Pressure ring and neck tension

[PopCharlie]

I have a new 6br that I have been working on loads for. I'm using 95 gr. Bib FB bullets. This batch has a .2437 pressure ring, per the box they came in. I have been accounting for the pressure ring when setting neck tension. My rifle has a .266 neck, so I turn necks to .010. What I've been doing is sizing with a .262 bushing, then using a .2425 pin to set the neck tension. This give me about .0015 tension, including pressure ring. So far I have not been pleased with the groups, but I have been seating bullets to varying depths, all below jamb, like jamb -.003, -.006, etc. I just loaded 25 rounds, same tension, but jamb + .003, +.006 etc to + .015. 5 rounds each. Just curious, should I account for the pressure ring when figuring neck tension? Am I heading in the right direction?
This rifle has an 8 twist Bartlein barrel. .266 neck with .060 freebore. Defiance Rebel action.

PopCharlie

 

[Bill Norris]

Following.

 

[HTSmith]

I was hoping someone smarter than me would chime in but its been a while so what the heck. To me the measurement that counts the most is the neck diameter with a bullet loaded. In your case the largest neck diameter may be across that pressure ring. Then compare that to your bushing or pin. I suspect you are a little light on neck tension, but that may or may not make a difference depending on powder etc. So far as seating depth, I generally start as deep into the lands as I care to go (I don't like a hard bolt close) and work back. Mr. Robinette is great source of info, so a call could be in order. A well built 6BR shouldn't be too hard to get to shoot.

 

[BondJamesBond]

I don't throw my 2 cents in very often due to the knowledge on this site but I think your neck tension sounds pretty close to me, if you like light neck tension. I do...it gives me super consistent BTO measurement.
But more important it sounds like seating depth testing isn't complete, then a fine tune of powder after that.
Then micro adjustments on neck tension if your barrel likes the load.
The advice above is gtg, If you restart load dev. seating .010-015 jammed (then back out testing) but see if the bullet moves after bolt close, if it doesn't your golden IMO
What do your groups look like?

 

[KenOath]

I have a new 6br that I have been working on loads for. I'm using 95 gr. Bib FB bullets. This batch has a .2437 pressure ring, per the box they came in. I have been accounting for the pressure ring when setting neck tension. My rifle has a .266 neck, so I turn necks to .010. What I've been doing is sizing with a .262 bushing, then using a .2425 pin to set the neck tension. This give me about .0015 tension, including pressure ring. So far I have not been pleased with the groups, but I have been seating bullets to varying depths, all below jamb, like jamb -.003, -.006, etc. I just loaded 25 rounds, same tension, but jamb + .003, +.006 etc to + .015. 5 rounds each. Just curious, should I account for the pressure ring when figuring neck tension? Am I heading in the right direction?
This rifle has an 8 twist Bartlein barrel. .266 neck with .060 freebore. Defiance Rebel action.

PopCharlie

So your bullet/Prodgie at the widest point measures .2437” in diameter ?

Reason I ask is a common free bore diameter is .2436-.2438”….some even .244”.

 

[PopCharlie]

So your bullet/Prodgie at the widest point measures .2437” in diameter ?

Reason I ask is a common free bore diameter is .2436-.2438”….some even .244”.

Yes, the bullet at its widest point is .2437, per the box the came in from the manufacturer. My caliper (Mitutoyo) shows them to be .244.
PopCharlie

 

[JFrank]

I believe that you would need a mic to measure that pressure ring correctly.

 

[PopCharlie]

I don't throw my 2 cents in very often due to the knowledge on this site but I think your neck tension sounds pretty close to me, if you like light neck tension. I do...it gives me super consistent BTO measurement.
But more important it sounds like seating depth testing isn't complete, then a fine tune of powder after that.
Then micro adjustments on neck tension if your barrel likes the load.
The advice above is gtg, If you restart load dev. seating .010-015 jammed (then back out testing) but see if the bullet moves after bolt close, if it doesn't your golden IMO
What do your groups look like?

Group's are not great. I usually get 2 to 3 shots it a single hole, then 2 shots outside the group, opening the group up to about .5. Sometimes sometimes all 5 shots are scattered in a cluster at .5 at the widest. The rifle is new, it has 200 rounds through it. I shoot at 100 yards. That's all I have access to.
I decided to jamb the bullets after reading info on this site. I usually don't jamb bullets.
Seating depth has been very consistent. Witin .0005, best as I can neasure. I use a Short Action Custom bullet comparator. I use an KM arbor press with a Wilson Micro-top seating die. I have the force pack installed as well. With neck tension set as i describe in my OP, I get 14 to 16 lbs of seating force. I have not chambered a round to see if the bullet moves. I will try that.
PopCharlie

 

[KenOath]

If they are actually .2437”, you might want to check the reamers fb diameter, eg. if it’s a .2436” and the bullet has a diameter of .2437” it’s making contact with something before the rifling/ lands… possibly not good for accuracy..

 

[Webster]

I have a new 6br that I have been working on loads for. I'm using 95 gr. Bib FB bullets. This batch has a .2437 pressure ring, per the box they came in. I have been accounting for the pressure ring when setting neck tension. My rifle has a .266 neck, so I turn necks to .010. What I've been doing is sizing with a .262 bushing, then using a .2425 pin to set the neck tension. This give me about .0015 tension, including pressure ring. So far I have not been pleased with the groups, but I have been seating bullets to varying depths, all below jamb, like jamb -.003, -.006, etc. I just loaded 25 rounds, same tension, but jamb + .003, +.006 etc to + .015. 5 rounds each. Just curious, should I account for the pressure ring when figuring neck tension? Am I heading in the right direction?
This rifle has an 8 twist Bartlein barrel. .266 neck with .060 freebore. Defiance Rebel action.

