Heavy bolt lift with mild 6cm load

[megafans]

I am a relatively new reloader and am having a strange problem with my 6cm load showing signs on over pressure with a mild load of 40.0gr. The bullets will chamber just fine but after firing the bolt is sticky on extraction and I’m not sure if the brass looks ok or not.

Components:
- Virgin Lapua 6cm SRP brass
- 40.0gr of H4350
- Federal 205M small primers
- Hornady 110gr ATip seated to COAL of 2.790
- Hornady reloading manual

Equipment:
- A419 zero press
- Short Action Customs Dies
- 21st century mandrel
- Redding #1 shellholder
- SuperTrickler
- A&D FX120i scale
- Magnetospeed (40.0gr gave me an average of 2950fps over 25 rounds)

Rifle:
- Defiance deviant tactical
- 6CM Hawk hill barrel, 26”, 1:7 twist
- The rifle was chambered and assembled by Altus

The brass has not been sized, I only used a mandrel to straighten the case necks and set the bullet tension to about .0015

I took a quick measurement and it looks like the brass shoulders grew about .006-.007 after firing, is that normal?

The pictures I posted are of the fired brass, I found two of them on the right side that appeared odd to me, seems like the primer is flattened. I also see what appears to be swipes (although I’m not sure if they are false or not) and one round had what looks like soot on it after I fired it. Do the others show any signs of over pressure?

I worked up this load using the Hornady manual which shows the max at 41.7gr of H4350, so I’m not sure why I’m seeing pressure signs at this load weight. The previous lighter loads did not have a heavy or sticky bolt lift. Any help would be appreciated.

 

[spife7980]

You are getting overpressure signs because you are over pressure.

 

[megafans]

What’s with the random Hornady LRP in the pics? It looks flat to me. Probably a stouter load.

As for the heavy bolt…well, there’s your sign. Back off a half grain and see if you get acceptable velocities without the heavy bolt. Otherwise, your brass looks okay and primers look fine. Hornady loads are going to assume Hornady brass which is thinner walled than Lapua and thus, you won’t get to Hornady’s max with Lapua. I’d be looking for a lower powder charge if it was me…it’s winter and things will only get hotter from here. A mildly over pressure load now may be pretty stout in August. This current load won’t blow your face off but it will be hard on brass and heavy bolt lift sucks.

I was shooting factory Hornady 108gr ELD before shooting my loads so it looks like I mixed one of them up when I was leaving the range. I hadn’t noticed that until now. Thanks for the help!

 

[AccuSol-ERN]

On non-prefit barrels I chamber with headspace between .000-.001" on a ptg GO gage.

What is your velocity?

Also, you can run into pressure with a wet bore/chamber. Make sure the bore/chamber is clean and dry.

I am betting you are running too stiff a powder charge for Lapua brass......you can't interchange reloading data like that......case capacity (and strength) varies too much.

Ern

 

[John Glidewell]

Try dropping a bullet in the neck of fired brass. If it does not drop right in then you may need to turn the necks down.

Also, how many rounds on it and how often are you cleaning? If you have or are starting to get a carbon ring it can show as pressure.

 

[megafans]

On non-prefit barrels I chamber with headspace between .000-.001" on a ptg GO gage.

What is your velocity?

Also, you can run into pressure with a wet bore/chamber. Make sure the bore/chamber is clean and dry.

I am betting you are running too stiff a powder charge for Lapua brass......you can't interchange reloading data like that......case capacity (and strength) varies too much.

Ern

My average velocity over 25 rounds was around 2950, it is possible that my chamber/bore could have still had some oil in it from my last cleaning. Sounds like I’ll need to go back down to 39.5

 

[megafans]

Try dropping a bullet in the neck of fired brass. If it does not drop right in then you may need to turn the necks down.

Also, how many rounds on it and how often are you cleaning? If you have or are starting to get a carbon ring it can show as pressure.

I just tried this and the bullet would not drop in. I’m not sure exactly on the round count but probably close to 500, I don’t do a full cleaning very often, maybe once or twice a year. But I’ll often use a boresnake after a range session.

 

[John Glidewell]

I just tried this and the bullet would not drop in. I’m not sure exactly on the round count but probably close to 500, I don’t do a full cleaning very often, maybe once or twice a year. But I’ll often use a boresnake after a range session.

