impact m4. And I repeat from above must you tear down the entire barrel every time you want to rotate the barrel??
I have an m4 .35 800mm barrel and I don't think I can pull this off.... Maybe I'm wrong though. Thank you very much for the awesome response!It appears there is usually a black mark on the outside of the barrel that should be discernable once the barrel nut is removed. I would mark the position of the barrel nut so it can be retorqued to the same position each time. Mark the position of the black mark as if it were on a clock face for reference, if you can't see one make a black mark with a sharpie, say at 12 oclock high. Removal of the barrel is NOT necessary or recommended as getting the O-rings back in exact position is hit or miss at best. Make a large target with a single aimpoint and shoot 2 or 3 rounds to see where it groups and write the clock position that produced that group. REMOVE barrel nut, rotate the barrel in a one hour increment clockwise, retighten barrel nut then shoot another group. Your group will change in reference to the aimpoint and previous group, write the barrel position down and the group it produced for reference then repeat the process till you do a full rotation of the barrel, then observe the pattern that the barrel has produced, it will be roundish, or an oval in shape. The result you are looking for is to find the barrel position that produced the highest point in the circle or oval and then set that as the finished position you want to reassembly with. This will supposedly give you the best performance between point of aim and scope correction. If you need more detail reference indexing on the forums in a general internet search, there are much better descriptions of the process and it's advantages than mine, good luck and we'll try to answer any questions that we can.
I'm having an issue I believe because I have an 800mm m4 barrel.... The .35 is different I think. You couldn't supply me with some photos could you? Thank you for this wonderful response though!No, you do not need to tear down the shroud and liner in order to index. You do need to remove the shroud and the threaded tensioner (10mm open end wrench), mark the end of the muzzle with a sharpie, then shoot once all is back together.
Repeat, moving the sharpie mark position each time. You should be able to move it with your fingers but sometimes it will require a plier to do so. Just use something like a piece of leather to protect the liner sides from galling.
There is no need to remove the liner.
It's somewhat tedious but has a lot of value.
If you try this without reassembly, it won't work as there are different harmonics at play if the liner is not tensioned and shrouded.
mike
The M3 port is a separate part and does not rotate with the liner.But the port spins too unless I'm an idiot here....
I'm sorry for my ignorance here. I can't quite grasp the purpose of the slug. And how does it not get stuck in there!?Okay.
This works for me, perhaps it will for you too....
I use a slug of the correct caliber of my rifle. It should have a flat base, a slight dish base will also work though.
Simply scribe with an awl to make a visible mark, then push the nose of the slug into the muzzle so that it's snug and won't move.
Do your indexing leaving the slug in place until you have decided that you know where within the 'clocking' you want the top dead center.
Still leaving the slug in place, then tighten the barrel nut into place noting where that slug mark is to assure proper alignment.
Done!
This is what it looks like from the muzzle end. You can see the etched mark that aligns with the red sharpie mark used for that alignment.
mike
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