Jump to content
Military Firearm Restoration Corner

Won't Pass Go Gauge


metzgeri

Recommended Posts

I recently aquired a NOS Swedish action barreled to a NOS Swedish 6.5x55 barrel. Both look brand spanking new and the serial numbers/stamps (lack of them) indicate they were never used by the military. The entire barreld action was also reblued beautifully. Obviously, the action and barrel were surplused here to the states and a gunsmith put them together. The previous owner states this as well.

 

The rifle will not pass the Forster 6.5x55 Go Gauge.

 

I know there are discrepancies between CIP and SAAMI. And, I do believe Forster gauges are SAAMI spec'd whereas a NOS Swedish barrel would be based on CIP. So, do I have a problem here? The rifle will chamber an m/41 Swedish round. I just wonder if there could be a problem when headspace is too short.

 

What do you guys think? Do I need to have the chamber finish reamed?

 

metzgeri

Link to comment
Share on other sites

 

Thanks for the replies, guys.

 

There is no resistance to chambering an m/41 round or one of my FL sized loads with Graf brass. Both chamber and the bolt closes with ease. Extraction is good too.

 

I took some time tonight to strip the bolt, like you suggested, sonic1. I also cleaned the chamber area really good.

 

With a little "elbow grease" I'm able to close the bolt. But it sure isn't how it should close on a go gauge. So, I figure I'm right at the brink of passing go gauge.

 

Any further thoughts guys?

 

metzgeri

Link to comment
Share on other sites

I took some time tonight to strip the bolt, like you suggested, sonic1. I also cleaned the chamber area really good.

 

With a little "elbow grease" I'm able to close the bolt. But it sure isn't how it should close on a go gauge. So, I figure I'm right at the brink of passing go gauge.

 

Any further thoughts guys?

 

metzgeri

 

Well I hope that you used very little of that elbow grease since you never want to force on a gauge.

Further thought.... Lugs.

Are they all well mated? You mentioned that the action was NOS. Did you lap the lugs to mate?

Perhaps a light lap of the lugs would be all that you need to put the E grease away and slicken things up.

 

Otherwise it sounds like you are pretty much there.

 

Tinker

Link to comment
Share on other sites

Well I hope that you used very little of that elbow grease since you never want to force on a gauge.

Further thought.... Lugs.

Are they all well mated? You mentioned that the action was NOS. Did you lap the lugs to mate?

Perhaps a light lap of the lugs would be all that you need to put the E grease away and slicken things up.

 

Otherwise it sounds like you are pretty much there.

 

Tinker

 

Yeah, I know I shouldn't have forced the bolt. The "Mad Monkey" in me got the best of me!! :blink:

 

Another gunsmith in Cali. put this together. I plan to call him on Monday. I'm about 90% sure he didn't lap the lugs. The inner channels of the reciever are still blued and not polished. The bolt rides a little rough because of that. If he didn't polish them, I doubt he lapped the lugs.

 

Can you lap lugs with the barrel attached (without that spring-loaded thing-a-ma-bob screwed into the reciever)?

 

metzgeri

 

 

Link to comment
Share on other sites

Can you lap lugs with the barrel attached (without that spring-loaded thing-a-ma-bob screwed into the reciever)?

 

metzgeri

 

Well you need a spring somewhere.

Bubba might take a fired case and cut it in half. Then if he found a spring that just fit inside the body of the case

he'd be good to go to do some lapping.

A ball bearing between the spring and the bottom of the case helps. At the very least grease up the bolt face.

 

Just be sure to get out all of the lapping compound when you are done.

 

Tinker

Link to comment
Share on other sites

Hell, you might get away with simply unscrewing the barrel then screwing it back on only not so tight. Most folks overtighten anyway.

Link to comment
Share on other sites

Thanks for the advice tinker and z1r. Since the lugs probably need lapping anyhow, I'll rig up a "bubba contraption" and lap them. If it doesn't work (highly doubtful it won't) then I'll take your advice z1r.

