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Posted: 10/8/2010 8:23:47 PM EDT
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I'm recently reloading .308 for my new remington 700 SPS Varmint. I used Lee Full Sizing Die and Bullet Seating Die.
But I met with two problems: (1) Some of the ammo can chamber in while some won't. The bolt simply cannot close. The weird thing is that both the working and non-working reloads are from the same batch (passed through the Lee full length sizing die with the same depth setting). I need to mention that the cases are different though. All of them are Lake City old cases which were collected from different locations / at range before. What are the possible reasons? I compared one working reload (can close bolt easily) and one non-working reload (cannot close the bolt), as see in the picture 1. http://farm5.static.flickr.com/4150/5063571153_daa8b42a68.jpg I checked the O.A.L, both met specifications 6.660 cm (2.622 inch) The case length is 5.080 cm(2.008 inch) for the non-working one, and 5.112 cm(2.013 inch) for the working one. Both met specifications. The neck length is about 0.658 cm(0.259 inch) for the non-working one, and 0.688 cm(0.271 inch) for the working one. The suggested neck length is 0.3032 inch. For your quick length reference: http://www.6mmbr.com/308Win.html My guess of the cause of the problem is the full length sizing die wasn't set deep enough. I should give it one more turn to make the neck a little longer (with the O.A.L fixed). What do you think? (2) I noticed that all the fired cases have some black color powder residues left on there, as seen in the picture 2. What is the possible cause? http://farm5.static.flickr.com/4149/5064182838_6dc14457e4.jpg Thanks! |
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Work-hardened brass? If I understand correctly, you are using "old" brass with unknown # of firings and getting different rim to shoulder measurements.
Work-hardened brass tends to spring back after being sized. As far as I know, annealing is the only way to correct this. Someone will correct me if I'm wrong. BTW, welcome to the site. |
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My guess is, your guess is correct. You are not getting on the shoulder hard enough with your sizer.
The soot stain part way back on the neck is normal. It shows you are getting a seal on the neck before the gas gets back to the shoulder. Good photos, by the way. Thanks. |
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You don't have good understanding of how a sizer die functions.
The idea is not to make the neck longer, although that might be a side effect. We use the sizer to "set the shoulder" back; what we're doing is adjusting the distance between the case head and the case shoulder. We can measure that length with a gage of some sort. I recommend an adjustable gage such as the Hornady/Stoney Point or the one sold by Sinclair International. Don't turn the die down a full turn, that's way too far. Let's examine this a little. The die body is threaded 14 threads to the inch. That means that one turn of the die body moves the die 1/14 = 0.071 inches per turn. Most likely you need to adjust your die down only 0.001 or 0.002 inches, which would be more like 1/32nd of a turn. Since you're experiencing inconsistent sizing, the main suspect is lack of lube inside the case mouth. Without lube, the expander ball drags on the inside of the case mouth when it is withdrawn, and this stretches the shoulder slightly, essentially undoing part of the sizing operation. Try some lube inside the case mouth first, then turn the die body down just a little. |
Thank you for all your responses. 
With all the responses posted here and some other gun forums, the situation mentioned in the 2nd question (black residues on the neck after firing) is normal. It's caused by the gas remaining after pressure has decreased enough for the case necks to release their grip from the walls of the chamber. The heated discussion comes from the 1st question, "cannot chamber problem". The possible causes are: (sorted according to the number of posters who believe this is the reason) Reason 1. The shoulder to head (base) distance is too long for the non-working one. "This is named "headspace". Headspace on the left round is 1.749" (2.008-.259), while on the right it is 1.741". Non-uniform headspace after the same die indicates that the sizing die does not touch case shoulder, and need to be set deeper in the press. Do not lower the shoulders more than needed for your chamber - it will significantly reduce brass life." "The dirt at your pictures does not cover the whole case necks. It may clue that only top (dirty) part of the necks has touched your sizing die. This is another indicator that the die is not set deep enough. " "Work-hardened brass? If I understand correctly, you are using "old" brass with unknown # of firings and getting different rim to shoulder measurements. Work-hardened brass tends to spring back after being sized. As far as I know, annealing is the only way to correct this." "My guess is, your guess is correct. You are not getting on the shoulder hard enough with your sizer." "You don't have good understanding of how a sizer die functions. The idea is not to make the neck longer, although that might be a side effect. We use the sizer to "set the shoulder" back; what we're doing is adjusting the distance between the case head and the case shoulder. " Solutions: (1) Turn the full length sizing die a little deeper. Do not lower the shoulders more than needed for the chamber - it will significantly reduce brass life. Make 1/4 turn deeper then try it in the chamber to see whether the bolt will close. Repeat as needed. A case length headspace gauge is helpful to check the shoulder/neck positions. (2) Use a small base die (body die) The rounds that