Try giving it a full cleaning and make sure you do not have a bunch of carbon build up in the throat. You should be able to drop a bullet in the fired brass with little to no effort. If it is tight then you may need to turn the necks a little. Was it chambered with a match or tighter spec reamer?

 

[megafans]

Try giving it a full cleaning and make sure you do not have a bunch of carbon build up in the throat. You should be able to drop a bullet in the fired brass with little to no effort. If it is tight then you may need to turn the necks a little. Was it chambered with a match or tighter spec reamer?

Thanks, I’ll give that a try. I have a bore scope so I’ll take a look and see if I have a carbon ring in the throat. It’s possible that it maybe have been chambered by Altus using a match or tight reamer, it’s been several years since I had it built. I was also loading 108 ELD-M’s at the time (and factory hornady ELD-M ammo) and don’t recall having this problem until I recently switched to 110 Atips, is it possible that the barrel was chambered with a 108 ELD in mind?

 

[megafans]

So, a couple things to think about as you gain experience:

oily chamber or cases can cause weird things to happen as the brass case moves around instead of sticking to the chamber walls when then round goes off. This can look like pressure/cause heavy bolt lift.

brass that has grown too long can give erratic pressure signs as it starts to bump into the throat/back of the rifling/whatever that edge is called

if the chamber was cut with a “tight neck”, essentially requiring neck turning, you can get erratic pressure signs if you didn’t neck turn…but usually not until a couple of firings on the brass have moved material into the neck walls enough to thicken them a bit.

it’s a good idea, when starting a new cartridge, to get several sources of reloading info like whatever books you have, hodgdon’s website, your bullet manufacturer, (maybe even the internet…be careful) etc. and start with a low load that’s “low” in all of the sources and realize that you may not get to the “high” in any of them. Even with the same powder, brass, primer, and bullet as the “book” load, your barrel and chamber is unique.

Thank you Sir, this is very helpful. I’ll definitely work up a new load. Do you have any recommendations for a good neck turner?

 

[John Glidewell]

I would see if you have a carbon ring or excessive carbon in throat. Going by what you have posted it does not sound like you do full cleaning enough and it does not take much carbon to create a tight throat situation. Only had it happen once and it was due to lack of cleaning so I went back to a regular cleaning regime. I clean every 100 to 200 rounds in all my rifles, no more carbon issues.

 

[John Glidewell]

Also. What is your trim spec? Are you trimming your brass? If not, that can be an issue.

 

[OREGUN]

Thank you Sir, this is very helpful. I’ll definitely work up a new load. Do you have any recommendations for a good neck turner?

I’d rather sell a child than neck turn but if you insist…it’s all miserable. If you didn’t spec a tight neck there’s is NO WAY Altus chambered your barrel that way…(I’m not sure they would do it if you asked). But, I have used a Sinclair setup in the past and it has provided very consistent results. Likewise, I would really doubt they cut you a min spec chamber unless you asked for it specifically.

 

[John Glidewell]

I’d rather sell a child than neck turn but if you insist…it’s all miserable. If you didn’t spec a tight neck there’s is NO WAY Altus chambered your barrel that way…(I’m not sure they would do it if you asked). But, I have used a Sinclair setup in the past and it has provided very consistent results. Likewise, I would really doubt they cut you a min spec chamber unless you asked for it specifically.

Yup. My guess is carbon or not trimming or combo is causing issue. If it was fine for first 500 prob not a tight chamber, but something is causing it. Only a few things can cause this condition.

 

[secondofangle2]

Just curious, why would we need to know that you reload on a bling press (419) with a bling scale (ST & FX) to diagnose this problem?
Is it to lend an imprimatur of credibility to your reloading prowess?
You can have any piece of kit you want but if not used correctly...

Not trying to bust your balls, just wondering why you thought it necessary to include that information

To be constructive, how close are you to lands compared to your 108s? Are you jammed? Is bolt hard to *close*? Any chance your powder has dried out and lost water content? Finally, you are on a far end of the spectrum not cleaning but for every 500 rounds.

 

[Rocketmandb]

I’d rather sell a child than neck turn

Doesn't that depend on the child?

