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Thread: The [so called] Robinet 30 BR reamer - exposed!

  1. #1
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    Red face The [so called] Robinett 30 BR reamer - exposed!

    The [so called] Robinett 30BR reamer - exposed.

    Attached is a copy (pic) of the original, and only Robinett 30 BR reamer. A reamer featuring a single alteration is not a Robinett reamer, but rather, “something else”. The only reason that my name was attached to the reamer was/is because I ordered it: at the very least, upon any alteration, my name should have been removed.

    While alterations are neither necessarily bad, nor, good, they are different. When I ordered my original reamer - subsequent to, and different than Ronnie Long’s [original] reamer- I did not ask that it be proprietary, nor did I request to have my name attached/associated with copies of my dimensions: only that clones be readily available; no strings attached.

    Regrettably, beyond my control, there are a multitude of reamers bearing my name, many of them, with dimensional changes which, in combination with the short/light thirty caliber bullets, are undesirable. Here are two [common] ‘deal wrecker’ attributes:

    Excessive OAL, thus, too long a chamber neck length - typically, 1.560” (SAAMI Spec. .22 BR OAL). Mechanical neck-up processes reduce neck-length, thus OAL: 1.520” necked-up brass, in a 1.560” chamber will result in 0.040” ‘counterfeit’ free-bore.
    My tooling never produces a necked-up 6mm LAPUA case in excess of 1.515” long - most are 1.512-1.513” before trimming to square the mouths. Thus, the specified maximum OAL of 1.510” on the original reamer - this has worked very well. Note: few expand-up processes/tools produce OAL greater than 1.520” - more on this later; in brief, fire-forming does produce longer necks/OAL. Know the OAL of your reamer/chamber.

    Any amount of free-bore, especially in conjunction with #1(above). Already, #1 will all but preclude seating the short/light bullets against, or even near the lands - actual free-bore, in combination with excessive chamber-neck length [usually] spells poor results. Short 30 caliber BR quality bullets do not require any free-bore.
    Note: my original reamer features a [unusual] 1.75 degree throat angle - the typical 1.5 Deg. angle requires seating the bullet out even further! With the 1.75 Deg. throat angle, and brass trimmed only 0.010” short of filling the chamber-neck, the base of a typical short/light thirty caliber bullet, seated to contact the lands, will have only about 0.125” of shank in the case neck. Short case-necks, and free-bore erode bullet grip fast!

    Not quite as bad, is a poorly positioned, or, inadequate cone diameter (variously referred to as ‘throat’, ‘leade’, etc.): the cone should remove every vestige of land material, preferably, at least, skimming (cleaning-up) the bottom of the grooves, affording the bullet free access to the barrel/lands. A zero free-bore reamer does just this, right off of the chamber mouth. This is not to be confused with the typical 45 degree angle at most reamer mouths, which presumably is a better chamber:barrel transition than a perpendicular wall.

    There are two alterations, which, if ordering a new reamer, I would make to my original:
    Diameter, at the .200” (ahead of bolt-face) DATUM line , I would state, “not less than 0.4715”.
    Neck diameter 0.331”, no taper.

    Note: the hand written .315 above the neck, on this print, is the approximate neck-length of my brass, when trimmed for 0.010” clearance, or, when trimmed to 1.500” OAL.

    I hope that this is understandable and proves useful. Keep ‘em ON the X! RG

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    Last edited by R.G. Robinett; 09-26-2017 at 09:44 PM.

  2. #2
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    Randy

    Thanks For sharing the infamous 30BR Robinett reamer dimensions.

    Here is a good example of how things have changed over a 10 year time span. {Look at dates on reamer prints}!

    I ordered an off the shelf 30BR Robinett Reamer.

    I have no complaint's on this variant's performance.


    Russ
    Attached Files Attached Files

  3. #3
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    Quote Originally Posted by R Stiner View Post
    Randy

    Thanks For sharing the infamous 30BR Robinett reamer dimensions.

    Here is a good example of how things have changed over a 10 year time span. {Look at dates on reamer prints}!

    I ordered an off the shelf 30BR Robinett Reamer.

    I have no complaint's on this variant's performance.


    Russ
    Russ, precisely my point - though useful, your reamer is not and should not be labeled '30 BR Robinett'!

    A perusal of just the throat angle difference shows that, compared to 1.75 deg., the shallower (1.5 Deg.) angle moves the bullet another 0.035" toward the muzzle - displaying why free-bore is an undesirable attribute!

    Of late, I've been getting more phone calls: "I've got a 'Robinett' reamer and cannot reach the lands" . . . frequently, the caller's reamer combines excessively long chamber-neck/OAL, free-bore (0.020 to 0.035" are common), and the typical 1.5 Deg. throat angle - certainly NOT a Robinett reamer!

    While obviously useful, when a mechanical necking-up process will be used, your reamer, @ 1.520" OAL is about the most I'd live with. I'm not opposed to change - I am opposed to changing the attributes and retaining the 'name'! Keep 'em ON the X! RG

  4. #4
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    http://benchrest.com/attachment.php?...1&d=1504217108

    http://benchrest.com/attachment.php?...1&d=1504218713

    Randy, I have one of your reamers from when I first started shooting the 30BR some years back. It has 30BR Robinet on it. When I ordered my reamer that uses a 1.545 trim to length, I told Dave Kiff to make it exactly like that reamer except make the overall chamber 1.550.

    I all honesty, I never got a print of mine, and I never checked it except to be sure he did get the overall length correct.

    I just compared my reamer to my original Robinet Reamer. The body dimensions are identical, as is the .330 neck. But, my original Robinet has a slightly steeper throats angle, which I assume is the 1.750. My reamer apparently has a 1.5.

