308 Reload Question

[kelvinchufei]

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.



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?



Thanks!

 

[grubbylabs]

You should be trimming your case to 2.005 according to my Speer book. And make sure your die is all but touching your shell plate when you re size.

Don't know how much experience you have but those were my problems when I first started reloading. Hope that helps

And the max COL is 2.810

This is from the 13th edition of the Speer hand loading book I have.

 

[Nighthawk0083]

Maybe a factory crimp die might help

 

[kelvinchufei]

You should be trimming your case to 2.005 according to my Speer book. And make sure your die is all but touching your shell plate when you re size.

Don't know how much experience you have but those were my problems when I first started reloading. Hope that helps

And the max COL is 2.810

This is from the 13th edition of the Speer hand loading book I have.

I guess 2.005'' is the minimum case length

I double checked different sources of references: 2.005~2.015 would be all good.

 

[grubbylabs]

I can only say what my Speer book shows.

I picked up some range brass and once I trimmed my brass to that length and adjusted my die to stop about a match book thickness from the shell plate I have not had any problems clambering my 308 loads.

 

[Robert Wilson]

If I were you I would soot or magic-marker one of the "no-go" rounds and attempt to chamber it. This should show you where it's hanging up. You may also try measuring the diameter of the cases at several locations including the shoulder and at the expansion ring ahead of the base. Lake City .308 brass could easily have come from the generous chamber of a machine gun and really want to be FL sized in a small base die.

The residue is normal and is caused by the gas remaining after pressure has decreased enough for the case necks to release their grip from the walls of the chamber.

 

[jeeptim]

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 was trimmed all cases to 2,000 seemed to fix what was happening was the crimp was catching the bullet befor it was fully seated so it swelled the case just below the shoulder you cant see it but if you take your calipers around the case about 1/4'' from the neck and keep your thumb on the wheel and slide it to the neck and watch the needle it will taper down the bump up that bump up is what caused me a lot of stuck rounds in an m1a get a lee factory crimp die $8,39 at midway

 

[PCCUSNRET]

My guess is that 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. I had a similar problem last week reloading some LC brass. Most worked just fine running it through a FL die but on several pieces the bolt wouldn't close. I ran these pieces through a SB die and they worked just fine. The rifle this happened to me with was also a Remington 700. Hope this helps.

 

[ricehombre]

Sounds like a classic poor seating of primers. If you used a hand primer, go back and use the press to finish them off. I think you will find the little added seating depth will solve your problem. Some rifles have no tolerance for raised primers.

 

[Walkalong]

I agree with bunnylabs that you should trim your brass (after sizing) to 2.005. That doesn't seem to be the problem, but it is a safety concern.

Sounds like some of the brass was not sized enough. If you mark one of them and try to chamber it the rub marks will tell you where it is fat or long. Did you crimp? If so you may have slightly buckled some shoulders. It doesn't take much sometimes.

I would not think it is the primers, but never say never. I would not re-seat them in loaded cases, despite the fact it is improbable that they would go off. Do check to make sure they are not sticking way out, but I just don't think that is the problem.

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).

The die sets are designed to be turned all the way down against the shell holder. Sounds like you did not do that, so yes, that may be the problem right there.

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?

Normal residue. The better the seal (pressure related) and the cleaner the powder the less you will have, but some is normal.

Break down a couple of the rounds that will not chamber, re-size them with the sizer set down against the shell holder, trim them to 2.005. Check them to see if they will chamber. If they will, load them and try again. If they still chamber, you have solved your problem.

A case gauge is very handy to check cases after sizing. It can save some of these problems up front. At least check to see if sized cases will fit your chamber before loading them in quantity.

 

[kelvinchufei]

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.

 

[Walkalong]

Sounds like you are on the right track, and have gained much useful knowledge.

My advise stays the same. Break down a couple, re-seat primers, re-size with the die touching the SH, etc....

Betcha it solves the problem and you don't need a small base die.

 

[NCsmitty]

Your dimensional pictures hold the answer.

The cases you show not chambering, have a shorter neck, which equates to a longer shoulder.
As others have mentioned, you need to set the shoulder back on the bad cases with the FL die, by screwing it down a partial turn at a time until they fit.

Soot on the neck after firing is normal, as long as it doesn't extend down into the shoulder.
Lower pressures can keep the brass from obturating and sealing in the chamber, and the powder residue will leave a soot trace down into the shoulder in a worst case scenario.

You do not need to crimp the bullet in the case.



NCsmitty