Rounds jammed in AR chamber

[rodsvet]

I have a brand new Chrome lined upper from a reputed company. I load my 5.56 to nato specs with RCBS small base die and check every round in an EGW checker. The first two rounds that I chambered jammed in the chamber and it a brass rod and alot of oil the get them out. Fearing the whole time the would discharge from being hit. I could not open the action to try to dislodge the BCG. I sent it in and they ran 10 rounds of Wolf junk through it and said it is within spec. Anyone have this happen to them? The chamber seems too tight to me and my ammo is within spec. I will buy some factory ammo and try that. ???? Running a finish reamer will of course ruin the chrome plating. ???

[cheese1566]

Are running a dry or oiled chamber?

Make sure your your chamber is absolutely dry.

[Boolit_Head]

Your OAL could be to long, try something shorter. Especially if it is a .223 or a .223 Wylde chamber. I have a tight chambered .223 Wylde barrel that will do that if the OAL is to long.

[Premod70]

I don't use the EGW tool but I would first remove the bolt of the rifle and do a drop test of my resized brass just to see if the brass is OK then seat a bullet and again do a drop test. If there is a bind compare your rounds against a factory round by measuring the neck, headspace and bullet interference, good luck.

[Boolit_Head]

On mine they appeared to seat fine when dropped in but when seated with force would jam. All it took was to seat the bullet a bit deeper to keep it from touching the leade.

[UKShootist]

Not semi autos but both of my Savage rifles, one .223 BVSS and one .308 F/TR will sometimes trap brass that is neck sized rather than full sized or new. Any case that gets trapped (I'm getting good at getting them out now) will readily fit a Wilson chamber gauge and I can't figure this out. It seems that the jam is caused by the case body not fitting the chamber taper, as I now test chamber empty sized cases prior to reloading to make sure I don't get a jam on the firing line. Taper jams are solid, think Morse taper on a lathe. I can imagine all too well the havoc it can cause in a semi auto. Not much help but no small amount of sympathy.

[Ballistics in Scotland]

It could be a tight chamber or it could be inadequate headspace. While a thin piece of tape or sheet metal on the case-head is an inadequate means of measuring headspace, it should be good enough to determine whether the latter is the case.

The chances are that your grievance is with the reputed company. In such a case there is no substitute for making a Cerrosafe cast and finding out how it compares with the SAAMI specifications for the cartridge.

http://www.saami.org/specifications_and_information/index.cfm

[gnostic]

I've had problems with my AR locking up with minimally (+.002) out of spec rounds. And, using the forward assist just adds to the problem by jamming them in tighter. I've never seen a gun go off when not locked in battery, but I'm still nervous about clearing a loaded round...

[LUCKYDAWG13]

On mine they appeared to seat fine when dropped in but when seated with force would jam. All it took was to seat the bullet a bit deeper to keep it from touching the leade.
this is what was going on with one i had that and just a new barrel needed to be broke in

[rodsvet]

I'm going to pick up a box of factory, pull the bullet and powder of one and close the bolt over it. If it jams like my small based brass, then I will ***** to the maker. If it doesn't, then my ***** will be to RCBS. It's funny though, the rounds drop freely in and out of the EGW round checker in all 7 holes. Maybe the chrome plating is a little too thick?? I will let you know what happens. (unless I blow my head off removing a stuck round). Rod

[lefty o]

if they ran wolf thru it, it should run any half decent brass cased ammo. id start looking at OAL, and trim length.

[country gent]

I woukld also recomend a good chamber cleaning both brush and then patches, see what comes out. Some chrome jobs have rough spots or "flash" in them that can cause problems. Dependingon the cut chamber and also the thickness of the chrome deposited there could be a problem. A chamber cast would show it, but on an AR the easiest way to do the cast is to remove the barrel. trying to pour thru the ejection port or trickle in thru the upper is really hard and almost imposible to keep the cerrosafe hot enough to make a good cast. The other way to go is to Ink one of the cartridges with a magic marker case shoulder neck and bullet. chamber carefully and remove it Look for "bright" marks to show where its hitting and binding. Even with small based dies headspace needs to be checked also. a stack up between die and shell holder could leave shouklder a coupe thousandths to long. You dont state how far closed the bolt is going, Is it close to rotating closed or open more so. Were the dies purchased new or used? I have a set of 308 dies that will still size to factory /military chambers, but in my tight chambered match rifles have an issue. These have sized close to 40,000 rounds over the years.

