30BR Neck Tension - Bushing Size

[gunsandgunsmithing]

Mike,

Is that enough leeway with naked bullets? I shoot 30.8 of N120 with HBN coated bullets in my Major.

Greg J.

Greg, I may be dense here but what do you mean by "leeway"?

Also, my 30 BR rifle is new and I'm thinking about coated bullets. Never used any for my 6 BR shooting but I'm beginning to learn that many 30 BR shooters use them.

Which of the coatings/processes do you recommend? I have a thumbler tumbler by the way.

Thanks - John

John, Greg was referring to what I stated as a starting load. I modified my post to say start at 29.0. I doubt you'd have any problems but, n120 is a little faster than h4198, and it is possible to put too much in a case...particularly in some barrels. You should be fine with using 29.0gr of n120 with the 110-118gr bullets as a starting point in either a 30Major or a 30BR. Just work up slowly from there.--Mike

 

[GSPV]

Exactly what Mike said.

I have shot some primer pockets loose shooting naked bullets with coated bullet powder charges. Just trying to keep that from happening.

Greg J.

 

[GSPV]

I'm not the best on the coating deal. I have a pretty simple way of doing it. Here goes.

o I use Lyman's Super Moly kit except that I throw away the moly and use HBN.
o I got my HBN from

Tom Madden
TAI Lubricants
PO Box 1579
Hockessin, DE 19707
USA
(302) 326-0200
(302) 326-0400 fax
nyoil@aol.com
www.lubekits.com

The process runs like:

1. Wash the bullets off in acetone and let them dry. Afterwards, avoid contaminating them in any way.
2. Get the impact media and the bullets hot. I put them in the oven at 200 for 30 minutes.
3. I put 1/2 teaspoon of HBN in the media, put on the cover and let them go for 4 hours.
4. After sorting them out of the media, I "polish" them by running a few at a time back and forth in old hunting socks. I use three socks in series about 30 seconds per batch per sock.

I'll try to post pictures this evening.

 

[22turborimfire]

Greg,

Thanks very much, how long have you been shooting this coating and what or how do you clean your barrel after ? My email address is Haggoodlooking@aol.com if you choose to email me . Thanks for any and all the info you have ..



Jim W

 

[tenring]

Forgot I saved this old Robinett article on the OP question:

Though 'neck-tension', bushing size, seating depth are not, "carved in stone", most barrels will provide TOP performance using 0.002" of total neck-clearance (in this case, a .328" loaded-round neck diameter, as measured across the heel of the seated bullet) and sizing with a .324" bushing. Often, less 'neck-tension' makes for somewhat poor grouping . . . but, all barrels are not created equal, so, some experimenting may be in order . . .

"but i used this formula 330-308=22/2=11" - assuming that you are experiencing disappointing performance, this could be a large part of your "problem". With a bullet sans a pressure-ring (rare on a custom, hand-swaged bullet - most will have a 0.0003" to 0.0004" pressure-ring), you are set up for ZERO clearance between the case-neck and chamber: you have a force-fit; your actual loaded-round neck-diameter (with a custom bullet) is probably about .3304"!

Again, while not an absolute, neck clearance ranging from 0.0015" to about 0.003" has a proven performance record. If you own a 30BR chambered barrel (.330" neck diameter) which does not shoot acceptably small groups, using the 'default' .324" neck bushing, .328" loaded round [neck-diameter], and a 'jam-seat', you have an unusual barrel - not necessarily a bad one, just somewhat out of the norm: you'll have to "hunt-up" what your barrel 'wants' . . .

MORE neck-tension is usually a good thing, less, not so good . . . but, either way, it appears that you NEED some clearance - .011x2= .022"+.308"=.330" . . . with a 'custom bullet, thus pressure-ring, you are forcing the loaded round - remember, about .3304" - into the [.330"] chamber. Good shootin'! RG