6mm BR bullet seating question

[firebal]

I have just purchased 12F ( Savage) 6BR rifle and am having difficulty understanding bullet seating depth. My chamber is 1.583" in length and I'm having trouble keeping the heavier bullets off the rifling without jamming base of bullet through primer. Seems like the bullet ogive is so high....... What am I doing wrong.? Years ago I used to load for .243 and .22-250. No problem then, but I must be forgetting something....Help

 

[fdshuster]

firebal: Most everyone I know is using the Hornady (formerly Stoney Point) chamber OAL gauge to determine bullet seating depth. If you bought the 8 twist, it should be throated for the heavier/longer bullets. With that in mind, I don't understand your "jamming base of bullet through primer". On the other hand, if yours is the slower (12?) twist, it may have a shorter throat, not really suitable for the "heavyweights", since the 12 would not stabilize them anyway. Can you provide more info on the rifle and bullets used? Feel free to send a PM.

 

[firebal]

Sinclair Chamber Length Gauge........Before that I used an empty fired case and slipped a bullet, painted with marker ink, in case and chambered it to find barrel lands for that particular bullet. Measured, of course. Then I could load to either jump or jam off that baseline measurement.....

 

[fdshuster]

firebal: PM sent

 

[firebal]

May be I should have given more info.....1) It's a 1:8 twist
2) Sinclair "plugs" are inserted into trimmed case of like cal. which, when chambered, ends up giving you length from base of cartridge to lands of rifling when removed and measured. That's how I got 1.583.....Case length should be/is 1.560"
3) I have old "Stoney Point", but they don't offer case in 6mmBR.
4) Due to twist and 30" barrel, my best shot (pardon pun) is any 95 to 108 gr bullet.
5) I may just go back to putting different bullets in fired case and "paint" bullet with marking ink to measure where ogive hits lands on rifling,

 

[LHSmith]

May be I should have given more info.....1) It's a 1:8 twist
2) Sinclair "plugs" are inserted into trimmed case of like cal. which, when chambered, ends up giving you length from base of cartridge to lands of rifling when removed and measured. That's how I got 1.583.....Case length should be/is 1.560"
3) I have old "Stoney Point", but they don't offer case in 6mmBR.
4) Due to twist and 30" barrel, my best shot (pardon pun) is any 95 to 108 gr bullet.
5) I may just go back to putting different bullets in fired case and "paint" bullet with marking ink to measure where ogive hits lands on rifling,

Those plugs measure where your chamber neck ends. You have to find out your leade...which varies greatly. Try using 000 steel wool on the bullet instead of marker to highlight the engraving.
Also those Sinclair plugs are chamber neck dia. specific.....make sure you mike them to see what you have.
Hornady (who now makes the Stoney Point tool) does indeed make a modified case in 6 BR.... but you should verify the neck dia. of this modified case is compatable with your Savage

 

[fdshuster]

firebal: O.K. now I understand. Your 1.583" measurement was taken with the Sinclair chamber length gauges, and you have a .023" gap in front of your seated case: case length 1.560", chamber length 1.583". I've used the same gauges on all my chambers. Your job now is to establish bullet seating depths using any one of the before described methods. I do prefer the Stoney Point/Hornady OAL gauge, and as LHSmith mentioned 6BR modified cases are available. Hornady is making them with a .272"/.273" neck diameter, so you would not have any problems with your factory no-turn neck, if you decide to use your Stoney Point tool for throat dimensions.

 

[SS427]

FYI - My Hornady 6BR modified case wouldn't fit into my no turn .272 chamber because it is expanded so the bullets slip in and out. I had to turn it down to get it to fit. No big deal, just be aware it may not fit otherwise.

 

[firebal]

OOK..............Thanks everyone. I didn't see the 6br case offered where I looked to purchase. They had everything but......... I will look elsewhere....And I will check plug dia........Again, thanks much.

 

[fdshuster]

firebal: Modified 6BR case available from : Midway, new master catalog #33, page 316, product# 153-820, $4.99. Sinclair Intl. catalog #2009B, page 29, item# CFG-6BR, $5.50. Otter: You are correct about the new Hornady cases being oversized in the neck. A friend of mine bought one and said he spent a lot of time reducing the neck diameter with emery paper to get it to fit in his no-turn .272" neck. he also said Hornady includes a warning note that the neck dia. may have to be reduced. I bought mine when they were still being made by S.P, and the neck dia., as purchased is .263", easily fitting in my .265" necked chambers (2). Just measured the neck wall thickness with a tubing mic, and it is .0095", as-purchased: I never outside neck turned it.

 

[lpreddick]

re the 6mmbr modified case: after my gunsmith chambers a new gun for me he fires a few rounds then threads one to screw onto the hornady gauge. i can then measure case base to ogive bearing with every bullet i care to try. the generics work but a case fired in the chamber is probably more accurate. at on time i had 3 22-250s with different chambers so i engraved the guns name/lable on the side of the case to avoid using the wrong one in measuring.

if i can see you, i can touch you.BANG!