So when one is shooting reloads and is seeking to interpret the various factors that help give an understanding of “pressure” - what is “heavy bolt lift” – what does it feel like.

I shoot mainly 98 Mausers, mine are all properly set up and timed, so there is not much variation in bolt lift on an empty chamber.

With a high pressure load in a 98 Mauser does the bolt lift feel like there is additional resistance during the initial lift sequence, or just at the top when the extraction cam commences its work ??

From my reading on the ‘Net (not the most reliable source I know) I am aware that there are other factors pertaining to the cartridge that can cause heavy bolt lift besides pressure.

Thanks

Foster

Some of my Weatherbys can't take the same load as others of that caliber. I call it tight bolt, and back off a couple grains, always solves my problem.

With an over pressure round the bolt will resist from the start of the lift.

Sometimes this is due to the brass flowing into the extractor

Often the first sign of elevated PSI - as shown by the bolt - is a "clicking" sound at the top of the bolt lift. It comes when the bolt "pops" the case from the chamber - that is, a case that is beginning to stick to the chamber walls because of high pressure. After this, if you keep increasing powder charge, the bolt will become increasingly difficult to lift, until you get a stuck or frozen case. Usually, this is all preceded by or associated with extractor marks and maybe a blown primer pocket.

It is important to know, that as PSI rises, powder burn rate increases with increasing rapidity, thus risking a pressure excursion.

IMO, when you hear the bolt "click" (i.e., when using fresh brass), you're at MAX and you should consider backing down a grain or two.

Please know that multiply reloaded, poorly elastic, "work-hardened" brass will also stick to the chamber and cause the bolt click, even though it was fired at normal PSI. You should not use "work-hardened" brass, except for low-pressure target practice loads.

My definition: if the average 6 year old girl can't lift it with two fingers, it's time to consider dropping the powder charge a grain or two...

I ignore bolt lift; I watch primers and when they get real flat, I back off a grain or 2 and go for it. Brass hardness will affect bolt lift which is not necessarily a sign of pressure.

I am with dpcd on this one.

I make my decision based on what the primers look like, not "bolt lift"

If the brass is soft and starts yielding causing heavy bolt lift the pressure is too high for that brass.

The pressure may not be too high compared to the industry standard but, if your brass is yielding your pressure is too high for that batch of brass regardless of what the primers do.

With a run of the mill factory hunting rifle
a rough unpolished chamber can cause heavy bolt lift with normal or even mild pressure. If you have that issue a smith could remove the barrel and correct the rough finish in about 10 minutes.

Partially you have to know the rifle.. Is the bolt lift effort harder than after firing a known mild load?

This is one of the "feels" of reloading.. I don't place much store in it, other than as an idiot light... If you lock a bolt you are so far over pressure that you can Hurt yourself and others

Che is another voodoo.. Once you get enough for most people to be able to measure, you are way way too far

I look at load books and quickload first, then examine primers and any bright marks on cases.

quote:

Originally posted by SR4759:
If the brass is soft and starts yielding causing heavy bolt lift the pressure is too high for that brass.

The pressure may not be too high compared to the industry standard but, if your brass is yielding your pressure is too high for that batch of brass regardless of what the primers do.

Well said. If brass is too soft in the head area then the head will expand and cause sticky bolt lift even if the pressure is relatively mild. Whatever load at whatever pressure that causes sticky bolt lift is too high for that particular brass.

Similarly, brass which is too soft will exhibit sticky bolt lift before there is enough pressure to "flatten" primers. Besides, the "flatness" of the primer has much more to do with the amount of headspace (how loosely the cartridge fits the chamber) than with absolute pressure. Primers fired in chambers with generous headspace (relative to the cartridge brass) will always have a flattened appearance, while those fired in a tight chamber (again, relative to the brass) will have rounded edges unless and until pressures reach rather high levels.

Those of us who can remember when primers were actually somewhat spherical (convex) on the bottom side can also remember when "reading primers" had marginally more value than it does with today's flat-bottomed primers which only have a slight radius at the very edge.

I think you have to look at all of the information mentioned by many of the posts before mine. Using only one indicator is like driving and texting- you can do it but sooner or later it will bite you in the a#*.
Some actions will extract a case that the primer falls out of just as easily as a normal load, the next will help read the pressure by requiring more effort to lift the bolt as pressure increases.

Yep you have to know what the bolt feels like with a normal load. I've really only felt heavy bolt lift a couple times. As Jeff said it was the idiot light saying I was "way over" pressure. I can probably tell the difference between 55,000 and 75,000 via bolt lift. Other than that it is not something I worry about.