 

[Rocketmandb]

Thank you Sir, this is very helpful. I’ll definitely work up a new load. Do you have any recommendations for a good neck turner?

All kidding aside, I agree with @OREGUN - neck turning is not something you should start with. Eliminate other factors first.

 

[megafans]

Just curious, why would we need to know that you reload on a bling press (419) with a bling scale (ST & FX) to diagnose this problem?
Is it to lend an imprimatur of credibility to your reloading prowess?
You can have any piece of kit you want but if not used correctly...

Not trying to bust your balls, just wondering why you thought it necessary to include that information

To be constructive, how close are you to lands compared to your 108s? Are you jammed? Is bolt hard to *close*? Any chance your powder has dried out and lost water content? Finally, you are on a far end of the spectrum not cleaning but for every 500 rounds.

Not at all, it was purely because it’s my first time posting in this forum and was trying to get ahead of any questions as to what equipment I’m using. I didn’t notice any change on the bolt closing, only on the opening. I just chambered one of the fired brass and pulled the trigger and the bolt was also pretty hard to open as well. If that means anything.

I’m not sure how close to the lands I was with the 108’s but with the 110’s I measured about 2.873 COAL to the lands, 2.1660 CBTO.

It’s possible my powder dried out, it’s probably 5+ years old but I’ve always kept it in the original containers and in a temperature controlled environment and routinely rotated the containers.

 

[megafans]

Looking at my target from the previous range trip, I’m getting the following velocities:

39.5 - 2931
39.7 - 2934
39.8 - 2941
39.9 - 2950
40.0 - 2960
40.1 - 2973

 

[jakelly]

My average velocity over 25 rounds was around 2950, it is possible that my chamber/bore could have still had some oil in it from my last cleaning. Sounds like I’ll need to go back down to 39.5

When was the last cleaning?
Make sure your chamber is clean and dry.

Measure the unfired and fired cases just above the case head, in the web. To do this correctly, measure at three points 120* apart on the circumference. Also measure the Hornady factory ammo, unfired and fired in the same spot.

Are these velocities from this brass, powder, and projectile? It seems like you are switching load components, like brass and projectile, and then referencing that as if it were the same “load”. If you switch any of those components, you need to work up or develop, again.

Looking at my target from the previous range trip, I’m getting the following velocities:

39.5 - 2931
39.7 - 2934
39.8 - 2941
39.9 - 2950
40.0 - 2960
40.1 - 2973

 

[AccuSol-ERN]

I’d rather sell a child than neck turn but if you insist…it’s all miserable. If you didn’t spec a tight neck there’s is NO WAY Altus chambered your barrel that way…(I’m not sure they would do it if you asked). But, I have used a Sinclair setup in the past and it has provided very consistent results. Likewise, I would really doubt they cut you a min spec chamber unless you asked for it specifically.

Correct. ANY tight neck barrels I've done, I make the customer supply the reamer.

For 6creed I use a SAAMI spec reamer, which I believe is .277" neck diameter.

After hearing more information. Please clean your rifle thoroughly and retry. Let us know what happens.

I have the habit of automatically assuming in any rifle problem situation that the rifle is clean and maintained. A METRIC SHIT TON of problems can be resolved by good cleaning techniques and schedules.

No insult to the original poster......but I would pay good money to castrate the person who coined "don't clean until there is a problem".

Ern

 

[Cascade Hemi]

You're pushing a 110 to almost 3k fps with a powder that is too fast. You have pressure signs because you're over pressure. Reduce load, switch to a slower powder, change bullets, use a friction modifier. Lapua brass has less capacity than Hornady. Tight necks and carbon fowling will make it worse.

Also, you need neck clearance. Turning necks isn't the boogie man. Empower yourself with a decent turning station so you can troubleshoot shoot your own problems without random guessing on the internet.

 

[Cascade Hemi]

What is the basis for this assessment?

Ummm, Experience? Industry recognized practices? 130 years of metallic cartridge history in the US? How is this even controversial?

just because someone found some random range brass with tight necks doesn't mean it's not improper. People are stunningly stupid.

 

[AccuSol-ERN]

I seriously doubt it is a tight neck issue. A .277" reamer neck diameter is MORE than enough clearance. This however implies there is not a wall of carbon stucco in the neck or throat area.

