Best Bullets for a 1.560" Case Length/Zero FB 30BR Chamber

K

Kyle Schultz

Member
I'm a F-Class shooter who is buying a used 30BR rig to shoot in local VFS matches. The package does include a newly chambered 30BR barrel. The reamer used to cut the chamber has a 1.560" case length with zero free bore. 0.330" neck.

I've already bought 100 pcs of necked-up 6BR brass from a local friend. He advises the case length prior to any trimming runs about 1.525". I'm well aware of the fire forming methodology used by Jackie Schmidt (and others I'm sure) that yields brass in the range of 1.55" before trimming. However, I don't have a spare 6BR barrel available and I would have to hire a gunsmith to open up the 6BR neck to .330". Then I would still have the component expense of fire forming the brass.

My plan right now is not to trim the necked-up brass for now. Maybe after 2 or 3 firings, the necks will grow and I can trim the brass to something near 1.54". I know I'll have to deal with carbon ring issues. And at this point, given my inexperience, I don't know whether the 112-1118gr custom bullets like to jump or be jammed.

I'm hoping the community might offer some guidance as to specific bullets and their relative seating depths that might be appropriate for this chamber I'm inheriting. TIA!
 
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I think you should...

TX_Oilman said:
I'm a F-Class shooter who is buying a used 30BR rig to shoot in local VFS matches. The package does include a newly chambered 30BR barrel. The reamer used to cut the chamber has a 1.560" case length with zero free bore. 0.330" neck.

I've already bought 100 pcs of necked-up 6BR brass from a local friend. He advises the case length prior to any trimming runs about 1.525". I'm well aware of the fire forming methodology used by Jackie Schmidt (and others I'm sure) that yields brass in the range of 1.55" before trimming. However, I don't have a spare 6BR barrel available and I would have to hire a gunsmith to open up the 6BR neck to .330". Then I would still have the component expense of fire forming the brass.

My plan right now is not to trim the necked-up brass for now. Maybe after 2 or 3 firings, the necks will grow and I can trim the brass to something near 1.54". I know I'll have to deal with carbon ring issues. And at this point, given my inexperience, I don't know whether the 112-1118gr custom bullets like to jump or be jammed.

I'm hoping the community might offer some guidance as to specific bullets and their relative seating depths that might be appropriate for this chamber I'm inheriting. TIA!
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I think you should just neck up 6BR cases to 30, turn necks as needed and fire form. The cases will expand to conform to the reamer dimension. Regarding 0 freebore, I prolly would start with .925" jacket bullets or something close. A 1" jacket 118 gr may work but if it has a pressure ring it may slip down below the sized portion of your neck, depending on what you size the neck with. good luck with your new acquisition.
 
TX_Oilman said:
I'm a F-Class shooter who is buying a used 30BR rig to shoot in local VFS matches. The package does include a newly chambered 30BR barrel. The reamer used to cut the chamber has a 1.560" case length with zero free bore. 0.330" neck.

I've already bought 100 pcs of necked-up 6BR brass from a local friend. He advises the case length prior to any trimming runs about 1.525". I'm well aware of the fire forming methodology used by Jackie Schmidt (and others I'm sure) that yields brass in the range of 1.55" before trimming. However, I don't have a spare 6BR barrel available and I would have to hire a gunsmith to open up the 6BR neck to .330". Then I would still have the component expense of fire forming the brass.
I
My plan right now is not to trim the necked-up brass for now. Maybe after 2 or 3 firings, the necks will grow and I can trim the brass to something near 1.54". I know I'll have to deal with carbon ring issues. And at this point, given my inexperience, I don't know whether the 112-1118gr custom bullets like to jump or be jammed.

I'm hoping the community might offer some guidance as to specific bullets and their relative seating depths that might be appropriate for this chamber I'm inheriting. TIA!
Click to expand...

My reamer actually makes a chamber with a 1.550 overall length. The cases generally come out of my fireform barrel at about that length. I trim them to 1.545.

If you make cases by necking them up in the conventional manner, they will be quite a bit shorter. It's a product of pushing material back instead of blowing it forward.