 

Much thanks to all for the help.

 

metzgeri

Link to comment
Share on other sites

UPDATE and question (Sloooowwwwly but surely):

 

I took a couple spent 6.5x55 cases, FL resized them, cut them in half with a tube/pipe cutter, chamfered the edges and used a cut-down mosin bolt spring to come up with a jig to put pressure on the bolt as I lapped. I've read about it on various forums but there is no tutorial so there was a bit of "learning curve", not much.

 

I started by using layout dye on the lugs and found that only one lug was contacting and at about 40%. I spent 3 hours tonight (after making the above jig) just lapping, cleaning and checking. My rough count is about 200 bolt laps (up, down=one...). I used clover 320grit (equivalent to valve lapping grit). After cleaning and rechecking go gauge, I made significant progress, the bolt is closing more on the go gauge. It is still safely not closing on the no-go gauge. I now have about 50% contact on the one lug too.

 

Hopefully I can get both lugs contacting 80% and still safely not closing on the no-go gauge. We'll see....

 

Question for the experienced: While lapping, I am not rotating the bolt so far back that the lug angles are being lapped. I'm interested in only lapping the contact surfaces that exist when the bolt is fully closed. Is this a prudent precaution?

 

metzgeri

 

Pictures: Original Lug contacting surfaces, Jig compared to 6.5x55 case, Jig assembled

 

post-3608-1241844039_thumb.jpg

post-3608-1241844064_thumb.jpg

post-3608-1241844073_thumb.jpg

Link to comment
Share on other sites

Question for the experienced: While lapping, I am not rotating the bolt so far back that the lug angles are being lapped. I'm interested in only lapping the contact surfaces that exist when the bolt is fully closed. Is this a prudent precaution?

 

Sounds right to me.

Link to comment
Share on other sites

Well, 2nd day and finally got it!! It took me about 3 more hours and all told, about 450 strokes of the bolt to get the Go gauge to pass. Most of the time was spent cleaning the bolt and chamber, re-checking headspace with Go/No-Go gauges and re-checking lug fit with bluing. The actually lapping really didn't take that long at all. I re-checked headspace every 60 or so strokes and saw good progress along the way.

 

Here's the final results below. I have about 80% contact on one lug and what looks like about 95% on the other. I ended up switching to a black sharpie marker because that gave me a better indicator towards the end. The blue Layout Fluid didn't want to wear off (probalby because it was too smooth).

 

The bolt closes nice and snug on a Go gauge (without any force) and is still not closing confidently on the No-Go gauge. Thanks to all for suggestions and help.

 

metzgeri

post-3608-1242302628_thumb.jpg

post-3608-1242302648_thumb.jpg

Link to comment
Share on other sites

Well done. I've often thought of ways to make a jig to lap lugs, beats paying the price for a jig. Very nicely done. Seems to me that your way would be more accurate verses the plunger method with the barrel taken off. Your method takes everything into account.

 

Now for the question. By laping the lugs, you *possibly* removed a bit of the harding layer. Do you plan to re-heat treat, or shoot as is? I'm just wondering and learning.

 

Brenden

Link to comment
Share on other sites

Well done. I've often thought of ways to make a jig to lap lugs, beats paying the price for a jig. Very nicely done. Seems to me that your way would be more accurate verses the plunger method with the barrel taken off. Your method takes everything into account.

 

Now for the question. By laping the lugs, you *possibly* removed a bit of the harding layer. Do you plan to re-heat treat, or shoot as is? I'm just wondering and learning.

 

Brenden

 

Not planning to reheat. I lapped until the bolt closed nice and snug on the go gauge (without any force). I'll be checking headspace for lug setback later when I'm finished getting her together and shoot her. I've read about your concerns on other posts before but I'm not totally convinced their legit...we'll see.

 

metzgeri

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...