Again, start with a clean dry rifle then look at your load data.

Keep us posted.

Ern

 

[Cascade Hemi]

Chill bro…you’re 130 years old? No wonder you are so defensive.

The huge majority of shooters across the history of even your long life have never even consider neck turning nor do they ever need to. You made it sound like it was the OPs only option because he “needs neck clearance”. That’s just extremely unlikely. I’d have figured after your century of experience you would know that. And the idea that a bullet will simply drop into a fired case is asinine.

Go reread my post. Tight necks are a contributing factor when loading at the top of spec pressure with a powder that is arguably inappropriate for the bullet weight. You need neck clearance, whether that is from cleaning or brass turning. OP has new Lapua brass, a bullet should drop into the fired case if his necks are . 0155" or thinner (assuming the chamber was cut .277).

Turning necks isn't that big of a deal. Perhaps people that just up and decide standard practices are untrue may also struggle with easy tasks. I don't know what to tell you though because it appears you're having a hard time understanding basic written language too.

 

[Cascade Hemi]

I seriously doubt it is a tight neck issue. A .277" reamer neck diameter is MORE than enough clearance. This however implies there is not a wall of carbon stucco in the neck or throat area.

Again, start with a clean dry rifle then look at your load data.

Keep us posted.

Ern

Fair point.

 

[megafans]

When was the last cleaning?
Make sure your chamber is clean and dry.

Measure the unfired and fired cases just above the case head, in the web. To do this correctly, measure at three points 120* apart on the circumference. Also measure the Hornady factory ammo, unfired and fired in the same spot.

Are these velocities from this brass, powder, and projectile? It seems like you are switching load components, like brass and projectile, and then referencing that as if it were the same “load”. If you switch any of those components, you need to work up or develop, again.

I measured .4685 on the new brass and .4695 on the fired brass across 3 different cases. The velocities I posted are using all of the same components that I listed previously.

 

[megafans]

What is the basis for this assessment?

@megafans OP: can you give us the measurement of neck diameter on piece of fired brass and if you have one loaded up, on that too?

For example, my 6CM necks (factory Hornady 108 ELDM) measure .2705 new out of the box and .2735 once fired (Bugholes did the chamber. My ask was “for factory ammo”). Using Lapua brass your numbers will be different but that’s the kind of numbers I’m curious about. And no, a new bullet won’t drop in the that fired case either.

Neck diameter of the fired brass is .2750, new is .2705, loaded is .2725

 

[High Desert duck]

@megafans Double check your scale calibration, and your OAL. .006 to .007 sounds like a bunch of expansion but not out of spec. Mine grow .003-.004 on virgin brass.
This almost is the exact, (I’m at 39.4 and I run the CCI 450) same recipe I am running in all of my 6cm. I have no pressure signs, and nice round primer edges. And they are running at 3050fps from my match gun (4 groove 700 rounds) and 3000fps from my practice /local gun (5r 1900 rounds). I would not say it’s a load issue unless your scale is un-calibrated or broken. (Unlikely). When you say stiff bolt, how stiff? Like just more than and empty chamber or I had to beat it open with a 2x4? I can’t see the case heads on my phone very well and you don’t mention any swipes or ejector marks.

My best guess is with .006-.007 growth in the shoulder is the brass is expanding back into the bolt face and giving false pressure signs. The length looks a little long to me, but my smith hand throats for me so my OAL will be different, but double check you not jammed. I’d Stop load development and check by loading up 5 once fired cases and repeat. Bet the signs are gone.
It could be a gun or a chamber issue but it looks like you had a good smith and good components. Could be a carbon ring a borescope will tell you,

Attached screen shot is direct from the Hodgdon website. Yes it’s Hornady brass vs his lapua but he’s still 1.4 grains under, and his speed looks close considering he’s got a 26” barrel. I’m running a 28” and the test barrel is a 24”.
Be safe I’m just some guy on the internet.

 

[Cascade Hemi]

Neck diameter of the fired brass is .2750, new is .2705, loaded is .2725

Unless you have .001 of carbon in your neck, which I've never seen in 20+ years of habitually not cleaning guns, then you have a .275 chamber with .015+ casenecks. You're also at the top of max charge weight and your barrel is probably overdue for a cleaning.

