Shoulder bump issues

[nathwald]

Hi guys

New to reloading and I have run into a problem when trying to get .002" shoulder bump in my RCBS FL die. Equipment used is the RCBS rebel press with their full length sizing die, reloading for a CZ 527 .223. Using Hornady headspace gauges to measure. I measured my once fired brass out of the .223 and my longest cases measure to 1.457" so that sets my target headspace to 1.455". I verified this using the Eric Cortina method to find proper headspace. stripped my bolt, removing the firing pin and extractor, and I still have to apply force to be able to close my bolt with cases measuring 1.547". my sizing die is set up as per the instruction, Ram all the way up and screw in FL die to touch the shell holder. lower ram and screw die down another 1/4 turn so that the press cams over. I cant get any shoulder bump at all doing this, I tried bringing the die down more in 1/8 turn increments to the point where I cant cam over anymore and still no shoulder bump.

Now that I think about it, I've always had to apply a bit of force to close my bolt even when chambering factory rounds. I checked the headspace on some factory rounds as well and got a measurement of 1.458". so my question is, Is my rifle chamber on the smaller side or is this a die issue? and how would one go about fixing it.

Nathan

 

[Brad243]

Once your shell holder is touching the ram, that's all the sizing you're going to get. Screwing it down more, isn't going to size more as the ram still stops when it contacts the die.

It sounds like your chamber is on the small side of tolerance, which is good. But your dies aren't on the smallest end.

So for options:
1) buy new dies hoping for smaller dies (maybe)

2)buy smaller/shallower shell holder allowing the shell to sit higher and therefore go into the die more

3)remove 3 thousands from your die allowing you to run a standard shell holder further into the die

4)remove 3 thousands from the top of your shell holder, allowing the ram to travel higher. (I think most people would do this, but remember that once you do this that shellholder is only good for those dies/load/rifle)

5)buy custom dies (most companies will offer this for a price..)

Most people would do 3 or 4. 4 is probably the easiest. You only have to do .003 so you can probably do it easy enough with some oiled sand paper on a piece of glass or marble.

Remember that if you do 4 you will need to keep that shellholder with those dies. If you used it for other dies you might be oversized that brass. If you do 3, that die will pretty much be just for that gun.


Also since you state you are new to reloading, be cautious approaching max book loads (or using buddy's loads) as a tighter chamber can have higher pressure than a looser chamber using the same loads. (Just work up, and be safe)

 

[Biologist]

Once your shell holder is touching the ram, that's all the sizing you're going to get. Screwing it down more, isn't going to size more as the ram still stops when it contacts the die.

Typo? - I am guessing you meant when the shell holder is touching the "die bottom".

I would challenge that, because on regular factory sizing dies, the case does not go all the way in flush to the bottom of the die to FL size it. Touching the bottom of the die, then going 1/4 turn further as per the factory instructions already means you are shorter than the full ram extension. The case head and some of the web in regular FL sizing dies is south of the die bottom. The ram/shell holder is pushing on the case head, not the die bottom. FL sizing dies do allow for screwing down in the press to shorten head space from ram contact.

Nathwald: One variable at a time here to figure this out. Forgive this first stupid question, but lets check the number of Hornady head space comparator you are using: is it # A.330? If its a larger HS comparator insert, that may be your problem because its indexing too far back on the case and not giving you a reading on the shoulder datum line area for the proper head space measure.

One revolution of the die is approximately 0.072". The 1/8 turns you are doing are about 0.009", which is huge. You can use a fine tip marker to mark the lock ring in approx. 1mm increments with a 1mm space between each, and mark benchmark line on the side of the die. Turning 1 of these marks on the ring relative to your benchmark line on the die will approximate 0.001". Its not exact and does not have to be because you measure each increment with your calipers and HS comparator. You can lock your ring on a mark or the empty space between the marks when you achieve the head space you want, which is no more than 0.002" short of the longest fireformed cases.

If you were able to chamber factory rounds, your chamber is not too small, so I think that chamber discussion is a red herring. Your fireformed cases are what you need to focus on, and you need to measure several to see what the average long measure is because of variable spring-back case to case. Its not unusual for any rifle chamber to be 1-2 thou longer or shorter than the SAMMI spec, which itself already has a chamber variance allowance for .223 Rem of 0.001" for max-min.

 

[bc308]

Hi guys

New to reloading and I have run into a problem when trying to get .002" shoulder bump in my RCBS FL die. Equipment used is the RCBS rebel press with their full length sizing die, reloading for a CZ 527 .223. Using Hornady headspace gauges to measure. I measured my once fired brass out of the .223 and my longest cases measure to 1.457" so that sets my target headspace to 1.455". I verified this using the Eric Cortina method to find proper headspace. stripped my bolt, removing the firing pin and extractor, and I still have to apply force to be able to close my bolt with cases measuring 1.547". my sizing die is set up as per the instruction, Ram all the way up and screw in FL die to touch the shell holder. lower ram and screw die down another 1/4 turn so that the press cams over. I cant get any shoulder bump at all doing this, I tried bringing the die down more in 1/8 turn increments to the point where I cant cam over anymore and still no shoulder bump.

