Gunsmithing Receiver Blueprinting and Barrel to Receiver Joint

#2
Re: Receiver Blueprinting and Barrel to Receiver Joint

Good read for certain. Do you advocate the low barrel torque?

Sounds like they determined that the barrel is going to move during every firing, and leaving it somewhat loose (35-45 foot pounds) with all the surfaces trued will allow it to reset the same every time? Very interesting for sure!

Thanks for the link
 
#5
Re: Receiver Blueprinting and Barrel to Receiver Joint

Wow, this article will make you want to blueprint all of your rifles! Now I have to wonder HOW bad all of my rifles are out of alignment!
 
#6
Re: Receiver Blueprinting and Barrel to Receiver Joint

I’ve read this before and find the article intriguing in that most of all of his receiver truing is done by hand with piloted cutting tools.

So should this also answer some of the questions of what is best to true with a machine or with precision piloted hand cutting tools? If you agree with the truing of the action for accuracy and the findings of this article then one must also agree that truing the action with piloted tools is just as good as well, otherwise if not the data in the article is flawed and not worth anything except the paper it's written on.

25 ft lbs is a little light for a field rifle and as stated is more in line for a BR rifle. Most if my builds will get 60 – 65 ft lbs.
 
#9
Re: Receiver Blueprinting and Barrel to Receiver Joint

I personaly blue print all my factory action back to 100% spec within .0002" , is it needed , no , does it make the gun shoot better , probably not! But in my oppinion it eliminates more variables to guess at if the gun starts shooting bad. I've seen Rem 700 action that only had one lug making contact and a visible gap between the action and lug where the reciever face was not square that would shoot 1/2 MOA out to 500yds consistantly , Now it was threaded to a properly chambered Hart barrel.
I have also seen BR gun have a barrel screwed on by hand and fired 20-30 times and need a wrench and some stout pressure to break it loose as with a right hand twsit barrel it will snug it self up each firing.

I think that alot of the "blue printing" we have done is more "preventitive" or Just in case" measures more that truely needed. Though if I were a smith building guns for a living I would not build a factroy gun wihtout blueprinting it
 
#10
Re: Receiver Blueprinting and Barrel to Receiver Joint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 81STFACP</div><div class="ubbcode-body">Has anyone blueprinted a gas gun receiver like the M1A?</div></div>

Not sure about the M1A, but I know several chaps with blueprinted ar-15/ar-10 uppers.

I do believe GAP does some blueprinting on AR-10 uppers they build, but I don't work for GAP so don't take my word as gospel on that.
 
#12
Re: Receiver Blueprinting and Barrel to Receiver Joint

I dont know if I agree with using piloted tools to cut the threads and square things up. I have used Mansons blueprinting kit before and I did a few actions. After I got my shop up and running I went back and re-indicated the actions in my blueprinting fixture. All the "trued" surfaces needed to be re-cut as I was measuring a good amount of run out.

It just makes a lot more sense to me to dial in the bolt bore raceway and single point cut everything. It seems to be what works the best for me!

Mark
 
#13
Re: Receiver Blueprinting and Barrel to Receiver Joint

Very interesting read. I kinda wonder about hand turning all those tools, it's hard to hand turn a tool without inducing some kind of bias in the situation.
I use a very low torque on my Savages and got rid of the bedding under the chamber and it seems to have made a big difference as the rifle stays consistent as it heats up from firing, before it would start moving.
 
#14
Re: Receiver Blueprinting and Barrel to Receiver Joint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: US Handgunner</div><div class="ubbcode-body">I dont know if I agree with using piloted tools to cut the threads and square things up. </div></div>

I dont either. I single point everything.
 
#15
Re: Receiver Blueprinting and Barrel to Receiver Joint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigngreen</div><div class="ubbcode-body">
I use a very low torque on my Savages and got rid of the bedding under the chamber and it seems to have made a big difference as the rifle stays consistent as it heats up from firing, before it would start moving.
</div></div>

I need to do more testing, but what happens when the barrel heats up and wants to expand but there is contact from bedding at the bottom of the barrel? Makes you wonder if you want it there.