PopCharlie

I would think that since the pressure ring is only a few 10 thou bigger than the bearing surface that springback is sufficient that contact is always made between the case neck the bearing surface and the pressure ring. Because the bearing surface contact is much larger than the pressure ring contact, the bearing surface grip is by far the biggest contributor to resistance to bullet release. What does Tony Boyer do?

 

[WIB3]

Check your mike with a gauge pin to verify that It is reading correctly. I am not a FB shooter but.2437 seems a little fat. We are working with extremely small tolerances be sure your measurements are dead on. Starting with neck turning and moving forward. Measure a loaded round at the PR. I personally like a clearance of about .003 . There is really no need to get any tighter. If with a .266 neck, your fired cases should be around.2650 ish. With only half of the neck, the back portion closet to the shoulder will always keep your loaded round concentric with the bore.

 

[WIB3]

The 6br is a very accurate cartridge right from the start. By no means an I trying to insult anyone on this forum. A novice will have good gratification with the cartridge but it will always get better for those who put forth the effort. Measure, measure and measure. There are many who claim that they are capable of measuring to a .0001. Very few can. Measuring that small requires more knowledge than just purchasing a high dollar mic and having no idea how to set it up. Furthermore, don’t have absolute trust in the box of bullets which states a .2437pr. Bullet makers don’t have the time to measure every bullet. As a competitive shooter, hate to say it, that is your job. Give yourself a little wiggle room in your loaded rounds.

 

[dkhunt14]

Most of my guns like a little more tension then your using. Especially if you shoot them in the lands. Without tension they get pushed back in the case. It would be hard to have them all push the same amount. I like at least .002 tension. Another thing I dont like, is if the pressure ring is seated past the sized part of the neck. Matt

 

[PopCharlie]

Most of my guns like a little more tension then your using. Especially if you shoot them in the lands. Without tension they get pushed back in the case. It would be hard to have them all push the same amount. I like at least .002 tension. Another thing I dont like, is if the pressure ring is seated past the sized part of the neck. Matt

I am jambing, but this time I will load with .003 tension. That's all I'm changing this time. The flat base bullets I'm using are not seated past the sized part of the neck.
95 gr Bib FB. It'll be fun to see what the do.
PopCharlie

 

[RGRobinett]

I am jambing, but this time I will load with .003 tension. That's all I'm changing this time. The flat base bullets I'm using are not seated past the sized part of the neck.
95 gr Bib FB. It'll be fun to see what the do.
PopCharlie

PopCharlie, I'm with dkhunt14 here - I'd begin at least 0.003" smaller than the measurement across the seated pressure-ring (.263" for .266" loaded round). RG

P.S. Oh, I forgot: do away with the expander also.

 

[geo.ulrich]

after you fire a round before resizing can you slide a bullet in with no drag. if you can't necks are to thick seems .010 is pretty thick for .266 nk dia... try turning a few smaller like .009... also fb bullets and freebore dia. are not that picky, base of bullet swells when powder is ignited just the opposite of b.t bullets.. what powder and charge are you using...

 

[PopCharlie]

after you fire a round before resizing can you slide a bullet in with no drag. if you can't necks are to thick seems .010 is pretty thick for .266 nk dia... try turning a few smaller like .009... also fb bullets and freebore dia. are not that picky, base of bullet swells when powder is ignited just the opposite of b.t bullets.. what powder and charge are you using...

With this load, I'm using 29.1 gr Shooters World Precision Rifle and BR-4 primers. ES has been ok, at around 15. Average velocity is about 2630. It's a mild load. Once I get the seating depth/tension righat, I'll walk the powder charge up.
PopCharlie

 

[PopCharlie]

PopCharlie, I'm with dkhunt14 here - I'd begin at least 0.003" smaller than the measurement across the seated pressure-ring (.263" for .266" loaded round). RG

Thanks for chiming in Randy. I'm gonna run .003 for this batch I'm loading now.
BTW: Thanks to everybody for their posts.
PopCharlie

 

[geo.ulrich]

With this load, I'm using 29.1 gr Shooters World Precision Rifle and BR-4 primers. ES has been ok, at around 15. Average velocity is about 2630. It's a mild load. Once I get the seating depth/tension righat, I'll walk the powder charge up.
PopCharlie

In my experience your velocity is WAY low. most shoot 103's at around 2950. your shooting a lighter bullet which should run a little faster.. I have no experience with the powder you are using but will say its not really one of the go to powders for the b.r. case.. try 4895 or vv135.. I wouldn't even bother with e.s. get the thing to group then check velocity....

 

[PopCharlie]

In my experience your velocity is WAY low. most shoot 103's at around 2950. your shooting a lighter bullet which should run a little faster.. I have no experience with the powder you are using but will say its not really one of the go to powders for the b.r. case.. try 4895 or vv135.. I wouldn't even bother with e.s. get the thing to group then check velocity....

I have been using H4895 with 90 gr Berger BT. I'm also just starting to use n140. I don't have enough n135 to really test anything.