Foster,

You can educate yourself regarding bolt lift.

To begin, for this purpose use only strong bolt-action rifles that you completely trust.

Cases begin to fail increasing rapidity as you exceed 65,000 PSI, but a first-rate, well constructed, bolt-action rifle should be able withstand ~150,000 PSI without failure.

The cases will show signs of failure long before your first-rate bolt-action rifle fails.

Suppose you're working-up a hot hunting load from below your anticipated max load powder charge.

Start at least ~10% below that max amount and work-up in 0.5 or 1.0 gr increments. Because the max varies from rifle to rifle, I also load a few grains over the anticipated max charge. If PSI signs show-up before I get to these higher loads, I don't shoot them.

Use NEW brass and a chronograph, if you have one.

Shoot two rounds at each charge and note carefully how easy the bolt lifts.

As the powder charge increases, note when you first hear the bolt click as the case pops free from the chamber walls; the click occurs at the top of the lift and will usually precede heavy bolt lift. (I've never done it, but one could actually measure the lift with pound scale and record the result.)

Record your velocity at each charge. Excessive velocity correlates with excessive pressure.

With each load make observations regarding primer changes, such as increasing flattening and cratering.

Also, note the appearance of impression marks made by the ejector port, if present on your bolt face. Rem 700 bolts are good for this; Mauser actions are not as good. With the Rem 700 bolt face a slight impression mark will occur just before the bright ejector port mark occurs. When I see this early (often barely discernible) impression, I stop – that’s my maximum.

Keep track of each case and note the pressure needed to insert a new primer by using a hand-help priming tool. As PSI increases primer pockets loosen-up faster and faster and usually this becomes really noticeable as you exceed 65,000 PSI. If I can push the primer back out of the case with finger pressure and a hand held deprimer, I throw the case away. I like to get at least three reloadings from the primer pocket, some insist 5 or more.

As you increase PSI – especially at 65,000 PSI and above – pressure excursions are more likely and can result in stuck cases and/or blown primers. You don’t want this to happen as you watch the trophy of a lifetime walk away while you have an inoperable rifle.

Repeat this with different powders and bullets, gaining experience. You will begin to recognize the reproducible case changes and bolt-lift issues as the PSI increases.

Bolt-lift increases as PSI increases and becomes quite noticeable when the case begins sticking to the chamber walls.

Finally, you’ll then need to decide where you are comfortable with your reloads and the PSI signs they show as you travel along this PSI spectrum of changes.

I have many wildcat cartridges and I’ve had to work-up my own loads for the past 30 years. This has been my approach and I’ve done it many hundreds times with dozens of different bolt-action rifles. It works.

Regards, AIU

quote:

Originally posted by Stonecreek:

quote:

Originally posted by SR4759:
If the brass is soft and starts yielding causing heavy bolt lift the pressure is too high for that brass.

The pressure may not be too high compared to the industry standard but, if your brass is yielding your pressure is too high for that batch of brass regardless of what the primers do.

Well said. If brass is too soft in the head area then the head will expand and cause sticky bolt lift even if the pressure is relatively mild. Whatever load at whatever pressure that causes sticky bolt lift is too high for that particular brass.

Similarly, brass which is too soft will exhibit sticky bolt lift before there is enough pressure to "flatten" primers. Besides, the "flatness" of the primer has much more to do with the amount of headspace (how loosely the cartridge fits the chamber) than with absolute pressure. Primers fired in chambers with generous headspace (relative to the cartridge brass) will always have a flattened appearance, while those fired in a tight chamber (again, relative to the brass) will have rounded edges unless and until pressures reach rather high levels.

Those of us who can remember when primers were actually somewhat spherical (convex) on the bottom side can also remember when "reading primers" had marginally more value than it does with today's flat-bottomed primers which only have a slight radius at the very edge.

Agree with Stonecreek re reading primer flattening. This has to be done in considering case fit in chambers as the photo below shows even factory ammo can show signs of high pressure due to looseness in the chamber (Norma ammo showed propensity to be fairly loose in chamber specs). The photo is of a fired factory loading (Norma) 7x61 S&H cartridge case from the super strong Schultz and Larsen rifle. No issues with bolt lift, loose primer pockets, ejector marks or any other indicators of high pressure.

Thanks for your informative replies Gentlemen.

I only have one “modern” rifle, a CZ in 7x64. Some time ago I worked up loads in the conventional manner, looking for the documented pressure signs. Because there is a paucity of Data for 7x64 with non European powders one is somewhat on one’s own.

