Am I being an idiot - Why am I getting pressure signs here?

[JCN17]

The rifle is a 22” Bartlein 6.5cm barrel chambered by bugholes with a terminus Zeus qc. About 160 rounds on the barrel so far, mostly not suppressed.

Same issue with two different loads
- 143gr eldx with 40gr h4350 with br2 and COAL of 2.864”
- 140gr eldm with 39gr h4350 with br2 and COAL of 2.853

Both in virgin Lapua brass prepped by trimming slightly to 1.906-1.908, 21st century expander mandrel at .262, and champher/debur.

Rifle initially shot great, multiple groups around .2 moa. I noticed heavy bolt lift intermittently, primarily shooting the 39.0 h4350 and eldm combo listed above, but didn’t know what to make of it and it kept shooting well. I scoped it and noticed what I thought was carbon ring initially, cleaned it out, and the rifle kept shooting well. Only had about 30 rounds through it after a good cleaning and scope to make sure the ring was gone, when I had very heavy lift shooting 14 rounds of the 40.0gr eldx load above, which seemed to be getting worse the longer I shot.

I scoped it again after I got home and included pictures of that in this post. It looks like a lot of carbon ring to me, which I don’t understand for only about 30 rounds of 6.5cm.

My chronograph died and I’m waiting on a Garmin to arrive, but initially had Chronographed the eldm load at 2520fps.

I tried decreasing my powder charge, and I am still seeing the same pressure signs of heavy bolt lift and ejector marks.

Am I trimming my brass too short and seating the bullets too long, resulting in premature issues with carbon ring? It doesn’t feel like I’m jamming the bullet into the lands when I close the bolt. Can’t figure out what’s going on, but I thought I was seating 20 and 40 thousandths off the lands based on my initial measurements. I’m assuming the problem is me and something I’m doing, but since I’m using brand new brass and not doing much to it, I don’t know what could be going on. Appreciate the help.

 

[Dolomite]

Is that lead deposits in the second picture?

Not sure if those loads are hot but could be virgin brass expanding. The ejector mark is mainly from the ejector spring so heavy.

Seems like false pressure since the primers look ok.

Try shooting it without the suppressor to see if it makes a difference.

 

[JCN17]

I tried without the suppressor but it didn’t seem to help. Not sure exactly what I’m seeing on the borescope, I thought it was just carbon ring. The bolt lift is significantly heavier than it usually is, and before I started having issues I was shooting the exact same loads with no ejector marks, normal bolt lift, and much better accuracy.

 

[JCN17]

I thought about false pressure but should I be having so much heavy bolt lift if that’s it? And it getting worse the more I shoot?

 

[ARShooter91]

Make sure any solvent and or oil is out of the chamber? Also any of that condensation present when shooting? Looks like a little bit of moisture in the second pic

 

[JCN17]

That’s right after shooting 14 rounds, it was pretty dry out. Seemed to be getting worse the more I shot. Would any remaining solvents be worse the first few shots and then improve?

 

[jpjulian]

I would scrub the dickens out of that chamber and throat and I would drop the powder charge at least a couple grains. I don't believe in false pressure signs. Either there pressure signs or there aren't. You have pressure signs. I'd offer a charge weight but I'm on a cruise ship at the moment and I think they are censoring some web sites.

 

[Pat McGroin]

It sounds like he tried that and confirmed the carbon was gone and dropped the charge, then wasn’t having problems until after more shooting. I’d say that carbon is the issue but not sure why you’re accumulating that so quickly with a h4350 and low powder charges, especially if you’re also having the issue unsuppressed

 

[Dolomite]

I would guess that this is lead deposits accumulating at the mouth of the chamber and as you shoot more and more the build up may not be allowing the brass to expand at the case mouth and causing the heavy bolt lift. Or it could be the lead at the mouth of the brass that is not allowing the case to come out freely which cause the heavy bolt lift. Of course this is just a major assumption. Are you getting any copper shavings as you seat the bullet? Are all the case mouths chamfered smoothly before seating the bullet? Is the chamber smooth and no tiny burrs scrapping the bullet?