Clean your barrel to bare metal and reshoot a pressure ladder.

 

[secondofangle2]

Brass can do funny things when it expands and contracts ("flows") under pressure, especially if it doesn't have enough room to expand, or a lot of/too much room. Having gone through a a tough period of "false pressure signs" in a 338LM, I would take the fired cases, bump the shoulder back about 0.002 (measuring each one, one at a time for this test) and see if the same thing happens when fired through a clean gun

 

[jakelly]

I measured .4685 on the new brass and .4695 on the fired brass across 3 different cases. The velocities I posted are using all of the same components that I listed previously.

And the unfired dimension on the Hornady?
Do you have a tight rub mark on the web?
Do you have a “click” when raising the bolt handle?

I don’t think this is a pressure issue, at least in the conventional sense, the load is pretty well known and the velocities are in-line with expectations.

I think your chamber might be a little tight in the web. The SAAMI spec I saw showed the web spec as .4708 @ .200”. Yours sounds a little tight (provided your measurements are accurate). The brass chambering fine and clicking on extraction has me thinking the camming abutments are pushing the case in, which you barely notice, but when removing, the press fit is really detectable. My best guess as to why it just showed up, is the Lapua is harder than the Hornady, but the pressure could be a bit higher, too.

Research “clickers” for more insight. If I’m right and this is your problem. You are probably going to need to open/clean up your chamber some. You might have to call Altus.

 

[megafans]

And the unfired dimension on the Hornady?
Do you have a tight rub mark on the web?
Do you have a “click” when raising the bolt handle?

I don’t think this is a pressure issue, at least in the conventional sense, the load is pretty well known and the velocities are in-line with expectations.

I think your chamber might be a little tight in the web. The SAAMI spec I saw showed the web spec as .4708 @ .200”. Yours sounds a little tight (provided your measurements are accurate). The brass chambering fine and clicking on extraction has me thinking the camming abutments are pushing the case in, which you barely notice, but when removing, the press fit is really detectable. My best guess as to why it just showed up, is the Lapua is harder than the Hornady, but the pressure could be a bit higher, too.

Research “clickers” for more insight. If I’m right and this is your problem. You are probably going to need to open/clean up your chamber some. You might have to call Altus.

I’m not seeing any rub marks on the web and no click when raising the bolt handle. Here’s what the Hornady manual shows for the dimensions.

 

[megafans]

@megafans Double check your scale calibration, and your OAL. .006 to .007 sounds like a bunch of expansion but not out of spec. Mine grow .003-.004 on virgin brass.
This almost is the exact, (I’m at 39.4 and I run the CCI 450) same recipe I am running in all of my 6cm. I have no pressure signs, and nice round primer edges. And they are running at 3050fps from my match gun (4 groove 700 rounds) and 3000fps from my practice /local gun (5r 1900 rounds). I would not say it’s a load issue unless your scale is un-calibrated or broken. (Unlikely). When you say stiff bolt, how stiff? Like just more than and empty chamber or I had to beat it open with a 2x4? I can’t see the case heads on my phone very well and you don’t mention any swipes or ejector marks.

My best guess is with .006-.007 growth in the shoulder is the brass is expanding back into the bolt face and giving false pressure signs. The length looks a little long to me, but my smith hand throats for me so my OAL will be different, but double check you not jammed. I’d Stop load development and check by loading up 5 once fired cases and repeat. Bet the signs are gone.
It could be a gun or a chamber issue but it looks like you had a good smith and good components. Could be a carbon ring a borescope will tell you,

Attached screen shot is direct from the Hodgdon website. Yes it’s Hornady brass vs his lapua but he’s still 1.4 grains under, and his speed looks close considering he’s got a 26” barrel. I’m running a 28” and the test barrel is a 24”.
Be safe I’m just some guy on the internet.
View attachment 8086531

It’s not so stiff that I have to pound on it, but definitely a good amount more than an empty chamber. I have to apply moderately heavy force to get the bolt to lift. I’ll see if I can post some videos later tonight. I’m planning on giving the rifle a full cleaning and then to load up some rounds at 39.5gr using the once fired brass with 110 Atips and also some using the 108 ELDM’s just to compare again.