They will never grow enough to make any difference. I have cases that I have fired 15 to 20 times, and they have only grown about .005 inch. That means you will always have about .040 or so between the end of the case and the end of the chamber's neck.

I really don't know how big of a problem this will be. Maybe none. But the way VFS has evolved, you really don't want to leave anything on the table as far as the Rifle goes. It's a pretty tough game.

I tell you what I will do for you. If you have fifty brand new primed and sorted Lapua 6BR cases, send them to me and I will blow them out for you. You can trim them, and neck turn them afterward.

At least you will start out right.

They will last a long time.

I shoot either Bart's 112's or BIB 112's. I shoot both with 4198 at around 3040 fps with around a .010 jump and very light neck tension.

I've won with both, and lost with both.:p

The "Zero" freebore will work fine with a BIB 118. Randy's 118 has a higher number ogive, and will actually be in the case about the same as 112, even though it's made on a tad longer jacket.
 
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So, what is the preferred Free Bore for a 30BR Chamber? I am going to have a 30BR Barrel chambered for my BAT 6PPC and was planning on using the 95 Grainers.

Bob
 
I agree,,,,Benchrest is loaded with tallented people that are willing to help their fellow shooters,,,we all learn and grow together,,,,the biggest lesson to learn is that no one beats us ,,we beat ourselves,,hahaha,,,there are no losers ,,,,,Roger
 
I'm proud of you, Jackie!

After perusing and even stating, my opinions/experiences, on the "recruiting thread" (classes for Br), this generous offer exemplifies THE best of benchrest! :cool: 'Atta boy, Jackie! :D RG
 
Well, he is sending me 100. Those will do him for 3 years.

Let's just say he caught me in a generous mood:cool:
 
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Bob, depends on the bullet

rkittine said:
So, what is the preferred Free Bore for a 30BR Chamber? I am going to have a 30BR Barrel chambered for my BAT 6PPC and was planning on using the 95 Grainers.

Bob
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I am not familiar with 95 grainers, but I will assume they are short. Do you know the ogive of that particular bullet? I shoot bullets on the .925 jacket from 7 to 8 ogive and mine has zero freebore. If I use a 7 ogive 118 grain bullet on the 1" jacket, I have difficulty maintaining seating as my compressed charge will float the bullet out a few thousandths. If the seating is finicky then it is problematic and needs reseating just prior to going to the line. As Greg mentioned, the other issue with little to no freebore and depending on sizing die, is the longer bullet may be seated deeper into the case beyond the point the neck is sized by the die. I don't think you would have any of those issues shooting a 95 grainer. If you are unsettled on a particular bullet and may experiment for life, then having some freebore, .010-.030" may be a better option than zero. Hopefully more knowledgeable shooters can provide better/more definitive advice. I do not know of anyone shooting the 30br that has more than .030" freebore but neither do I know of anyone anyone using more than a 122 grain bullet in the 30br.
 
Thanks, I am not sure I know what the measurement is. I was going by the recommendations on another site for 30BR and questioned the Aero Free Bore. They talked about 90 and 95 grain projectiles. I want to do the right thing when I purchase the barrel and have it chambered for 100 yard score shooting.

Bob
 
rkittine said:
So, what is the preferred Free Bore for a 30BR Chamber? I am going to have a 30BR Barrel chambered for my BAT 6PPC and was planning on using the 95 Grainers.

Bob
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The answer to the free bore questions is "zero".

There is no reason to shoot anything heavier in a 30BR VFS Rifle than a 118. The heavier bullets will do nothing but produce more recoil.

A well tuned 30BR with top quality 112-118 grn bullets coming out of a 1-17 or 1-18 twist will rival any chambering on the planet for pure accuracy.
 
Did not mean to steal the thread, but was thinking along the same lines and thank you for the input.

Bob
 
It pays to know the jacket length and ogive.

rkittine said:
Did not mean to steal the thread, but was thinking along the same lines and thank you for the input.

