Preparing 30BR brass

[mk_gram]

Wes,

When Hart installed the new 30BR barrel they also worked the bolt for the new caliber and it work well. Thanks for the tip,

 

[artbosco]

I measured the chamber length of my rifle and it is 1.567 and the brass length after expanding is 1.525 (+/- .001). This means the freebore is .042 but I still have to trim the case length to have them all uniform. If I trimmed them all to 1.520 I would have .047 freebore (I assume "freebore" is the difference between case length and chamber length).

1) Should I shoot them once without trimming the length and then trim?
2) Will the brass length get longer after I shoot them the first time?
3) What should the maximum freebore be?

Freebore is the distance from the leading edge of the neck chamber to the beginning of the barrel's rifling.

Click here to see a picture of where freebore is located: http://benchrest.com/attachment.php?attachmentid=9251&d=1267208204

What you appear to have is an inordinately long chamber for a 30BR. Right now I'd say you have no idea how much freebore you actually have. The best way to find out is to obtain a drawing of your reamer. By looking at the dimensions on the print you'll be able to assess exactly what your freebore is, assuming the actual chamber was reamed to the prints dimensions.

When I first open a box of Lapua 6mmBR brass the case length usually measures a + or - .0005" inch of one another, and is approximately 1.550 inches long. When I expand mechanically with a K&M Expand Iron the case shrinks to approximately 1.520". During fire forming it shrinks a little further, albeit not much. It does not get longer, it gets shorter. Take measurements as you're preparing the brass to verify these facts for yourself.

I'd recommend you do not trim until after you fire form and then trim to 1.500 inches for uniformity. Max freebore depends on the length and ogive of the bullets you intend to use. Review this article for recommendations: http://www.accurateshooter.com/cartridge-guides/30br/

I just happen to use Zero freebore, 118 grain, Ronnie Cheek bullets built on a .925" jacket with a 9 ogive. Once you find out what your true freebore is then you can make decisions about what bullets might perform well in your rifle.

I highly recommend you read and reread the article I referenced above, and don't be afraid to call some of the experts who graciously provided that information. They're extremely helpful.

 

[mk_gram]

Outdoorsman,

The diagram was very helpful. Once I have gotten this sorted out I am going to write a "30BR Case Preparation and Loading Instructions for Dummies" myself. I have found the information on the website is very helpful but not enough information for someone who lacks basic knowledge.

It appears that I will have a gap of .040+ between my case length and chamber length. I don't think there is anything I can do about that. I thought maybe I would buy some Remingtom 7mmBR or Norma 6mmBR brass and see how long the case lengths are. I guess I could complain to Hart if the rifle will not shoot because of the .040+ gap.

I have turned the necks on 10 cases and found the equipment was very well made (K&M Neck Turner and the K&M Expander) and easy to use. The expander has a depth guage screw and it appears you can use this or not. I had to cut the screw length by 1/4 of an inch so it would work for my cases.

Thanks for all the input!!!

Mark G.

 

[P1ZombieKiller]

Outdoorsman,

The diagram was very helpful. Once I have gotten this sorted out I am going to write a "30BR Case Preparation and Loading Instructions for Dummies" myself. I have found the information on the website is very helpful but not enough information for someone who lacks basic knowledge.

It appears that I will have a gap of .040+ between my case length and chamber length. I don't think there is anything I can do about that. I thought maybe I would buy some Remingtom 7mmBR or Norma 6mmBR brass and see how long the case lengths are. I guess I could complain to Hart if the rifle will not shoot because of the .040+ gap.

I have turned the necks on 10 cases and found the equipment was very well made (K&M Neck Turner and the K&M Expander) and easy to use. The expander has a depth guage screw and it appears you can use this or not. I had to cut the screw length by 1/4 of an inch so it would work for my cases.

Thanks for all the input!!!

Mark G.

If you get the right tools, slow down enough to know and understand what it is you should be doing, this process is pretty easy. I'm glad you are on the right track.

 

[25AI260]

MK_...
i think if you were to fire form your cases you'd get a longer neck then mechanically forming... i see no reason to trim way back to 1.500
you didn't mention or i mis it what twist rate your barrel is... ?

IMO..the threads on on 'how to' although is somewhat helpful sounded much to me as a sales pitch
it got off a little negative in the begging turning necks in a commercial chamber doesn't seem dollar for layout worth for what Mite increase accuracy also the fact of trimming the brass .003 or .004 off the necks in a .005 oversized chamber should lead to cracked necks an shoulders down the road all that work an money an have cases go in 2 or 3 firings ..... ! i really didn't finish reading it.

