CZ 527 bolt lugs worn?

Colorado Redneck · July 14, 2015, 03:29 PM

I have a CZ American in 222 Rem. Over the 3 years of using this gun (bought new by me) the MAX COL (not headspace as I originally posted) has increased about .045 inches. I have no exact count of rounds, but less than 3000 for sure. Never loaded super hot. When I clean the bore , looking into the throat with strong reading glasses the throat looks practically pristine---no signs of erosion to the lands. 222's have a reputation of extended bore life, so this has puzzled me. Still shoots sub MOA, but used to do 3/8" regularly.

It occurred to me while cleaning it today, could the bolt lugs be wearing which would let the bolt face back. What do the bolt lugs look like to those of you that have experience and most of all to owners of CZ micro bore rifles? Looks to me like they could be wearing.

Thanks!

Dixie Gunsmithing · July 14, 2015, 05:06 PM

I doubt them being worn, as if they were, you would have headspace problems. Have you tried a no-go headspace gauge in it? That will at least tell if it is worn, as it should be somewhere less, towards a go gauge from the factory. If the bolt will not close on a no-go, then you're in good shape.

mehavey · July 14, 2015, 05:15 PM

Quote:

...the headspace has increased about .045 inches.

What are you using to determine/measure headspace?

Colorado Redneck · July 14, 2015, 05:55 PM

Maybe I used the wrong terminology? If so I will edit the original post. Maximum COL is the actual dimension that is getting longer. I am not sure the headspace is changing.

So that is my theory at the moment.

Two methods to determine max-COL:
1. Push bullet into lands gently, and measure barrel crown to bullet tip, then measure muzzle crown to bolt face, subtract difference.
2. Slightly deform fired case mouth, push bullet into case a couple of 1/100 inches, and use marks-a-lot to color the bullet bearing surface, then insert that dummy round into chamber and gently close the bolt. Then open bolt and gently remove the dummy round. Make sure the bullet is into the case mouth the same distance as it was in the chamber (by observing case mouth marks in the marks-a-lot coloring) and measure the resulting dummy round.

I use 3 different bullets (from the same box) to do both operations.

If the bolt lugs were in fact wearing, I am theorizing that the Max COL would increase. And the probability is very high that I am full of hooey. Just looking for opinions.

At this time I don't have go/no-go gages at my disposal. That is a great idea---would answer my question pronto. I guess I could take a piece of new brass and start cutting out round pieces of scotch tape and one at a time add those to the case head, insert empty case into chamber and close bolt. Those are .003 inches thick, so by doing that if it took more than about 4-5 to prevent closing the bolt that might indicate some lug wear???

William T. Watts · July 14, 2015, 06:20 PM

Wilson cartridge case gauge, I have a gauge for every caliber I load for, you can make direct comparison between your fired case and one you have resized. Sounds like you've just about shot the throat out of the barrel, It isn't the chamber lengthening it's throat erosion that is the problem. Accuracy probably not as good as it used to be either. It also sounds like you've not done enough reading to help you understand the reloading process to learn the changes that occur when you've shot that many rounds thru a barrel.. William

Colorado Redneck · July 14, 2015, 07:58 PM

Deleted--- no sense in my being snippy.

Colorado Redneck · July 14, 2015, 08:46 PM

William---I understand throat erosion happens. My understanding from the reading I have done is, the 222 Rem is not prone to throat erosion and has the reputation of going many thousands of rounds without very significant erosion. I am surprised that the measurements I have done indicate as much as .045 inches over less than 3000 rounds.

As well, accuracy has diminished some---read my original post.

I have a Hornady head space gauge, and that would not indicate whether or not there is throat erosion. The fired cases are not different than they have ever been. Does that fact answer my question then? The difference is all throat erosion? Dang!

Thanks

William T. Watts · July 14, 2015, 09:27 PM

That much throat erosion for that many rounds fired isn't unusual, nor is it unusual to find a longer than normal throat on a new rifle (I happen to have a Winchester in 22/250 with a long throat). On the up side my magazine will allow a much longer OAL than would normally be found for this round. I would guess you are using a Ball powder for your .222 Rem, as I recall you didn't mention what powder or what primer and no mention of the charge being used?? BTW I've loaded ammunition for about 45 years and can't remember buying factory ammunition unless it was purchased with a new firearm to give me an idea how my handloads differ from factory ammunition dimensions.. William

William T. Watts · July 14, 2015, 09:51 PM

Colorado Redneck I spent two years 2000 & 2001 in Trinidad at TSJC Jr. College attending Gunsmithing school after I retired from the Post Office. I returned to Arkansas after developing a heart problem but still have many fond memories of your state!! BTW if your magazine will allow the extra OAL length to counter the longer throat you may be able to shrink your group size by adjusting your powder charge and playing with it a bit.. William

Colorado Redneck · July 14, 2015, 10:06 PM

Reloading components for 222 Rem:
IMR4198--21.0 gr.
Rem 7 1/2 primers
Nosler 40 gr. BT

Good comment about the free bore on this rifle, as it was was long right from the factory. And now I am using the most accurate COL from the last round of experimenting--2.220 compared to 2.130 COL in the SAAMI spec's. Still off the lands a long ways--can't remember the max COL and too pooped to go downstairs to look. I have a magazine follower (actually an insert that fits into the magazine compartment) and shoot the gun single shot style, as it is used exclusively for prairie dogging, and I save the brass.

