264 WM heavy bolt lift

[AG74]

Have been doing load development on my 264, Rem 700 action, 26" Lilja barrel with 8" twist, H-S Precision stock. Have found 68.0 gr Retumbo to give good accuracy with 140 gr Partitions (3120 fps), with 140 gr Accubonds ( 3250 fps) and with 142 gr LRAB (3100 fps).

Since 140 Ballistic Tips are of the same size and BC as the Accubond, I decided to load a few as practice rounds. The first 4 shot fine at an avg of 3170 fps, but the fifth shot nearly locked the bolt. Chrony indicated 3211 fps. It was very stiff/heavy to lift. The case however showed no real pressure signs.

The only thing I noticed was some residual case lube on the case, which was sticky. Could this have caused the problem?

I have fired the 140 Accubond with 68.5 grains of powder at up to 3300 fps with no pressure signs, so I didn't think an NBT at 3211 would cause this problem. This load has worked fine in this rifle with3 different bullet types. Not sure what caused this anomaly.

A friend and I load these and have a pretty good quality check, so I'm pretty confident there wasn't an extra grain of powder or anything, same with seating depth. Here's the load info:

Nosler brass, 2 times loaded, neck sized only. All cases measured less than trim to length.
68 gr Retumbo
WLRM primer
140 gr NBT
COAL 3.25"

Rifle has had 24 rounds through it since last good cleaning.

Thanks for the help.

 

[bigedp51]

Lifting the bolt straight up is primary extraction and is to break the case free of the chamber walls. When the bolt is hard to lift it means the case is still sticking to the chamber walls. And the Hodgdons loading data shows you are 4 grains over maximum.

On top of this neck sizing only doesn't give your brass any extra "spring back" from the chamber walls that full length resizing will.

Another problem is the expansion just above the belt where the belted magnum collet die is needed to reduce the base diameter.

There is no free lunch at maximum loads and the brass takes a pounding. And even at lower loadings if you have softer brass you can have problems.


Simple Trick for Monitoring Pressure of Your Rifle Reloads | Hodgdon Reloading

 

[bigngreen]

Slick cases will definitely be a possibility, anything that reduces the traction of the case to the chamber wall will allow more bolt thrust.

 

[Trnelson]

I've NEVER just switched any component and hit the range. Your post demonstrates WHY, especially at the outer fringes of what's proven safe previously. When I switched to 140g SST from the 140g Berger I dropped to the stating load for the 140 SST and ran into pressure less than 1-1/2g above the hornady published minimum data. Powder is cheap, ER visits are not. Be safe, play nice

 

[AG74]

I've NEVER just switched any component and hit the range. Your post demonstrates WHY, especially at the outer fringes of what's proven safe previously. When I switched to 140g SST from the 140g Berger I dropped to the stating load for the 140 SST and ran into pressure less than 1-1/2g above the hornady published minimum data. Powder is cheap, ER visits are not. Be safe, play nice

Thank you for your input, I appreciate it.

I've started low and worked up with the Partition, Accubond and LRAB, and encountered no pressure signs. Since the Ballistic Tips and Accubonds are from the same manufacturer, are the same dimension, weight, ballistic coefficient, and sectional density, I did not consider that a change of component. Ballistically speaking, the two bullets should be identical. Terminal performance is where they differ, correct?

 

[bigedp51]

Slick cases will definitely be a possibility, anything that reduces the traction of the case to the chamber wall will allow more bolt thrust.

Oil, grease or water in the chamber does increase bolt thrust, "BUT" this increases the force applied to the bolt face and locking lugs. And it doesn't add more outward pressure/force on the chamber walls.

The OP problem is the case is not springing back from the chamber walls and his load exceeds the elastic limits of the brass. He needs to full length resize his cases and reduce his load. And this would allow the case to spring back from the chamber walls.

 

[bigngreen]

Oil, grease or water in the chamber does increase bolt thrust, "BUT" this increases the force applied to the bolt face and locking lugs. And it doesn't add more outward pressure/force on the chamber walls.