 

[goinghunting]

Any denting on the exterior of brass? Like something dirty from suppressor got back into chamber, like if rifle was sitting with butt on ground, muzzle up...

 

[JCN17]

Any denting on the exterior of brass? Like something dirty from suppressor got back into chamber, like if rifle was sitting with butt on ground, muzzle up...

Nothing like that, brass looks good besides the ejector marks which I can feel with a fingernail.

 

[Rider47]

As per your primers, you do not appear to have high chamber/case pressure (and the loads are not hot), but the fired cases do appear to be backing harder into the boltface than is normal (or else your headspacing of the bolt is off - do you have a hard bolt on closing before firing?). Cases can back hard into the boltface if the cases have even a thin layer of lube and there is no adhesion of brass to the sidewalls of the chamber and pressure is fully directed backwards. (Lubing cases to move them back and blow the shoulders out forward is a technique often used to properly fireform some wildcat cases from the parent cases.) As has been suggested, thoroughly dry out/clean the chamber and fully remove any lube from the cases. Also, as has been suggested, make sure that subsequent to trimming (new Lapua cases do not need trimming) that careful chamfering of the inside and outside of the case mouth is performed, with complete removal of small bits of removed brass (I use compressed air). Hopefully this might help. Your images show poor focus - can you adjust your borescope to get improved images?

 

[supercorndogs]

I would go back and confirm bullet jump. If they are confirmed not to be jammed I would confirm headspace next. Your action has a lot of power when closing the bolt handle. You wouldn't notice a heavey jam.closing as things cam into place. You might notice it extracting an unfired round if it's a really hard jam.

 

[DocRDS]

Not much experience other than you are nowhere near max loads.

One thing has caused me problems with pre-mature pressure signs: improperly sized brass (Don't be lazy like me and check em!). I would find stiff bolt close though. GL

 

[Haney]

I would let the brass grow after you give the barrel a good cleaning .You could try a piece and run your bore scope in there to get a look at the carbon and brass to see what is going on . If heavy bolt lift lessens after a few rounds it could be a solvent issue .

 

[TheOfficeT-Rex]

How far is the shoulder moving when fire formed?

With a QC barrel, I’d pop it off to scrub it down- but before you start, plunk a round in it. It should drop in and out freely, and you should be able to spin it in the chamber. If it’s dragging on something, it helps narrow the troubleshooting.

 

[ShtrRdy]

As another data point, try some factory ammo if you haven't already.

 

[AllenOne1]

Are the outside of your case necks showing a lot of carbon? To me it looks like you are building carbon in the chamber where the neck should be sealing. If so you are losing the space needed for the neck to expand and release the bullet as you shoot more rounds.

I would also load some of the once fired brass and see if filling the chamber with the expanded brass fixes the issues or makes it worse. After cleaning the chamber area.

 

[Aftermath]

I tried decreasing my powder charge, and I am still seeing the same pressure signs of heavy bolt lift and ejector marks.

Am I trimming my brass too short and seating the bullets too long, resulting in premature issues with carbon ring? It doesn’t feel like I’m jamming the bullet into the lands when I close the bolt. Can’t figure out what’s going on, but I thought I was seating 20 and 40 thousandths off the lands based on my initial measurements. I’m assuming the problem is me and something I’m doing, but since I’m using brand new brass and not doing much to it, I don’t know what could be going on. Appreciate the help.

I would go back and confirm bullet jump. If they are confirmed not to be jammed I would confirm headspace next. Your action has a lot of power when closing the bolt handle. You wouldn't notice a heavey jam.closing as things cam into place. You might notice it extracting an unfired round if it's a really hard jam.

It does seem like the charge and velocity are mild which leads me to think something is wrong with your headspace or the brass sizing. I second what @supercorndogs is saying and start by going through the entire process from start to finish. Be sure you keep, and mark, a couple of pieces of fired brass to use for comparison. Those should be real close to actual chamber dimensions and can be used to set up your equipment so you aren't overworking the brass and such.

 

[Baron23]

I’m certainly not one of the reloading experts on the board but I reload for two 6.5 CM rifles with 140 hybrids and my initial thoughts (for what they are worth):

1. Your powder charge is mild to me. I am loading 42.1 of H4350…and have another accuracy “node” at 40.9 and have zero pressure signs.