won't chamber may have been fired in an automatic (semi or full) and the brass needs to be run through a small base resizing die. From RCBS: The Small Base Die set is intended for use for ammunition to be used in auto, semi-auto, and lever action rifles so that the loaded round chambers and extracts easily. The Small Base Sizer Die sizes the case from the shoulder to the head of the case a couple of thousandths smaller than a Full Length Sizer Die. In certain calibers it also sets the shoulder of the case back a thousandth or two more than the Full Length Sizer Die. Reason 2. The non-working case wasn't trimmed enough "You should be trimming your case to 2.005 according to my Speer book." "Had the sam prob. Ended up being a seating crimp problem it only takes a lil bit longer case then an other i mean just a lil what i did waswhat i did was trimmed all cases to 2,000 seemed to fix" Solution: Trim the case more. Reason 3. The case mouth wasn't lubed well. "Since you're experiencing inconsistent sizing, the main suspect is lack of lube inside the case mouth. Without lube, the expander ball drags on the inside of the case mouth when it is withdrawn, and this stretches the shoulder slightly, essentially undoing part of the sizing operation." Solution: Try some lube inside the case mouth first, then turn the die body down just a little. ** Comment: What do you think of these methods? About adjusting the shoulder position method, any one of the two solutions would require running through a sizing die again. Removing bullet and pouring away the powder are not difficult. The problem is to (A) decap the LIVE primer carefully and slowly with decap rod on the die (B) or take off the decap rod on the die and do the resizing only. What do you think? Thanks. |
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At this point all you know is that a case won't fit in you chamber. The neck measurements you listed really can not be that accurate, especially down to the thousandth. The most important measurement, is going to be from the case head to the shoulder so that you can see whether you have full length sized your brass enough.
While I agree that you probably have not bumped the shoulder back far enough and need to adjust your full length sizing die down some more, you would be much better off if you had either a case gauge or some sort of case comparator gauge. If you are only going to be shooting these loads in the same rifle, you really just need to get the comparator as it makes setting your dies up very easy. I take a case that has been fired and measure it as shown here: 
I then adjust my sizing die down in small increments (1/16 turn) and re-measure the case. I do this until I get a measurement that is .001" (I use .002" if the brass is going to be fired in an semi auto) smaller than the once fired case. Without one of these tools, you will only be able to set your dies up with trial and error and will likely be overworking your brass resulting in having to trim more and reducing case life. Loading for a bolt action also doesnt require you to full length size the brass each loading. Instead, you can get a neck sizing die which won't size the case body at all. Neck sizing can only be done, once the case has been fired through your gun and you will likely be able to get 4-5 loadings of neck sizing before needing to bump the shoulder back using a full length sizing die setup as described above. From there, you just need to verify whether the neck needs to be trimmed. You can do that either by measuring the OAL with your calipers or putting the brass in the case gauge and seeing if the neck falls between the two steps: 
Quoted:
About adjusting the shoulder position method, any one of the two solutions would require running through a sizing die again. Removing bullet and pouring away the powder are not difficult. The problem is to (A) decap the LIVE primer carefully and slowly with decap rod on the die (B) or take off the decap rod on the die and do the resizing only. What do you think? Thanks. I would just recommend taking out the decapping pin/rod. That being said, you would not have any problem decaping a live primer by going slowly. It has been discussed here many times and having done it myself quite a few times, never been an issue. |
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Lake City brass, when fired from a M1A really gets abused. They usually will stretch .005" or more, not because of headspace, but because the action is so violent and the timing early. This brass is extremely tough too.
It resists being resized more than any other type of brass available. Usually the only reason a M1A shooter will leave this brass at the range is: 1. It's been fired four times and is shot out. 2. They don't reload. Otherwise they will take it home and load it again. I'm guessing this brass is the culprit. Adjust the die and try again. Check for incipient case head seperation with a sharpened paper clip. Chuck any case that is "grabby" when tested. |
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Quoted:
Lake City brass, when fired from a M1A really gets abused. They usually will stretch .005" or more, not because of headspace, but because the action is so violent and the timing early. This brass is extremely tough too. It resists being resized more than any other type of brass available. Usually the only reason a M1A shooter will leave this brass at the range is: 1. It's been fired four times and is shot out. 2. They don't reload. Otherwise they will take it home and load it again. I'm guessing this brass is the culprit. Adjust the die and try again. Check for incipient case head seperation with a sharpened paper clip. Chuck any case that is "grabby" when tested. OP, listen to borderpatrol and AEroE as they gave you the correct answer. |
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