View Full Version : Noob Question about chambered ammo
I was wondering if this is a common problem, or if it's just my rifle?
When I clear a chambered round, the bullet tip is somewhat deformed. It happens with all types of ammo. FMJ, Hollow Points, and the TAP I keep in it bedside. Is this a problem? Is there something wrong with my rifle? Is that ammo still reliable?
I try not to shoot the TAP because of the expense, but the target ammo seems to function fine.
I'm sorry if this is something I missed in my search. Thanks for your help.
pretty common, the bullet hits the feed ramps and gets a little dinged up. i'm not aware of any fix for this...
Thanks! I just didn't know if it was something malfunctioning. Im using TAP 75 with the plastic tip and the tip was pretty chewed up
I have no experience with either... but wouldn't that effect accuracy? Do you have M4 feed ramps on your upper, and rifle on your barrel?
http://www.ar15barrels.com/tech/feedramps2.jpg
...When I clear a chambered round, the bullet tip is somewhat deformed.
How deformed? Can you post a pic?
Wait until you look at the primer of the unfired cartridge that was chambered and extracted. You will have another question. ;)
Wait until you look at the primer of the unfired cartridge that was chambered and extracted. You will have another question. ;)
Hehe. :D Now we play the waiting game.
Wait until you look at the primer of the unfired cartridge that was chambered and extracted. You will have another question. ;)
You beat me to it. That freaks people out.
Hahaha am I in for a surprise?
I'm going to the range tomorrow. Ill make sure to post some pics ASAP.
Belmont31R
02-12-10, 23:55
Its normal to have some light scratching on a chambered round. You're rubbing relatively soft metal against steel. If you have gouges you might want to take a look at the feed ramps for burrs.
Its not a good idea to chamber rounds repeatedly. It weakens the primer potentially making it unreliable in the future. LEO have had problems with this using the same duty rounds every day, and chambering the same rounds over and over. The firing pin on the AR15 is free floating so the inertia of the BCG slamming forward sends the firing pin into the round. Its not enough to set it off obviously but enough to dent it. Do it enough and you start messing with the internal parts of how the primer fires. Another potential issue with this is bullet set back. You can loosen the grip the case has on the round, and the bullet can set back into the case causing a kaboom do to the increased pressure a set back bullet creates.
arizonaranchman
02-13-10, 11:15
Yes these guns tend to be a little rough on rounds when you chamber them. The case and bullet are scratched to some degree. If it's really bad you can lightly buff it by hand with a piece of emory paper and see if it smooths it out a bit.
Interesting thread that may have saved me some serious grief. I'm not a "subject matter expert", but I've been a student of shooting/reloading since Nixon was in office. :eek:
Maybe on soft points, but (IMO) if you have quality M4 receiver and barrel cuts you should not see any bullet tip deformation on FMJ or OTM bullets.
I happened to have 5 dummy rounds (no primer or powder) on my reloading bench this morning that were used in setting overall length, function testing, etc.; four 75gr Hornady OTMs plus one 55gr Hornady FMJ. They had already been chambered in my Noveske once with no deformation of the bullet tips (but they did show some minor scratching on the side of the bullet).
I again loaded them in a mag and ran through the Noveske, then in two other rifles with with the following results:
1) Noveske Complete 16" Upper, 1x7, & Noveske Lower: No bullet tip deformation.
2) Older Colt Lower and Colt Upper Receiver with a hint of M4 type receiver cuts & 14.5 BM barrel, 1x9: no bullet tip deformation.
3) Older Colt Lower #2 and Complete BM 20" Upper, 1x9 - no receiver cuts: This was a Pisser - no bullet tip deformation, but two of the 75gr bullets were driven back into the case, one catastrophically!
3a) BM 20" upper again with new dummys (3ea 75 & 55gr): Same results - 2 out of 3 of the 75 OTMs driven back into the case - one completely! No problems with the 55s. Moderate tos omewhat heavy scratches on the sides of the bullets (one chambering), no tip deformation. Fortunately I've never tried the 75gr reloads in this rifle!
1a) Noveske again with more new dummys: Loaded the same mag and chambered twice. No issues except one of the 75s actually ended up a few thou longer, (the others ended ~.0002 shorter). Light to moderate scratches on the sides (two chamberings); no tip deformation.
FWIW, the 20" BM Upper was already on the wish list to be replaced. No doubt about it now. BTW, this upper was purchased in 2000 as a replacement for the original Colt upper from ~1993.