2. Your COAL is not that long unless you specified a particularly short freebore when ordering. I just don’t see how you can be jammed if you have 150-200 thou of freebore.

Headspace issue? Have you put a gage in it?

 

[secondofangle2]

What reamer was used?

 

[JCN17]

What reamer was used?

Not sure on that. SAAMI spec reamer done by bugholes, I didn’t ask for anything special.

 

[JCN17]

I’m certainly not one of the reloading experts on the board but I reload for two 6.5 CM rifles with 140 hybrids and my initial thoughts (for what they are worth):

1. Your powder charge is mild to me. I am loading 42.1 of H4350…and have another accuracy “node” at 40.9 and have zero pressure signs.

2. Your COAL is not that long unless you specified a particularly short freebore when ordering. I just don’t see how you can be jammed if you have 150-200 thou of freebore.

Headspace issue? Have you put a gage in it?

I have checked it with go and no go gauges and it checks out, closes on go and won’t close on no go. I didn’t order short freebore, believe it was a standard saami reamer

 

[JCN17]

Are the outside of your case necks showing a lot of carbon? To me it looks like you are building carbon in the chamber where the neck should be sealing. If so you are losing the space needed for the neck to expand and release the bullet as you shoot more rounds.

I would also load some of the once fired brass and see if filling the chamber with the expanded brass fixes the issues or makes it worse. After cleaning the chamber area.

Here’s a close up of a couple necks where I saw the issue. It does look like there’s a fair bit of carbon to me

 

[JerkyFreak]

Necks lool fine to me.

In my limited experience with new barrels, they all speed up to some extent within the first 100+ rounds as the barrel wears in. Hence the reason why it's normally not a good idea to do final load development during this time. I got caugt twice. Also, fired brass gives higher velocity over virgin brass for the same load.

Could it be that your initial load was at the maximum and then went over as the barrel wore in?

Or else you have really soft brass...

 

[JCN17]

As per your primers, you do not appear to have high chamber/case pressure (and the loads are not hot), but the fired cases do appear to be backing harder into the boltface than is normal (or else your headspacing of the bolt is off - do you have a hard bolt on closing before firing?). Cases can back hard into the boltface if the cases have even a thin layer of lube and there is no adhesion of brass to the sidewalls of the chamber and pressure is fully directed backwards. (Lubing cases to move them back and blow the shoulders out forward is a technique often used to properly fireform some wildcat cases from the parent cases.) As has been suggested, thoroughly dry out/clean the chamber and fully remove any lube from the cases. Also, as has been suggested, make sure that subsequent to trimming (new Lapua cases do not need trimming) that careful chamfering of the inside and outside of the case mouth is performed, with complete removal of small bits of removed brass (I use compressed air). Hopefully this might help. Your images show poor focus - can you adjust your borescope to get improved images?

I appreciate the replies. I’ll attach some hopefully better board scope pictures. I adjusted the lighting to try to get better quality images. I also disassembled one of these same rounds that I was having trouble with, inserted the brass into the chamber with a closed bolt, and took some images from the muzzle end.

Bolt close might be a little more difficult than it should be, I’m not 100% certain on that. I did just notice that using the same comparator, my headspace measurement was 1.481-1.482 on the new Lapua brass, and was consistently 1.4845 after one firing. I just measured some of the pieces that showed ejector marks and heavy bolt left and found measurements from 1.4865-1.4875, and the first shot which did not show any of these signs measured 1.4845 like a lot of the previous rounds which did not have heavy bolt lift. So there seems to be some variance in headspace, but I’m not sure how that would be possible. They aren’t consistently getting longer like the barrel is backing off. Also, I just checked it with go and no-go gauges again and it checks out.

As for lube, I haven’t used any lube on these, except for dipping top 1/3 into imperial dry neck lube before using the expander mandrel, after which I wipe the outside off with a microfiber towel. I have then been chamfering inside and outside using a Lyman case prep station and then running a nylon brush through the neck after. That is my whole process aside from trimming before like I mentioned, which I will stop doing with new brass.

