Heavy Bolt lift on Tikka 6.5

I enjoy poking fun at the unclean among us from time to time, but if we all belonged to the same range we’d most likely all be friends. Our kids don’t like to clean, they are wrong of course, but as grown adults they can do as they please. I’ve followed Form to wrap my head around his experience with it so if I chamber a rifle for one of the kids it’s not going to cause them fits if it’s not cleaned.

There are obviously some rifles that survive without cleaning, and some that struggle at low round counts. Little is said about how to reliably identify which is which other than a lot of shooting. Hopefully, this will shed a little light on it, but I’m not an expert on fouling, this summarizes my understanding of it.

Below is the SAAMI print for the 6.5 Creed, and it shows ammo at the top and the chamber at the bottom. For the chamber, the little note to the side says the acceptable tolerance is the stated minimum size or up to .002” over, which will be a big clue as to why some SAAMI chambers seem tight and others don’t.

Carbon fouling issues can effect the neck of the case and/or the throat just in front of the neck.

Looking at the throat, its minimum dimension is .2645”, which only leaves .00025” between each side of the bullet and the chamber. Regular aluminum foil is .0007” and Saran Wrap is around .0003” - that .00025” minimum bullet clearance is very small indeed. If the chamber is max size, there’s an additional .001” clearance on each side of the bullet - 4x as much room for throat fouling to accumulate before being an issue. For the throat to be so carboned up to cause problems, often a loaded round will have scratches on the bullet if it’s chambered, so that’s something to look for.

Looking at the neck, the numbers are harder to make sense out of because the thickness of the brass comes into play, but just like the throat, if it’s on the tight side, there’s not as much room for fouling to build up and prevent the bullet from easily releasing from the case. It’s often said by the benchrest crowd if a new bullet can easily drop through a fired case neck there’s enough room in the chamber for a clean release - makes sense to try that and if it’s like a hot dog down a hallway at the mouth of the case, the neck clearance from fouling is not likely to be the issue.

Neck minimus are .296” at the mouth to .297” at the junction with the shoulder, so maximum size to still be within the SAAMI spec is .298” and .299”. Machinist gage pins are only a few bucks - I have a full set so it’s easy to check, but if I didn’t, the $20 for .297” and .298” pins would tell a great deal. Pins labeled + are slightly over size, and pins labeled - are under.

For our kid that doesn’t clean, I’ve checked to see the neck is at least in the middle range, and if that ever causes problems it can be opened up with a reamer. Some factory chambers have necks and throats well over max SAAMI.

Finally, $50 for a cheap borescope can quickly tell if there’s a thick carbon ring, or if cleaning has removed one. Just drop a hint to your buddy’s wife that it would be a great Christmas present for him, and you can borrow his. :)

That’s literally all I know about it.

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Cleaned the rifle the other week and got out to shoot. Still had the same problem, some rounds were fine while others had a heavy/hard bolt lift. Was running the bolt on an empty chamber and noticed it seemed heavy, got out the t3x 223 and yes it was heavier on the 6.5. I did get the UM short handle and 1" ball for both rifles. When installing the the one that went on the 6.5 I had to file a bit to get it to fit in there. I can't say for sure if the heavy bolt lift and the new handle all happened at the same time or not (don't remember). @Formidilosus or @Unknown Munitions have you guys had anything like that happen? Is it even possible?
 
Cleaned the rifle the other week and got out to shoot. Still had the same problem, some rounds were fine while others had a heavy/hard bolt lift. Was running the bolt on an empty chamber and noticed it seemed heavy, got out the t3x 223 and yes it was heavier on the 6.5. I did get the UM short handle and 1" ball for both rifles. When installing the the one that went on the 6.5 I had to file a bit to get it to fit in there. I can't say for sure if the heavy bolt lift and the new handle all happened at the same time or not (don't remember). @Formidilosus or @Unknown Munitions have you guys had anything like that happen? Is it even possible?
Since you have 2 Tikka's, swap the bolts and see if there is the same "heaviness" on the 223 action as the 6.5 action. If it is, then it is your bolt and how it is assembled.