Mark
 
#16
Re: Receiver Blueprinting and Barrel to Receiver Joint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 81STFACP</div><div class="ubbcode-body">Has anyone blueprinted a gas gun receiver like the M1A? </div></div>
Dobber used to do a sort-of blueprinting on the Grade A M14s at Crane. The receiver faces were checked for square vs. the threads (which were also checked for distortion) after they welded the lugs on. The bolt face was also trued in a special jig they had then lapped in the rifle. He had all kinds of interesting things that I am sure he didn't let me in on all of them.
 
#17
Re: Receiver Blueprinting and Barrel to Receiver Joint

i use 300 lb/ft torque to turn a standard chamber into a match chamber
grin.gif
 
#18
Re: Receiver Blueprinting and Barrel to Receiver Joint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: US Handgunner</div><div class="ubbcode-body"> I need to do more testing, but what happens when the barrel heats up and wants to expand but there is contact from bedding at the bottom of the barrel? Makes you wonder if you want it there.</div></div>

Measure a small piece of metal with mics and note the measurement. Now, tightly hold that piece of metal to heat it up in your hand for 5 minutes. Measure it again. The dimensions changed on it as will the barrel/receiver when you go from the winter months to summer months. If there's a barrel pad present what do you think will happen.........refer to the small piece of metal you held in your hand and measured
wink.gif
 
#19
Re: Receiver Blueprinting and Barrel to Receiver Joint

Answer these questions and you'll find out if a barrel pad is a bad thing.

Does the barrel heat up at the same rate along its length?

What part of the barrel sheds heat more quickly?

Where does most of the heat in a barrel reside during sustained fire?

Does the bedding material not react to heat?

Is the bedding material more sensitive to heat and tends to move with the hot barrel or does it remain hard and become the source of stress? (Hint: How do you remove pillars that have been bedded in place?)
 
#21
Re: Receiver Blueprinting and Barrel to Receiver Joint

Thats why they make Chocolate & Vanilla ice cream boys........different choices and desires.

Some use the bedding pad and some dont. If it works for you and gives you that warm and fuzzy I say run with it.
 
#22
Re: Receiver Blueprinting and Barrel to Receiver Joint

just to be clear, i was not using that question to prove one way is better than the other. i just figured since we were using heat expansion as the reasoning to bed one part or the other, we should consider the receiver ring that is bedded may also be expanding more/less/the same as the first inch or inch and a half of the barrel.
 
#24
Re: Receiver Blueprinting and Barrel to Receiver Joint

Exactly my point....or part of it anyway....The bottom line is, the barrel will resonate the same way shot to shot with a barrel pad or without. The bedding, whether its a pad or under the receiver isn't always the same, no different than the barrel or the stock. The key is consistency from shot to shot regardless of what method is used....

Just trying to invoke a little thought here Gentlemen....
grin.gif
 
#25
Re: Receiver Blueprinting and Barrel to Receiver Joint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Skunkworks</div><div class="ubbcode-body">Just trying to invoke a little thought here Gentlemen....
grin.gif
</div></div>

It's all good.

Don’t forget, it's your anniversary..........better go make the wifey happy
wink.gif
 
#27
Re: Receiver Blueprinting and Barrel to Receiver Joint

It would be interesting to see the temperature variation from front of receiver, recoil lug, and first few inches of the barrel with temps taken before shooting, after each shot and then after a string of shots. Also it would be entertaining to do the same with the bedding compound. I would imagine you could accomplish this fairly easy using a laser temp gauge and some free time.
 
#28
Re: Receiver Blueprinting and Barrel to Receiver Joint

The way I look at it is of the scientific method. The more variables you can hold constant, the more accurate and repeatable results you will obtain. You should try to reduce the variables in your shooting to those of the surrounding physical environment and mechanics of the shooter himself. Anything else that can be taken out of the equation (rifle/ammo construction) to cause possible variation in repeatable results, should be removed. In other words, don't allow the equipment to be the shortfall in the accuracy of your shooting.
 
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