Bolt Bore Reaming

[Brent]

Kirby, Kregg and anyone else using Greg's .705 reamer/mandrel.

Question pertains to reaming through the front receiver ring as the reamer breaks through to the feed ramp on the lower, "thin" side.

Have two actions, both 700's (both mine thankfully) that the reamer grabbed and locked up and leaving a nick in the top of the feed ramp on the bolt's bearing surface right in the middle.

I've corrected the setup so this cannot happen again but requires a bushing be made for each action, not a big deal but another step none the less.

The problem is with the front bushing and it being pushed out of it's support area on the bottom by the reamer flutes leaving the reamer "unsupported" on the bottom while still having to finish cutting through the top support another .400 or so further, not good.

I made a threaded bushing to fit the receiver thread and shoulder up to the face and bored it out to .690 or so in case the threads were off axis, then I bored both ends out to .750 ID but leaving a .250 area in length immediately inside the receiver face that was still .690 ID that the reamer is forced to bore through before reaming through the front receiver ring, thus offering the support needed behind the flutes before they enguage the abutment area. This works perfect but, as you understand, will not work for any other action because of thread misalignment in every one of them is different. The threaded bushing is being bored out to accept "replaceable" internal bushings with the .690 ID so all I have to do is turn the OD and ID and part off to make a bunch at once.

I wonder if you have found another fix to this issue of unsupport in the front ring and how you approached it?

 

[chris matthews]

Brent,
I don't use the method you are describing but I am curious as how a 705 reamer cuts anything when most of the Remingtons I am seeing (especially new ones) are more like 708-710 in the front half of the raceway by the lugs?
I guess it would cut on one side or the other if the action is crooked (which I agree most are) but I just don't see how you are getting a true reamed hole....
Not knockin your method....just asking you to clarify it for us.

 

[Brent]

Chris,

I'm not sure if you are familiar with how the GTR reamer is located/aligned and supported in the existing raceway but it will cut evenly on all sides with the precision ground bushings that guide the reamer via the integral mandrel at the front of the reamer. However, it does not take a rocket scientist to see that there is no support/alignment at the front throughout the whole length of cut on the front ring, unless something like what I have done is used to support the reamer shank when it pushes the front bushing out into the magazine well. BTW, the reamer mandrel is supported at the front and rear both before it cuts through the .690 bushing I made up, if it was not, nothing would ever be in alignment.

The reamer setup Greg has put together works very well but I'd like to see him address the lack of support in the front ring and offer a solution.

I'll have to take a few pix, some of this is a little difficult to explain, for me anyway.

Have you been measuring the front support area at 708-710 with something turned to the specific diameter or by some other means?

Kirby ant Kregg have probably done more than I have and could coment on that more than I. Greg Tannel that I am aware of (very possibly incorrect on that), and so far, myself, have not run into what you describe and see the 705 cleaning up both front and rear. What I've seen is 702 to 703, and one at 704 at the front. I haven't seen any smaller or larger, yet. But you are right, a 705 would be insufficient if one was found to be even 705... in my mind anyway. I am thinking about having Greg make me a 708 reamer so I don't find out the hard way and get into a pinch for time and have to wait on one, but 710 may even be a better choice?

The two of mine that were left with nicks in the lower ramp area would be good to ream with the larger OD as they both were exactly .001 large when it was all said and done, obviously taking more off the lower, thin side as the bushing fell low into the mag well.

I'll have to turn the front bolt bushing .001 larger and hone the top one down to fit in order to keep "perfect" alignment in this case.

I may pay the extra and have the next reamer made with the both the smaller OD mandrel and larger OD reamer shank portions each extended 3" further.

Both sections of the reamer IMO are very close to being too short for a LA and would never work on any longer custom action I build, they would also work much better on a LA if it were longer, then you could ream the front ring coming in from the rear, which makes more sense considering the thin area on bottom would be cut last at the very end, not at the begining.

A guy could ream from the rear with the existing length reamer mandrel but he'd need a full set of 3" long bushings for the the front ring so the mandrel would engauge it "far enough" for alignment before cutting through a warped tang.

