Trueing the action?

Bcraft1111,

Bolt sleeving is a proceedure that is used to tighten up the bolt body fit in relation to the receiver bolt way.

If you take a Rem 700 receiver, there will be anywhere from around 0.006" to the worst I have seen, 0.015" clearance between the bolt body and the baring surfaces of the bolt way in the receiver.

Even if an action is perfectly trued, there will still be a canting of the bolt body occuring when the rifle is in the cocked position.

The reason, when the striker assembly is retained in the rear(cocked) position, it is held there by the sear suface which ingages the striker assembly at an angle on the bottom of the bolt. This angle is needed as it not only hold the striker back but it also powers the sear down against the trigger so it will not slip off.

The angled surface retaining the striker assembly forces the striker assembly and thus the entire bold body vertically until it is stopped by the top baring surface of the receiver bolt way.

As I stated earlier, this can vary from anywhere from around 0.006" to 0.015".

What happens as a result of this lifting of the rear portion of the bolt body is that because the front of the bolt as some tension against the bolt face from at least the plunger assembly and generally but the case contact in the chamber. As a result, the forward section of the bolt does not life.

So now we have a bolt that is cocked, ready to fire. The rear portion of the bolt body is higher then the front of the bolt body because the rear has been camed up and the bolt will pivot if you will around the front baring surface of the bolt and receiver.

What this canting does is actually lift the top bolt lug baring surface off its mated locking lug recess in the receiver.

So even though we have maticulously printed this receiver, when the rifle is cocked ready to fire, only one locking lug is baring solid. This will occur even with perfectly lapped in lug baring surfaces.

When the trigger is pulled, the sear drops and allow the striker to start moving forward toward the firing pin, but it also allows the entire bolt to drop from its elevated position and as such when the striker lands on the primer, it will often be in a different location from one shot to another.

The vibration pattern will also be different in the bolt body as a result of this bolt drop.

Sleeving greatly reduces this problem.

You take the bolt and set it up in the lathe and take releif cuts just ahead of the bolt handle and just behind the bolt lugs. These are not long cuts, generally around 1.200" long for the rear and around .400" for the front. They are also not overly deep cuts, just enough to hold a sleeve in place.

Then two bushings made of either 4130, 4140 or 416 stainless are split and fitted to the bolt body. These halves are epoxied in place using either Brownells Steel bed or plain old J-B Weld.

They are allowed to set up for 15 hours or so and then they are turn down to match the bolt ways of the receiver. The tighter the fit, the slower the bolt will need to be worked to prevent bolt binding. This is especially true with a double sleeved bolt, front and rear. This system is generally used on target and varmint rifles where paniced working of the bolt is not an issue.

For big game hunting, I highly recommend only sleeving the rear surface. It still does a great job controlling bolt lift and the bolt will also work much smoother in an excited state. Results in consistancy are very close to but not quite equal to a double sleeved bolt but vastly superior to a non sleeved bolt.

Again, bolt sleeving is just one part of a properly accurized receiver. ITs like deburring your flashholes on your cases. Alone, it will not make a drastic difference on target, combined with all the other accurizing proceedures, it will add up to as consistant an action as you could possible have built.

Now for a big game rifle that is designed for easy carrying and for shooting off hand out to 300 yards, the benefits of this will not be realized even though they will be there. There is simply to much human error when shooting off hand to see the results.

Good Shooting!!!

Kirby Allen(50)
 
Fiftydriver,
How long does it honestly take you to complete a total blueprinting job how you do it?? If I was to send you a factory Rem 700 today, how many weeks until it's tricked out and back in my hands?
I have a gunsmith who I love, and he does about the same techniques as you describe. He is very very knowledgeable, but I feel he is not very punctual. Whatever he tells me the finish date will be, I always double it!
 
Goodgrouper,

For a totally printed and accurized receiver, including bolt sleeving, Your looking at around a 2 week turn around.

Actually thats what it would be without bolt sleeving right now. I generally spend Mondays and Tueday mornings accurizing actions for the rest of the weeks rifle building so I do them all at once since the fixtures are all set up on the lathe.

I know most gunsmiths tend to stretch the trueth a bit as far as turn around but I assure you that you would be looking at around 2weeks inthe shop time with shipping time extra.

If your interested let me know, I had to send my receiver botl way reamer back for repairs so it will a a couple weeks before I get it back.

Kind of held up right now. Luckily, I got the reciever reaming finished I needed to so far so not to far behind.

Good Shooting!!

Kirby Allen(50)
 
Kirby: Do you use a reamer to chase the receiver threads or recut threats with single point cutter? Which produces better results and why?

Thanks,

Robert
 
Dirtybob1,

When I fully accurize an action that will be rebarreled I always single point recut the threads. The reason is simply, this is the single best way to true the receiver threads so they are on the exact same axis as the receiver bolt way.

Chasing the threads with a precision tap will clean up the threads but they will still be on teh original axial location as they were from trh factory, generally significantly off the axis of the botl way.

Single point thread cutting is the best way I have found to true up receiver threads.

When I am accurizing a rifle that the owner wants to use the factory barrel on, I will then simply chase the receiver threads with a precision 1.0625" tap(Rem 700) to clean up the threads and remove any burrs that may be present.

This assures that when I fit the barrel I can "feel" how quality a fit I have with the barrel threads as I fit the barrel. Without this cleaning of the original threads, it is impossible to get an accurate idea of the thread fit you have machined.

Again this is only when a factory barrel will be reused as you can not true the receiver threads without increasing their diameter and this would result in an even looser thread fit then is offered by the factory.

For top results, single point thread cutting this the only way to do it.

Good Shooting!!!

Kirby Allen(50)
 
i hate to see this go bye! mines already in his shop /ubbthreads/images/graemlins/grin.gif
 
Strongly suggest that anyone that is considering truing an action such as a 700 rethink it from a money standpoint.

There are custom actions that cost the same or less even than a trued 700. For example Jerry Stillers Predator is out now for $600, it is Rem footprint, will take rem bottom metal and is tighter than a trued 700 but less than true BR action and costs less than 700.

Bruce Baer is selling the Lawton actions in 1.350 (Rem footprint), 1.450 and 1.650, all for less than trued 700.

Most of the smiths that answered this thread quoted around $200-300 plus for truing action and most did not include sleeving the bolt(anothe $150-200). Add that to the cost of the action $350-400 and you are in the $700-900 range and it is only worth $400-500 max when you are done vs the other actions holding 90% value.

Now some will say, "but I already have the action". Yes and you can sell it for $350 right now too.

BH
 
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