[leadman]

Using the small base dies will cause the case to lengthen so make sure you are contacting the shell holder firmly. Then check the case length and trim if needed. If it does not cure the sticking problem rent a set of headspace gauges from 4D or Elk Ridge reamer rentals. About $10 to $15 to check the chamber. If the Go gauge does not let the bolt close then call the seller and tell them to fix it.
As mentioned make sure the chamber is clean and your overall cartridge length is good.

[wyrmzr]

I've found that, with my AR, my cases need to be 1.755 or under in length, and I need to use a small base die. If I don't, I'll spend more time getting cases out of the chamber than I do shooting.
Strangely (or maybe not), my bolt action Savage Axis will handle cases up to 1.770 without the small base die.
My guess is that when my AR barrel was made, it was one of the first off the line after they re-tooled. So, it's simply got tighter tolerances than the Axis. One thing to remember is that, if you take 6 of the same barrels from the same manufacturer off the shelf and mic the chambers, you may find you've got 6 barrels that measure differently. This doesn't apply to some manufacturers, but that's because they have very tight QC, and ensure that every barrel comes off the line with the exact same dimensions. Naturally, those barrels tend to run in the $600 and up range.

[rodsvet]

My brass is trimmed to 1.745, my OAL is 2.250. The outside dimension of the loaded rounds is .251 and the bullet measures .2235 just in front of the case mouth. The case rim is .3775 and the base of the case measures .3755. They drop in and out of an EGW .556 case gauge. The barreled upper will be back on Tuesday and I will super clean the chamber and bore. I will load up and mic a few dummy rounds and see what happens when I chamber a case. I've had in the past the shoulder collapse slightly when too aggressive a crimp was used and had a round not fully chamber (maybe 1 in 1,000). Since using the EGW chamber checker, I catch any out of shape rounds even that look good to the naked eye. I'll let you guys know what happens. Rod

[RKJ]

I've had that same problem and after getting some info from different forums, I seated the shoulder back and trimmed my brass to 1.750. It worked. A huge PITA but necessary. Good Luck.

[M-Tecs]

These work very well for setting the proper shoulder set back.

http://www.hornady.com/store/Headspace-Gauge-Kits/

http://www.sinclairintl.com/reloading-equipment/measuring-tools/case-gauges-headspace-tools/rcbs-precision-mic-cartridge-headspace-tool-prod33476.aspx

[JonB_in_Glencoe]

I had a very similar problem

http://castboolits.gunloads.com/showthread.php?308387-AR-frustration

[w5pv]

I had to shorten the oal from 1.160 to 1.150 to end a similar problem in a Colt 45.The rounds would hit the forcing cone and cause the cylinder not to rotate correctly the brass would drag,this was in a Ruger 45 colt/45acp convertible.

[popper]

Get a good chamber brush. Drop sized / unloaded brass into the chamber first - set your die so the shoulder is pushed back many thou.. Gradually set closer to the gauge 'normal'. Stop when the bolt closes easily pushing on the BCG. I'd also trim those cases back a good ways to make sure neck isn't pinching. If factory works OK, check dimensional differences vs your sized/expanded brass. Be sure to scrap any brass with the shoulder pushed back too far - brass is cheap. Gauges are good for checking shoulder position, not much else. It's a good idea to check the first few sized to insure nothing changed from the last die run.
Edit: seems to be a frequent question asked, no sticky on it. Sooo. With all the new AR type reloaders (yes it is a PITA to get them out) but works for bolt rifles also.
1) get some common factory and shoot it. if it goes bang, chamber is reasonable. Else -- RMA with ammo SKU# and return it.
2) get a chamber gauge - any kind will check shoulder position. Use who ever's sizing die. SB, X, standard, I don't care.
3) trim the neck back 10 thou or so.
4) set die to push the shoulder back (shorter, ~10 thou.) on sized brass. You may need to remove some metal from the die or shell holder to do this.
5) manually load the brass & close the bolt - don't force it - use a brass rod if it doesn't un-chamber easily.
6) set shoulder out further & repeat. When the bolt closes easily, you're there. Do a couple more just for fun. Remember you have to push the extractor over the rim so a little force is needed.
7) re-check with case gauge for trim length. Case dia. fit in your chamber vs a Sheridan or other gauge is 'luck of the draw'. Not knocking them, they aren't cut same as your chamber.
8 if this doesn't work, use the short ones, color the case to see where it hangs. Over-crimp can buckle or bulge the shoulder/neck too.

