6PPC case neck wall thickness

[gene pool]

Gentlemen,

I am new to 6PPC but a long time reloader of other cartridges. Please excuse my asking basic PPC questions that I know you probably have covered in the past.

I saw in another thread where someone mentioned the wall thickness of trimmed case necks. They said “the neck of the brass is suppose to be turned to .0083.”

I turned my (first batch of) cases to .0092 which makes the loaded rounds barely fit the .262 chamber. Tolerances are so close that the brass springs back when fired thus eliminating the need to neck size for bullet tension.

My questions are, (1) is .0083 the standard for 6PPC case neck wall thickness? (2) Should I turn more off my .0092 brass? (3) Does accuracy suffer (especially fliers) with brass not turned to .0083?

Thank you in advance,
Gene

 

[BoydAllen]

Gene,
There is a tendency to think that closer clearances are somehow better. If you asked all of the top shooters in short, and for that matter long range benchrest, I would be surprised if one would tell you that he is running clearances anywhere near that close. Many have concluded that having too little clearance may not give the most consistent bullet release. One of the best I know told me recently that he shoots for something close to two and three quarter thousandth total clearance for his 6PPC. As far as some thickness being standard, pick a number you like, it will be your standard, and change it if you like. Just remember to run the cases through a one piece die that is small enough to size the necks unless you want a turning after firing to make the necks thinner next to the shoulder than forward of that. Due to the chamfer, and the need to have a small space to support the bottom of the bushing, Bushing FL dies don't quite size the whole neck, unless you are using a Jones die and bushings.

 

[potatoe]

Gene,
There is a tendency to think that closer clearances are somehow better. If you asked all of the top shooters in short, and for that matter long range benchrest, I would be surprised if one would tell you that he is running clearances anywhere near that close. Many have concluded that having too little clearance may not give the most consistent bullet release. One of the best I know told me recently that he shoots for something close to two and three quarter thousandth total clearance for his 6PPC. As far as some thickness being standard, pick a number you like, it will be your standard, and change it if you like. Just remember to run the cases through a one piece die that is small enough to size the necks unless you want a turning after firing to make the necks thinner next to the shoulder than forward of that. Due to the chamfer, and the need to have a small space to support the bottom of the bushing, Bushing FL dies don't quite size the whole neck, unless you are using a Jones die and bushings.

Meaning .00025 ish clearance? or .002-.003 clearance?

 

[BoydAllen]

Meaning that his the clearance that he is trying for would be written .00275 which I purposely did not write that way because it overstates the precision with which they are probably turned. I have bullets that have different sized pressure rings. One in particular is on the large size, .2437ish. To get to where I want to be I have turned some brass to .0079. If I were planning a new reamer. O would probably opt for .263 to get back the neck thickness that I have lost turning for more clearance.

 

[gene pool]

Gentlemen,

Thank you very much, and especially you, Boyd, for such a complete and explanatory reply. Fortunately, I only have 30 rounds of brass done this way. As for the remainder, I will turn some more off the necks.

For people like me this forum is priceless.

Gene Pool

 

[artbosco]

I saw in another thread where someone mentioned the wall thickness of trimmed case necks. They said “the neck of the brass is suppose to be turned to .0083.”

I turned my (first batch of) cases to .0092 which makes the loaded rounds barely fit the .262 chamber. Tolerances are so close that the brass springs back when fired thus eliminating the need to neck size for bullet tension.

My questions are, (1) is .0083 the standard for 6PPC case neck wall thickness? (2) Should I turn more off my .0092 brass? (3) Does accuracy suffer (especially fliers) with brass not turned to .0083?

Today's trend in a .2620" neck is to trim until the OD [outside diameter] of the loaded round measures .2600" at the pressure ring on a flat base bullet. If you're using a boattail the measurement is still .2600".

All this means is that you turn what you need [no specific number all the time] to arrive at the outside diameter with a seated bullet, in a dummy round, to achieve the desired OD. The trend in the past was to allow as little as .0005" total clearance, to as much as .0015" total clearance. Today, .002" is more the norm.

Watch these videos for further info by Jack Neary, a recent BR Hall of Fame inductee: http://www.youtube.com/view_play_list?p=7D85822FD9E41FF2

 

[bozo699]

I saw in another thread where someone mentioned the wall thickness of trimmed case necks. They said “the neck of the brass is suppose to be turned to .0083.”

I turned my (first batch of) cases to .0092 which makes the loaded rounds barely fit the .262 chamber. Tolerances are so close that the brass springs back when fired thus eliminating the need to neck size for bullet tension.

My questions are, (1) is .0083 the standard for 6PPC case neck wall thickness? (2) Should I turn more off my .0092 brass? (3) Does accuracy suffer (especially fliers) with brass not turned to .0083?

Today's trend in a .2620" neck is to trim until the OD [outside diameter] of the loaded round measures .2600" at the pressure ring on a flat base bullet. If you're using a boattail the measurement is still .2600".

All this means is that you turn what you need [no specific number all the time] to arrive at the outside diameter with a seated bullet, in a dummy round, to achieve the desired OD. The trend in the past was to allow as little as .0005" total clearance, to as much as .0015" total clearance. Today, .002" is more the norm.

Watch these videos for further info by Jack Neary, a recent BR Hall of Fame inductee: http://www.youtube.com/view_play_list?p=7D85822FD9E41FF2

I second the videos.
I was recently turned onto Jacks youtube video's by a friend and there well worth the watch, I suggest a notebook and plan on pausing and rewinding and take good notes.
Wayne.

 

[BoydAllen]

Another little trick worth knowing is that you can pick up a cheap one piece die, the kind that has an expander ball, just to keep handy for if you want to return necks. There are probably less expensive ones, but the Hornady FL die is one that I have. They make it both ways, with a bushing and without. For what I use it for you want it without. The neck of the die produces sized neck diameters (without the expander so you can evaluate the die) about like a bushing that is a little smaller than .258. With this die, you can FL size a fired case, bumping the shoulder your usual amount, and and then use your expander die and mandrel to get it ready for re-turning, confident that the entire neck has been sized, so that you do not excessively thin the part adjacent to the shoulder that a bushing cannot quite reach, unless, as I mentioned in an earlier post, you are using a Jones setup. I should add that if you happen to be using a powder that does not require as much neck tension as I believe 133 likes, that the Hornady die produces extremely straight brass.

 

[gene pool]

Thanks again to all for your comments. I copied them and put them in my PPC reloading file for future reference.

I just FL resized (without the expander ball) the fired cases and realized they needed trimming since they had grown a little. So tomorrow I will get them all the same length for the additional turning.

Gene Pool