The OP problem is the case is not springing back from the chamber walls and his load exceeds the elastic limits of the brass. He needs to full length resize his cases and reduce his load. And this would allow the case to spring back from the chamber walls.

When your running at the top or your cases are getting tight it takes very little to cause the issue. I've seen moisture in a chamber do this on several occasions, when you don't have the case walls gripping the chamber that case slams the bolt at the full pressure your running with and it will definitely give you bolt lift, I shoot some rifles that you want moisture in the bore for fowling but if much of that gets in your chamber you'll lock up or separate a case.
In what the OP wrote the heavy bolt lift was on a case that was sticky with lube, not really a hard to trouble shoot situation especially when you have a number of the same load running fine then you get to a lubed case and then trouble.
We went through this several years ago and when the shooter and several others tested it to verify a little water was all that was needed to recreate the situation, not saying it 100% that but I would definitely not dismisses it!

 

[RT2506]

Things I have learned. Retumbo is very sensitive near the max load. Even 0.2 grs more can go from no problem to ejector marks on the case and hard bolt lift.
The Nosler BT and AB ARE NOT THE SAME BULLET. The AB is a bonded bullet and thus it's core will react differently than the BT when the bullet hits the lands and it don't take much differences to cause pressure to spike when you are at and in your case OVER the listed MAX load in my Hodgdon data. My data list only the 140 Nosler partition but Max load is 63.5 grs Retumbo.
In my Rem 700 27 3/4" Shilen barrel 264 Win mag I use the 130 Accubond with WW cases made from 7mm Mags, CCI 250 primer and load 10 thousands off the lands and with 66.5 grs Retumbo and get 3350 fps and outstanding accuracy. When I did my work up there was no data listed for the 130 AB so I used the starting load for the Hornady 129 gr SP which list a Max load of 67.5 gr Retumbo. At 66.5 grs everything was was great but when I went to 67 grs I had very hard bolt lift and heavy ejector marks on the case with very flat primers. Did some more loads and found at 66.7 gr gave stiff bolt lift and slight ejector mark on the cases. But 66.5 gr works perfect with no problems even with temps in the 80s like it is often in east NC during deer season.
The advice of all the component makers of "Start at the starting load and work up if you change anything in a load" is sound advice. Just some things a crazy old man that has been loading for about 40 years has learned. By the way, the Accubond is a super deer bullet for these speedsters that for me reacts the same from 30 to a little over 500 yards so far. Bullet enters destroys the vitals and exits with a quarter size hole and the deer goes FLOP on impact.

 

[MagnumManiac]

Oil, grease or water in the chamber does increase bolt thrust, "BUT" this increases the force applied to the bolt face and locking lugs. And it doesn't add more outward pressure/force on the chamber walls.

The OP problem is the case is not springing back from the chamber walls and his load exceeds the elastic limits of the brass. He needs to full length resize his cases and reduce his load. And this would allow the case to spring back from the chamber walls.

If a case is slick in the chamber, it WILL cause stiff bolt lift, even a moderate load does this.
Neck sizing only poses no problem on 2 firings, it takes 4 or more firings for a case to expand to the point where it us difficult to chamber, and brass that was hard to chamber often is easy to chamber after being fired.
Why is the Hodgdon manual gospel? Those loads mirror what QL spits out and my pressure trace in my own 264 gets above 70gr before max pressure is reached. Most places are still focussed on CUP readings for this cartridge, which are most likely wrong anyway.
Also, belted magnums pose no such issue with a bulge above the belt if the cases are sized correctly in the first place. That die is a money spinning gimmick!
The simple answer to the OP is keep your cases clean and dry.

Cheers.
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[bigedp51]

MagnumManiac

I'm a rabid anti case greaser because it increases bolt thrust and can damage your rifles. And one thing I can tell you is the slight amount of lube left on the OPs case did not increase the chamber pressure. The only way lube can increase chamber pressure is if it prevents the case from expanding and when also squeezed in front of the bullet.

Hard bolt lift is caused by the case not springing back from the chamber walls and causing drag on the chamber walls. And this happens when you exceed the elastic limits of the brass at higher than normal pressures.

