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Post by madcat on May 21, 2015 10:39:38 GMT -8
Thought I would put this up for comparison. 6.8 /sized and trimmed unfired/ onced fired. As you can see the only difference is the shoulder shape.
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Post by GLSHOOTER on May 21, 2015 12:13:16 GMT -8
Is there a case spec diagram anywhere for the AM30? I believe I understand how to form the brass but trying to get a visual on what we're doing to the parent case as it is formed up Nothing that would help you in the least. Once you shot the first one you could appreciate what a 30 degree shoulder is. That's what any print will show. Greg
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Post by geepee3 on May 21, 2015 13:35:40 GMT -8
Thought I would put this up for comparison. 6.8 /sized and trimmed unfired/ onced fired. As you can see the only difference is the shoulder shape. Here is a little different comparison at the datum point using the Hornady headspace gauge and blackened out shoulders to see contact point. Left. Federal 6.8 SPC case necked up and trimmed, headspace measurement 1.343" . Federal 6.8 SPC shot in my A-30 barrel shoulder fire formed shoulder, headspace measurement 1.3575". Federal case A-30 resized for rifle chamber, headspaced at 1.353". There is a .009"-.010" difference between the datum points of certain new brass and once fired resized brass. Now I have had no issue other than stamping of new brass because of excessive headspace. I was able to duplicate the issue the original poster had with the same bullet and case hand cycling them. But in real live fire I have had no extraction issues with the components I have used. That would be the Nosler and Lapua bullets I listed in an earlier post. Glenn
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Post by GLSHOOTER on May 21, 2015 16:57:40 GMT -8
Take a ruler at a 23 degree angle against a vertical sevice. Pick a spot four inches out from the wall. Mesure from the table top to directly above that spot to the top of the ruler. Now rotate the ruler up to 30 degrees. Now measure from the distance from the four inch table dot vertically up to the top of the ruler. Did it get bigger than the first one?
You just saw a datum line shift forward. Also firing the case slides it up.
Greg
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Post by madcat on May 21, 2015 17:29:46 GMT -8
Haha ! I have no idea what you said with ruler thing.
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Post by GLSHOOTER on May 21, 2015 18:37:01 GMT -8
Haha ! I have no idea what you said with ruler thing. Look at the shoulder on a new formed case. Measure a point in half way from neck to shoulder edge. this is the DATUM LINE on a 23 degree shoulder. Now if you fire that case and find the mid point again, measuring from base to DATUM LINE, this is the NEW datum line on a 30 degree shoulder. You will note it is taller, giving a longer base/datum line number. This is also due to the case filling the chamber for a few thousandths raising the line. This is why we see a change in datum line from new to fired. I just talked to Ritch about these "short" cases. It seems that when guys are making there case and checking the length they are dropping the BCG with the full force of the buffer spring... DO NOT DO THAT!!!!! If you do you are slamming the shoulder into the chamber and basically pile driving it to be smaller. After repeated droppings you will have extraction issues. It won't work manually but if you fire it everything lengthens out and extraction will be fine. To check your case fit pull the upper OFF the lower. Insert a case manually into the chamber and close the BCG with finger pressure or a bit of a sharp push. If it chambers and EXTRACTS easily with the charge handle you are close. Now to get it dead nuts, since you used the set up gage probably, unscrew your die 1/8 turn and make a new case. Repeat as above. Does the bolt close and does the case extract EASILY, I mean slick as owl snot on extraction? If so then you turn it OUT 1/8 more turn again and repeat until you A: have a failure to lock up or B" a hard extraction. Once you reach Maximum screw the die back in and check it with a newly made case. Did it get easy again? If so make up FIVE cases and manually insert and cycle them with your fingers and charge handle. If you are set right and you pull that CH the case should pop right out and go flying. This is how we made cases before we got the set up gage. You have to realize that tolerance stacking of your dies, the bolt face and minute chambering differences can add up to several thousandths. These are wildcats but in the real world even a pure SAAMI set up from ANY manufacturer can encounter this. All measurements are IN SPEC but together they are not so perfect. If You have ANY questions on this please contact Ritch or me. Greg
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Post by geepee3 on May 21, 2015 18:43:38 GMT -8
Haha ! I have no idea what you said with ruler thing. Me neither! But a 23 degree angled shoulder 6.8 SPC case will fit inside an A-30, 30 degree formed shoulder. As I mentioned before. My concern has always been with excessive headspace between certain new necked up 6.8 SPC cases in relationship to the rifles chamber. Not between new necked up 6.8SPC cases and fire formed A-30 cases. Glenn
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Post by GLSHOOTER on May 21, 2015 19:20:04 GMT -8
Yes it will. You need to read about Ackley Improved case forming. That's what is happening here basically.
