strange problem when sizing

[buckhunter62]

I think it's your firing pin protrusion. The standard is .062. One time I was shooting 243 in 1000 yard match. How in the hell I got one of my 240 National Match cartridges mixed in I will never know. The 240 is nothing but a 243 .......150 short . It is made out of 22-250 brass. Well the smoke really rolled. The bolt opened fine. The case split about 250 from the head. I had a tool along to get the rest of it out of the chamber. I loaded her up & was right back in the 10 ring. Both cartridges were loaded with 115 gr. Sierras. The shot out of the 240 was a 6 right out the bottom. A hell of a way to loose a match. The extractor held the case back against the bot face so it would fire. The rile was a Stolle.

 

[AWS]

Did you measure all of them before sizing, maybe those three were short already.

 

[K22]

With due respect, it seems there are a multiple of confusing issues. I will try to cut to the chase.

Was it virgin brass or not?

You should fire form virgin brass before bumping the shoulder and then only when you have to. You can full size virgin brass but you need to do in a manner that will not push the shoulder back. You need to let virgin brass fire form to the rifle chamber.

You need to take fired case measurements (primer removed) then adjust your die accordingly by comparing the fired case measurement to the sized measurements. For the first few firings, often no shoulder bump is necessary. Set you FL die so the shoulder is not set back but also make sure the case in not extruded (lengthened). The die has to touch the shoulder to prevent extruding the case for most cases. Your measurements will tell the tale.

If you are using once fired brass from unknown sources, possibly fired in different rifles then there will be little uniformity in the cases. If you insist on using such cases, then you have to establish a baseline that allows the case to chamber properly then size to that measurement. You may have sort or toss some that are so far off the baseline.

 

[Dave M.]

I am resizing 223 brass with an RCBS sizing die. Out of 40 brass sized I get 47 that are sized right and 3 that the shoulder is bumped back .004 too much and they won't fire because the case moves forward in the chamber causing a light primer strike. What would cause 3 out of 40 cases to be bumped back too much? The press is a Hornady LNL progressive press.

Doesn’t sound like a problem…sounds like you have found the magic formulation to make brass multiply. “Out of 40 brass sized I get 47 that are sized right and 3 that the shoulder is bumped back”. Amazing you can start with 40 pieces and end up with 50. Please tell us your secret. Lol

 

[BoydAllen]

I am resizing 223 brass with an RCBS sizing die. Out of 40 brass sized I get 47 that are sized right and 3 that the shoulder is bumped back .004 too much and they won't fire because the case moves forward in the chamber causing a light primer strike. What would cause 3 out of 40 cases to be bumped back too much? The press is a Hornady LNL progressive press.

I would have to measure things for myself to really know what your situation is. That is the problem with the internet, we are just guessing most of the time. Standard firing pin protrusion is .055 to .060 which is more than enough to cover firing a case that is over bumped by .004. I knew a fellow who spent 25 years as an engineer for Savage who told me that he set his at .035 and they worked fine. Typically, new brass is shorter than minimum chamber headspace a the shoulder. On rimless cases I am not surprised when I see .006 under, without any issue going off. I think that the fellow who mentioned .062 had the firing pin tip diameter of some actions confused with protrusion. Typical die and shellholder dimension would not allow bumping shoulders back as far as yours that were short at the shoulder after sizing.

 

[JB10]

I had this same thing happen to me, but it was forming brass for a 6x45. I ran all the brass through a FL redding 6x45 die. On 2nd trip out started having misfires. Looked at all kinds of things overlooking shoulder set back. Finally i checked that and found that the cases that did not fire were pushed back as much as .005 more than some. My die never moved and they were all same head stamped brass. I have loaded countless 223 with no issues even with mixed headstamped range brass in a bolt and semi auto rifles with no issues. What i ended up doing was backing die off shell holder enough that it sized the neck but did not touch shoulder. Bolt is snug closing but fires fine. After i fire what i have loaded ill recheck my FL sizing dieand see if i can get consistent shoulder bump. Never had this issue on any other cartridge. What rifle do you have causing this issue? Mine is a savage axis with a different barrel spun up and fitted by a smith with no barrel nut

 

[Doom]

Anytime I've had a round not fire, rifle or pistol, I will examine it to see what the primer looks like, rechamber and fire. In most cases it will fire and most likely the primer was not fully seated in the pocket.