[rodsvet]

Well I got the upper back today and they said it was in perfect shape. I cleaned the chamber and barrel and then chambered a round. Stuck tight! After much work, I freed the stuck case. I then took 20 round that do drop into my EGW round gauge and pulled the bullets. I ran them through a cheap Lee die and reinstalled the bullets. All 20 chambered and un chambered easily. So it's the junk RCBS die. I don't think I will ever buy another thing they make. I bet that they are having this garbage made in China or Mexico. Now I can get out and pull 2,000 rounds, run them through a clearly superior product and get back to shooting. Stay away from their small based **** dies!!

[M-Tecs]

If you want to send it to me I can check it for you. I have an optical comparator so I can inspect it fully.

I would also recommend figuring out what the issue is before pulling 2,000 rounds. They may be fixable without pulling 2,000 rounds.

[rodsvet]

M-Tecs, thank you for your offer. I'm going to pull 100 resize with the Lee, reload and see if they are consistent. The funny thing is that they drop in and out of my EGW case checker and mic out to spec. I have 3 other AR's and haven't checked them against the 2,000 rounds. Three of the barrels are from DS Arms and they pay shipping both ways whenever I ask for an adjustment. They say the barrel is in spec. Their test showed no fault with the chamber. I may be giving you a PM when work slow down and arrange something. Thanks again, Rod

[rodsvet]

RCBS responded to my email and said to cam over the die 1/4 turn. The rounds do chamber and eject when doing this. It REALLY seems to strain my 45 year old Rock Chucker. Do any of you machinists out there think it would be possible to machine a few thousandths off the die base so camming over would not be needed? Say maybe .0010 and you could then start at 2 or 3 and increase it till it set back the shoulder just enough? Or maybe some one makes a shell holder that is .0010 thinner? Rod

[GONRA]

GONRA's not sure if this is appropriate,
but its always safest to hava Really Robust Press to get uniform headspace, etc.

Use STP Oil Treatment or TriFlow Synthetric Grease for a Case Sizing Lube.

RCBS small base dies have always verked perfectly for me.

[rodsvet]

The Rock Chucker is a fairly robust press. I have been told that the Lee classic cast is even stronger and some of the guys swag bullets with them. I just feel that if the die were a little shorter that camming over would not be needed.

[M-Tecs]

You can get them as individuals http://www.redding-reloading.com/index.php?option=com_content&view=article&id=35:competition-shellholder-sets

Take your expanding button out and try it. You could be pulling the shoulder out with the button. Case mic's are invaluable for this.

[jcren]

The Rock Chucker is a fairly robust press. I have been told that the Lee classic cast is even stronger and some of the guys swag bullets with them. I just feel that if the die were a little shorter that camming over would not be needed.

Had this problem with a Rossi 243 with a short chamber. Instead of changing your die, knock a few thousandth off the top of the shell holder. Will allow you to push the case further in and can be done with a DA and patience.

[rodsvet]

I deprime with a Lee deprime only die. Then when I size and trim the case mouth is tight enough that I don't need a crimp. I've had the shoulders widen enough to hamper chambering even though they look good to the naked eye. The shell holder idea or buying the thinner shell holders seems like the way to go instead of machining the die. Thanks for the input! Rod

[rodsvet]

Actually the Redding shell holders I think hold the case farther away from the die. I want to go in the other direction. So I will try sanding down a shell holder 10 thousandths and hope it doesn't leave the case in the die. Although without the expander in the die pounding the case out (carefully with PB Blaster) shouldn't be too difficult. Thanks again for the input, Rod

[lefty o]

camming over will not hurt your press, they are made to do it.

[M-Tecs]

Actually the Redding shell holders I think hold the case farther away from the die. I want to go in the other direction. So I will try sanding down a shell holder 10 thousandths and hope it doesn't leave the case in the die. Although without the expander in the die pounding the case out (carefully with PB Blaster) shouldn't be too difficult. Thanks again for the input, Rod

I see that. Sorry for the bad info. At one time someone made minus shell holders also. I thought it was Redding but they are not cataloged.