This is a wildcat. You make cases to fit your chamber. You deal with head space in your case making to fit your needs. Your chamber tells you what to adjust be it fire forming, neck turning or the use of a mandrel. More on the last tomorrow.
Greg
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Post by cpct on May 22, 2015 11:04:26 GMT -8
Greg, Your explanation of "Old School" forming made perfect sense to me. Kind of wished it was posted a longer time ago. Anyway, between all you said, and talking to Rich, I'm able to get all my formed brass to eject. I'll be fire forming tomorrow with 35 rounds. I know I only need 3-4 to get the data I need to set the dies, but oh well, it'll be fun to finally shoot the dang thing!! Incidentally, I'm shooting the 130 grain Hornady soft points over 29 grains of H335 @ 2.30.
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Post by GLSHOOTER on May 22, 2015 16:06:22 GMT -8
Greg, Your explanation of "Old School" forming made perfect sense to me. Kind of wished it was posted a longer time ago. Anyway, between all you said, and talking to Rich, I'm able to get all my formed brass to eject. I'll be fire forming tomorrow with 35 rounds. I know I only need 3-4 to get the data I need to set the dies, but oh well, it'll be fun to finally shoot the dang thing!! Incidentally, I'm shooting the 130 grain Hornady soft points over 29 grains of H335 @ 2.30. The funny thing is I've sent that to quite a few people so many times I thought I posted it. I t may well be on another Form. The one thing I left out and I will add is that if you don't have the tool you just unscrew the die off the shell holder about 0.100 and making cases in 1/8 turn increments slowly pushing everything back.I have an experiment on new brass that might even make it easier than that I am going to do tomorrow. I'll post my results on that on Saturday. Greg
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Post by cpct on May 24, 2015 14:44:51 GMT -8
I got it running flawlessly now. Thanks to Greg and Rich, all my cases are formed, I have a process to do it, and the brass is perfect. Off to load development now. Thanks to Rich for the phone conversations to iron this all out. It really is as easy as they describe. just have to be careful and put in the time. I don't need 0.194 group accuracy for my application, but I need reliability, first and foremost. Accuracy is on what I'm willing to accept. Minute of pig vitals inside 200 yards is all I want.
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Post by GLSHOOTER on May 24, 2015 15:11:10 GMT -8
I got it running flawlessly now. Thanks to Greg and Rich, all my cases are formed, I have a process to do it, and the brass is perfect. Off to load development now. Thanks to Rich for the phone conversations to iron this all out. It really is as easy as they describe. just have to be careful and put in the time. I don't need 0.194 group accuracy for my application, but I need reliability, first and foremost. Accuracy is on what I'm willing to accept. Minute of pig vitals inside 200 yards is all I want. That is great news. Thanks for the feed back. I like my bacon hickory smoked. Greg PS: We don't NEED a the 0.194 but that's why we have a wallet.
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Post by cpct on May 24, 2015 16:28:36 GMT -8
You got it!!! I'll be bringing some up to Coos Bay in late June. Come and get it.....bbq time at Ten Mile Lake.
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Post by madcat on May 24, 2015 18:14:36 GMT -8
How about a picture of your rig?
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Post by cpct on May 24, 2015 19:31:53 GMT -8
I don't know how. Rich told me sbout a photobucket account, but I forgot what he said. Sounded more complicated than forming A30 brass!! I posted it on BHW's Facebook page. Once I figure it out, I'll post here.
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