Bolt Lug Wear on Tikka T3x -- Ok?

[GTDX12S]

Would appreciate help with understanding issue I have not encountered before. Sorry for long read, want to include detail for context:

Recently started break-in process on new Tikka T3x Roughtech in 6.5 prc. Cleaned barrel before shooting it (what came out was worthy of a separate post). Shot 20 rounds of factory Hornady 147gr ELDM, cleaned barrel to metal. Shot another 20 147gr ELDM and cleaned barrel to metal again. Applied lube (shooter's pro gold) to bolt lugs before each session. Inspected after each session and noticed nothing on lugs. Next 2 sessions were 15 handloads, of Hornady 120gr ELDM to book loads. Again lubed lugs before each session and noticed nothing unusual. 5th session was 15 of same 120gr ELDM, lubed bolt lugs before. Inspected after and noticed wear patterns shown in pictures. Shot it again today and noticed patterns seem more pronounced with new round dimple on lower bolt lug. The wear patterns showed up between rounds 60-85. Now at 100 rounds.

Throughout all of the sessions with the T3x the bolt has functioned perfectly, closes easily on all rounds with no noticeable sticking on bolt lift.

This the third rifle I have handloaded for. Have 700+ handloads on Custom 280 Ackley and 400+ Bergara B14 Hunter 6.5 Creedmoor. No unusual wear on bolt lugs of either.

Ok, with that bacground here are my questions:
1) What are possible causes of the wear patterns on bolt lug and recess lug?
2) Any possible safety issue?
3) Will this affect accuracy/precision? [planning to start developing hunting loads now with barrel at 100 rounds]

Thanks in advance with help on this!

Pics follow groups 1&2 of bolt lug and lug recess (bore scope pic poor resolution)

 

[jackieschmidt]

At least they are both making contact.

You don’t have a problem. Shoot your rifle and enjoy it.

 

[Hal]

After you lube the bolt lugs, hold the trigger down as you close your bolt.
Try to keep forward pressure on the bolt as it's closed, trying not to wipe the lube off as the bolt is closed.
Don't forget to lube the camming surfaces on the back of the bolt.

Hal

 

[GTDX12S]

@jackieschmidt - both making contact for sure! Good to know it is not a problem. Will continue to monitor.

@Hal - follow the practice you describe of lowering the bolt with trigger held down after lubing the lugs (usually run it twice) to try and keep the lube on, and do also lube the back of the bolt on the camming surface.

Thank you both!

 

[boltfluter]

After you lube the bolt lugs, hold the trigger down as you close your bolt.
Try to keep forward pressure on the bolt as it's closed, trying not to wipe the lube off as the bolt is closed.
Don't forget to lube the camming surfaces on the back of the bolt.

Hal

This is very good advice. Keep your lugs lubed, as you have been doing, and keep on shooting. Tikka has very good heat treat on their bolt lugs. I have not seen any galled lugs in over 200 bolts I have had in the shop. Carry on.
Paul

 

[FNSafari]

dont forget a good hi pressure grease to the lugs, just a little!

 

[LeoHuhta]

Are you doing a good job of cleaning the lug recess as you go?
Cleaning and lubricating the bolt is only 1/2 the job.

 

[280ai]

Beautiful even lock up SHOOT IT

 

[Kevin1990]

Thanks for posting this. years ago I had a tika. I had the exact same thing happen on a tikka and sold it. (told the guy the issue). Glad to get confirmation from other posters that its totally fine.

not trying to hijack post, but is this galling, or normal wear?

 

[Pete Wass]

There must be a better something to lube bolt lugs than most of us use, something that won't wipe off easily and make a greasy mess!

 

[47WillysGuy]

For comparison, this bolt has over 5000 rounds on it. You say yours has a 100. I believe, IMHO, something is going on. Looks like grit or grinding compound is affecting the barrel and bolt lugs.

What came out upon cleaning that was worthy of a second post??

 

[LCazador]

For comparison, this bolt has over 5000 rounds on it. You say yours has a 100. I believe, IMHO, something is going on. Looks like grit or grinding compound is affecting the barrel and bolt lugs.

What came out upon cleaning that was worthy of a second post??