 

[jakelly]

I’m not seeing any rub marks on the web and no click when raising the bolt handle. Here’s what the Hornady manual shows for the dimensions.

Those dimensions are for the brass, not the chamber. But they are still nearly as large as your fired brass. Which would mean your chamber is tight. IIRC you need .0025”+ with large magnums to avoid the issue. Obviously with smaller cases the expansion needed would be smaller, but .002” is probably still needed and you don’t even have .0015”.

 

[megafans]

Those dimensions are for the brass, not the chamber. But they are still nearly as large as your fired brass. Which would mean your chamber is tight. IIRC you need .0025”+ with large magnums to avoid the issue. Obviously with smaller cases the expansion needed would be smaller, but .002” is probably still needed and you don’t even have .0015”.

Here’s what I found for the chamber

 

[jakelly]

Yeah, that’s a good bit bigger than your chamber isn’t it?

 

[Cascade Hemi]

OP doesn't have "clickers", it's new brass.

 

[jakelly]

New brass chambers and extracts fine. Once fired Lapua has problems. .001” is too little clearance at the web.

If my thoughts are right, he’ll know right away as reducing his charge won’t really solve the problem. He can go below 2900 and it still won’t be “right”.

Again, if I’m right, the only proper solution is to switch to smaller brass and maybe small base dies (meh) or open his chamber.

 

[Cascade Hemi]

Clickers and a tight case web to chamber fit doesn't cause heavy bolt lift, especially with new brass.

This one time at band camp I had a 6CM chamber cut, unbeknownst to me, with a .275 neck. I then used .0155 thick brass, 115DTACs, and H4350. I chased every issue OP is chasing now, to the T. Factory Hornady loaded ammo worked fine. Seriously no shit. Clean the gun, change powders, turn the necks. In that order, easiest to hardest.

OP, clean the gun and shoot a 10 or 15 rd pressure ladder, low to high, in .2gr increments to find where pressure starts. Use the same new brass if you have more. If you need a die that will size the case webs, send me a PM and I will give you a Forster die that was cut too small (sizes new brass webs .001).

 

[CK1.0]

Umm, I think that brass looks fine. The Lapua SRP stuff anyway, that random Hornady LRP case sure looks like it was too hot.

40gn of H4350 with a 110gn A-tip netting 2950fps seems like a very reasonable/normal/usual load to me.

I just think it's the new brass.

New brass can be wonky, I just found out the other day (the hard way) that my virgin Apha OCD brass is 6 thou under SAAMI minimum, it's growing 8-9 thou on the first firing to fit my chamber, with lots of FTF's like if one had bumped the shoulders back too much, except it's brand new virgin brass, fun times lol.

As a new reloader, I would watch that whole COAL thing though... COAL is basically a useless measurement (besides whether it'll fit in your mags or not, for which you can just use a f'ing mag lol). If you don't have one already, get a comparator so you can measure base-to-ogive, a vastly more useful measurement. Using COAL, even if the number looks good/safe, you still could possibly be jammed in the lands, adding pressure, and not even know it.

 

[AccuSol-ERN]

And the unfired dimension on the Hornady?
Do you have a tight rub mark on the web?
Do you have a “click” when raising the bolt handle?

I don’t think this is a pressure issue, at least in the conventional sense, the load is pretty well known and the velocities are in-line with expectations.

I think your chamber might be a little tight in the web. The SAAMI spec I saw showed the web spec as .4708 @ .200”. Yours sounds a little tight (provided your measurements are accurate). The brass chambering fine and clicking on extraction has me thinking the camming abutments are pushing the case in, which you barely notice, but when removing, the press fit is really detectable. My best guess as to why it just showed up, is the Lapua is harder than the Hornady, but the pressure could be a bit higher, too.

Research “clickers” for more insight. If I’m right and this is your problem. You are probably going to need to open/clean up your chamber some. You might have to call Altus.

PLEASE DO NOT MODIFY YOUR CHAMBER IN ANY WAY!!!

Although chamber dimension issues can happen.....this is not a first choice fix. In regards to "clickers" thats a discussion for another day. I have yet to get any Pro-Clicker groupie to explain why the 6.5prc has the same clearance (at .200) as other cartridges we have all shot for decades without issue.