I really appreciate the help with this. I’ve spent a ton of time trying to figure this out and a lot of range trips, but have not made any much progress.

I was thinking for a next step I would go back to the range without cleaning, confirm the issue is still present with the same ammunition, and then try some factory rounds.

 

[JCN17]

Necks lool fine to me.

In my limited experience with new barrels, they all speed up to some extent within the first 100+ rounds as the barrel wears in. Hence the reason why it's normally not a good idea to do final load development during this time. I got caugt twice. Also, fired brass gives higher velocity over virgin brass for the same load.

Could it be that your initial load was at the maximum and then went over as the barrel wore in?

Or else you have really soft brass...

I guess I can’t say anything for certain, but based on my chronograph reading I really do not think I was at maximum or anywhere near it. Like others have mentioned, the primers seem round to me and this seems like force being directed backward, for some reason. I’ve never had a problem with Lapua brass but until I solve this I guess I can’t rule anything out

 

[Long Range 338]

I would start with a couple of items:

- sizing die setup (make sure you're not creating an issue where your brass is slamming against your bolt face. The ejector mark is concerning).

- seating depth, use a marker to find your seating depth and make sure you're not buried into the lands.

- if you think the brass is suspect, you can measure your case capacity with water to compare pieces that showed pressure signs vs pieces that did not.

- you've already addressed powder charge and carbon ring so I'm assuming these two items are not the issue.

 

[JCN17]

I would start with a couple of items:

- sizing die setup (make sure you're not creating an issue where your brass is slamming against your bolt face. The ejector mark is concerning).

- seating depth, use a marker to find your seating depth and make sure you're not buried into the lands.

- if you think the brass is suspect, you can measure your case capacity with water to compare pieces that showed pressure signs vs pieces that did not.

- you've already addressed powder charge and carbon ring so I'm assuming these two items are not the issue.

I will take a couple of the loaded rounds that I have had issues with, seat the bullet farther, and see if that solves the issue. I know it isn’t a sizing issue because this is brand new Lapua brass that has never been sized. I have had the issue with two different lots of Lapua so I think it isn’t likely the brass.

 

[Long Range 338]

I know it isn’t a sizing issue because this is brand new Lapua brass that has never been sized.

That doesn't mean your brass is not undersized. Compare your new unfired brass with your go gauge. Excessive headspace could look like pressure.

 

[JerkyFreak]

Is that not a carbon ring?

Colour the seated bullet with a sharpie, chamber the round and extract. Look for marks on the bullet ogive. This should give an indication if the ogive is touching anything.

Primers are not great for pressure signs when loading to minimal or zero headspace. It is usually more accurate to use brass expansion. In your case the brass gets slightly extruded into the ejector hole and you have heavy bolt lift. So, unless you have very soft brass, those are very good indicators of over-pressure.

 

[JCN17]

I believe that’s a carbon ring also but unsure why I’m having issues with that after like 30 rounds of 6.5cm

 

[Dolomite]

Try measuring the loaded rounds CBTO and not COAL. Hornady is not the most consistent. I bet you see a lot of inconsistencies. Next use a comparator tool to measure the touch to the lands. Compare that number to your CBTO of your loaded rounds what do you see?

If your seated into the lands with a moderate load the brass will blow out and fit to the chamber causing heavy bolt lift and ejector mark.

Are the loaded rounds in the lands or out the lands?

Lapua brass should take about 2-3 firings before it fits to your chamber. You find the correct headspace measurement after 2-3x fired cases so don’t bump the should after the first firing.

If you insert the 1x fired case in the chamber and close the bolt remove the firing pin assembly it should drop freely. if bolt doesn't drop freely the brass is the size of your chamber. At that point bump shoulder till the bolt drops freely.

 

[JCN17]

Try measuring the loaded rounds CBTO and not COAL. Hornady is not the most consistent. I bet you see a lot of inconsistencies. Next use a comparator tool to measure the touch to the lands. Compare that number to your CBTO of your loaded rounds what do you see?

I will recheck that after I scrub out the barrel but based on my initial measurements before I started loading the eldx load is 40 thou off and the eldx load is 20 thou off the lands

 

[CheapBasterd]

That looks like a lot of carbon built up on the necks. If its on the necks its probably built up in the chamber.

