Oversize Remington Bolt Question

[LynnJr]

When putting a 0.704 bolt into a 0.705 action how much of the receiver actually gets bored?
From looking at an action it looks like the rear 1.5 inches and at the front only about 1/2 inch. Does that sound right?

[ar15barrels]

The receivers start out between 0.701" and 0.703" as they come from Remington.
The WHOLE receiver bore gets opened up.
There are areas missing of course, where the cartridges feed up through the bottom and the loading port on top.
There is often a single point of contact all the way along the left side of the ejection port cut though.
The MAIN points of contact are the lug abutments and the bridge right behind the magazine cutout back to the primary extraction cam.
Behind that, the tang gets cut as well.

[LynnJr]

Is it possible to bore the action 0.704 the same as the bolt then lap the bolt into the action?
Or is that left edge contact what kills the deal?
I ask because i have a bolt sitting here at 0.704 and while snug it fits all the way to the start of the loading port. Can i just lap it in?

[ar15barrels]

Is it possible to bore the action 0.704 the same as the bolt then lap the bolt into the action?
Or is that left edge contact what kills the deal?
I ask because i have a bolt sitting here at 0.704 and while snug it fits all the way to the start of the loading port. Can i just lap it in?

The most common method of opening up the receiver to 0.705" is via the Gretan/PTG reamer and pilot system.
I suppose you could setup the receiver in a lathe and single point bore it to 0.704", but that's a more complicated job than fitting a couple bushings and running the gretan piloted reamer through the receiver.

If the bolt will slide into the receiver through the bridge, go ahead and put some 320 or 500 grit lapping compound in there and go to town.
You may find that it's actually the tang lifting the bolt and keeping it from sliding through the port.
Try the bolt backwards (from the front towards the back) and see if it will pass through the lug abutments.

[LynnJr]

I tried it backwards and the lugs go through the abutments but that's it.
It looks like it hitting nearest the front scope mount hole.
And yes the tang seems to be putting upward pressure on the bolt body itself.
I am going to add some lapping compound and watch a very long movie.

[ar15barrels]

I tried it backwards and the lugs go through the abutments but that's it.
It looks like it hitting nearest the front scope mount hole.
And yes the tang seems to be putting upward pressure on the bolt body itself.
I am going to add some lapping compound and watch a very long movie.

Measure the bolt body diameter in the middle of the lugs and then about 1/4" behind the lugs.
In my experience, PTG uses 0.700" from the rear face of the bolt lugs to the nose.
The custom ordered diameter starts just behind the lugs and is carried back to the handle.
The area in back where the cocking cam is back to 0.700" again.

[divingin]

Good stuff. Thanks for the discussion.

[ar15barrels]

I tried it backwards and the lugs go through the abutments but that's it.
It looks like it hitting nearest the front scope mount hole.
And yes the tang seems to be putting upward pressure on the bolt body itself.
I am going to add some lapping compound and watch a very long movie.

If you have a set of gauge pins that covers 0.700" to 0.705" range, see what the largest one is that will slide completely through the receiver.
This will give you an idea how much you need to lap out.
During that measuring, you will also probably figure out that one end is larger than the other.

[LynnJr]

Here is a picture of how far the bolt slides into the action.
It measures very small between the lugs and 0.704 behind the lugs then tapers to less than 0.700 before it gets thicker again where the bolt handle gets welded on.

[LynnJr]

Here is the result of lapping for the entire Clint Eastwood movie The Good The Bad and The Ugly. It's about 2/3 completed.