I know it is common to have a little bit of bullet jacket scoring as the bullet is pushed past the feed ramps in the barrel extension. Most uppers I’ve seen exhibit this effect on bullets.
Question for the pros: how deep of a score or groove in the jacket is too deep?
Further, do these small marks or grooves on the bullet jacket have any substantive effect on accuracy inside 200 yards?
Sent from my SPH-D710 using Tapatalk
It shouldn’t be any worse than this. Just a little scratch. As far as accuracy being affected I wouldn’t think so. Especially at 200yds maybe at 600. This is a 62gr. Tsx . Then again my post count is low so I’m just an idiot.
I’m not the expert that some are but unless it’s really substantial it should not have to much of a effect 10 meters out to 200. I’ve shot so really chewed up ammo out of M-16a2’s without being dispersed outside e type silhouette. I’ve even cut tips off exposing the steel cores ( not recommended) but to prove a point zeroing M-16a2’s with some soldiers complaining about how crappy Mil. Spec ammo is.(90s) The rounds would still group under 1 in. on 25 meter zero range. I think that the engagement with rifling and base of the bullet has more effect than the point for the first few hundred meters with 64 grn. and lighter. Higher grn. bullets in 5.56 I have no experience.
I’ve not had a need for heavier bullets in 5.56 yet.
I think it’s fair to say that deep scratches are not helping accuracy and feeding.
IMO, sharp feedramp edges should be smoothed out to promote overal well being of man and machine.
I agree. I always useaside jewelers rouge and/or small round file to break the edges of the feed ramps of a barrel before i install it.
I have a friend who had a completed upper from a reputable manufacturer (they use two consonants for their logo). Gun shoots and functions 100%. But on our last range trip, i noticed that a round he pulled out of the chamber and it had some pretty deep scores in the jacket. Its still a low round count upper, but it also shoots fine.
I didn’t say anything to him, but i still wanted to poll the collective.
Sent from my SPH-D710 using Tapatalk
They don’t get scored on the way into the chamber, they get scored on the way out. If you fire the round, it never gets these scratches in it. The angle the extractor pulls the case out of the chamber drags the bullet along the sharp edge of the inside of the barrel extension lugs/ feed ramps. Normally you would fire any round that is chambered, so it isn’t an issue.
Also, don’t forget that on any gun with a rifled barrel, the bullet diameter is actually larger than the bore diameter. The rifling cuts grooves into the bullet on its way out of the barrel.
This is a non issue.
This.
Pull your charging handle back slowly and observe the round as it is extracted…You’ll see the round make contact with the extension lugs…
The bullet shouldn’t be touching the rifling in a 5.56 chamber.
^^ That’s not what Hookuleez is saying.
There isn’t any rifling in the chamber. It does get pressed into the rifling in the bore when it is fired though.
I thought the scoring was from the square notch in the back edge of the feed ramps. I could be wrong.
I’ll do a test once i get off shift and will advise the outcome.
I’ll put a dot with a Sharpie onto the top of the case while it is loaded into the magazine. I’ll then slowly feed it into the chamber and slowly eject it (noting the position of the dot during the process). I’ll report back.
The scoring certainly could be from the ejector and extractor dragging the case against the ejection port side of the barrel extension. I’ll report back.
Sent from my SPH-D710 using Tapatalk
I stand corrected. the last sentence of the 2nd paragraph threw me.
Looking forward to your results Buford! I just did a quick test myself and find that the bullet gets scored both on chambering and extraction.
My testing method was this.
The marks are the same shape, at least on my particular setup.
Hookuleez is right in my case. I conducted my experiment on my upper (which leaves some very slight scratches that are even more faint than the above picture) and the scratches are actually engraving on the bullet as it is dragged against the ejection-port-side of the barrel extension upon EXTRACTION.
Granted, I have already polished my feed ramps (as I do on every barrel I install), so any marks that may be left by the feedramps are simply non-existent.
And we learn something new every day…
Ah ha! Nice update Buford, I guess I should polish my feed ramps…
I should mention my feed marks were slightly less marring, a smoother line, whereas my ejection marks looked exactly like talywhacker’s picture above, with a little bit of chatter
Yeah, I don’t see any feed marks on my upper…only extraction marks. This was after feeding and extracting 12 rounds. 6 fast and 6 slow.
Obviously, the extraction marks will not affect a round that is fired.