The 280 Remington is very very close in terms of case capacity and I used that data as a guide. In my rifle using Norma brass, Fed 210 primers I was able to get 160 gn projectiles moving at just over 2900 fps, which is pretty close to 7mm Mag performance. I didn’t encounter any of the commonly documented pressure signs such as primer, deformation, ejector slot extrusion, case head expansion or loose primer pockets etc. My notes show one round of one load at a velocity of 2918 fps had “heavy bolt lift”. I must say that I backed off these loads and now run this rifle at 2800 fps with 160’s.

Since then I have acquired Quickload, and have used my recorded data to model what sort of pressures I might have been running. With My 7x64 it is predicting velocities within 20 fps of the actuals I’d recorded. It calculated that the load I noted the heavy bolt lift for was probably just over 67,000 psi. Just as well I backed off and thanks to all those in the supply chain for the reliable componentry - ammo and rifle !!

More recently I have been working on loads for a commercial 1923 Mauser 250 Savage. I have been getting some “abnormal” bolt lifts, close to normal for the first part of the lift cycle, but heavy for the final extraction, but since I’d struck the phenomena so little I didn’t have any idea whether it was pressure related, due to a brass issue, or a rifle/chamber issue – The rifle has a brand new barrel, chambered by a very competent smith with a new reamer.

Quickload calculations/brass observations for my 250 load/rifle/observed velocities seem to rule out excessive pressure (it says my loads are around the 50,000 psi mark) which led me to think I may have some other brass issue. I checked the brass carefully and a few cases had “grown” significantly, something that apparently not uncommon in the 250 Savage.

So with the knowledge gained from your shared wisdom I will try some evenly trimmed brass and see if there are any further issues.

quote:

Originally posted by eagle27:

good lord -- that may be a factory load, and i see this in 270 factory brass all the time, but a flatten and flowed (top hat and brim) primer will get me to pull down those loads, if they were my reloads

quote:

Originally posted by jeffeosso:

quote:

Originally posted by eagle27:

good lord -- that may be a factory load, and i see this in 270 factory brass all the time, but a flatten and flowed (top hat and brim) primer will get me to pull down those loads, if they were my reloads

Why??? roger

quote:

Originally posted by bartsche:

quote:

Originally posted by jeffeosso:

quote:

Originally posted by eagle27:

good lord -- that may be a factory load, and i see this in 270 factory brass all the time, but a flatten and flowed (top hat and brim) primer will get me to pull down those loads, if they were my reloads

Why??? roger

Looks like any standard Remington OEM load in my 7mm SAUM. The 160gr. Federal Premium Partition loads on a warm day (90 degrees) get sticky bolt lift - the kind that takes an overly solid shove on the bolt…HARD shove that is.

Flattened primers? Pretty much normal that one.

My reloads are much tamer…even just 50 fps on the chrono or a 10gr. diff in bullet weight makes a huge difference.

I would agree that if reloads I would be concerned with that level of primer flattening but in the absence of any other pressure signs and if the muzzle velocity was at the expected level for the bullet weight and powder, I would be quite happy using them especially so in the fine Danish Schultz and Larsen rifle apparently tested at over 120,000psi.

The Norma factory 7x61 ammo with 160gr bullet (the fired case shown in the photo) had an advertised MV of 3100fps and chronographed in my rifle at 3040fps on a temperate day.

My favourite reload in my 7x61 was the 160 Sierra SBT doing a very consistent 3000fps using only 59.0grs IMR4831 and a standard primer. A superbly accurate and hard hitting load that accounted for many an animal over many years. The primers were flattened to some extent but no other pressure signs or issues. Bolt easy to lift and good case life when sized to the shoulder and not the belt.

quote:

Originally posted by bartsche:
Why??? roger

cuz i am chicken .. flat primers and a tophat rim are WAY over my comfort level

quote:

Originally posted by jeffeosso:

quote:

Originally posted by bartsche:
Why??? roger

cuz i am chicken .. flat primers and a tophat rim are WAY over my comfort level

I hear and understand and respect your take on this.
If there is a little excess head space when the powder is igniting the primer starts to move back before the case. The case than follows, flattening the primer and pressing it diametrically so the primer fills the total rear end of the primer pocket, giving you the top hat appearance. This is done at normal working pressures. It is a minor head space problem ( IN THIS CASE ) and not one of excessive pressure. roger

head space can cause the flattened primers like shown in the picture. I think primer appearance is one of the least reliable signs of pressure. However, to get a proper take on the situation, you have to look at a combination of several items for any of it to be meaningful: primer appearance, ease of extraction, case head appearance, case longevity, etc.

quote:

oldIf there is a little excess head space when the powder is igniting the primer starts to move back before the case. The case than follows, flattening the primer and pressing it diametrically so the primer fills the total rear end of the primer pocket, giving you the top hat appearance. This is done at normal working pressures. It is a minor head space problem ( IN THIS CASE ) and not one of excessive pressure. beer roger

Exactly. The only "dependable" pressure signs from "reading" primers are pierced firing pin holes and gas escaping around the primer. Even then, there are other non-pressure issues which can cause both of these phenomena.