As the existing 12" reamer is, reaming from the front and cutting the last bit of the tang barely leaves any of the 705 reamer body in the support area of the front ring, it almost goes right through bofore it's done cleaning up the tang.

If the reamer mandrel section was longer, going in from the rear would be an option, if the reamer shank behind the flutes was longer it would just be easier doing LA's from the front, or longer customs period.

Greg said it's about another $100 for longer than 12" reamers because it's not standard stock I guess.

 

[kregg]

i havent had any rem actions that sloppy 0.705 cleans the one's that i have done up. you could have greg make you one that would cut 0.710 i did have one grab on me one time and after that i started to ream them driffrent. i dont run the cutter all the way threw the action, i cut one and pull it out and go to the other end of the action and put the cutter in and cut it because the other end of the action has be opened up to 0.705 so i put a 0.705 bushing in that end and were your cutter is cutting have a bushing there that fits tight and it cuts over the ramp with no promblem but i make sure my rpm's are pretty fast when i push it threw with oil on the cutter.

 

[daveosok]

Hey Brent

Is this reamer sprial fluted?

 

[chris matthews]

Brent,
I have used the Manson tooling and on several, the 700 to 705 tapered bushing falls right through the front, had Kiff make a 705 to 710 bushing and that works better- so that would put them a bit over 705 depending on how far they slid in....not saying they are all like that but have seen quite a few. But then again we (GA Precision) built over 600 rifles last year, so that's alot of recievers to true up....
Was talking to Gordy Gritters about it and he admitted that several times the 705 reamer cuts nothing but air.....
Thanks for further explaining it...

That's the cool thing about gunsmithing.... there are a bunch of ways to do things and we might not all agree on how to get them done but the bottom line is one little bitty hole on the target when we are through.

 

[Brent]

Chris,

Many ways to get the job done, I agree. Options range from a few to seemingly endless. I've seen some very creative thinking over the last few years, amazing some of the things people come up with.

I've seen the tapered bushings/reamer setup Manson offers but never thought it would position the reamer mandrel dead center in the existing bolt bore because of the larger diameter end of the bushing's taper contacting on one side before the other like it would inserting it from the rear of the rear receiver ring or the rear of the front receiver ring. There it would contact on the tang further back on the bushing and lift the bushing from true axial alignment as it was inserted until it contacted the top of the rear ring and stopped. That would also tend to tip the bushing unless it was positioned on the mandrel before hand to keep that part from happening. In the worst case, the bushing could only cause the new bolt bore axis to deviate from the existing one by no more than .0025" at each end, so it wouldn't be enough of a problem that the bolt lugs bound up in the reaceways on the new axis. A larger than .705 OD reamer would surely be needed with this setup though. Isn't Manson's reamer .715? Is yours .715?

The one place I can see the tapered bushing working perfectly, and maintaining the original bolt bore axis is if it were placed in the front ring from the front side where it would contact the top and bottom abutment at the same moment.

I'd have one made but I don't understand how it could stay tightly fitted, as the reamer pushed it out it would begin to get slop around because of the taper. Those are the main reasons I went with the straight bushing/reamer setup GTR has made.

With the straight bushings I can find the bushing size that barely fits each end, then polish the bolt bore until the next .0005 larger bushing will just fit and pass through the bore with a little bit of effort, ie. no slop. When reamed the finish is super sweet and as close to the existing bolt bore axis as one could ever be.

One other way I've thought alot about would use tapered bushing, quite a bit more taper than the Manson bushings but these would be smaller in OD and slide into a collet with the same taper on the inside and straight on the outside, expanding it to fit perfectly, but straight on the outside so the reamer could push it through as it advances.

Is Gordy using the Manson setup too, GTR or something different?

Fun stuff! /ubbthreads/images/graemlins/smile.gif

 

[Brent]

Daveosok,

The reamer has a slight, very slight helix, 5, maybe 10 degrees tops, from memory. I'll have to look at it again.