Dimension on my new barrel installation

[desmooreragdoll]

Hi;
I just picked up my Sako L 579 action and newly fit barrel. After doing some measuring, I find that there is a gap of .122" between the bolt face and the barrel.
That seems extreme.
I can not find dimension for the action.

Thank for any help

 

[gunsandgunsmithing]

Hi;
I just picked up my Sako L 579 action and newly fit barrel. After doing some measuring, I find that there is a gap of .122" between the bolt face and the barrel.
That seems extreme.
I can not find dimension for the action.

Thank for any help

That seems VERY extreme. Verify safety before firing. That does not sound right at all to me. How deep is the bolt face?
There is some discrepancy is what you'll find for tenon dimensions. Apparently some had metric threads and some imperial., but tenon length is nominally .870 long. MOST, brass is approximately .150 thick at the solid portion of the brass around the primer. If it has more protrusion than that I would not consider it safe to fire. I think it is likely that the protrusion should be about your .122 figure. If you pull the barrel, you can get the needed dimensions from the action. Which brings up the question..how did you measure the gap without having the barrel off, or do you? If so, it should be pretty simple to check.

 

[Ggmac]

Use some clay , lightly oil the barrel face close the bolt cocked , DO NOT FIRE , open bolt measure .
If you're counting the bolt face recess to barrel , you should be ok . A savage is .135 ish , the Mauser is .110 ish , Rem 783 is .145 ish

 

[desmooreragdoll]

I have the barrel off to contour.
I used a Mitutoyo caliper, it was difficult so I went out to the shop and got a depth mike.
New numbers, from the bolt face not the recess to the receiver. .866
End of barrel to shoulder .760, I now get .106
The end of the barrel is beveled for the extractor.
I have a 12x36 lathe, but don't wont to get in to barrel work.
If it is not right or not safe I will take it back.

 

[Ggmac]

Now I need the depth of the bolt face . if you insert a new or resized case in the chamber , how much is protruding , it should be less then .150
And should equal the .106 plus the depth of bot face .
SORRY ! NO COFFEE YET . Personally I only want .003-.005 between bolt nose and barrel . I know how the extractor and extractor cut are timed on the barrel/ bolt and measurements should be the same .
Gary

 

[Ggmac]

Just thought . If you had some clay and just reassemble , hand tight to verify the other numbers . The clay compression numbers should be within a few thousandths

 

[Roeder]

Hi;
I just picked up my Sako L 579 action and newly fit barrel. After doing some measuring, I find that there is a gap of .122" between the bolt face and the barrel.
That seems extreme.
I can not find dimension for the action.

Thank for any help

With the naked barrel, can you insert a case into the chamber and take a close up of the back of the barrel from an angle? It will be obvious to any experienced smith if there is an issue.

 

[gunsandgunsmithing]

It sounds like you are close to being where you need on shank lengths an headspace of cartridge protrusion check headspace with a go an no go guage everything good on headspace you are fine.

Stan, read those numbers again bud. Bolt, not bolt face, to end of barrel=.866. That dimension would establish barrel tenon length. He said his is .760. For a .866 measurement to the front of the bolt nose, I'd want the tenon to be about .860 long. If the measurements he gave are correct, he's about .100 to short on the tenon and likely has that much excess protrusion and unsupported case.

 

[Stan Taylor]

Stan, read those numbers again bud. Bolt, not bolt face, to end of barrel=.866. That dimension would establish barrel tenon length. He said his is .760. For a .866 measurement to the front of the bolt nose, I'd want the tenon to be about .860 long. If the measurements he gave are correct, he's about .100 to short on the tenon and likely has that much excess protrusion and unsupported case.

If someone orders a barrel for a L579 sako chamber threaded for a sako that's what they get an they have to set headspace.
.
headspace.

 

[gunsandgunsmithing]

If someone orders a barrel for a L579 sako chamber threaded for a sako that's what they get an they have to set headspace.
.
headspace.

Probably a stupid question, but what does T.R. and AF stand for?

 

[Ggmac]

Stan, read those numbers again bud. Bolt, not bolt face, to end of barrel=.866. That dimension would establish barrel tenon length. He said his is .760. For a .866 measurement to the front of the bolt nose, I'd want the tenon to be about .860 long. If the measurements he gave are correct, he's about .100 to short on the tenon and likely has that much excess protrusion and unsupported case.

I wasn't going to say anything , I thought he may have gotten a pm from the op. But ..