ETA: My problems with setback (above) appear to be compounded by weak neck tension. The brass was IMI that was sized in a Dillon trimmer die (only) - no expander ball should mean more neck tension right?...Wrong! I just ran the same tests again with brass that was sized in an RCBS die and had no setback issues in the 20" BM upper. Still, this shows the M4 barrels/receivers perform better.
I've talked to officers that have had the primer problem. They pull out their rifle for a felony stop or other incident that warrants a long gun, and chamber a round. Since 90% of the time they don't have to shoot, they eject the round and top off the magazine with the previously chambered round. Doing this several times really dings up the primer and when they had to shoot, "click!. Fortunately, two guys were only going to deal with game when the misfire happened, and another that was in a OIS had additional back up to put the suspect down. Needless to say, all of them have a little box where they put once chambered rounds now.
Ok sorry for taking so long to post. I just got back from the range. I haven't had time to clean my rifle yet either so please overlook the mess.
Before
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01585.jpg
After
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01591.jpg
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01592.jpg
Before
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01587.jpg
After
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01588.jpg
Feed Ramps
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01597.jpg
Blankwaffe
02-13-10, 16:38
Might be my eye balls,but am I seeing rifling/leade marks on the ogive of the bullets in picture #2?
I don't see anything to be concerned about.
Might be my eye balls,but am I seeing rifling/leade marks on the ogive of the bullets in picture #2?
Layman's terms? Im not familiar with that.
lanceriley
02-13-10, 18:36
nothing to be concerned about.
John_Wayne777
02-13-10, 20:42
The feeding cycle of an AR is not exactly gentle. It's not uncommon in a lot of ARs to see that the rounds get scratched and scuffed up when they are forced out of the magazine, up the feed ramps, and into the chamber. The dimples in the primer are also normal, as the AR uses a free-float firing pin which smacks against the primer when you chamber a round.
...
When I clear a chambered round, the bullet tip is somewhat deformed...
How deformed? Can you post a pic?
[QUOTE=mnoe82;571722]...After
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01591.jpg
http://i175.photobucket.com/albums/w135/clevelandairsoft/DSC01592.jpg
You are GTG. I was concerned when you said that the actual tip was deformed.
Blankwaffe
02-13-10, 23:08
Layman's terms? Im not familiar with that.
What Im talking about is the lightly marked ring around the fat part of the bullet before it starts its taper to a point just in front of the cartridge case neck in the "after" pic.Also looks to me like there might be individual rifling marks spaced evenly on the bullet right in front of the ring I mention.Again could just be my eye balls and OCD since nobody else has commented on it.
But it caught my eye due to the fact I had this same indicator on some short leade Armalites years ago with some different brands of ammo.The primers will usually be very flat from the increased pressure if the bullet is forced into or touching the leade due to lack of jump.
A simple redneck test I used to determine the condition with different brands of loaded ammo was to remove the upper from the lower,remove the BCG and clean the chamber very well with a chamber brush and solvent.Patch dry,inspect for spotless clean,and then take one of the cartridges in question and drop it in the chamber,give it a light push with a finger tip on the case head to make sure the round is firmly seated in the chamber.Tip the muzzle up and if the round drops out of the chamber/receiver o.k.....if it sticks in the chamber,lightly tap the round out with your cleaning rod from the muzzle and check the bullet to see if its marked by the rifling on the ogive.If its marked it could lead to pressure issues.
Only issues I ever really had with the tight leade chambers was with the longer heavy bullets above 60gr....for the most part.Although some Q3131A and particularly Wolf 55gr. loaded to the long side,or that used bullets with a more foward placed ogive,typical of some soviet ball ammo...which would force the bullets ogive into the leade of the chamber and cause some pressure issues.
Otherwise I see nothing out of the ordinary as the others have stated.Apparently the weapon functions perfectly or you would have mentioned an issue.
Sorry if I caused any confusion.
Yall are great. Thanks for the info!
Looks like the mag too me... some of mine do that. Depending on how the feedlips are..
My 2 Cents :D
I think these scratches often result when manually extracting a previously chambered round. (clearing the chamber) Next time you clear a chambered round, pull back on the charging handle slowly and observe how the tip of the bullet makes contact with the barrel extension. It's probably only scarring the round on the way out. If this is the case everything should be fine, especially during normal cycling. I personally wouldn't do it with the same round repeatedly though. Hope this helps.
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