Now that I think about it, I've always had to apply a bit of force to close my bolt even when chambering factory rounds. I checked the headspace on some factory rounds as well and got a measurement of 1.458". so my question is, Is my rifle chamber on the smaller side or is this a die issue? and how would one go about fixing it.

Nathan

If this is not a typo, 1.547 is longer than 1.455.

 

[Biologist]

If this is not a typo, 1.547 is longer than 1.455.

Ya I caught that too. SAAMI chamber length for .223 Rem is 1.4636" to 1.4736". My reloading manual says 1.467". However comparator tools do not measure true head space, so the actual number the OP is seeing on calipers is relative to the comparator tool he is using.

 

[Brad243]

Typo? - I am guessing you meant when the shell holder is touching the "die bottom".

I would challenge that, because on regular factory sizing dies, the case does not go all the way in flush to the bottom of the die to FL size it. Touching the bottom of the die, then going 1/4 turn further as per the factory instructions already means you are shorter than the full ram extension. The case head and some of the web in regular FL sizing dies is south of the die bottom. The ram/shell holder is pushing on the case head, not the die bottom. FL sizing dies do allow for screwing down in the press to shorten head space from ram contact.

Yes good catch on my ram/shellholder bit.

On my rcbs full length dies the instructions say to put the die in, screw it down to the shell holder, then lower the holder and screw the die down one eighth to one quarter lower. So the shell holder should be making contact with the die body when sizing brass.

So the top of the shell holder and the bottom of the die body create a hard stop. So if they are not sizing the brass small enough, material will need to be removed from either the top of the shell holder, or the bottom of the die body.

Turning the die lower doesn't change the space between the shell holder and the top of the die on this set up, it just stops the ram sooner. At least on my set up.

 

[nathwald]

Once your shell holder is touching the ram, that's all the sizing you're going to get. Screwing it down more, isn't going to size more as the ram still stops when it contacts the die.

It sounds like your chamber is on the small side of tolerance, which is good. But your dies aren't on the smallest end.

So for options:
1) buy new dies hoping for smaller dies (maybe)

2)buy smaller/shallower shell holder allowing the shell to sit higher and therefore go into the die more

3)remove 3 thousands from your die allowing you to run a standard shell holder further into the die

4)remove 3 thousands from the top of your shell holder, allowing the ram to travel higher. (I think most people would do this, but remember that once you do this that shellholder is only good for those dies/load/rifle)

5)buy custom dies (most companies will offer this for a price..)

Most people would do 3 or 4. 4 is probably the easiest. You only have to do .003 so you can probably do it easy enough with some oiled sand paper on a piece of glass or marble.

Remember that if you do 4 you will need to keep that shellholder with those dies. If you used it for other dies you might be oversized that brass. If you do 3, that die will pretty much be just for that gun.


Also since you state you are new to reloading, be cautious approaching max book loads (or using buddy's loads) as a tighter chamber can have higher pressure than a looser chamber using the same loads. (Just work up, and be safe)

Thank you Brad this makes a lot of sense

If this is not a typo, 1.547 is longer than 1.455.

sorry this should read 1.457"

Biologist, I am using the A .330 bushing

I would challenge that, because on regular factory sizing dies, the case does not go all the way in flush to the bottom of the die to FL size it. Touching the bottom of the die, then going 1/4 turn further as per the factory instructions already means you are shorter than the full ram extension. The case head and some of the web in regular FL sizing dies is south of the die bottom. The ram/shell holder is pushing on the case head, not the die bottom. FL sizing dies do allow for screwing down in the press to shorten head space from ram contact.

While its true that the case doesn't go all the way into the die, its the shell holder touching the bottom of the sizing die that limits how much you can shorten the head space. and even when I tried bringing the die down another 1/8 turn the headspace measurement didn't change

If you were able to chamber factory rounds, your chamber is not too small

As I said in the original post, I'm having to apply force in order to chamber factory ammunition. and the headspace measurements seem to bear that out. as the factory round has a longer headspace measurement then my fireformed brass. I did some load development using a few different bullet weights and I measured the headspace on the fired brass of the hottest loads and they measured to a pretty uniform 1.457" that's why I'm using this as my chamber headspace measurement.

