Need help with a 6 PPC Bore Rider chamber!

Having studied the print for some time and spoken to Dave Kiff (its designer) at some length about it, I will take the liberty of pointing out a couple of things that may not have jumped out upon first inspection.

Of course the parallel section (.2435 dia.) is pretty standard except that at .111 it is longer than any other 6PPC drawing than I have seen.

The tapered section in front of it, that is .200 long has a taper of .53 degree per side (31'-48", calculated from the dimensions), and the smaller dimension at its front takes that part of the cut up to about half the height of the lands on a barrel with a .237 bore.

Forward of that section, the lands are cut at the more common 1.5 degree angle.

For the person that wanted to know about the .233 dimension, it should be remembered that this is a reamer print, which corresponds to the chamber dimensions in those areas where the reamer cuts, but may have dimension for the reamer grinder that a chamber print would not. In this case it tells him what the diameter of the reamer is to be at the point where the degree and a half taper ends.

Looking at the middle section again....it starts with a cut that cleans off the lands at its big end and if we do a little calculation the lands are likely to start to show about .026 into that taper, assuming a groove diameter of .243. So, about .137 in front of where the 45 degree transition from the neck part of the chamber ends, the bottom of the lands start to show, and the effective leade angle at that point is about a half of a degree.

My conversation with Dave had started with the intent of just ordering a throating reamer but he told me that all of the dimensions had been designed to work together (meaning that the long parallel section was part of the design and that shortening it up to put more bullet in the case neck might change performance)so I took his advice and ordered (for a friend) the chamber reamer. It is supposed to be here today, and I imagine that by tomorrow that a chamber will have been cut, and wind permitting, testing begun. We have some of the 65 gr. BTs as well as some Columns.
 
Attached is a Excel copy of my Bore Rider reamer print. It's a little different than Lou's print. The freebore on my reamer is .2436" for .077" from there it tapers to .2398" in .250" more length then the 1 degree 50' leade starts. You normally think of the jam being where the 1 degree 30' or 1 degree 50' leade (in my reamer) starts. I don't see that any normal benchrest bullet would ever be able to be seated out to even get close to where it was touching the 1 degree 50' and still seat in the neck. My bullet is .2432" on the diameter. It's touching somewhere on the taper between the .2436 and the .2398". That's why I'm not sure exactly where its touching. I have about a 1/16" of bearing surface inside the neck. The 65gr Berger BT like Lou was using won't touch anything in my chamber and fit in the neck as the BT is too long on it. My reamer is a .265" neck diameter. I have pin gages to check for finished neck diameters, but the pin gages are in .0005" increments and not in .0001" increments. The goal in any chambering is to get the reamer to cut as close to reamer size as is possible. In practice, the necks I've checked sometimes will take a pin .0005" over what the reamer is marked, but never .001" oversize. It would be nice to have a set of pin gages in .0001" increments for checking necks, but in wide range of neck diameters for a PPC, not very practical. I'm not sure what the benefit of knowing exactly what the actual neck diameter is would be anyway.

I'll have to do some chronographing and testing with the chamber to see how it compares to the Bukys reamer that I have with .080" freebore with a 1 degree 50' leade. I was planning on using LT-32 with it at Phoenix, but wound up shooting 29.4 gr of 07 lot of 133.
 

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Attached is a Excel copy of my Bore Rider reamer print. It's a little different than Lou's print.

In practice, the necks I've checked sometimes will take a pin .0005" over what the reamer is marked, but never .001" oversize. It would be nice to have a set of pin gages in .0001" increments for checking necks, but in wide range of neck diameters for a PPC, not very practical. I'm not sure what the benefit of knowing exactly what the actual neck diameter is would be anyway.

I'll have to do some chronographing and testing with the chamber to see how it compares to the Bukys reamer that I have with .080" freebore with a 1 degree 50' leade. I was planning on using LT-32 with it at Phoenix, but wound up shooting 29.4 gr of 07 lot of 133.

