Neck tension w/ N133

[SS427]

I'm getting some decent groups with my 6PPC, with a few in the teens, some in the low .2s, but a number of them are in the .3s. I'm pretty sure I can do better and I certainly want to get more consistent.

I did extensive seating depth adjustments and I'm pretty sure I have the right seating depth. Did the same thing with powder charge, and while I'm not loading at the range yet, conditions have been pretty consistent - cold and dry. 29.2 grains is my load of N133.

My understanding is N133 likes a lot of neck tension, which I am doing. Based on how the bullets seat I would not want to use more tension. So my question is, should try a little less tension to see if that improves accuracy, or should I look somewhere else?

One other place I will be looking is bullets after I mess with the tension, assuming that is what I should do. I'm using Barts 68 grain boat tails as I couldn't get the flat base variety at the time. I tried 5 rounds of Berger 68 flat base match bullets with the same load and seating depth off jam as the Barts, and got 4 into a .166 hole, but the 5th bullet was .3 out of the group. Any bullet advice?

I'm open to all suggestions. I'm just getting started and I can use all the help I can get.

 

[boltfluter]

I have tried neck tension all over the spectrum and have always come back to .002 for the best results. This is in my 6ppc and .22 Waldog both running VV133. Granted this is in my guns but hope it helps. Paul.

 

[WyleWD]

A couple questions... Is this a new or relatively new barrel? Barrel length and twist rate?

Have you tried a lower powder charge with the bullets you're using? Say about 28.3-28.7gr or so?

As PPR stated, I've tried quite a few different neck tensions trying to squeeze some more accuracy out of em, and some rifle / loads / bullets combinations like em low, some like to have a strangle hold put on the bullets.

Sounds like you have it leaning the right direction, but MAN aren't those "fliers" a PIA. Drive ya nuts sometimes. :'( WD

 

[BoydAllen]

It sounds like you may have been a tad hot on that group with the flier. After I had started shooting competition,(which I have not done for a while) the late Del Bishop counseled me that 133 likes a lot of neck tension, so I started using .003. I saw some improvement and stuck with that. I will caution you that with the advent of reamers that have larger neck diameters, that you should take this into consideration when considering any advice on this subject. My chamber has the common .262 neck that came about when that dimension was needed for the SAKO .220 Russian brass. If you have a chamber with a larger neck diameter, and correspondingly thicker necks, you will not need as much difference between sized and loaded diameters to arrive at the same seating force as would be the case with thinner brass. What is your barrel's twist? I think that BTs made on .825 jackets may be a little more twitchy to tune with a 14" twist under certain ambient conditions. What do the marks (if any) on your bullets look like? What is your charge weight?

 

[SS427]

New barrel, about 125 rounds through it. 22 inches and 13.5 twist. Have tried lower powder charges but best results were 29.2 and .006 off jam.

Boyd, the powder charge with the Bergers were based on the how the Barts were doing. I have not done a full work up with those bullets yet. I will back off the powder charge and do some 3 shot groups to see if I can eliminate the flyer. The .166 group was nice without the flyer, and the Bergers or other flat base bullets could be the ticket.

The marks on the Barts bullets are a little longer than wide. With the Bergers they were pretty much square.

I'm running .003 to .0035 tension with a .262 chamber. I think I could turn my brass neck down slightly more, as I'm running .0015 clearance. You suggested .002, but the pre-turned brass I have is slightly thicker. I'm hearing you say, along with the other posts, that less neck tension is not the way to go.

 

[mikecr]

What's the length of your neck sizing?

 

[SS427]

I assume you are talking about trim to length. 1.490 and right now they are all about 1.493. I'm not positive about the reamer that was used, but I'm pretty sure it was a 1.525 reamer.

A couple of range sessions ago I was cleaning and could feel a slight tightness due to carbon build up near the throat. I did about 10 passes with JB and it cleaned right up; at least I didn't feel any tightness.

Read your question again, and maybe you are asking how far down the neck do I size. I would say about 3/4 down the neck. I've checked closely and the pressure ring of the 3 bullets I've tried do not extend below the sized part of the neck. (I'm using a customer FL die built to the reamer specs, supplied by the gunsmith.)

 

[mikecr]

If I understand correctly you're running neck brass turned to 8.75thou thickness.
((0.262-0.0015)-0.243)/2
I don't see how you would get a lot of tension with that, and it might be less than you think.

How bout this; size a neck, seat a bullet, measure neck OD, then pull it and measure what your neck OD springs back to (your actual tension is the difference applied).
There is nothing more you can do to raise peak pressure/powder(the goal here) but obtain sized, non annealed neck IDs 3thou under cal, and/or jam your bullets, or find a quicker lot of N133.

 

[SS427]

Mike, the neck of the brass is suppose to be turned to .0083, but I get .0085 when I measure with my ball mic.

Loaded, the neck at the pressure ring measures .2607. (Clearance would be .0013, not .0015 as I said earlier.)

I'm using a .257 bushing.

According to my calculations, factoring in a spring back of .0005, I have: .2607-.2575=.0032 of neck tension. That sound about right? All my brass is currently loaded so will try your experiment later.

When seating bullets with an arbor press, I can feel quite a bit of tension, but remember I'm new to this. You seem to be implying I should step up to a .256 bushing perhaps?

 

[BoydAllen]

With single radius ogive bullets in the 7 to 7.5 range I like marks that are shorter than wide, about half to a third. This is where I started some friends with Berger 68s, and with a little powder adjustment they were into the ones, with very good conditions and excellent equipment. With double radius ogive bullets that have a bigger number where the rifling touches, I like to be close to jam, perhaps .003 to .004 off. I believe that the double radius ogive designs are less critical as to seating depth. The older designs can shoot with the newer stuff, but to me they seem to be a lot more touchy on the depth being right. IMO lots of fellows don't have an efficient load work up routine.

Boyd

 

[SS427]

Boyd, I can't figure out what sort of design the Barts boattail is. The website describes all the other Barts bullets, but only says "This is Bart's new boattail design that has been winning everywhere!" So what you said below, I can't figure out how to apply to this bullet.

I have some Barts loaded up that I plan to shoot this weekend, and if I get similar results will be developing a load around the Berger 68s. I will use your seating advice and go for marks that are half as long as wide and go both directions to 1/3 and 3/4 as long as they are wide. I will also drop the powder charge as well.

I'm followed the load work up routine detailed in the Tony Boyer book with the Barts, and will do the same with the Bergers. I sure am glad he shared all that info.

 

[bozo699]

Boyd, I can't figure out what sort of design the Barts boattail is. The website describes all the other Barts bullets, but only says "This is Bart's new boattail design that has been winning everywhere!" So what you said below, I can't figure out how to apply to this bullet.

I have some Barts loaded up that I plan to shoot this weekend, and if I get similar results will be developing a load around the Berger 68s. I will use your seating advice and go for marks that are half as long as wide and go both directions to 1/3 and 3/4 as long as they are wide. I will also drop the powder charge as well.

I'm followed the load work up routine detailed in the Tony Boyer book with the Barts, and will do the same with the Bergers. I sure am glad he shared all that info.

Yes it is a very good read isn't it? Boyds gave me some excellet pointers for the 6ppc that are not in "the" book though, Lots of knowledgable folks out here that have learned a thing or two on there way, and I have been blessed with them sharing there success with me Now if only I would apply some of it ???
Wayne