Bolt won't close!

[ultratec1]

Ok I have been loading .223 and 5.56 for some time now and have not had this problem but I can't figure out what is going on.

Here is the dilemma... I am reloading 60gr vmax for a CZ527 varmint. I am using all once fired Hornady brass, which has all be resized with my RCBS dies (full length). I set the OAL under the max ( can't recall exact length) and all of the brass is under the max for trim length. So looking at it from my angle....everything is good to go. However I am sooo wrong. I took the first test loads out yesterday and the first 4 rounds loaded and shot great. The 5th round the bolt would not close and lock. I ejected it and tried a different round which closed and shot fine. Well the next 2 rounds did the, "no close" with the bolt. I ejected them and examined the rounds. I noticed that the bullets had marks on them from the rifling.

The thing is all the rounds were very close to exact same as far as OAL when loaded. I am using the RCBS competition die.

So to recap, all brass has been resized, under trim length, and rounds measured roughly the same OAL. Just certain rounds would not allow the bolt to close. I even came home and shortened the OAL on the rounds that wouldn't close and after I did it, the problem was still there.

Any ideas what is going on


On a side note that may help, when I was loading the rounds I noticed that some of them seated rough.

 

[rcmodel]

Are you crimping, either on purpose, or by accident?
It's easy to buckle the shoulder with the crimp section of the seating die if it is adjusted too low.
And you can't see it.
They just won't chamber.

Anyway.
Completely Color some of the rounds with a magic marker, then try to chamber them again.

Where the marker rubs off is what is tight where.

rc

 

[119er]

Somehow improperly or undersized cases or you may have different weight or ogive profile bullets in your box. That's all I can think of off the top of my head. Do you have a case gauge or bump gauges to check the problem rounds? Marks on some of the bullets and not others leads me to believe that mixed bullets is most likely your problem.

ETA: by undersized I mean not sized enough!

 

[ultratec1]

rcmodel- The die is the RCBS comp die and does put a crimp on the die (at least not that I am aware of)

119er- the bullets came directly out of a new, opened by me right there, box of Hornady V-max. I am wondering if for some reason they are, like you stated, not resized completely or something went wacky while I was resizing and they did not get fully resized.


I will try what you guys suggested by marking the trouble cases and see where it is hitting. Thanks for the ideas

 

[kimbernut]

Bump

Try taking a couple apart and try the case alone in the chamber. I'm betting the bolt won't close on the empty case. Wax or lube the case and Bump the shoulder back just a bit. 1/8 turn on the size die so that the press cams over a little harder. I think you will find the bolt will close on it now. If not bump it another 1/8 turn but one time normally works for me. I've had this trouble with 3 rifles and called RCBS on the first one. This was their advise and it has worked for me each time.

 

[gamestalker]

You may have short stroked the press when resizing on some of them, or like RC said you might have collapsed a few shoulders.

I use RCBS comp dies also, but I still believe it is possible to make hard contact on the case mouth with them, thus distorting the shoulders, even if they don't crimp.

GS

 

[higgite]

A couple of questions. You said all the rounds, good and bad, were "very close" to the same OAL, but later you said they were "roughly the same". Can you quantify that? If your nominal OAL puts the bullets close to the lands, "roughly the same" can make a difference in whether they hit the lands or not.

What rcmodel and kimbernut said about checking the cases makes sense, but it seems that if you saw rifling marks on the bullets, the OAL for those cartridges had to be too long. But, if that's the culprit, it's puzzling that re-seating the bullets deeper didn't fixed the problem. Please don't take offense at my asking, but are you sure your calipers were zeroed when you measured OAL?

You also mentioned that you resized V-max bullets. Did you really?

 

[Andrew Leigh]

You stated that on rounds that would not chamber that you could see rifling marks on the bullets. You are seating into the lands and this is why you cannot chamber.

I would suggest that you have not measured you COL accurately and ogive differences are causing some to seat deeper than others. When using the bullet in case method to establish the COL it is not uncommon for the ogive to grip on the lands and it pulls the bullet out of the case neck. This leads one to believe that your COL is longer than what it is and you end up loading into the land as a results.

If you then took them home an re-seated reducing the COL and they still did not chamber then you have another problem compounding matters and that is that you have stretched the necks during sizing. Insufficient lubricant on the inside of the case neck causes excessive friction, when you pass the case neck back over the expanding mandrill then this friction result in the neck being stretched out and away form the base of the case.

Buy a slightly over calibre soft nylon brush and use this to lube your case necks on the inside. The slight oversize is to enable you to deposit a lick of lube behind the inside of the shoulder.

To check, take a new case and hold it next to a problem case, you should be able to see if there are any variance in the angle of the shoulder. If you are pulling the case shoulder out then the angle will be more obtuse.

 

[mxjunky78]

Sounds to me like there's a slight buckling at the case neck and shoulder joint. I've had this happen before and didn't notice what it was until after busting out the calipers and micrometer.

 

[rsrocket1]

Take one of your "won't close the bolt" cartridges, color it completely with a magic marker and try chambering it again. The ink will show rub marks where it is preventing the bolt from closing. From there you can perform your fix(es).

 

[Reloadron]

I ejected them and examined the rounds. I noticed that the bullets had marks on them from the rifling.

That being the case I have to agree with Andrew (Post #8) in that the loaded cartridges are too long.

Ron

 

[MEHavey]

While the OAL may be engaging the rifling, that isn't why the bolt won't close. (Bolt camming leverage will seat any bullet almost as a passing afterthought.)

Given that the OP says no crimp -- double check that -- look to the shoulder/sizing dimension as the culprit.
(Do you have a Hornady comparator?)

 

[fguffey]

Any ideas what is going on

Yes, I do not assume the case has been full length sized and returned to minimum length. I know what minimum length sized is and I know when the case dimensions match a factory round. I have comparators, I do not have a head space gage for everything because between the case and chamber I only have one head space dimension, it is in the chamber.

Any ideas what is going on

If I am having trouble sizing a case I want to know how much resistance the case has to resizing, it is more than nice to know when trying to determine if my press has the ability to overcome the case's resistance to sizing.

My presses and dies have threads, threads make my dies adjustable. I can increase the presses ability to overcome resistance to sizing or I can back the die off the shell holder because it is not necessary when sizing a case to a chamber.

That being the case I have to agree with Andrew (Post #8) in that the loaded cartridges are too long.

And when the bolt was opened opowder spilled out then the bullet had to be driven out with a dowel.

On a side note that may help, when I was loading the rounds I noticed that some of them seated rough.

To crush the case at the shoulder/case body juncture is effortless, happens when a reloader decides to crimp bottle neck cases. I have presses that will crush a case with the weight of the handle.

F. Guffey

 

[gamestalker]

I agree totally with what MEHavey stated.

Unless that bullet is seated really, really long, the bolt will jam it into the lands, although you'll feel a lot of resistance, it will close. I do a good deal of range loading in which I jam them, a style of loading I've been using for many years, and a good deal of BR shooters do this as well.

I still contend that it has something to do with the brass. Either a resizing issue, or something to do with the seating die adjustment distorting the brass.

GS