Mike, with judicious care you can use something like the Starrett half-ball small hole gages and check neck and freebore diameters as short as about 0.040" long or so in chambers that are short like the PPC. I have used a rubber surgical tube and gone deeper for longer chambers but it is really a pain!

http://www.amazon.com/Starrett-S830...&sr=8-1&keywords=starrett+small+hole+gage+set

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Jerry, I have a couple of them somewhere. Been a long time since I used it.

It takes some practice to use them but you can get really accurate measurements after you develop the "feel". Practice on a neck sizing bushing after you get confidence of its actual diameter using pin gages.

The reason neck bushings are good for practice in using small hole gages is that if you pick the bushing up with the hole gage you are still too tight. If you can't pick the bushing up you are too loose. When you feel the drag but can't pick the bushing up you have the right feel!


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For what it is worth...I ordered a bore rider reamer in .300 UltraMag...after chambering the barrel I looked at it with my borescope and it does NOT remove the lands completely..hense you may get land marks on your bullet even though it is in the freebore part of the chamber..


Eddie in Texas
 
Well I went to Phoenix me and Angelina my granddaughter shot.
Both shooting bore riders. LT 32
I was using Chuck Miller bullets she shot Chuck Miller bullets at 200 and columns100 yard
I won the 2 gun Took small group for 200 yard heavy gun.
Bunch of other trophies
Angelina shot fantastic for the first time shooting a bag gun. She took forth in a light varmint 100 yards . she shot a .109 for small group at 100 yards lt varmint. She shot small group in the light varmint 200 yards with a .290. The light varmint 200 she was leading after two and second after four groups.
The wind had been blowing about 10 to 15 miles an hour switching . she started her group and we had a twister come through while we were shooting and she really didn't know what to do and thought it calm down fired a shot and it went way out.
If not for that one shot she would've done fantastic in the light gun. She made me extremely proud for shooting a bag for the first time and only being 10 years old.

Bore rider or not, that little gal is just talented!!
 
Half-Ball Small Hole Gauges

Mike, with judicious care you can use something like the Starrett half-ball small hole gages and check neck and freebore diameters as short as about 0.040" long or so in chambers that are short like the PPC. I have used a rubber surgical tube and gone deeper for longer chambers but it is really a pain!

http://www.amazon.com/Starrett-S830...&sr=8-1&keywords=starrett+small+hole+gage+set

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Could these be used to measure the neck dimension in a chamber? I have a .219 Donaldson Wasp & do not recall the neck diameter.

Thanks,

davejones
 
I saw that this post had come back up on the screen. I've shot rifles chambered with the Borerider reamer in just about every match that I've shot this year which has been quite a few. I've been very impressed with the barrels chambered with this reamer. Enough so that everything I have is slowly being converted over to the chambering. Whether its any better or not than a standard freebore, I don't know, but I've done well shooting it. I've been shooting BT bullets this year made on my Rorschach point up die which has a long bearing surface and a Niemi .060" BT. I am touching the lands and getting a faint mark from the lands where the bullet is touching. I've shot both 133 and LT32 in the chambering. I chronographed loads after the Muchas Gracias match at Raton and was getting 3320 fps. Walt had trouble with his sporter and was going to shoot his HV out of class. He used one of my rifles instead and placed 2nd in the 100 yard shooting his moly coated 65gr. BT and 28.2 gr of T32. Since my reamer has a .265" neck, he used an extra seater that I had and used it as it was. He was hard into the lands, but had very little of the bearing surface of the bullet inside the neck. If you look at the reamer prints, Lou's and mine, the bore rider part of the freebore is a little different between the two reamers. If I did the math correctly, the actual angle measurement of Lou's reamer is about 30 minute of angle and with mine it's about 24 minute of angle. That's what gives the reamers their different look when you look at the chamber with a borescope from the traditional 1 degree 30 minute leade.
 
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