09-29-2018, 10:16 PM
(This post was last modified: 09-29-2018, 10:49 PM by Mad Charlie.)
When I first started messin' with Grendel I built the first one with a Satern bbl and bolt from Brownell's, along with 200 Lapua cases and an assortment of bullets. The new Lapua cases datum-ed at 1.207. I started out with one of the starting loads found in a book and assembled five rounds. I took my new rifle out to my side yard where my backstop is and fired for function test.
Everything was peachy until I went back in the house and measured datum of the fired cases, to set up shoulder bump. My eyes almost bugged out when I saw 1.220! Having not seen anything like that in over 40 years of handloading, I thinks to myself "There has GOT to be something wrong with this barrel!" On the phone to Steve Satern, asking, "Did this bbl. accidentally get chambered for a 7.62x39 bolt or something? No, he says we check 'em all. Welll, ohh-kayy, if you say so.
So I just figured that I had a long chamber and had to fire form my cases, like the A.I. guys did. I bumped my case shoulders back .005 and continued merrily on my way. No problem. I later discovered that SAAMI min. is 1.220 and I didn't have a long chamber after all.
Then along came the Alexander Arms bbl, it datum-ed out at 1.214, so I keep my cases separated between the two, that and a set of Redding shell holders, makes it easy to get the bump I want, and brass catchers makes it easy to keep them separate. I have four bolts, they vary from.134-.136, I will load accordingly. I have the Redding shell holder sets for every bottleneck cartridge I shoot.
I am a very firm believer in firm contact between shell holder and die when sizing, I get the most consistent results this way. I use my 43 yr old Rockchucker to size cases, it has enough looseness now to pretty well self center. I seat with the Forster.
New Lapua-1.207
New Starline-1.2085-1.210
New Hornady-1.209
Hornady Modified Case-1.208- I just do the math when finding the lands with different bullets.
DCM, you might try these techniques, maybe help you out. I had thought about my bbl. being mis-chambered, but I did not consider actually using a 7.62x39 bolt before I spoke with Satern. Just bump the shoulder .005 and call it good. And mark your boxes.
Yeah, seems like these chambers are all over the place, and everyone that makes them thinks their idea is "better". How about everybody just make them to SAAMI.
Everything was peachy until I went back in the house and measured datum of the fired cases, to set up shoulder bump. My eyes almost bugged out when I saw 1.220! Having not seen anything like that in over 40 years of handloading, I thinks to myself "There has GOT to be something wrong with this barrel!" On the phone to Steve Satern, asking, "Did this bbl. accidentally get chambered for a 7.62x39 bolt or something? No, he says we check 'em all. Welll, ohh-kayy, if you say so.
So I just figured that I had a long chamber and had to fire form my cases, like the A.I. guys did. I bumped my case shoulders back .005 and continued merrily on my way. No problem. I later discovered that SAAMI min. is 1.220 and I didn't have a long chamber after all.
Then along came the Alexander Arms bbl, it datum-ed out at 1.214, so I keep my cases separated between the two, that and a set of Redding shell holders, makes it easy to get the bump I want, and brass catchers makes it easy to keep them separate. I have four bolts, they vary from.134-.136, I will load accordingly. I have the Redding shell holder sets for every bottleneck cartridge I shoot.
I am a very firm believer in firm contact between shell holder and die when sizing, I get the most consistent results this way. I use my 43 yr old Rockchucker to size cases, it has enough looseness now to pretty well self center. I seat with the Forster.
New Lapua-1.207
New Starline-1.2085-1.210
New Hornady-1.209
Hornady Modified Case-1.208- I just do the math when finding the lands with different bullets.
DCM, you might try these techniques, maybe help you out. I had thought about my bbl. being mis-chambered, but I did not consider actually using a 7.62x39 bolt before I spoke with Satern. Just bump the shoulder .005 and call it good. And mark your boxes.
Yeah, seems like these chambers are all over the place, and everyone that makes them thinks their idea is "better". How about everybody just make them to SAAMI.