Thanks for the comments!

Colorado Redneck · July 14, 2015, 10:13 PM

Took these a few weeks ago north of Greeley about 25 miles or so, on the Pawnee National Grass Lands. The yellow flowers are poisonous to sheep. The generic name is "Bitter Rubber Weed." Still really pretty!

Dixie Gunsmithing · July 15, 2015, 06:58 AM

The only way to know if it is headspace, would be to check it with a no-go gauge, and see if it will close. That doesn't mean it is dangerous yet, but that is the limit it can go. Generally, newer rifles will not close on a no-go gauge, but will on a go, since the go is used to gauge them at the factory. If the bolt will close on a field gauge, then it is dangerous to shoot.

The headspace is the measurement from where the necked down taper is, to the rear of the cartridge or bolt face.

F. Guffey · July 15, 2015, 10:19 AM

Quote:

I have a CZ American in 222 Rem. Over the 3 years of using this gun (bought new by me) the MAX COL (not headspace as I originally posted) has increased about .045 inches.

No one measure the length of the chamber from the shoulder to the bolt face when they start. Then there are the few, the ones that can and keep up with bolt set back.

Added to the difficult as in the bolt setting back beyond the system that acts as a third lug, meaning if the bolt sets back .045" something else has to give. If the maximum case overall length has increased I would suspect something is going on in the throat as in gas cutting/throat erosion.

F. Guffey

mehavey · July 15, 2015, 12:07 PM

FG...
the OP's apparently talking about distance-to-lands, not headspace.

sirgilligan · July 15, 2015, 01:40 PM

After a few new firearms that had problems I started photographing all of the internals of my firearms so I could have a reference point. This is a CZ 527 in .223 REM. Now, I don't have a picture from the same angle as yours.

Colorado Redneck · July 15, 2015, 02:20 PM

William got me straightened out. The fired cases are still about the original headspace gauge reading as when first measured a couple years ago. Don't know why the logic he explained didn't come to me before posting.

If the bolt lugs were eroding then the case length to the datum line would have increased at least some when fired. Not happening. Evidently throat erosion is the culprit here. May have more rounds down the tube than I thought, or maybe this is normal for this caliber. I know the 22-250 and .204 Ruger suffered lots of throat erosion to the point one was replaced and one was re-barreled. Someday then, this CZ will need one of those options. Dang it---I like the little gun and hoped it would maybe last a long time.

Thanks again---surely do appreciate the input.

Roger

July 14, 2015, 07:58 PM	#6
Colorado Redneck Senior Member Join Date: January 6, 2008 Location: Northeast Colorado Posts: 1,993	Deleted--- no sense in my being snippy. Last edited by Colorado Redneck; July 14, 2015 at 08:38 PM.

July 14, 2015, 09:51 PM	#9
William T. Watts Senior Member Join Date: January 20, 2010 Location: Central Arkansas Posts: 1,074	Colorado Redneck I spent two years 2000 & 2001 in Trinidad at TSJC Jr. College attending Gunsmithing school after I retired from the Post Office. I returned to Arkansas after developing a heart problem but still have many fond memories of your state!! BTW if your magazine will allow the extra OAL length to counter the longer throat you may be able to shrink your group size by adjusting your powder charge and playing with it a bit.. William Last edited by William T. Watts; July 15, 2015 at 07:18 PM.

July 15, 2015, 01:40 PM	#15
sirgilligan Senior Member Join Date: October 28, 2009 Posts: 614	After a few new firearms that had problems I started photographing all of the internals of my firearms so I could have a reference point. This is a CZ 527 in .223 REM. Now, I don't have a picture from the same angle as yours. __________________ SirGilligan - "If you find your back is up against a wall, maybe you have been backing up for too long." iOS Apps: BallisticsGL Gun Log Gun Log SPC WatchForce

July 15, 2015, 02:20 PM	#16
Colorado Redneck Senior Member Join Date: January 6, 2008 Location: Northeast Colorado Posts: 1,993	Thanks for the responses William got me straightened out. The fired cases are still about the original headspace gauge reading as when first measured a couple years ago. Don't know why the logic he explained didn't come to me before posting. If the bolt lugs were eroding then the case length to the datum line would have increased at least some when fired. Not happening. Evidently throat erosion is the culprit here. May have more rounds down the tube than I thought, or maybe this is normal for this caliber. I know the 22-250 and .204 Ruger suffered lots of throat erosion to the point one was replaced and one was re-barreled. Someday then, this CZ will need one of those options. Dang it---I like the little gun and hoped it would maybe last a long time. Thanks again---surely do appreciate the input. Roger

July 14, 2015, 05:06 PM	#2
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	I doubt them being worn, as if they were, you would have headspace problems. Have you tried a no-go headspace gauge in it? That will at least tell if it is worn, as it should be somewhere less, towards a go gauge from the factory. If the bolt will not close on a no-go, then you're in good shape.