    I never noticed this untill you just brought this up. However, as you can see by the picture, that is where my reamer puts the 112 bullet in the case where I shoot them with just a tad of "jump".
    I guess we learn something every day.
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    Last edited by jackie schmidt; 08-31-2017 at 07:32 PM.

  5. #5
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    Randy

    That's why I posted the reamer drawing that came with my reamer was to show proof of different reamers.
    My reamer print is 7 years old. That makes the 30BR Robinett 17 years old and still winning matches.

    In all honesty you have to pat yourself on the back! with all the changes everyone has made to your original design the 30BR Robinett still just flat out shoots!

    Randy
    If you know of a good bullet maker maybe that guy could make some 6-ogive bullets that would remedy the long free bore
    !

    PS: It's better than having your name written on every bathroom wall from coast to coast!

    Thank you for an awesome cartridge!
    Russ

  6. #6
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    Randy

    I just looked at my 30BR Robinette reamer. here's more proof that things really will change with time.

    Robinett is spelled Robinette
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    Russ

  7. #7
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    Quote Originally Posted by R Stiner View Post
    Randy

    I just looked at my 30BR Robinette reamer. here's more proof that things really will change with time.

    Robinett is spelled Robinette
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    Russ
    Yup - someone knew how to spell!

    As you noted, so long as one can get the bullet either into, or, near the lands, many (most?) of the changes are harmless: your reamer exhibits no 'bad' dimensions, and with the contemporary tooling, most people get necked-up length of about 1.52, so have room to trim to suitable length, thus making it very good.

    For those extra long 'throated' barrels, I do know someone who makes a 7 ogive 118 Gr. bullet, based on the 1.00" long jacket, which usually mitigates the issue - bearing surface is about 1/16Th of an inch (0.060"+/-) longer than the shank on a 112-7.

    The other solution to a long-necked chamber is to use one of the fire-form methods, which produce longer necks than does mechanical necking-up. I confess to having never used any of the 'pistol powder'/cream-0f-wheat, wax-plug etc. methods, however, faced with one of the 1.560" long chambers, I'd certainly explore the options.

    The best F-F method, though not as accessible as the no bullet/plug methods, is that employed by Jackie Schmidt,
    detailed here in the past - essentially, one takes a worn out 6BR barrel, runs a .330" (or, whatever is desired) diameter chucking reamer into the chamber to re-cut the neck, then, loads the 6BR brass with a cheap 6mm bullet and shoots 'em. This, I believe is a very good method, providing not only a pretty full chamber neck, but also producing a perfectly squared up case prior to trimming & turning the neck-walls to the desired thickness.

    For comparison, the fired cases (Lapua 6BR NoNORMA), sent to me, by Jackie, many years ago, measure 1.540". My LAPUA 6BR 'NORMA' brass, right out of the 'old' gold boxes, runs from 1.552" to 1.555". So, Jackie's method retains a substantial portion of the original neck-length (Note: my brass is of a different Lot, however, the gold box stuff was pretty consistent). With my 'old school' mechanical process - a series of Klindhorst neck expanders - the 1.55+" long brass shrinks to not over 1.515" . . .

    There is nothing magic about any of this - ya just need to KNOW what you have!

    My gripe is that when I get a caller, wanting to know the trim length, etc., I don't have a clue! Oh, and gripe #2 - a 'gunsmith' who chambers a barrel and cannot provide the chamber dimensions information [to his customer] should probably go the bottom of that customers gunsmith list. RG
    Last edited by R.G. Robinett; 09-14-2017 at 12:13 PM.

  8. #8
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    I know this is an old thread...

    I remembered seeing this thread awhile back and did a search for the Robinett reamer and found the thread. Thought I'd check my print against Randy's print and see what how close mine was to his. Mine is identical to his, even to the 1 degree 45' freebore. I'm sure that has a lot to do with the date of the reamer. My reamer was from 10/26/2001. About 11 months after Randy's original reamer. Gee, it's hard to imagine that I've had the reamer that long. Time certainly gets away, one day at a time.

  9. #9
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    Jackie Schmidt will remember all the hand wringing I went through a couple of years ago when I bought my used 30BR. Seller (a VERY well known gunsmith and benchrest shooter) said the new barrel he was suppling was cut with a "Robinett" reamer. When I asked for the print he sent me one with a 1.560" chamber length. Jackie helped me out with some long-length cases. None of them would chamber. I started fiddling around and figured out the actual chamber length was more like 1.520". Regardless, 2k rounds later, the gun still shoots lights out.

  10. #10
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    Thumbs down Here is a print of a [so called] Roninett 30 BR reame which I saw for sale this week.

    Again, there is nothing magical about my original reamer (though, it works GREAT) - just that it has specific dimensions - any dimensional change IS NOT a "Robinett" reamer! Further redundancy : Never did I give permission, nor did I ask to have my name associated with any reamer.

    P.S. this reamer (link below), with the short/light thirty caliber bullets (.925" - 1.00" long jackets), unless one employs a Fire-Form method similar to Jackie Schmidt's, is very likely to disappoint. It certainly IS NOT a clone of my reamer! RG

    http://forum.accurateshooter.com/att...1-pdf.1106811/
    Last edited by R.G. Robinett; 05-23-2019 at 11:01 PM.

  11. #11
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    I sent a reamer back a 30 BR reamer

    that had .060" free bore in it for a zero re-grind and got back a .040" with Robinet etched on it and here in lies the problem. Unless one has an optical compairator or some other method of measuring, one never really knows what they have. Disenchanting, to say the least!

    Pete

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