Tony Z: specifics for reaming SR primer pockets to take LR

My apologies Charles, been away from the forum for a bit.

As i only intended to do a small number for a trial i simply set a sizing die in the four jaw chuck of my lathe and just lightly tapped in each case. The friction there was more than enough to hold each case. To do the reaming, all i did was grind up a sort of "D" reamer and set it up like a small boring bar in the tool holder. The front was just flat and had a small clearance rake. It had a stop collar on it for depth control. Snuck up on a case until the primer seating felt right. Then just did about twenty cases. As for a chamfer for a lead in for the primer, i just used my old RCBS case mouth chamfer tool. The cartidge brass can be a bit of a pain to ream especially if the tool is not clearing properly. I recall running a speed of about 260 RPM and just feeding the tool in slowly. When finnished i just levered the case out by the rim, or if it was a little sticky i tapped it out using a rod through the die. Lastly i just drilled out the flash hole using a pin vise
If i was to do a number of cases and often, i would make up a collet to hold each case and then grind up a form tool that did the hole as well as the chamfer.

Tony Z.
 
Bob Kingsbury said:
After opening the primer pockets up to large, were you able to find an improvement ?
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Bob, this particular 6BR, and only this one, gave me the vertical heebee geebees. Yes it cured it, but the pressures rose a fair bit where max loads were about one grain less than what i had used with the SR primer. Only regret is that i did not try the small flash hole first up. As i said in the other post, this same barrel was later chambered to 6x47 using the 6.5x47 Lap cases. It too showed annoying vertical that was cured when i went to the cases formed from 308 Lapua brass with the LR primers again. I suspect the barrel was "different" as all other 6 BRs i have had prior and since did not show any of the traits this particular tube did. My result proves nothing more than that i could cure a problem in that barrel.

One thing i did recall recently since the first original post Charles is referring to is that in one of my endeavors with that 6 BR, i had tried a compressed charge of H4350 and a 450 mag primer (107 SMKs). It was better than the Varget loads were in most respects, but velocity was limited to the amount of 4350 that could be crammed into the case without it pushing the projectile back out with the loose neck tension i was using. But when i revisited this powder with the large primer, a velocity gain was there. This is something i would like to try again sometime.

Tony Z.
 
Bob, Here is the original post. I've edited my comments because Toney responded as I was searching for it, and I believe your interest is in the 6.5x47 Lapua case.

Here is my two cents worth. From what i have seen of my own and others combinations, when it comes to small primers and some cartridges, there seems a need to go to the 450 mag primer. Now that should tell most of us that all is not well.
I had a 6BR once, it showed plenty vertical at long range, and even short, with the 205M, so i went the 450 route and the vertical closed up. Powder was the usual Varget, pills were 107 SMKs and all in a 700 action that had been bushed back to the 62 thou firing pin. Spring preload was 19 lb. I adjusted the spring to a stock Rem item at 26 lb preload. Nothing changed. So out of frustration i took 12 BR cases, reamed the pockets to accept LRPs and the problem went away. Now i know very well that this is very unusual in a 6 BR.

It doesn't end there. With better things to do with my time than ream 6BR primer pockets to LR, i took the barrel and just extended the chamber for the then new 6x47 chambering using the new 6.5x47 Lapua brass. Well the vertical came back. CCI 450 primers again, and it did close up, but again like the same barrel when a 6BR, nothing spectacular. So then i went to Lapua 308 cases, resized and shortened to fit the 6x47 chamber, but with 210 Ms in as primers, the vertical disappeared. Now that is number two example.

Number three. 30x47. Yep, using Lapua 6.5x47 cases once again, nothing but vertical at 600 yards. Four to six inches of it. Sometimes less. But groups were always more vertical than lateral. So once again off to the great 308 Lapua brass, 210Ms and many hours sizing and shortening cases, then fire forming, and my first competition group at 600 yards was a 1.6xx", mostly lateral. Went on to win the match while surrounded by some very hot shooting rigs in great calibers.
So do you think i am skeptical of the small rifle primer? You bet ya.
The story can go on as i have seen numerous other examples, not with the 6 or 30 BR, but more with the 6.5x47 based cartridges. As for Matts example with the new 308 cases, never in a thousand years will i go that route. I will leave that one to others.

Tony.
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