 

[cosmic]

Well - I would suggest that anytime you target such a small shoulder bump, you may encounter some resistance with the bolt. This is likely due to the die not having exactly the same profile as the chamber, causing interference somewhere on the case. Back in the stone ages, before the existence of comparators and other fancy gismos, it was common to use the bolt resistance as a gage for proper sizing. Simply, you would adjust the die in outward increments until you felt resistance.
If you want to improve your understanding of your interference issue, take a magic marker and paint one of your resized cases and feed it into the the chamber, close the bolt and see where the scuff marks are.
As a newbie, I suggest you not get too caught up in achieving tight clearances - it can cause trouble. BTW - Have you ever considered a neck sizing die? They are a lot easier to use, and you minimize the risk of run-out. (Welcome to another reloading rabbit hole )

 

[maple_leaf_eh]

Well - I would suggest that anytime you target such a small shoulder bump, you may encounter some resistance with the bolt. This is likely due to the die not having exactly the same profile as the chamber, causing interference somewhere on the case. Back in the stone ages, before the existence of comparators and other fancy gismos, it was common to use the bolt resistance as a gage for proper sizing. Simply, you would adjust the die in outward increments until you felt resistance.
If you want to improve your understanding of your interference issue, take a magic marker and paint one of your resized cases and feed it into the the chamber, close the bolt and see where the scuff marks are.
As a newbie, I suggest you not get too caught up in achieving tight clearances - it can cause trouble. BTW - Have you ever considered a neck sizing die? They are a lot easier to use, and you minimize the risk of run-out. (Welcome to another reloading rabbit hole )

I agree that tolerances are something few mortals are able to judge by feel or by eye. The bolt handle will tell you if those single decimal place thousandths of an inch are really there or not. Once the case is fired, you are not going to know any difference.

I found this on the interwebs for comparison, "Since a ream of paper contains 500 sheets of paper , we divide 2 inches by 500. This will then give us a value of 0.004 inches (about 0.0102 cm), which is the thickness of a single piece of paper." Yes you can tell the difference mathematically, but are your stubby grubby fingers THAT good?

 

[Chilly807]

If factory ammo is giving you trouble closing the bolt, the problem is 99% likely to be a short headspace in the rifle.
If it's new and still under warranty, get it back to CZ and have them correct it or replace it.
If you can get access to a set of go-no go headspace gauges I suspect the bolt wouldn't close on the go gauge.

If you are particularly fond of this rifle as it is, then one option is to get an adjustable full length sizing die. They let you set the shoulder where you want it, and size the neck via a bushing.

Whidden and Forster both make them, there may be others.
Give Hirsch Precision a call, they're familiar with what you need. A friend recently got one of the Whidden dies from them in 223.

https://www.whiddengunworks.com/click-adjustable-sizer-die/

With an in-spec chamber, you should be able to adjust a regular RCBS die to do what you're trying to achieve. I say that because I've done it myself.

Other than sorting the rifle out, your options are an adjustable die, a shorter shell holder, or grinding the bottom of the die. As the guys have said, the shell holder is the cheapest item to replace.

Your measurements are quite short compared to mine. Using a .330" bushing, my 223 cases measure 1.460" to the shoulder datum as they come out of the rifle, on average. 1.462" is a very tight fit. I try for 1.458-1.459" using a Lee die with a Forster split lock ring in place of the original Lee arrangement.
That's in a Tikka T3x Varmint.

Be aware that if we both measured the same case using our respective tools, we might not get the same measurement because of subtle differences in the tools.

 

[Brad243]

He is having resistance on factory ammo. Suggesting his chamber is too tight or his factory ammo is too big.

Measure some different factory ammo. If a bunch of them are longer than you may need to send the gun back for warranty or have a gunsmith ream it larger. You want this extra room for reliability and the ability to chamber any ammo. Or if it will be kept clean and only fed your clean handloads, make peace with that.

Maple leaf was speaking on the thickness of paper, which gave me a thought, cut two slices of paper to fit into the bottom of your shelholder (think thin feeler gauge, or better yet if you have feeler gauges that will fit, or shim stock) you could effectively raise the brass in the shell holder, letting it size the few thousandths smaller. This would let you know if sizing the case shorter will even fix your bolt feel issue.


If sizing the case more doesn't fix it, it could be the neck portion of your chamber is cut undersized leading to resistance on factory, meaning again, you may want to send the gun back intead of turning all your necks.

OR another thought for your handloads, your expander ball could be opening the neck of your case too wide when sizing, again leading to that resistance closing on an empty sized case.

Can of worms.

 

[Brad243]

If factory ammo is giving you trouble closing the bolt, the problem is 99% likely to be a short headspace in the rifle.
If it's new and still under warranty, get it back to CZ and have them correct it or replace it.

I sort of worked around this In my post, but yes, I'd try other factory ammo, and if the problem persists, this is the best course of action.