Bob
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When selecting bullets for various 30BR, or, other 30 Cal. "throats", and bullets of 125 gr., or less, bear the following in mind:
1) ZERO free-bore X 1.5 Deg. lead angle - opt for 7-8 ogive bullets based upon the .925" long jacket, or,
9-10 ogive bullets based on the 1.00" long jacket. With the bullets seated to just touch the lands, all of these combinations will place the bullet-base approximately mid-neck, or, slightly less.

2)Any free-bore length in excess of 0.010", with a 1.5 deg. lead angle, use 7-8 ogive bullets based upon the 1.00" long jacket - this free-bore length, in combination with a .350" long neck, will accommodate seating up to a 155 Gr. bullet, based upon the 1.150" jacket length, while keeping ALL of the bullet in the neck. Free-bore in excess of 0.010" rapidly limits bullet length/weight options.

3) The combination of ZERO free-bore x 1.5 deg. lead, and 7-8 ogive bullets, based upon the 1.00" long jacket, with the most popular/useful powders (H-4198 & N-130), will result in greater compression of the powder charge.
With too little neck-tension, this may result in the powder charge pushing the bullet enough to alter the seating-depth: simply use a smaller/tighter neck-bushing, which, for thirty calibers, usually, but not always results in smaller Agging, than less grip.
a) If your sizing die does not resize either all, or, most of the neck - say, all but the last 0.060" or so, have it altered to accommodate doing so.
b) or, see 1) above & shoot/use 7-8 ogive bullets based upon the .925" long jacket.

Here are a few (relative) 30 cal. bullet shank length comparisons, obtained with my OLD (original black) Sinclair
[hexagonal] bullet comparator - of course, these are for my bullets, and your bullets may vary:p:

1) 112 Gr., 7 caliber tangent ogive - .360"
2)118 Gr., 10 caliber tangent ogive - .330"
3) 118 Gr., 7 caliber tangent ogive - .420"

Again, though dies/bullets of supposedly the same nose configuration(s) vary, bullets of the "same" ogive should be relatively close (me'plat/knock-out pin diameter will make for differing nose/shank lengths) - there are numerous variables.:eek:

More , as Bob Dylan would say, of my, "useless and pointless knowledge" - a lead angle of 1.5 Deg is a"best" match for bullets featuring 9-10 caliber tangent ogive; a 1.75 Deg. lead angle is almost perfect for tangent 7 caliber nose radius! :eek::p

Seating-depth is a variable which cannot be compared - not even from reamer-to-reamer from the same maker, ground to the same "print" - most reamer makers work to +/- 1/4 Degree angularity . . . so, your .1.5 deg. could be anywhere between 1.25, and 1.75 degrees . . . I'll leave the length calculation(s) to you!:p

It's a miracle that any of this stuff works . . . Keep 'em ON the X! ;)RG

P.S. An important attribute of ZERO free-bore: the cone diameter must begin at the chamber-mouth, and at, "not less than 0.3085" - this accommodates getting the bullet against the lands: a "ring" around the [bullet] circumference, though not a total wreck, is undesirable: individual land marking is desirable.
 
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R.G. Robinett said:
More , as Bob Dylan would say, of my, "useless and pointless knowledge" -

-An important attribute of ZERO free-bore: the cone diameter must begin at the chamber-mouth, and at, "not less than 0.3085" - this accommodates getting the bullet against the lands: a "ring" around the [bullet] circumference, though not a total wreck, is undesirable: individual land marking is desirable.
Click to expand...

The 'cone' diameter makes a big difference, in our experience. With the throats done as a seperate operation (no throat on the chamber reamer), we had plenty of chances to experiment with .3084-.3088 measured diameters after cutting. .3085 & .3086 were indistinguishable 'on target' at both 100 and 200 yds., at .3087 things were still pretty good at 100 yds. but started getting herky at 200.

And since Randy waxed Dylan-esque :cool: with his lyric from "Tombstone Blues" (from Highway 61 Revisted), I'll add that heeding R.G.s advice on throats will keep you from getting "Tangled Up In Blue..." (from Blood on the Tracks). :cool:
 
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