 

[Rio Precision Gunworks]

Strip your bolt. Take out the firing pin assembly. Remove the ejector. Where you only have the extractor in and the bolt will fall free with gravity.

Take a piece of:

-Virgin case
-Fired and unsized case
-Fired and sized case
-Virgin case with bullet loaded to the length you're using
-Fired and sized case with bullet loaded to the length you're using

Report back which allow the bolt to fall free with gravity and which stick a little (or a lot). Also report if you have cleaned the barrel when you do this test or if its in same condition as pics above.

Make sure you put the rim of the brass in the extractor by hand (may need to removed bolt each time) so you're not using any force when pushing in to overcome the extractor groove.


Also, list the following measurements:

-neck diameter of loaded round
-neck diameter of fired and empty case as it comes out of the rifle (non sized)
-base of case of virgin case (0.200 line)
-base of case of fired unsized case (0.200 line)
-base of case of fired sized case (0.200 line)


Otherwise, we will just be guessing until something works.

 

[Rio Precision Gunworks]

Also, since its a QD barrel (or if I read it wrong and its not, but if you have a barrel vice), pull the barrel and check if virgin and fired brass fall freely into chamber. The stripped bolt will do similar, but this will allow you to visually see about where brass is sticking if it is.

Here is an example. Its at the 44sec mark if the video doesn't start at the right spot:

 

[Rider47]

Two observations:
1) The "carbon" around the top only of the fired necks, combined with the non-carboned rest of the necks and case indicate a very tight fit of your cases at the shoulder and bottom of the neck, with this fit likely before firing. This indicates you are likely not knocking back the shoulders enough for your chamber (which may be somewhat short?) or at least has a tight/narrow spot partway up the neck. Discoloration from powder burn (not "carbon buildup") is stopped partway down the neck - somewhat odd. You seem to have a tight spot in the case to chamber area partway up the neck. Is the base of your bullet seated below this discolored area? Perhaps this area of the cases are not getting resized enough for your chamber? It is almost like you have the "dreaded doughnut" at the bottom of the case neck/shoulder junction.
2) Your shoulder measurements show a clear difference between ejector issue cases (longer) and non-issue cases (shorter). Again, another issue that your issue cases are indexing HARD against the boltface upon firing and expanding the shoulder forward, whereas not so much on those cases that do not show the ejector marks as much.
Test: I would suggest you get a thick black magic marker and completely blacken several rounds. First try to chamber and extract them without firing and observe/photograph/post them. Then the same after firing.

Lapua brass is relatively soft and is likely showing an issue where harder cases might not.
I do not believe this issue has anything to do with a "carbon ring" or "lead buildup" in the barrel.

 

[supercorndogs]

Two observations:
1) The "carbon" around the top only of the fired necks, combined with the non-carboned rest of the necks and case indicate a very tight fit of your cases at the shoulder and bottom of the neck, with this fit likely before firing. This indicates you are likely not knocking back the shoulders enough for your chamber (which may be somewhat short?) or at least has a tight/narrow spot partway up the neck. Discoloration from powder burn (not "carbon buildup") is stopped partway down the neck - somewhat odd. You seem to have a tight spot in the case to chamber area partway up the neck. Is the base of your bullet seated below this discolored area? Perhaps this area of the cases are not getting resized enough for your chamber? It is almost like you have the "dreaded doughnut" at the bottom of the case neck/shoulder junction.
2) Your shoulder measurements show a clear difference between ejector issue cases (longer) and non-issue cases (shorter). Again, another issue that your issue cases are indexing HARD against the boltface upon firing and expanding the shoulder forward, whereas not so much on those cases that do not show the ejector marks as much.
Test: I would suggest you get a thick black magic marker and completely blacken several rounds. First try to chamber and extract them without firing and observe/photograph/post them. Then the same after firing.

Lapua brass is relatively soft and is likely showing an issue where harder cases might not.
I do not believe this issue has anything to do with a "carbon ring" or "lead buildup" in the barrel.

Lapua brass is relatively soft compared to what brass?

 

[Rider47]

Lapua brass is relatively soft compared to what brass?