Outdoors"""
[Rich,
The use of an expander ball is not part of the turning process and introducing the Hornady turner along with the K&M turner is complicating matters.]

i didn't say the expander ball was part of turning necks, what i said was i used it to make it fit... sorry if i implied that, what ever works at the time
also you mentioned introducing the hornady neck trimmer wasn't good ... could explain that i not really sure i get what you mean....?

ps/ MK_ go ahead write for 'dummies' we all learn may something new! ... good for you

 

[artbosco]

Outdoorsman ... you mentioned introducing the Hornady neck trimmer wasn't good ... could you explain?

You used the word "trimmer" in the above question, did you mean "turner"?

My response below is based on the assumption you meant turner.
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I read your earlier statement to mean you were introducing another turner ["i use the Hornady to skin the neck"] as the first tool used to turn necks.

If that was the situation, then after you expanded with the K&M Special 6mm to 30 caliber mandrel, your necks would have expanded to a diameter created for use on the K&M Turner Mandrel.

Unless the Hornady Mandrel is EXACTLY the same diameter as the K&M Mandrel, you end up with brass that's turned to a different dimension because of how it sits on the mandrel.

By using two K&M Turners with the same size K&M Mandrel, you are more likely to have all cases fit the mandrel with the same degree of tightness and get a more consistent depth of cut.

Consistency, in your end product, is what you're trying to achieve. Regardless of company, when turning, always use tools by the same manufacturer.

 

[mk_gram]

Today I turned 10 pieces of brass and then loaded them with 37 grains of H4198 powder and 115 grain bullets. I went to our local range and fire formed the 10 rounds. I was very pleased with the results. I also had to get my scope adjusted. Although I only shot at 50 yards the final 3 were dead center with about a 3/8 inch single hole. The brass is about .001 shorter in length. It seems the .040 gap between chamber length and case length is not too big of a problem.

 

[mk_gram]

I did not answer some questions but here is some information that will answer some of them. The barrel twist is 1:18 and the neck diameter is .333.

In all the information I read there is nothing I found about min/max powder loads. I am using H4198 powder with 115 grain bullets.

Mark G.

 

[P1ZombieKiller]

Today I turned 10 pieces of brass and then loaded them with 37 grains of H4198 powder and 115 grain bullets.

37???? thats pretty hot. Did you check for pressure signs? I don't know anyone shooting that much powder in their 30BR. I use 33.4 of H4198.

 

[artbosco]

Today I turned 10 pieces of brass and then loaded them with 37 grains of H4198 powder and 115 grain bullets.

It seems the .040 gap between chamber length and case length is not too big of a problem.

As Wes mentioned above, 37 grains is a real hot load and not necessarily the most accurate.

I use 34.5 because of the results I get, and after discussing where the accuracy nodes are for H-4198, with Randy Robinett.

And, as you'll see when you take a look at the chart on this page: http://www.accurateshooter.com/cartridge-guides/30br/ , some of the founding fathers, including Randy and 30 BR Shooters of the Year, don't come close to a charge like that either.

Look at the H-4198 loads preferred by Randy Robinett, Al Nyhus and Joe Entrekin.

I would suggest, that through competitive experience, they learned something about the dynamics of this cartridge, the loads it prefers, and where the accuracy nodes are.
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When cleaning, it's recommended that you spend extra time in the .040" gap area with a brush that contains JB Bore Cleaning Compound each time you clean.

Spin the brush about 30 revolutions. This will ensure that the inevitable carbon, which is going to be deposited there, does not continually build up.

A build up in that gap, will affect accuracy. Guaranteed.

 

[25AI260]

Outdoors""".. yes i meant turner sorry..
i understand what you meant now i can see a posible problem there effecting consistency in the loads.. although using the K&M lastly which fit tighter should be better then the other way around... since this has all been done pre firing it probably ? isn't make a drastic difference..
all the prep work on these cases from here on will if needed will be with one tool/brand... i hear ya..!

Mk_ why asked about the twist i was 'guessing' you mite had a faster twist thinking the use of a heavier longer bullet with that gap .40+.. glad you had a postive experence at the range... i mite get to go wed or thurs.. yippie !
how did you ever get 37 grs in that little case ... wow !

while i'm at it i have a question on neck length... i don't have the numbers right in front of me but my chamber is shorter then average
how close to the end of the chamber can i leave the neck---
Edit: can i leave the neck after fire forming is done ?

 

[artbosco]

can i leave the neck after fire forming is done? how close to the end of the chamber can i leave the neck?

After I fire form twice, I trim my necks to 1.500" because I want consistency in length, before I start using them in competitive matches.

If you're not competing, then there's no need to trim after fire forming. However, it's highly recommended you do.

Since my chamber length is 1.520", I never let my case length exceed 1.510", allowing for what is probably the norm these days, of a safety cushion of .010". Having said that, there are a few who only leave .005" as a cushion and even fewer you chance a .003" cushion.

