Did you unscrew your barrel and measure it?
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Chamber Dimensions
- Thread starter Engineering101
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Did you unscrew your barrel and measure it?
J E Custom
Well-Known Member
+1
After reading all of the post, I have to agree that ether it needs to be taken apart or have another Gun Smith look at it.
There are many different barrel shank dimensions for the Sako and there is a possibility that the smith used the wrong drawing and fabricated the shank wrong, or did not adjust for the new cartridge.
Your question as to the shank having no dimensional requirements, "THEY DO" AND SHOULD BE ADHERED TO.
If you take the barrel out of the action, you can see if the mark/ring on the brass lines up with the end of the shank.
It is very hard for anyone to diagnosis your problem without actually having it in there hands, and
with firearms, the need to be correct is very important for many reasons.
Keep us posted.
J E CUSTOM
Engineering101
Well-Known Member
With all the input from this thread and looking at the rifle and brass it appears that my smith just didn't push the reamer far enough into the barrel. Maybe there was something wrong with the reamer. (PT&G has been having "issues" lately.) Even were that the case he should have known that it wasn't right. Now that I've become an "expert" on case protrusion from the chamber it is obvious to me. I'll be going back to the smith to sort it out. Thanks again for all the input guys.
shortgrass
Well-Known Member
If the condition you've discribed is accurate, the guy that did the work should not be called a "gunsmith". That title gets used pretty 'loosely', these days.
Defens
Active Member
This confuses me then. If the chamber wasn't reamed far enough, but the barrel was properly installed otherwise, you'd have incorrect headspace and the bolt wouldn't close.
Seems to me that the opposite problem occurred. The first problem was that the barrel wasn't installed in the action properly, and then the rifle was short-chambered to "correct" for that error. As others (and I think you) have noted, just reaming deeper won't correct that problem - it would just add excessive headspace to your existing problem. You'd either blow out the shoulder, or just as likely the gun might not even fire, since the firing pin would just push the cartridge into the chamber.
You need to correct the barrel installation first, then fix the headspace.
Engineering101
Well-Known Member
I don't know what steps my "smith" took in what order to arrive at this point - screwed up, but it will be fixed. Let us move on to a much more interesting question. It will take a bit of explanation.
This rifle appears to be "different" than other 26 Noslers I've read about and seen data for. One difference is that it takes about 4 grains less powder to get the same velocities compared to published data. In the 26 Nosler that is bad because it makes it even more difficult to get a full case and, as I said, I had a load detonate on me when I tried IMR 7828SSC. The result of that detonation is show in the pic of the case earlier in the thread. A second difference is that this particular 26 Nosler seems to be unusually touchy/erratic. Could stretching of the back part of the cartridge walls (which would cause a change in combustion chamber volume during ignition) contribute to it being erratic and easier to get detonation? I don't suppose it would make things better.
This rifle appears to be "different" than other 26 Noslers I've read about and seen data for. One difference is that it takes about 4 grains less powder to get the same velocities compared to published data. In the 26 Nosler that is bad because it makes it even more difficult to get a full case and, as I said, I had a load detonate on me when I tried IMR 7828SSC. The result of that detonation is show in the pic of the case earlier in the thread. A second difference is that this particular 26 Nosler seems to be unusually touchy/erratic. Could stretching of the back part of the cartridge walls (which would cause a change in combustion chamber volume during ignition) contribute to it being erratic and easier to get detonation? I don't suppose it would make things better.
Engineering101
Well-Known Member
Edd
I've used most of the powders for which Nolser has data. I got pressure spikes and ES greater than 100 fps. On one of Kirby Allen's old posts he indicated that the stick powders tended to cause pressure spikes in his big overbore rigs and suggested ball powder as a solution. I took that advice ended up with a decent load using 85.5 grs US869 which gets me right at 3,300 fps with the 140 gr Accubond. It won't behave with any other powder.
I've used most of the powders for which Nolser has data. I got pressure spikes and ES greater than 100 fps. On one of Kirby Allen's old posts he indicated that the stick powders tended to cause pressure spikes in his big overbore rigs and suggested ball powder as a solution. I took that advice ended up with a decent load using 85.5 grs US869 which gets me right at 3,300 fps with the 140 gr Accubond. It won't behave with any other powder.
Kennibear
Well-Known Member
Where is it written that cases have to protrude from the barrel or they will jam on firing? The Ruger #1 falling block single shots have the cases submerged in the barrel proper. My #3 45/70 has the rim set into an recess in the chamber with the case absolutely flush with the barrel proper. Remington sold their rifles based on "three rings of steel" surrounding the cartridge head - even on the 742 semi-auto. Unsupported case heads have always been a negative in action design. I would say that the barrel needs to be as close to the bolt head as is possible within safe operating parameters and reliable functioning of the action. Trusting the brass case to contain the pressure without steel backing just does not make sense. Even modern handguns tout their "fully supported chambers". Blow out a few 45ACP cases in a 1911 with the attendant picking out brass shards from your fingers with tweezers and that should remove any thoughts of unsupported brass being a good idea!
KB
KB
shortgrass
Well-Known Member
How about this, get the teneon length fixed and the chamber properly headspaced and it just might be that the "touchy/erratic" condition will no longer exist. 
Engineering101
Well-Known Member
shortgrass
That is exactly what I'm thinking. Get this rifle setup as it should be and it will stop being touchy. There really is no other explanation for it.
That is exactly what I'm thinking. Get this rifle setup as it should be and it will stop being touchy. There really is no other explanation for it.
Canadian Bushman
Well-Known Member
I just read an article in hodgdons reloading guide where the author had similar issues with the 26 nosler. He even included a picture of a overpressured case that he had loaded slightly too low. His solution was also us869 and seating the bullets .04-.05 off the lands to eat up some case and smooth out the pressure curve.
This aside, typically most bolt actions the bolt is pretty close to touching the barrel in battery and very little of the case is unsupported by either the bolt or barrel. I agree with the others about dismantling the weapon or having a second smith confirm tenon length.
This aside, typically most bolt actions the bolt is pretty close to touching the barrel in battery and very little of the case is unsupported by either the bolt or barrel. I agree with the others about dismantling the weapon or having a second smith confirm tenon length.
Hired Gun
Well-Known Member
I can fully diagnose the issue described just by his explanation. I'm very disappointed in the responses from the senior staff here. If the head space is in spec based on the "Go" and "No Go" the issue is the bolt nose relief is cut too deep. I don't need the old barrel to copy for any gun. Just by measuring up the bolt and action and drawing blueprints to work from I add in my bolt nose clearance length and radial clearance based on good working clearances for the intended use of the rifle. A good general clearance is .010" around the bolt nose and .010" from the end of the bolt nose to the bottom of the bolt nose relief. Same thing on cone bolts. I typically go for as much case support as possible. I run the same clearance from the end of the lugs to set the tennon length same as the bolt nose whatever that is depending on the usage of the rifle. Some competition rifles I run closer and Police or Military duty rifles get a little more clearance. You don't want the rifle jammed up by dirt or an unburned kernel of powder.
Here is a Remington bolt with .007" clearance across and depth wise. This was an outdoor precision long range application.
Here is a Remington bolt with .007" clearance across and depth wise. This was an outdoor precision long range application.