Federal, Winchester, Hornady, Lake City.

 

[Rover31]

I'm curious as to how the barrel feels when you clean it. Smooth and easy or do you find rough areas? Does it come clean easily or take a while?

 

[supercorndogs]

Federal, Winchester, Hornady, Lake City.

That's not my or most other experience with it.

 

[JCN17]

Strip your bolt. Take out the firing pin assembly. Remove the ejector. Where you only have the extractor in and the bolt will fall free with gravity.

Take a piece of:

-Virgin case
-Fired and unsized case
-Fired and sized case
-Virgin case with bullet loaded to the length you're using
-Fired and sized case with bullet loaded to the length you're using

Report back which allow the bolt to fall free with gravity and which stick a little (or a lot). Also report if you have cleaned the barrel when you do this test or if its in same condition as pics above.

Make sure you put the rim of the brass in the extractor by hand (may need to removed bolt each time) so you're not using any force when pushing in to overcome the extractor groove.


Also, list the following measurements:

-neck diameter of loaded round
-neck diameter of fired and empty case as it comes out of the rifle (non sized)
-base of case of virgin case (0.200 line)
-base of case of fired unsized case (0.200 line)
-base of case of fired sized case (0.200 line)


Otherwise, we will just be guessing until something works.

Really appreciate the reply. I also attached a couple pictures of the bolt face. After preparing the bolt like you mentioned except that I wasn’t able to get the extractor out. This was all done without cleaning, barrel is still as seen in pics.

Unsized fired brass that did NOT have heavy bolt lift at the time of firing - very little resistance

Unsized fired brass that DID HAVE heavy bolt lift at the time of firing - there is clearly much more resistance

Virgin case - unfortunately I don’t have any of these as I thought I had my load figured out after not initially having issues and loaded up everything I had. I disassembled one of the unfired rounds and it falls with minimal resistance on that, case has been trimmed, champhered, and expanded mandrel .262

Unfired case with bullet loaded to the length I’m shooting - minimal resistance

I have never fired a sized round through this rifle, only new Lapua that I trimmed, champhered, and expander mandrel .262. Actually even even set up dies for this rifle. Would it be helpful if I did that and tried to chamber them as you describe or is that not necessary because I’m not having issues with sized brass?

- Neck diameter of loaded round - .2915
- Neck, diameter of fired and empty case - .2945 (there is no difference in this measurement between the cases that had heavy bolt lift and the ones that did not)
- .200 line with fired unsized brass - there seems to be some variance here. I measured a bunch of them and .4695 is what I’m getting on most of the rounds that DIDN’T have heavy bolt lift, but the ones that DID have heavy bolts lift seem to be .4685. (hopefully I’m taking this measurement accurately, included a picture of what I did). If I measure with the case parallel to and between the end of the caliper like in the second picture they all measure .470.

- headspace using SAC comparator, unfired brass is 1.4810 - 1.4820
- headspace fired brass with NO heavy bolt lift - 1.484 - 1.485
- headspace fired brass that DID have heavy bolt lift - 1.4870 - 1.4875
- internal diameter of neck after firing without sizing - .265 (all brass is the same whether there was heavy bolt lift or not)

 

[JCN17]

I'm curious as to how the barrel feels when you clean it. Smooth and easy or do you find rough areas? Does it come clean easily or take a while?

Seems smooth and cleans easily

 

[JCN17]

Also, since its a QD barrel (or if I read it wrong and its not, but if you have a barrel vice), pull the barrel and check if virgin and fired brass fall freely into chamber. The stripped bolt will do similar, but this will allow you to visually see about where brass is sticking if it is.

Here is an example. Its at the 44sec mark if the video doesn't start at the right spot:

I will do this when I clean it and report back

 

[Rio Precision Gunworks]

Really appreciate the reply. I also attached a couple pictures of the bolt face. After preparing the bolt like you mentioned except that I wasn’t able to get the extractor out. This was all done without cleaning, barrel is still as seen in pics.