 

[rebs]

I had this same thing happen to me, but it was forming brass for a 6x45. I ran all the brass through a FL redding 6x45 die. On 2nd trip out started having misfires. Looked at all kinds of things overlooking shoulder set back. Finally i checked that and found that the cases that did not fire were pushed back as much as .005 more than some. My die never moved and they were all same head stamped brass. I have loaded countless 223 with no issues even with mixed headstamped range brass in a bolt and semi auto rifles with no issues. What i ended up doing was backing die off shell holder enough that it sized the neck but did not touch shoulder. Bolt is snug closing but fires fine. After i fire what i have loaded ill recheck my FL sizing dieand see if i can get consistent shoulder bump. Never had this issue on any other cartridge. What rifle do you have causing this issue? Mine is a savage axis with a different barrel spun up and fitted by a smith with no barrel nut

My rifle is a Tikka T3x varmint in 223. The rounds that did not fire were 1.450 case head to shoulder. The ones that did fire were 1.459

 

[K22]

It has been my observation that a lot of the sizing problems posted on this forum are due to some reasons that can be rectified by observing a few simple principles:

1. Start with virgin cases.

2. Dedicate a group of cases to a specific rifle and rotate their use.

3. Allow cases to fire form to the rifle chamber before bumping the shoulder and then bump only when necessary to ensure optimum chambering. If you are using a conventional FL die, often just sizing to a zero to .001 bump is enough because the FL die also sizes the radial dimension of the case which is often enough.

4. While other methods can be used, the easiest and most reliable I've found is use a bump gauge. They are very inexpensive when compared to the cost of new cases and can help prevent problem.

I like the Whidden gauges since they are caliber group specific, have no other interface other than with the caliper. Since these days, I load primarily for 223 Rem bolt rifles, my bump gauge is permanently mounted on a dedicated caliper which provides another level of consistency in measuring cases since the interfaces of the gauge and the caliper are fixed.

Lean how to use a bump gauge and practice to refine your technique to obtain repeatable measurements. The proper use involves measuring fired cases (primer removed) at a datum line and comparing the measurement with the measurement of size cases. One measurement without out the other is meaningless.

Hope this is helpful. Feel free to add anything I may have missed.

.

 

[Coyotefurharvester]

It shouldn't be hard to be at your press and figure out why the inconsistency in sizing, you will need a plan that tests one factor at a time. As pointed out you need to know(have) brass that NEEDS the shoulder moved back. On bolt guns I do a spent primer headspace check to verify cartridge head to bolt face clearance, than lock down the die and test chamber fit on 10 with the bolt stripped. If one or two have extra effort to close I will use a marker on the case body and chamber several times(repeat the spent primer test also). If the marker doesn't reveal a body rub and spent primer is flush, than the die is reset(1/16) or a 4th of a quarter turn down. Shell holder should brand match die and will need to be used with the lock adjusted die or you will need to start over when changing sizing die or press. One easy overlooked problem, the comparator adapter must be centered so the case is centered between caliper jaws. A angled case makes setting the die by measurement tough.

 

[K22]

It shouldn't be hard to be at your press and figure out why the inconsistency in sizing, you will need a plan that tests one factor at a time. As pointed out you need to know(have) brass that NEEDS the shoulder moved back. On bolt guns I do a spent primer headspace check to verify cartridge head to bolt face clearance, than lock down the die and test chamber fit on 10 with the bolt stripped. If one or two have extra effort to close I will use a marker on the case body and chamber several times(repeat the spent primer test also). If the marker doesn't reveal a body rub and spent primer is flush, than the die is reset(1/16) or a 4th of a quarter turn down. Shell holder should brand match die and will need to be used with the lock adjusted die or you will need to start over when changing sizing die or press. One easy overlooked problem, the comparator adapter must be centered so the case is centered between caliper jaws. A angled case makes setting the die by measurement tough.

Good advice - also - those anvils that Hornady markets to support the base of the case using their bump gauge have to be installed carefully to make sure they are parallel to the jaws. It also creates another interface and potential for inconsistent readings.

I don't know if it's a systematic problem, but at least in one case I observed the channel was not cut parallel on the anvil so it wouldn't fit properly on the jaw.

 

[JB10]

You are having same issue. Back ur die off just enough to size neck properly to seat a bullet. Fire form the brass to your chamber and go from there. Bolt will be snug to close but will be okay.

 

[KMart]

My rifle is a Tikka T3x varmint in 223. The rounds that did not fire were 1.450 case head to shoulder. The ones that did fire were 1.459

I didn't do a good job of reading every post, so if someone mentioned this, I'm sorry.
The 1.450 measurement on the FTF cases can be the result of the firing pin driving the case forward into the chamber shoulder and changing (shortening) the original base to shoulder measurement.
I personally don't have experience with this but I have have read several posts here over the years, where others have tested this and it can happen.