 

[Biologist]

Nathwald: I stand corrected on my original interpretation. I agree with you and folks here that its likely your rifle's chamber is significantly shorter that the SAAMI minimum headspace. Hence, the fireformed cases are fireformed too short to be resized because they are shorter than the die's minimum size headspace length (assuming the die is not too long inside). I now get the issue of the die bottoming out on the shell holder without the case being sized.

I did not "get it" at first because I thought all FL sizing dies were made short enough in headspace to allow for short chambers, and I could not imagine a chamber in a quality rifle to be cut under the minimum SAAMI headspace length, and that error not being caught by a final QC check at the factory. The spec is a generous 0.010" for the headspace variance in that .223 cartridge (and many common cartridges), and surely I thought that the final QC with go and no-go gauges at the factory would catch such a problem. To be undersized that much below the minimum headspace allowance is hard to believe, but apparently the factory did let this happen. So this thread has been helpful in my improved understanding of trouble shooting problems I had not encountered before.

So ya, maybe return the rifle for a refund or re-chambering at the company's expense.

 

[nathwald]

Since this is a rifle that I purchased secondhand (original purchase date was 2017) contacting CZ isn't really an option.

I did as was suggested and used a .003" feeler gauge to bring my headspace measurement down to 1.454", this was definitely an improvement so I used sandpaper and took .003" of the top of my shell holder and resized a bunch of brass. I came up with mixed results. Some of the resized brass that was fired from the rifle in question chambered really well, the stripped bolt falls under its own weight no assistance needed. other pieces needed a minimal bit of help chambering the empty brass. I also resized brass that was fire formed in different rifle and even with the same headspace measurement these are considerably harder to chamber. So at this point I'm not sure what to think. I did try trimming the expanded portion of the neck to verify that this wasn't the issue.

 

[Chilly807]

Since this is a rifle that I purchased secondhand (original purchase date was 2017) contacting CZ isn't really an option.

I did as was suggested and used a .003" feeler gauge to bring my headspace measurement down to 1.454", this was definitely an improvement so I used sandpaper and took .003" of the top of my shell holder and resized a bunch of brass. I came up with mixed results. Some of the resized brass that was fired from the rifle in question chambered really well, the stripped bolt falls under its own weight no assistance needed. other pieces needed a minimal bit of help chambering the empty brass. I also resized brass that was fire formed in different rifle and even with the same headspace measurement these are considerably harder to chamber. So at this point I'm not sure what to think. I did try trimming the expanded portion of the neck to verify that this wasn't the issue.

The brass that was fired in another rifle might need to go through a small base die before it will work in yours, if the rifle it was originally fired in had a "generous" chamber. The standard die doesn't squeeze the base of the case enough to correct this in some situations.

You can try blackening the outside of the entire case with a Sharpie marker and see where it's tight.

If the case head to .330" datum dimension is the same on one case that chambers easily and one that doesn't, that measurement is not the problem.

Try pushing the case into the chamber with the tip of your finger. It should slide in smoothly and come to a definite stop when the shoulder contacts the front of the chamber.

Then you should be able to insert the bolt and have it close smoothly.

The tight cases are probably sticking in the last 1/4 inch of their way into the chamber.

 

[bigedp51]

When sizing the case leave the ram at the top of the ram stroke for 4 to 5 seconds, this decreases shoulder spring back. Measure the shoulder
location and see how much spring back you are having after sizing the case. The case shoulders should be more uniform with less spring back. After sizing check the shoulder location for even spring back meaning shoulder location.

The more the case is fired the brass becomes harder and springs back more. Holding the case at the top of the ram stroke for 4 to 5 seconds will make the neck and shoulder location more uniform.

Annealing case necks and why.

This annealing process is a heat treatment of the neck shoulder area to restore original softness (malleability) and achieve UNIFORM properties.

 

[cosmic]

Since this is a rifle that I purchased secondhand (original purchase date was 2017) contacting CZ isn't really an option.

I did as was suggested and used a .003" feeler gauge to bring my headspace measurement down to 1.454", this was definitely an improvement so I used sandpaper and took .003" of the top of my shell holder and resized a bunch of brass. I came up with mixed results. Some of the resized brass that was fired from the rifle in question chambered really well, the stripped bolt falls under its own weight no assistance needed. other pieces needed a minimal bit of help chambering the empty brass. I also resized brass that was fire formed in different rifle and even with the same headspace measurement these are considerably harder to chamber. So at this point I'm not sure what to think. I did try trimming the expanded portion of the neck to verify that this wasn't the issue.

So, I think you have resolved your problem. Anytime you size brass, you will get a natural variance dimensionally, due to temper, etc. FWIW - Slight bolt resistance is not problematic, and desirable to many. You may wish to take a few more thou off the shellholder, thus allowing more sizing potential with your die. (eg other types of brass that need a bit more sizing.)