I'm going to agree with this post. Carbon deposits might do what is described in the original post. Do you have a lug cleaning tool to clean the lug area? Sold by Sinclair.

 

[GTDX12S]

Again, appreciate all of the posts sharing informaiton and ideas

@boltfluter - your experience with Tikka bolt lugs is good to hear. Did not think the condition of my bolt now was galling but was concerned that the contact on lockup was "cutting" away material.

What may not be clear in the pics is the depth of the removed material at the angled line at the top of the (+/- 45 to bolt) "mark." Am easily catching it with the tip of a fine tweezer. Guessing several thou has been removed.

@47WillysGuy - Decided to clean the new rifle before shooting it using Thorro Flush and was surprised by the amount of black gunk that came out on the first few patches. Did not seem to be getting it so I brushed it with Thorro Clean - 15-20 strokes - and then patched it some more with TF followed by dry patches. Ran borescope and at that point it was clean. I used the J Dewey BAC Bolt Action Lug Recess & Chamer Cleaning Kit after removing the bore guide to clean up the chamber and lugs.

Chamber and Lug cleaning is last step in my cleaning process when I clean my bolt guns and was done on the 2nd and 3rd cleanings metioned in 1st post.

@LCazador - When I ran the borescope in to look at the lug recess I noticed there is a good carbon ring starting to form. Has been 60 rounds since last cleaning. Was hoping to be able to go a 100 or so between, but the 6.5prc may not play that way. Will clean barrel, chamber, and lugs thoroughly and continue.

Had not described brass prep yet for any possible impact on chamering round. Have been running the Hornaday brass from the factory I started with as a test to see if after 4-5 firings I developed "clickers." At 5 firings now on 15 pieces and at the 200 line on the web am getting 0.531 after firing consistently at each firing (measured with mic and caliper). Using Horndady dies (decided to start with simple two-die set) am resizing web to 0.530-0.5305. No Clickers so far. Expect this is a 0.533 chamber but have not expanded the brass to dimension yet. Maybe it won't?

Using said dies I have full-length sized after each firing but am not bumping the shoulder more than 0.001 Most measure at fired HS or -.0005 after full-length sizing (measured with SAC comparator). Trimmed after 2nd firing to 2.018. Have grown to 2.025 on average after 5, am fixing to trim again.

So LSS don't think the reloading process, other than running with minimal shoulder setback (bolt closes Easily on resized loaded round), should be impacting the bolt lugs to cause the wear pattern.

 

[47WillysGuy]

From what I've read in post #13, bumping the case back 0.001" or less could be the problem. I would experiment and bump the cases back 0.002" -0.003". You have a cartridge case which holds 50 plus grains of powder and bullet traveling at around 3000 FPS. That's alot of pressure and heat and with 0.001" or less bump, the combination maybe what causing the wear pattern on the lugs. You are very right to be concerned of that indication on the bolt.

The way I set my head space is with a stripped bolt. No firing pin or ejector. I test the bolt fall by inserting it into the action with no case. The bolt should freely fall. I then full size a case back until the bolt freely falls again. I feel that gives enough bolt lug clearance so that the greased lugs stay greased and not wiped clean.

You have 3 options as I see it:
1-Leave it go as others have recommended.
2- Experiment with an increased headspace of 0.002-0.003 thousands.
3-Take the gun to reputable gunsmith and have him check your fire control.

Hope you find your solution. Good luck.

 

[boltfluter]

Would appreciate help with understanding issue I have not encountered before. Sorry for long read, want to include detail for context:

Recently started break-in process on new Tikka T3x Roughtech in 6.5 prc. Cleaned barrel before shooting it (what came out was worthy of a separate post). Shot 20 rounds of factory Hornady 147gr ELDM, cleaned barrel to metal. Shot another 20 147gr ELDM and cleaned barrel to metal again. Applied lube (shooter's pro gold) to bolt lugs before each session. Inspected after each session and noticed nothing on lugs. Next 2 sessions were 15 handloads, of Hornady 120gr ELDM to book loads. Again lubed lugs before each session and noticed nothing unusual. 5th session was 15 of same 120gr ELDM, lubed bolt lugs before. Inspected after and noticed wear patterns shown in pictures. Shot it again today and noticed patterns seem more pronounced with new round dimple on lower bolt lug. The wear patterns showed up between rounds 60-85. Now at 100 rounds.