"Back in the day" when primers had round bottoms there was a little more flatness gradation related to pressure, but now that primers have flat bottoms with only a slight radius at the edges, reading primer "flatness" is useful only to the degree that it can indicate relative pressures in the same rifle with identical cases previously fired in that chamber and neck-sized only. To make some pronouncement as to absolute pressures simply by looking at the shape of a fired primer when the fit of the case in the chamber is unknown is simply foolish.

There are a series of pressure indications used by the old benchresters, that many of todays experts say are without merit..I disagree with that, maybe because I'm a curmudgeon and have been using those indicators all my life and never damanged a rifle so far. I will explain some things on the subject that are seldom mentioned. Reloading 101

1. flat primers may or may not indicate pressure, rather they may indicate the soft metal used in their production, but this is not a given, don't panic but be aware.

2. Stiff bolts? fire a few factory or mild loads in your gun and feel the bolt lift immediately after firing to get the good feel, then if you feel any more resistence than that with your handloads, you are already in high pressure to one degree or another...If you let the rifle rest before extracting the case all is lost because the brass shrinks as it cools and you get a bad read, and that can be critical, so eject immediately after firing. If the bolt is stuck then wait 15 minutes and it will likely eject the case.

3. A loud crack as opposed to a boom is a real indicater to cut back several grains. Your in the worst of places.

4. Measure your case heads before and after firing a once fire formed case, or even a fired factory rounds first reload. The round has to be fired to fit your rifles chamber before is acceptable for reloading work ..It is said .0005 case base is allowable, but 0 is better.

5. Watch for a line in the brass case at the head, if the line is there straigten a paper clip with a hook on the end and see if you can feel a cut, if so the case is seperating, back off, and toss that case. I see this misused from time to time because of over sizing the cas to start with and even a mild load will cause this problem. When working up loads use neck sizing only and a lightly snug closing of the bolt on the reloaded case, especially on belted cases.

6. Always use a chronograph, today a chronograph can be had for a $100 bill. I like the pro Chrony as well as any I have tried. If your velocity is beyond what is accepted then your probably in in the red or close to it.

7. An extractor mark on the case head means troublel is brewing.

8. With a standard chamber never go over two grs. over book max and stopping at book max is always good advise as the additional velocity amounts to nada, and is hard on brass life. However todays reloading books are sometimes overly cautious because of frivoulous law suits and book max may, in fact, be a good starting load.

9. Always mic cases and never let them get over length. Always trim when needed. Don't inside neck ream or outside neck ream unless you have a bench rest chamber, thats too hard on brass and makes for loose bullets. Annealing is a good thing, but too much trouble with todays cheap brass in most calibers.

10. Most important of all is to use one case when working up loads..resize it and reload it with ever increasing half grain charges, feeling for loose primers, if loose then back off a gr. or two and quit..I would expect at least 10 loadings with a proper max round and 14 or 15 is normal...but if you only get 8 or 10 then your max and safe...you should be trimming about every 4th round with max loads.

NOTE: The quality of the rifles chamber is critical to all this and that makes it even more difficult, and you end up flying by the seat of your pants and for that reson alone one must use exteme care and always play it on the safe side..

Any one of these indicators in itself and by itself, may or may not mean much, but they are indicators, and when a couple of them come together or close, the time has come to cut back. They usually appear with flat primers, then perhaps a black gas escape ring around the flat primer, an extraction mark on the case head or maybe case head expansion and then a sticky bolt, in that order but not necessarily..Fortunatly for all of us the factories pressure test loads known as blue pills are way beyond what we load at and that is by design.

It's not an exact science, but watch for the above and use good common since, don't push your luck and the worst that will happen to you is on a rare ocassion if your pushing the string you will get a locked up bolt, maybe a blown off extractor and a ruined case, some gas in the face and little curly ques of smoke coming out of your cheeks, and the smell of burning flesh, and then you will get a whole bunch smarter. If your a dare devil and have to squeeze the last drop out of the case to brag to you brethen, then you will experience the ultimate in dare devilism experiences and that is a handgrande will go off in our face.

If in doubt cut it out!!