 

[Ggmac]

" newly FIT barrel "

 

[desmooreragdoll]

Mr Taylor I have never ordered A threaded and chamber barrel. The barrel was one of the match barrels blanks I already had. I took the action to a advertised rifle smith 140 miles one way, and went and picked it up. While there
I used his chamber gauges to check the head space, and it right. But head space is not the issue.
Thank you for your reply.

 

[desmooreragdoll]

The bolt recess is .059.
I have yet to order dies and components but I have one round that some one hand loaded. It must be from a chamber
larger than mine, and chambers a little hard.

I am unclear about the clay check, There is no space under the rim.

Thank you all

 

[Stan Taylor]

I wasn't going to say anything , I thought he may have gotten a pm from the op. But ..

I just deleted every thing I said except for quote to gunsmithing I ain't smart enough for these boys.

 

[Ggmac]

The bolt recess is .059.
I have yet to order dies and components but I have one round that some one hand loaded. It must be from a chamber
larger than mine, and chambers a little hard.

I am unclear about the clay check, There is no space under the rim.

Thank you all

The clay check is to determine the space between bolt nose and barrel . When compressed measure the depth of the clay . It should be close to the .106 plus the .059 . If added those numbers are a little to close for comfort .
It's possible to have correct headspace but a dangerous condition = case is sticking out too much and past the solid head . Only way this can happen is if the chamber wasn't cut deep enough and the barrel to bolt clearance is excessive .

 

[butchlambert]

I just deleted every thing I said except for quote to gunsmithing I ain't smart enough for these boys.

Stan, sometimes, no matter what you say, it is misconstrued. Probably nobody on this forum has chambered as many barrels as you.

 

[Stan Taylor]

Stan, sometimes, no matter what you say, it is misconstrued. Probably nobody on this forum has chambered as many barrels as you.

Thanks my friend.

 

[gunsandgunsmithing]

I wasn't going to say anything , I thought he may have gotten a pm from the op. But ..

The only reason I did was because, based on the numbers the op provided, it seemed to me to be a serious potential safety hazard if fired.
I'm not gonna blame or bash anyone and don't know what explains the discrepancy between Stan's numbers and what the op has or that the measurements are good or not.

But math is math and the numbers provided show .106" bolt to barrel clearance...Not the extractor. but the bolt nose. There should be a relief on one side(end) of the barrel tenon to give the extractor clearance at proper tenon length. I don't recall the depth of the extractor relief but I'd guess....030"...I'm going by memory here. That clearance has been put there because it is needed in the ones I've seen. The extractor would hit the end of the barrel tenon without it as it stands proud of the bolt nose by a few thou.

Even with it, the numbers told me that we had was .106" bolt to barrel clearance, when .003-.010" is more typical, and @ .006" clearance, that coincidentally add up to a nice, round, .100" mor than "typical". Typical doesn't make it right or wrong.

Also typically, bolt faces on MOST guns are between say .120-.150" deep. @.150+ .106" bolt to barrel clearance, you have .256 unsupported case...About .100 more than is "typical" also, but then the solid portion of most brass is also nominally about .150 thick, too. Again, about .100 too much unsupported case, IMO. That's A LOT!
Now, if the bolt nose is only .059 deep, that changes things a bit. We now have what, .165 clearance? Bad but not nearly as bad as .256!!!! Hugely different!

I made my post not to stir any debate but to keep the op from taking anything in this thread as saying he should shoot it like it is without verifying that it is safe. It sounds dangerous as hell to me...based on the numbers the op posted just before my post.

I didn't mean to ruffle anybody's feathers...It was and is there out of legitimate and IMO, justifiable concerns, for the safety of anyone firing a gun with the aforementioned clearances.

There...I say talk to your smith. Get everything verified and checked. I won't assume that he made a mistake without having it in my hands but it looks a lot like the tenon was cut short by an even .100" ---Mike

p.s.---I shouldn't have even posted my previous post but there were and are a lot of coincidences. I still say that there should not be an unexplained .106" clearance between the bolt and the tenon. If that's proper, there is no need in the extractor relief in the end of the barrel.

 

[Dusty Stevens]

^exactly. Need to do some checking for sure. An even .100 could be a measurement error (misread depth on the tool) or it could be an exact .100 cut by accident trying to hit another number. Either way the gunsmith will want to fix it (ups runs every day) and it needs to be looked at before its shot. Safety first.