July 14, 2015, 05:55 PM	#4
Colorado Redneck Senior Member Join Date: January 6, 2008 Location: Northeast Colorado Posts: 1,993	Maybe I used the wrong terminology? If so I will edit the original post. Maximum COL is the actual dimension that is getting longer. I am not sure the headspace is changing. So that is my theory at the moment. Two methods to determine max-COL: 1. Push bullet into lands gently, and measure barrel crown to bullet tip, then measure muzzle crown to bolt face, subtract difference. 2. Slightly deform fired case mouth, push bullet into case a couple of 1/100 inches, and use marks-a-lot to color the bullet bearing surface, then insert that dummy round into chamber and gently close the bolt. Then open bolt and gently remove the dummy round. Make sure the bullet is into the case mouth the same distance as it was in the chamber (by observing case mouth marks in the marks-a-lot coloring) and measure the resulting dummy round. I use 3 different bullets (from the same box) to do both operations. If the bolt lugs were in fact wearing, I am theorizing that the Max COL would increase. And the probability is very high that I am full of hooey. Just looking for opinions. At this time I don't have go/no-go gages at my disposal. That is a great idea---would answer my question pronto. I guess I could take a piece of new brass and start cutting out round pieces of scotch tape and one at a time add those to the case head, insert empty case into chamber and close bolt. Those are .003 inches thick, so by doing that if it took more than about 4-5 to prevent closing the bolt that might indicate some lug wear???

July 14, 2015, 06:20 PM	#5
William T. Watts Senior Member Join Date: January 20, 2010 Location: Central Arkansas Posts: 1,074	Wilson cartridge case gauge, I have a gauge for every caliber I load for, you can make direct comparison between your fired case and one you have resized. Sounds like you've just about shot the throat out of the barrel, It isn't the chamber lengthening it's throat erosion that is the problem. Accuracy probably not as good as it used to be either. It also sounds like you've not done enough reading to help you understand the reloading process to learn the changes that occur when you've shot that many rounds thru a barrel.. William

July 14, 2015, 08:46 PM	#7
Colorado Redneck Senior Member Join Date: January 6, 2008 Location: Northeast Colorado Posts: 1,993	William---I understand throat erosion happens. My understanding from the reading I have done is, the 222 Rem is not prone to throat erosion and has the reputation of going many thousands of rounds without very significant erosion. I am surprised that the measurements I have done indicate as much as .045 inches over less than 3000 rounds. As well, accuracy has diminished some---read my original post. I have a Hornady head space gauge, and that would not indicate whether or not there is throat erosion. The fired cases are not different than they have ever been. Does that fact answer my question then? The difference is all throat erosion? Dang! Thanks

July 14, 2015, 09:27 PM	#8
William T. Watts Senior Member Join Date: January 20, 2010 Location: Central Arkansas Posts: 1,074	That much throat erosion for that many rounds fired isn't unusual, nor is it unusual to find a longer than normal throat on a new rifle (I happen to have a Winchester in 22/250 with a long throat). On the up side my magazine will allow a much longer OAL than would normally be found for this round. I would guess you are using a Ball powder for your .222 Rem, as I recall you didn't mention what powder or what primer and no mention of the charge being used?? BTW I've loaded ammunition for about 45 years and can't remember buying factory ammunition unless it was purchased with a new firearm to give me an idea how my handloads differ from factory ammunition dimensions.. William

July 14, 2015, 10:06 PM	#10
Colorado Redneck Senior Member Join Date: January 6, 2008 Location: Northeast Colorado Posts: 1,993	Reloading components for 222 Rem: IMR4198--21.0 gr. Rem 7 1/2 primers Nosler 40 gr. BT Good comment about the free bore on this rifle, as it was was long right from the factory. And now I am using the most accurate COL from the last round of experimenting--2.220 compared to 2.130 COL in the SAAMI spec's. Still off the lands a long ways--can't remember the max COL and too pooped to go downstairs to look. I have a magazine follower (actually an insert that fits into the magazine compartment) and shoot the gun single shot style, as it is used exclusively for prairie dogging, and I save the brass. Thanks for the comments!

July 15, 2015, 06:58 AM	#12
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	The only way to know if it is headspace, would be to check it with a no-go gauge, and see if it will close. That doesn't mean it is dangerous yet, but that is the limit it can go. Generally, newer rifles will not close on a no-go gauge, but will on a go, since the go is used to gauge them at the factory. If the bolt will close on a field gauge, then it is dangerous to shoot. The headspace is the measurement from where the necked down taper is, to the rear of the cartridge or bolt face.

July 15, 2015, 12:07 PM	#14
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,894	FG... the OP's apparently talking about distance-to-lands, not headspace.