Jay
 
Since you have 2 Tikka's, swap the bolts and see if there is the same "heaviness" on the 223 action as the 6.5 action. If it is, then it is your bolt and how it is assembled.

Jay
So the 6.5 bolt is heavier/stickier than the 223 bolt, in both guns. Not the best way to test but with a trigger gauge it took 8ish pounds to get he 223 bolt up and 10-12 pounds for the 6.5 bolt. So there might be an issue with the bolt or bolt innards. I am no gun smith, can anyone point me in the right direction as far as what to look for (assuming i have to take the bolt apart).
 
Maybe a longshot, but have you lubed the cocking ramp on the 6.5 bolt? If not, it may be a little galled and causing additional friction.
 
Maybe a longshot, but have you lubed the cocking ramp on the 6.5 bolt? If not, it may be a little galled and causing additional friction.
I have not. I'm actually not 100% sure what that is. Are you referring to the "notch" under the bolt shroud that cocks the firing pin back?
 
Whats folks level of concern galling the bolt lugs and action with all this heavy bolt lift?

When folks are saying they dont clean unless accuracy drops off, or issues arise does that include bolts, lugs, action rails, ect? Or are we just talking the bore?

Ill admit to not making it a habit to have heavy bolt lift, and I do lube bolt lugs, so dont have experience galling or scuffing bolt lugs. But it does seem to me a logical concern.
 
@nephewjephew did you ever identify the issue?

Just had my Tikka 6.5CM rebarreled to a 6CM with an Ace 22" SP3 from UM in the factory stock (hogged out barrel channel). I've shot 100 rounds through it (4 different factory loads) and heavy bolt lift starts occurring with all of them after 5-6 rounds in a string. Goes away after things have cooled down and starts again when things heat up. Did not have this issue when it was a 6.5CM.

Using factory mags. Some ejector marks on brass but I'm not particularly knowledgeable on pressure signs. Photo might not help but there's a slight ejector ring mark on each of these except the Sig. For the others, maybe 2-5 out of 20, which doesn't exactly correlate to how many rounds had heavy bolt lift.

Sig 107 OTM - 2840 FPS Avg, max 2854 FPS
Hornady 108 ELD-M - 2885 FPS Avg, max 2905 FPS
Hornady 103 ELD-X - 2972 FPS Avg, max 3001 FPS
Barnes 112 OTM - 2914 FPS Avg, max 2960 FPS
Hornady 108 ELD-M - 2891 FPS Avg, max 2914 FPS

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My heavy bolt lift with the 6.5 has been intermittent and happens mostly when warm. When it doesn’t have heavy bolt lift action & cycling is smooth. I haven’t kept a log of MV to correlate to either however. I suspect it is an ammo issue.
 
@nephewjephew did you ever identify the issue?

Just had my Tikka 6.5CM rebarreled to a 6CM with an Ace 22" SP3 from UM in the factory stock (hogged out barrel channel). I've shot 100 rounds through it (4 different factory loads) and heavy bolt lift starts occurring with all of them after 5-6 rounds in a string. Goes away after things have cooled down and starts again when things heat up. Did not have this issue when it was a 6.5CM.

Using factory mags. Some ejector marks on brass but I'm not particularly knowledgeable on pressure signs. Photo might not help but there's a slight ejector ring mark on each of these except the Sig. For the others, maybe 2-5 out of 20, which doesn't exactly correlate to how many rounds had heavy bolt lift.