I, and a lot of others, believe .010" [10/1000 thousandths' of an inch] is a good gap for safety. And that isn't much, when you think about it.

 

[Steve Blair]

Since my chamber length is 1.520"

How did you measure this?

 

[artbosco]

Since my chamber length is 1.520"

How did you measure this?

I personally own a 30BR Robinett Pacific Tool & Gauge finish reamer, which so far, has only ground one chamber. That reamer was ground to a tolerance of + .0005" - 0.

My corresponding PT&G 30 BR Robinett reamer print #20345, indicates that 1.520" is the finished chamber length, and my gunsmith Billy Stevens has told me that's what his measurements were after chambering.

I also used the Sinclair International Chamber Length Gage: http://www.sinclairintl.com/.aspx/pid=32925/Product/Sinclair_Chamber_Length_Gage Handy little bugger, and it's inexpensive ... $6.95.

 

[mk_gram]

My mistake ... It was "32" grains of powder not "37" as I stated. "37" grains would not fit in the case.

 

[mk_gram]

One more question ... Since my chamber depth is 1.567 is it possible for a gunsmith to remove the barrel and trim .030 off the barrel length? Of course, if it still shoots well I would not do that but it still bothers me that there is the .040+ difference in the chamber length and the case length. Hart told they use a Manson Reamer.

Mark G.

 

[artbosco]

Since my chamber depth is 1.567 is it possible for a gunsmith to remove the barrel and trim .030 off the barrel length?

I'm sure a good gunsmith can accommodate that modification. Here's my recommendation: http://www.stevensaccuracy.com/ Or any of the others on this page: http://www.accurateshooter.com/technical-articles/gunsmithing/gunsmiths/

 

[mk_gram]

I just thought of one more question. I measured the neck thickness after turning the necks to remove the donuts and as best I can determine it is .012 thick. How do you determine how thick the case neck should be? I believe I read that it should not be less than .010. I "am" amazed at all the good tips you are providing!!!

One other thing that puzzles me is that the 30 Cal tools I used to determine the chamber length were .335 in diameter but my chamber neck diameter is .333 (which is stamped on the barrel). How does the tool fit into the neck chamber? It fits with no problem. I bought two of them and sanded one down to .332 in my drill press because I did not think it would fit. I then used them both (one at .335 and the other at .332) and came up with the same measurement of 1.567. After I fire formed the 10 cases they measure .333 neck diameter.

Mark G.

 

[mk_gram]

Outdoorsman,

I had a gunsmith in Leesburg, Virginia build me a custom 30-06 a few years ago. His name if Bob Altendorf but I have had no contact with him since. The 30-06 is a Mauser 98 action with a Shilen barrel. It turned out to be very accurate and a "nice" rifle. I met him at a gun show a few years after and he had a double barrel 45-70 he built with a shotgun action which he was selling. It looked menacing but if I recall was selling for $3,000. However, it did not interest me much. If necessary, I will follow your advice and find a recommended gunsmith but would hate to pay for the additional work.

Mark G.

 

[artbosco]

I measured the neck thickness after turning the necks to remove the donuts and as best I can determine it is .012" thick. How do you determine how thick the case neck should be? I believe I read that it should not be less than .010.

Here's how I determine the thickness of my brass.

First, I know that my 30BR chamber is .330" in diameter. I also know that I want the case neck to measure .328" with a bullet seated in it, to give me a total clearance of .002", or .001" on each side.

I know that the custom flat based bullet that I've chosen is .3084" measured at the pressure ring. That information is printed on the side of the box that Ronnie Cheek ships his bullets in, along with other info. Regardless, I measure it, to confirm that fact.

Now it's only a matter of simple math. .3280" minus .3084 = .0196". .0196" divided by 2 = .0098". The brass should be turned to .0098". Or, 9.8 thousandths.

.3084" bullet diameter + .0098" brass + .0098" brass = .3280" [loaded round diameter, measured at the pressure ring if your bullet has a pressure ring. Boattails don't have one.]

All of this is determined by the diameter of your chamber, and how much total clearance you want between the chamber and the load round.
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Now, let's just say your chamber is in fact .333". That you were going to use the same bullet I use, and you also wanted a total clearance of .002".

Your figures would be:
.333" chamber minus total clearance of .002" = .331" [the diameter of your loaded round measured at the pressure ring.

.3310" minus .3084 = .0226 divided by 2 = .0113. You would turn your brass to .0113" or said another way, to 11.3 thousandths.

Here it is expressed another way:

.3084" bullet + .0113" turned brass + .0113" turned brass = .3310" load round measured at the pressure ring.

Hope this helps.