k**********i
发帖数: 8706 | 1 I'm recently reloading .308 for my new Remington 700 SPS Varmint. I used Lee Full Length 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! |
f****a
发帖数: 4708 | 2 Did you use the body die? |
k**********i
发帖数: 8706 | 3 No.
Do you think it might be the ammo shoulder position problem?
【在 f****a 的大作中提到】
: Did you use the body die?
|
T*R
发帖数: 25894 | 4 of course, 308 is not rimmed, the center of the shoulder is what's used for
gauging.
【在 k**********i 的大作中提到】
: No.
: Do you think it might be the ammo shoulder position problem?
|
T******g
发帖数: 21328 | 5 嗯，rimless肩膀很重要, head spacing |
S**********s
发帖数: 4534 | 6 我压的.308也是这个问题。 用我的M1A可以chamber,换了别人的bolt action就不行了
。 |
c**********d
发帖数: 2428 | 7 你说你用的FULL SIZE，怎么出来的SHOULDER长度会不一样？你用了润滑了吗？LEE的步
枪DIE都不太好，虽然便宜。例外重要的是SHOULDER到弹底的尺寸，而不是SHOULDER到
壳口的尺寸。还有就是2。622的全长好像有点小。我以前都是用2。8左右的全长。另外
要注意不要COMPRESSED LOAD，COMPRESS的火药有可能把SHOULDER挤变形的。我曾经遇
上过这么一发，但一下找不到以前的照片了。 |
S*******T
发帖数: 5156 | 8 是不是你的full size die没有调好啊，明显那个合不了栓的子弹颈部尺寸不对。记不
记得我们在土猫家装他的303，要用力压然后才行。
我刚刚试了试自己装的，发现居然也有一发合不了膛。用的都是新弹壳，外表看上去也
和其他的子弹没有差别。真是奇怪。 |
k**********i
发帖数: 8706 | 9 So about the solutions:
1. Turn the full length sizing die one more turn deeper to move the shoulder
position?
or
2. Get a small base die to move the shoulder position?
Because I found some information mentioned both:
From RCBS:
Q. I see a Small Base Die Set listed for my caliber. Do I need these or
should I buy a Full Length Die Set or Neck Die Set? How does each set differ?
A. 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. The Full
Length Die Set or Neck Die Set is not normally recommended for ammo to be
used in auto, semi-auto, or lever action rifles. The Full Length Die set is
recommended for ammunition used in bolt action rifles, particularly for
ammunition to be used for hunting. The Neck Die Set can also be used to
produce ammunition for use in bolt action rifles. The Neck Sizer Die sizes
only the neck of the case so it will hold the bullet firmly. It does not
size the body of the case nor does it set the shoulder back. Neck sized
cases will usually chamber for three or more firings, depending on the
powder charge and chamber dimensions. However, over a period of time, a
slight drag will be noticed when the bolt is locked. At this point, cases
will need to be full length sized and the shoulder set back so they will
chamber and extract easily
for
发信人: TopHuang (Top+Gun), 信区: GunsAndGears
标 题: Re: 308 reload question
发信站: BBS 未名空间站 (Sat Oct 9 02:29:40 2010, 美东)
嗯，rimless肩膀很重要, head spacing
【在 T*R 的大作中提到】
: of course, 308 is not rimmed, the center of the shoulder is what's used for
: gauging.
|
k**********i
发帖数: 8706 | 10 因为我的case来源很杂，是unknown # of fired case, 还可能有全自动机枪打过的壳
子混杂
【在 c**********d 的大作中提到】
: 你说你用的FULL SIZE，怎么出来的SHOULDER长度会不一样？你用了润滑了吗？LEE的步
: 枪DIE都不太好，虽然便宜。例外重要的是SHOULDER到弹底的尺寸，而不是SHOULDER到
: 壳口的尺寸。还有就是2。622的全长好像有点小。我以前都是用2。8左右的全长。另外
: 要注意不要COMPRESSED LOAD，COMPRESS的火药有可能把SHOULDER挤变形的。我曾经遇
: 上过这么一发，但一下找不到以前的照片了。
|
|
|
k**********i
发帖数: 8706 | 11 上回我们在土猫家装子弹的问题是full length sizing die press难以压下去，这是没
润滑好shoulder to head(base)部分的典型症状，倒是和能不能chamber关系不大
【在 S*******T 的大作中提到】
: 是不是你的full size die没有调好啊，明显那个合不了栓的子弹颈部尺寸不对。记不
: 记得我们在土猫家装他的303，要用力压然后才行。
: 我刚刚试了试自己装的，发现居然也有一发合不了膛。用的都是新弹壳，外表看上去也
: 和其他的子弹没有差别。真是奇怪。
|
w*********p
发帖数: 7230 | 12 为什么非写英文，我头都大了
Lee Full Length Sizing Die and Bullet Seating Die.
cannot
are
the
though.
【在 k**********i 的大作中提到】
: I'm recently reloading .308 for my new Remington 700 SPS Varmint. I used Lee Full Length 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
|
k**********i
发帖数: 8706 | 13 Sorry啦
在好几个英文论坛里发了，然后同时copy & paste过来了，没有翻译成中文版
【在 w*********p 的大作中提到】
: 为什么非写英文，我头都大了
:
: Lee Full Length Sizing Die and Bullet Seating Die.
: cannot
: are
: the
: though.
|
S*******T
发帖数: 5156 | 14 对对，是这样的。但是你记不记得压完之后的弹壳颈部变短，前后变化就和你贴的这两
发一样。
【在 k**********i 的大作中提到】
: 上回我们在土猫家装子弹的问题是full length sizing die press难以压下去，这是没
: 润滑好shoulder to head(base)部分的典型症状，倒是和能不能chamber关系不大
|
T*R
发帖数: 25894 | 15 你啥时候走啊？我给你留言了。
【在 S*******T 的大作中提到】
: 对对，是这样的。但是你记不记得压完之后的弹壳颈部变短，前后变化就和你贴的这两
: 发一样。
|
k**********i
发帖数: 8706 | 16 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 short 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. |
w*********p
发帖数: 7230 | 17 师父又去哪里淫荡？
【在 T*R 的大作中提到】
: 你啥时候走啊？我给你留言了。
|
k**********i
发帖数: 8706 | 18 他们今天去hap baker打200码
【在 w*********p 的大作中提到】
: 师父又去哪里淫荡？
|
f*********n
发帖数: 11154 | 19 这信息不错，K大你把这个帖子Mark了收集进精华吧 |
k**********i
发帖数: 8706 | 20 经过这段时间的研究，问题终于找到了
首先做一下背景说明，我用的是Lake city 308 once fired case
由于是军用/军剩弹，大多数都有primer crimp, 需要用RCBS swager tool去顶一下蛋
壳的屁屁(primer pocket)把crimp去掉
问题在于我搞错了swager的次序：
我是full length sizing之后再整swager装primer的，虽然这样primer seat没有问题
，但是由于swaging die, 软软的铜蛋壳会变形！（虽然目测不容易观察到）
这是一个低级错误。 吸取教训之后, 正确的顺序应该是：
... -> deprime -> clean primer pocket -> swaging （once in the rest of the
case life )-> full length sizing -> seat primer -> ....
总而言之，就是再灌火药和座弹头的最后一步之前，要保证蛋壳尺寸的标准。
改进之后，所有的自装弹都能顺利上膛了。
另外，原帖中的bullet seating depth的确是太深了，调整了一下bullet seating die, 把全长提到了2.79~2.8寸，一切正常。 |