Military 7.62 cases are made thicker in the base and 5.56 cases are made harder to help the cases from sticking in the chamber. Meaning commercial cases vary in brass hardness and spring back rates and effect case sticking.

The OP changed components without reducing the powder charge and had hard bolt lift.............end of story.

 

[bigngreen]

This is such basic trouble shooting it hurts, the OP is firing 140 Accubonds at 3250 with 68 gr if retumbo his first 4 shots with the Ballistic tip his velocity dropped so his pressure dropped given that the second bullet though exact in design is softer so you'd expect lower pressure by a little.
The offending case is sticky with lube, not a little, sticky! What are the odds of the one case that is sticky is also the case that had a heavy bolt lift!
A number of years ago we had the exact same issue on the forum, went for pages till the OP and a couple other guys actually recreated the issue and guess what, something reducing chamber wall traction with the case caused excessive pressure signs and bolt lift. Not all that difficult a deal, the OP seems to all ready know what happened but wants to verify it with other, he's on the right track!
Simpy lifting the bolt has zero to do with the case outward expansion UNTIL the very top with is primary extraction, so if you have a heavy bolt lift from the bottom it's not expansion is thrust holding the bolt, when you have EXTRACTION issues at the top that is cases holding tight to the chamber, lube creates larger bolt thrust which gives you heavy lift!

 

[bigedp51]

So how many case greasers do we have here and are experts on the subject?

Did any of you ever hear about anyone who lubes his cases all the time complain about heavy bolt lift.

We seem to have a lot of experts who have no personal experience on the subject. Bolt timing effects the camming force during bolt lift and its breaking the case free of the chamber during primary extraction. Bolt thrust doesn't cause high chamber pressure. BUT high chamber pressure will cause brass to flow beyond its elastic limits and why you measure just above the extractor groove or belt for high pressure.

The British used the base crusher system of pressure taking where a hollow copper crusher was used and the firing pin passed through the hollow copper crusher. The case was oiled in order for full chamber pressure to register on the copper crusher. These same rifle were proof pressure tested with two oiled proof cartridges. After proofing if the Enfield rifles headspace increased over .003 the rifle failed proof testing. At no time did firing oil cartridges cause hard bolt lift but it will cause lug setback and a increase in headspace.

Below is from the "1929 British Textbook of Small Arms" and to this day the British used two oiled proof cartridges to test their small arms.

Bottom line, well used older rifles might have a problem with hard bolt lift at the top of the upward bolt movement due to bolt wear. If what you said above was true all neck sized cases would cause hard bolt lift from the drag on the base of the case.

 

[bigngreen]

This does the OP no good, you simple will not understand until you have real world experience and are asked to figure it out and prove it so unless the OP needs something else I have nothing to contribute.
If I remember right the Nosler manual warns about solvents or lube in the chamber form cleaning causing the symptoms of high pressure, which would include bolt lift.

 

[MagnumManiac]

MagnumManiac

I'm a rabid anti case greaser because it increases bolt thrust and can damage your rifles. And one thing I can tell you is the slight amount of lube left on the OPs case did not increase the chamber pressure. The only way lube can increase chamber pressure is if it prevents the case from expanding and when also squeezed in front of the bullet.

Hard bolt lift is caused by the case not springing back from the chamber walls and causing drag on the chamber walls. And this happens when you exceed the elastic limits of the brass at higher than normal pressures.

Military 7.62 cases are made thicker in the base and 5.56 cases are made harder to help the cases from sticking in the chamber. Meaning commercial cases vary in brass hardness and spring back rates and effect case sticking.

The OP changed components without reducing the powder charge and had hard bolt lift.............end of story.

He had hard bolt lift with ONE cartridge. He also said that cartridge had something on it.
I have traced, both 180gr BT'S and 180gr Accubonds with identical loads, no significant difference in pressure was noted, in my rifle.
There are more causes for hard bokt lift than just the brass expanding, a cratered primer can cause hard bolt lift, oil, grease etc etc.

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