Throughout all of the sessions with the T3x the bolt has functioned perfectly, closes easily on all rounds with no noticeable sticking on bolt lift.

This the third rifle I have handloaded for. Have 700+ handloads on Custom 280 Ackley and 400+ Bergara B14 Hunter 6.5 Creedmoor. No unusual wear on bolt lugs of either.

Ok, with that bacground here are my questions:
1) What are possible causes of the wear patterns on bolt lug and recess lug?
2) Any possible safety issue?
3) Will this affect accuracy/precision? [planning to start developing hunting loads now with barrel at 100 rounds]

Thanks in advance with help on this!

Pics follow groups 1&2 of bolt lug and lug recess (bore scope pic poor resolution)

View attachment 1539817


View attachment 1539818View attachment 1539819View attachment 1539820

My Tikka T3 has a similar look. I personally believe it comes from the rifle being fired with proof loads at the factory. I have seen many like this in the shop. I believe it looks more pronounced as the lugs seat to the lug seat, and the surfaces polish or lap each other as more rounds are fired. You have good contact on both lugs, which is a good thing. You have no galling, another good thing. I would just keep the lugs lubed, clean the lug seat area occasionally and carry on. If anything changes I would contact Tikka and have them check it out. As mentioned, lube the lugs, hold the trigger in the fired position, insert and close the bolt, then release the trigger. This way you are sure to get a coating of grease on the lug and lug seat and carry on. Just my take on it.
Paul

 

[K22]

Let me say from the start, I am not a gunsmith, not even close.

What I have to offer is an experience to share that looks a lot like you posted. Many years ago, I had a new bolt installed on a Remington Model 700. After a few hundred rounds I notice that one of the lugs was galled very similar to yours. I took it back to the smith who did the work and he passed it off as lack of lug lube. However, I routinely lube the lugs with Shooter's Choice bolt grease, very thin application. I suspected that the lugs were not mated properly with the receiver. The headspace was correct, however as he checked with go / no-go gauges.

I took it to another smith, (My current smith) a master gunsmith. After he blueprinted the action he confirmed that the lugs were not properly mated to the receive. It was steel grinding on steel aggravated by not mated properly. He reset everything, and I never had recurrence since and that was after several thousand rounds shot.

Where I am going with this is that the galling appears severe, more than what I would think would be caused by improper lube or debris. This looks like a factory imperfection. I choose not to call it a defect because it the rifle is shooting good therefore, I am not sure this needs to be fixed. Still, it would bother me wondering if it gets worse will it affect accuracy or will it just self-mate. I suggest that the gunsmith members chime in on that.

 

[LCazador]

As mentioned above you may want to consider more shoulder bump. Any carbon in the lug area may be due to a poor gas seal. A poor gas seal would appear as soot on the shoulder area.

 

[Webster]

Would appreciate help with understanding issue I have not encountered before. Sorry for long read, want to include detail for context:

Recently started break-in process on new Tikka T3x Roughtech in 6.5 prc. Cleaned barrel before shooting it (what came out was worthy of a separate post). Shot 20 rounds of factory Hornady 147gr ELDM, cleaned barrel to metal. Shot another 20 147gr ELDM and cleaned barrel to metal again. Applied lube (shooter's pro gold) to bolt lugs before each session. Inspected after each session and noticed nothing on lugs. Next 2 sessions were 15 handloads, of Hornady 120gr ELDM to book loads. Again lubed lugs before each session and noticed nothing unusual. 5th session was 15 of same 120gr ELDM, lubed bolt lugs before. Inspected after and noticed wear patterns shown in pictures. Shot it again today and noticed patterns seem more pronounced with new round dimple on lower bolt lug. The wear patterns showed up between rounds 60-85. Now at 100 rounds.

Throughout all of the sessions with the T3x the bolt has functioned perfectly, closes easily on all rounds with no noticeable sticking on bolt lift.

