|
|
Post by guncollector on Mar 30, 2018 11:38:53 GMT -8
Several years ago I purchased a 308 24 inch bull barrel. I assembled the upper and checked the head space.The bolt closed on my no go gauge. I called I called BHW and talked with a person about that. I can't remember his name. He basically told me I was not doing it right so I said fine. You are the expert. I'm not a gunsmith. The rifle worked fine. I went through the 60 round break in procedure with no problems. I put the rifle in my gun safe and did not fire it until recently for a number of reason like a divorce and then being in California for a while where I couldn't even take it. I had to leave all my guns with a friend until I finally got to Arizona. Anyway I was spending time shooting my 5 fn-fal rifles and my M1A. I decided to get out the AR308 with the BHW barrel and see what it would do. I used 30 once fired Lake City brass cases to work up a load I trimmed the cases to 2.005", loaded and fired them. No problems at this point but when I was prepping the brass to reload again I noticed the brass had stretched between .007 -.010" in one firing. I though that was very odd and I should have stopped there but I trimmed and reloaded them again. When I tried firing them again I noticed a bright ring around the first few cases just in front of the case head. The next round I fired I had a total case head separation. Well now I knew for sure I had a head space problem and that my initial check of the head space was correct. I have an AR in 260 Remington also so I swapped the bolts around to determine if I had an out of spec bolt. The bolt from the 308 worked just fine in the 260 Remington stretching the cases .003 which is the recommended shoulder setback for a semi-auto rifle.
So now, several years after purchasing the barrel, I find an apparent manufacturing defect. Will BHW or I guess now Columbia River Arms make this right? I can understand if they wouldn't. I am checking nere to see if anybody else has had a problem which was not detected for a period of time and, if so, did the company make it right? I appreciate your feedback.
|
|
|
|
Post by GLSHOOTER on Mar 30, 2018 14:09:12 GMT -8
It may well be in SAAMI MAX spec and to deal with it you don't push the shoulders back as much for when resizng. Your 260 MAY be at a minimum as might your bolt. Tolerance stacking can cause problems. T
he bright ring showing up after firing cases you have resized is usually indicative of pushing the shoulders back to far. Have you measure shoulder height of NEW fired ammunition in this chamber and used that figure to set your dies or did you just screw the die down to touch the shell holder? If you have set your die in that manner you are probably inducing the head space issue in the loading process. Check a few and post up here. If you don't have the commercial tools refer to the thread in the reloading area about the Poor Man's Head Space Gauge I wrote.
You should talk directly with BHW/CRA on this issue as they DO NOT monitor this board at all. It is run for shooters of BHW barrels by shooters of BHW barrels.
Greg
|
|
|
|
Post by guncollector on Mar 31, 2018 10:30:59 GMT -8
Thank you for taking the time to respond. I appreciate it. I have some unfired South African NATO spec 7.62x51. I measured 5 cases before and after firing using a Hornady headspace tool with a 400 insert. Here are the results.
Before firing After firing
Case #1 1.618" 1.628"
Case #2 1.619" 1.627"
Case #3 1.618" 1.628"
Case #4 1.618" 1.628"
Case #5 1.620" 1.628"
Does this look normal? I have several 308 rifles. 5 FAL's, an M1A and a couple of bolt rifles. I have never had case stretch like this. Maybe I have just been lucky and the chambers on all my rifles are at SAAMI minimum spec.
Thanks for taking the time to give me some help.
|
|
|
|
Post by GLSHOOTER on Mar 31, 2018 10:46:15 GMT -8
Pretty normal. The new 22 Nosler ammo is 9-10 on the stretch. Same on some 204. The ammo must fit every SAMMI chamber be it very small or very large. We routinely blow out shoulders 0.020 when wildcatting. The shoulder bump on FIRED cases should only be 0.003 to 0.004. You load to the chamber not the original shoulder height. To do the later again and again will get separations like you have. I have 308 cases with over 20 firings still going strong. Minimal bump and trim as needed.
Greg
|
|
|
|
Post by guncollector on Mar 31, 2018 13:10:51 GMT -8
Pretty normal. The new 22 Nosler ammo is 9-10 on the stretch. Same on some 204. The ammo must fit every SAMMI chamber be it very small or very large. We routinely blow out shoulders 0.020 when wildcatting. The shoulder bump on FIRED cases should only be 0.003 to 0.004. You load to the chamber not the original shoulder height. To do the later again and again will get separations like you have. I have 308 cases with over 20 firings still going strong. Minimal bump and trim as needed. Greg Ok Greg. Thank you very much. That is what I was doing. I was returning the cases to their unfired dimensions. Lesson learned. I appreciate the help. One would think I should know better and I should. I have been reloading for about 48 years and I never had this issue until now. Lucky I guess. |
|
|
|
Post by GLSHOOTER on Mar 31, 2018 13:25:52 GMT -8
Pretty normal. The new 22 Nosler ammo is 9-10 on the stretch. Same on some 204. The ammo must fit every SAMMI chamber be it very small or very large. We routinely blow out shoulders 0.020 when wildcatting. The shoulder bump on FIRED cases should only be 0.003 to 0.004. You load to the chamber not the original shoulder height. To do the later again and again will get separations like you have. I have 308 cases with over 20 firings still going strong. Minimal bump and trim as needed. Greg Ok Greg. Thank you very much. That is what I was doing. I was returning the cases to their unfired dimensions. Lesson learned. I appreciate the help. One would think I should know better and I should. I have been reloading for about 48 years and I never had this issue until now. Lucky I guess. Some dies/shell holder combos will put you as much as 0.015 BELOW minimal SAAMI height. Others won't even get you to SAAMI. There are curs for both thank goodness. Greg PS: I'm still learning!! |
|
|
|
Post by GLSHOOTER on Mar 31, 2018 16:45:19 GMT -8
22 Nosler factory brass moves 0.009 when fired in two SAMMI chambers I've had.
Most recommend using gauges made by the people that made the reamer. In this case PT&G. We have seen this over and over again in the past. Nothing new here at all.
Greg
|
|
|
|
Post by GLSHOOTER on Aug 19, 2020 16:37:05 GMT -8
I got a note about your posting but don't see it now. I read it this AM. Tell me about your measurements and I'll tell you my experience.
Greg
|
|