[rodsvet]

M-Tecs, Your info is always appreciated! Lefty, I just feels weird to stress the press. You must be correct because the RCBS tech guy said they recommend a 1/4 turn with their dies and presses. You'd think they would just shorten the die a few thousandths and let the reloader make his own adjustments. P.S. The Lee standard .223 die sets the shoulder back when you do the same with it. Rod

[cheese1566]

RCBS responded to my email and said to cam over the die 1/4 turn. The rounds do chamber and eject when doing this. It REALLY seems to strain my 45 year old Rock Chucker. Do any of you machinists out there think it would be possible to machine a few thousandths off the die base so camming over would not be needed? Say maybe .0010 and you could then start at 2 or 3 and increase it till it set back the shoulder just enough? Or maybe some one makes a shell holder that is .0010 thinner? Rod

so, you weren't camming over?

So then, you failed at RCBS die instructions (paper manuals, instruction sheets, and most reloading books...) by not properly setting the die and not camming over to take play out of the linkage system of the press.

So then you blame the die maker?

on some guns, you can adjust the die up to change sizing and headspace. Auto loaders, and those guns with tight chambers, may really need to be full length sized every time. this is done by proper adjustment instructed by the manufacturers.

PS, if one does modify a die or shellholder, please engrave it on the tool in case it ever falls into another loaders possession in the future.

[rodsvet]

I was camming over 1/8 of a turn. If I failed at anything it was reading your nonsensical post. Get out of the Black Hills and learn some manners. Oh, and I'm Glad you can read instructions, but am surprised by it.

[Boolit_Head]

Wow that is how you treat someone who was helping you? Figures for a Cali boy.

He was just saying what everyone else was thinking.

[rodsvet]

Boolithead, if you think he was trying to help then you read it wrong. He started out with an insult and then gave his advice which had already been given by others.

[Boolit_Head]

AND another one hits the ignore filter.

[cheese1566]

Well, I certainly hoped that made you feel better.:takinWiz: I can see why some leave here after being treated as such when one gives help. I hope you did notice that I was one of first to respond to your issue.

by the way, you haven't bashed your EGW case gauge....I hope you get rid of it and never buy another like your RCBS products...I wouldn't trust it if it is letting too big of rounds pass inspection then get hanged up in your chamber...it should be in spec like your chamber and should have caught those improperly sized cases.


Also, I love where I live and would never leave South Dakota. We don't treat others here like that.

[rodsvet]

Cheese, If I came down on you too hard, I apologize. The Black Hills are beautiful and you are fortunate to live there. I was trying to use the process of elimination to get to the root of the problem. I've had bad RCBS dies over the past 45 years. I've had badly machined products from Dillon and Lyman and others through the years. I suspected the chamber first as these rounds chamber in the EGW and two other AR's. When they Fit the EGW that was my first thought. I see no earthly reason to cam over when a shorter die would stress the press less. Were it a carbide die it would break the ring. You were the first to offer advice and I appreciated it. I'll try to get a little thicker skin from now on. Rod

[triggerhappy243]

I compared your loaded round to mine. your neck dia. is 3 thou. larger than mine. I use winchester brass.


My brass is trimmed to 1.745, my OAL is 2.250. The outside dimension of the loaded rounds is .251 and the bullet measures .2235 just in front of the case mouth. The case rim is .3775 and the base of the case measures .3755. They drop in and out of an EGW .556 case gauge. The barreled upper will be back on Tuesday and I will super clean the chamber and bore. I will load up and mic a few dummy rounds and see what happens when I chamber a case. I've had in the past the shoulder collapse slightly when too aggressive a crimp was used and had a round not fully chamber (maybe 1 in 1,000). Since using the EGW chamber checker, I catch any out of shape rounds even that look good to the naked eye. I'll let you guys know what happens. Rod

[rodsvet]

I just went out and randomly mic'd 5 loaded rounds neck diameter and they were all .246-.248. The .251 was where the crimp was applied and those rounds were too short to accept the lee factory crimp die correctly. They were 1.740. My Brass is mostly once fired FBI brass. Much of it fired full auto 12 inch barrels. Rod

[triggerhappy243]

try loads with no crimp. I never crimp.... no need to crimp in my setup. Your crimp may be putting a slight bulge in the neck, and that is where it is jambing.

[rodsvet]

With the short brass (1.740) the Lee factory crimp die was just barely catching the case mouth and causing a slight drag in the chamber. It's the shoulder setback that appears to be the problem. Rod

[triggerhappy243]

AH....... Wonders never siece.

[joelpend]

Exactly. I work some as a RSO at a local indoor range and I see this all the time. Real easy for improper crimp to swell the case just behind the shoulder. You can see it upon close inspection normally.


try loads with no crimp. I never crimp.... no need to crimp in my setup. Your crimp may be putting a slight bulge in the neck, and that is where it is jambing.