This the third rifle I have handloaded for. Have 700+ handloads on Custom 280 Ackley and 400+ Bergara B14 Hunter 6.5 Creedmoor. No unusual wear on bolt lugs of either.

Ok, with that bacground here are my questions:
1) What are possible causes of the wear patterns on bolt lug and recess lug?
2) Any possible safety issue?
3) Will this affect accuracy/precision? [planning to start developing hunting loads now with barrel at 100 rounds]

Thanks in advance with help on this!

Pics follow groups 1&2 of bolt lug and lug recess (bore scope pic poor resolution)

View attachment 1539817


View attachment 1539818View attachment 1539819View attachment 1539820

Top photo is real scary. This isn't damage from rubbing or galling. Actual indents. I did metallurgical failure analysis for 45 years. Maybe not an expert but experienced. You should never get indents, Cannot image whats going on. I would call Tika technical help. Is there an indent from Rockwell hardness testing on the bolt head o.d. non-contact surface? Maybe a combination of soft metal and high pressure. Just from looking at the bolt lugs on my 50 YO Rem 700 I would guess that the lugs are not hardened to a high level. I have scratches and no galling or indents. The lub you are using is probably OK but I shy away from custom made stuff for reloaders. I lube cases with a synthetic light vis oil. Don't have the can nearby to check, but I use some kind of Mobil1 extreme pressure grease for my bolt lugs. I worked in research for oils, greases and other products. I assume the bottom image is damage on the action lug contact surface? The actions and bolts are not made from hardened steel since they have to machined with lathes and milling machines. I don't know if anyone induction hardens the bolt lug area. Based on how easily it scratches I am sure the lugs are not very hard.

Put some magic marker on the lugs and work the bolt a couple times and see if you have flush contact across the surface..

The image seems to indicate the lug and the receiver contact don't come together properly. There is a lead in to the indent and it gets very deep at the other end. Are both lugs the same condition? I wouldn't shot the rifle until the problem was resolved. It may be safe but your damaging the bolt and the receiver surfaces.

If the bollt lugs were hardened buy some kind of heat treat I don't think it's possible to get dents in the lug surface. If you can easily scratch the lug contact surface with the corner of a razor blade it is not very hard. I would expect very shallow scratches if it was hard. Look at the image put up on Post #11 47WILLYSGUY. This is what I would call typical normal wear. That's what my Rem 700 lug looks like with abt 10,000 shots, several barrels.

 

[GTDX12S]

Took a couple days to work through it but developed some learnings from cleaning and testing that seemed worth sharing for everyone who has offered ideas and support in the thread.

After running the borescope in for a quick look to see how the chamber and lug recess areas looked I cleaned the rifle - thoroughly - starting with the lug recesses and chamber this time. Did not find carbon in the lug recessess or chamber except for a light carbon ring formed in front of where case neck ends. Nothing noteworthy - beyond some dirty grease in lug recesses -from cleaning these areas.

@LCazador - Have not observed any soot on shoulders of fired cases, does not seem like there is a gas leak.

After cleaning, disassembled the bolt and pulled the extractor to test case head space. BINGO.

@47WillysGuy - Thanks again for posting your thoughts on the minimal bump possibly being the issue. When I put a fired case in that measured 1.6050 on compartor the bolt did not drop and required a light push to cam over. Resized from there and found the bolt dropped freely between 1.6030-1.6035, 0.0015-0.002 below. Right where you suggested it should be.

Last up was to mark the lugs and check for contact.

@Webster - the pics below are of the bolt lugs marked with a black sharpie after reinstalling the extractor pin and caming over on a dummy round properly sized to 2 thou short of chamber headspace (as measured). First pic (L) is 9 that moves down (LH action), 2nd pic (R) is 3. Ran it twice. Looks lilke there is light contact accross both, with it more pronounced on 9

 

[GTDX12S]

So closing thoughts, this thread was truly helpful and has allowed me make a needed correction in my handloading process.

@boltfluter - your thoughts on Tikkas are encouraging! I like this rifle and it has shown some real promise through the first 100 rounds. Hoping it enjoys a long and happy life.

Thanks again to all!

Shoot Straight!