Unsized fired brass that did NOT have heavy bolt lift at the time of firing - very little resistance

Unsized fired brass that DID HAVE heavy bolt lift at the time of firing - there is clearly much more resistance

Virgin case - unfortunately I don’t have any of these as I thought I had my load figured out after not initially having issues and loaded up everything I had. I disassembled one of the unfired rounds and it falls with minimal resistance on that, case has been trimmed, champhered, and expanded mandrel .262

Unfired case with bullet loaded to the length I’m shooting - minimal resistance

I have never fired a sized round through this rifle, only new Lapua that I trimmed, champhered, and expander mandrel .262. Actually even even set up dies for this rifle. Would it be helpful if I did that and tried to chamber them as you describe or is that not necessary because I’m not having issues with sized brass?

- Neck diameter of loaded round - .2915
- Neck, diameter of fired and empty case - .2945 (there is no difference in this measurement between the cases that had heavy bolt lift and the ones that did not)
- .200 line with fired unsized brass - there seems to be some variance here. I measured a bunch of them and .4695 is what I’m getting on most of the rounds that DIDN’T have heavy bolt lift, but the ones that DID have heavy bolts lift seem to be .4685. (hopefully I’m taking this measurement accurately, included a picture of what I did). If I measure with the case parallel to and between the end of the caliper like in the second picture they all measure .470.

- headspace using SAC comparator, unfired brass is 1.4810 - 1.4820
- headspace fired brass with NO heavy bolt lift - 1.484 - 1.485
- headspace fired brass that DID have heavy bolt lift - 1.4870 - 1.4875
- internal diameter of neck after firing without sizing - .265 (all brass is the same whether there was heavy bolt lift or not)

View attachment 8322905
View attachment 8322906

View attachment 8322907

View attachment 8322908

Did you remove the ejector plunger when you tested the cases for bolt resistance?

 

[Rio Precision Gunworks]

That's not my or most other experience with it.

I can tell you from actual hardness testing, that's not the way it is. Not just coming to conclusions from feel in sizing or measurements. But from actual hardness testing.

Lapua isn't softer than any of those on average.

 

[JCN17]

Did you remove the ejector plunger when you tested the cases for bolt resistance?

Couldn’t get it at first, had to go pick up a different punch. Here’s what I found after removing the ejector, plunger and firing pin

Fired brass that had no heavy bolt lift at the time - bolt drops freely

Fired brass that did have heavy bolt lift and ejector mark at the time of firing - does not drop freely at all, feels like there is a ton of resistance

Unfired case with bullet loaded to same length as what i was shooting when having issues - falls freely all the way

I don’t have any more of this virgin brass, but I disassembled one of my rounds. I know this isn’t exactly the same because I trimmed champhered and used a .262 mandrel but it’s all I have. It falls freely on this

I’ve never sized any brass for this rifle, only virgin brass prepped with trim to 1.906 - 1.908, champher inside and out, expanded mandrel with dry media and .262 mandrel.

 

[Rio Precision Gunworks]

Ok, now we have an idea what's going on. All your measurements are fine as far as chamber fit. Base, neck, etc. So, that's all fine. Your base measurements don't indicate a clicker issue.Your loaded ammo is falling free with gravity. So you're not touching lands with bullet.

The rounds that have heavy bolt lift are expanding more and are basically oversized in the chamber after firing.


Take the brass that had the heavy bolt lift (and longer shoulder), and size them down until the stripped bolt falls free. Just size down enough the bolt falls free. You'll get a little resistance when you're close, then size another .001 or so and the bolt will fall free.


Then load and shoot that same brass and report back if it has heavy lift.

 

[JCN17]

Ok, now we have an idea what's going on. All your measurements are fine as far as chamber fit. Base, neck, etc. So, that's all fine. Your base measurements don't indicate a clicker issue.Your loaded ammo is falling free with gravity. So you're not touching lands with bullet.

The rounds that have heavy bolt lift are expanding more and are basically oversized in the chamber after firing.


Take the brass that had the heavy bolt lift (and longer shoulder), and size them down until the stripped bolt falls free. Just size down enough the bolt falls free. You'll get a little resistance when you're close, then size another .001 or so and the bolt will fall free.


Then load and shoot that same brass and report back if it has heavy lift.

Will do. Thank you. I assume I should do this with the barrel in its current state and not clean it first?