Ern

 

[megafans]

Thanks for all the help everyone, I’ll update the post once I clean the rifle and can get back out to the range for some additional testing.

 

[Pat McGroin]

Umm, I think that brass looks fine. The Lapua SRP stuff anyway, that random Hornady LRP case sure looks like it was too hot.

40gn of H4350 with a 110gn A-tip netting 2950fps seems like a very reasonable/normal/usual load to me.

I just think it's the new brass.

New brass can be wonky, I just found out the other day (the hard way) that my virgin Apha OCD brass is 6 thou under SAAMI minimum, it's growing 8-9 thou on the first firing to fit my chamber, with lots of FTF's like if one had bumped the shoulders back too much, except it's brand new virgin brass, fun times lol.

As a new reloader, I would watch that whole COAL thing though... COAL is basically a useless measurement (besides whether it'll fit in your mags or not, for which you can just use a f'ing mag lol). If you don't have one already, get a comparator so you can measure base-to-ogive, a vastly more useful measurement. Using COAL, even if the number looks good/safe, you still could possibly be jammed in the lands, adding pressure, and not even know it.

I also recently had weird issues with alpha brass that resolved when I switched to any one of several other options

 

[CK1.0]

I also recently had weird issues with alpha brass that resolved when I switched to any one of several other options

I haven't made up my mind yet about the Alpha brass yet...

On one hand, it's supposed to be the best shit ever, and on the other hand, my stuff came with shoulders as much as 6 thou under SAAMI minimum (so 13 thou under the SAAMI spec) which has been a headache. The primer pockets are solid though, so once I get them fire-formed they should last a couple of barrels I'd imagine.

 

[Pat McGroin]

I haven't made up my mind yet about the Alpha brass yet...

On one hand, it's supposed to be the best shit ever, and on the other hand, my stuff came with shoulders as much as 6 thou under SAAMI minimum (so 13 thou under the SAAMI spec) which has been a headache. The primer pockets are solid though, so once I get them fire-formed they should last a couple of barrels I'd imagine.

I also heard good things about it so I got a couple boxes with a new build. Mine was similar, also had a couple pieces over SAAMI spec that wouldn’t chamber until I ran them through a die which I have never had to do with new brass before. I was getting ejector marks and very stiff bolt lift with everything from below minimum to near max loads, and inconsistent brass growth. All issues resolved when I switched to Lapua, nosler, and multiple different lots of hornady with the same other components.

 

[9/11]

All kidding aside, I agree with @OREGUN - neck turning is not something you should start with. Eliminate other factors first.

I made up a 6mm cm round using 100 gr Hornady using 35.0 4166 and set out at 2.730 col upon firing the bolt lift was horrendous! This load was less than listed in Hornady manual for minimum! I have never experienced anything like this!

 

[megafans]

I made up a 6mm cm round using 100 gr Hornady using 35.0 4166 and set out at 2.730 col upon firing the bolt lift was horrendous! This load was less than listed in Hornady manual for minimum! I have never experienced anything like this!

That was my experience as well, the good news is that I took the advice I learned here and gave the rifle a very good cleaning, including scrubbing the chamber and throat and backed off to 39.5 and worked back up again, that fixed my heavy bolt lift issue!

 

[Sparticus14]

I made up a 6mm cm round using 100 gr Hornady using 35.0 4166 and set out at 2.730 col upon firing the bolt lift was horrendous! This load was less than listed in Hornady manual for minimum! I have never experienced anything like this!

Worth checking for a carbon ring

 

[45-90]

Sometimes you can not reach a max powder charge in listed in a manual. I had one load stated when I shot it blew a primer...its happened several times over the years. The next annual manual had a full grain lower charge, as the new maximum...just as I had to adjust my load. Gun powder is not an exact science, and the burn speed varies slightly from lot to lot... As many shooters have complained about a slower lot of Varget or H4350. Plus chamber and bore dimensions vary, brass brand and capacities vary. And why you work up a load for "Your" rifle. It appears your rifle is saying "no" to the top load with the components you're using.
Drop the powder charge a full grain and see if the problem dissappears.
Then investigate other problems if it still persists.