Sig 107 OTM - 2840 FPS Avg, max 2854 FPS
Hornady 108 ELD-M - 2885 FPS Avg, max 2905 FPS
Hornady 103 ELD-X - 2972 FPS Avg, max 3001 FPS
Barnes 112 OTM - 2914 FPS Avg, max 2960 FPS
Hornady 108 ELD-M - 2891 FPS Avg, max 2914 FPS

View attachment 908834

I don't see any flat primers, which usually happen along with ejector swipes when you do hit pressure. I do, however see that the cases look to be pretty dirty. Have you cleaned the chamber out really well and made sure that there isn't any residual cleaning gunk left in it? Also, I can't see the necks, but if they are smoked pretty good that may also be why you are starting to get heavy lift when it gets warm (i.e. carbon buildup in the neck area).

I would say start by giving the chamber (not the bore) a thorough cleaning and then make sure everything is out with a good shot of brake cleaner (or similar). If it still persists after that, there may be something else going on.
 
I don't see any flat primers, which usually happen along with ejector swipes when you do hit pressure. I do, however see that the cases look to be pretty dirty. Have you cleaned the chamber out really well and made sure that there isn't any residual cleaning gunk left in it? Also, I can't see the necks, but if they are smoked pretty good that may also be why you are starting to get heavy lift when it gets warm (i.e. carbon buildup in the neck area).

I would say start by giving the chamber (not the bore) a thorough cleaning and then make sure everything is out with a good shot of brake cleaner (or similar). If it still persists after that, there may be something else going on.
I cleaned the chamber thoroughly before the barrel swap, and it's still pretty dang clean after 100 rounds. Here's a picture of the necks with some of the 6.5 CM brass from pre-rebarreling. Pretty similar condition to my eye.

I want to say the heavy bolt lift started around shot 16 or 17 through the barrel with the Sig ammo. Would it be possible to build up that much carbon ring from 15 rounds? First three mags no issues. Then every second mag in a 10 shot string has issues. I did check the mags too. Shot 5 rounds with no issue, then reloaded the same mag and had heavy bolt lift.

Appreciate the help!

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I was trying the whole not cleaning approach with my rifles, but suddenly started getting heavy bolt lift and pressure signs. Eventually, rounds would not even chamber. I thought it was undersized brass shoulders at first, but it turned out to be the “imaginary” carbon ring.

Happened with both my Sako 6.5PRC and tikka 243. I bought Iosso brushes and Thorroclean system and cleaned until bare steel. Verified carbon ring with borescope.

After cleaning they’re back to normal!

Still haven’t needed to clean my 223’s or 6.5 creed but those aren’t so overbore. In the future I’ll try to trim brass to max length to avoid carbon buildup in front of the case mouth.
 
I cleaned the chamber thoroughly before the barrel swap, and it's still pretty dang clean after 100 rounds. Here's a picture of the necks with some of the 6.5 CM brass from pre-rebarreling. Pretty similar condition to my eye.

I want to say the heavy bolt lift started around shot 16 or 17 through the barrel with the Sig ammo. Would it be possible to build up that much carbon ring from 15 rounds? First three mags no issues. Then every second mag in a 10 shot string has issues. I did check the mags too. Shot 5 rounds with no issue, then reloaded the same mag and had heavy bolt lift.

Appreciate the help!

View attachment 909273

I wonder if you have a snug chamber and as the barrel heats up the chamber starts grabbing the brass. It isn't enough to lock it up but makes extraction more difficult.

Jay
 
Were the Sig cases shorter than the others? If they were, maybe they deposited some carbon at the end of the chamber that is "crimping" the necks when the chamber gets hot on the longer brass.

It could also just be a tight neck chamber that starts to act up when hot. The only way to tell that would be to neck turn your brass to remove a couple thousandths and see if that helps, but if you plan to continue to shoot factory ammo it doesn't make any sense to do that.
 
Just checked a few pieces from each box. All consistent length at about 0.915 (analog caliper). Just pinned the set screw and slid a few in there, pretty consistent.

Is it worth contacting UM about? Wanted to lay a little groundwork / educate myself before I did.
 
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