Relationship between headspace and chasing the lands?

[M-61]

excessive bump back situations)!!

Oh yes

 

[Wild Bill IV]

Oh yes

I'm sorry, M-61, I deleted that post!!! I was thinking of some of the older military rifles and their extractor claws!!! Some were over travel, some are spring out and others were slope fit!!! Yes, the two worse cases of chamber problems are a NO GO GAUGE Chamber and Excessive Bump Back situation!!!!!

 

[M-61]

But the rifle bolt is holding the case rim in the same spot as well as the shell holder is on your seating die.
But believe me, I am very often wrong.

Well, to a point. It is not holding it as securely or firmly or as ‘strongly’ as the shell holder.
Years ago a SHBF (shell holder bolt face) was in favor with some (me included) who had a shell holder welded to the bolt face.
To load you withdrew the bolt (no releases or buttons) bolt just pulls straight out. Insert your cartridge into the shell holder then slide the bolt with the cartridge held by the
Shell holder. It certainly was/is an interesting idea. I have the rifle to this day. 222. Had it built for me at the start of my benchrest shooting. 1975. How’d it shoot? Fantastic. However it was built by a highly skilled gunsmith named Ed Ferguson. Douglas barrel. Sleeved action (also an older school line of thought.) Does it shoot well today? Yup. Does this have to do with the SHBF? No clue.

 

[M-61]

Excessive Bump Back situation!!!!!

No problem you deleted it.
You are dead on with excessive bump back. Comes with a misunderstanding of headspace and case clearance combined with using incorrect names for what is meant.

 

[Wild Bill IV]

But the rifle bolt is holding the case rim in the same spot as well as the shell holder is on your seating die.
But believe me, I am very often wrong.

No!!! The ejector pushes the case forward allowing the case shoulder to rattle in or self center into the chamber shoulder!! The extractor does not pull the case back to the same conditions of the press/form die geometry!!!! This is the true beauty of the rimless bottleneck design itself in small arms firearms!!!

I need the opinion of a SMITH!!! Do the extractors over travel????
If so, the extractor would only limit or restrict the full case shoulder contact in NO GO GAUGE CHAMBERS or excessive bump back situations!!!!

 

[lawebb21]

No!!! The ejector pushes the case forward allowing the case shoulder to rattle in or self center into the chamber shoulder!! The extractor does not pull the case back to the same conditions of the press/form die geometry!!!! This is the true beauty of the rimless bottleneck design itself in small arms firearms!!!

I need the opinion of a SMITH!!! Do the extractors over travel????
If so, the extractor would only limit or restrict the full case shoulder contact in NO GO GAUGE CHAMBERS or excessive bump back situations!!!!

Just curious on what you think occurs in a drop port action which has no ejector and only has an extractor. I have this type action and bump .0035". I do however jam (which would in turn seat the round against the bolt face) but in a jumping bullet situation it seems that the round would essentially be free floating in the chamber (a very small amount but still). Just curious your thoughts on this.

 

[Wild Bill IV]

Well, to a point. It is not holding it as securely or firmly or as ‘strongly’ as the shell holder.
Years ago a SHBF (shell holder bolt face) was in favor with some (me included) who had a shell holder welded to the bolt face.
To load you withdrew the bolt (no releases or buttons) bolt just pulls straight out. Insert your cartridge into the shell holder then slide the bolt with the cartridge held by the
Shell holder. It certainly was/is an interesting idea. I have the rifle to this day. 222. Had it built for me at the start of my benchrest shooting. 1975. How’d it shoot? Fantastic. However it was built by a highly skilled gunsmith named Ed Ferguson. Douglas barrel. Sleeved action ( also an older school line of thought. Does it shoot well today? Yup. Does this have to do with the SHBF? No clue.

The good old days!!!! The Rem 222 was the best balanced cartridge design then!!! They were deadly accurate!!! It died out with the cheap, once fired surplus of 223 military brass (a penny a piece average)!!!!! And, the introduction of the Rem BR didn't help the matter of the 222 losing popularity!!!!

 

[Wild Bill IV]

Just curious on what you think occurs in a drop port action which has no ejector and only has an extractor. I have this type action and bump .0035". I do however jam (which would in turn seat the round against the bolt face) but in a jumping bullet situation it seems that the round would essentially be free floating in the chamber (a very small amount but still). Just curious your thoughts on this.

For bench and long range range completion, its a great design!!! ONLY ON EXTRACTING A LIVE ROUND, THERE COULD BE A PROBLEM WITH BULLET, CASE SEPARATION, SPILLING POWDER INTO THE ACTION!!! Only on firing pin strike, will the case moves forward slightly (dependent of bullet/neck fit class)!!! But, the case would still be centered from the double live center aspect (jammed bullet centered in the rifling on one end, the firing pin protrusion on the primer on the other end)!!! Thus, great case to chamber geometry!!

If I personally shot competitive, that would be my choice and configuration!!! You can't get any better in geometry for bolt cycling!!!

However, I prefer minimal or zero bump!!!! And sometimes, I played with slight compressed bump!!!! The reasoning is, I experimented with both the Forster reamers and the old RCBS neck turning tool!!! Mind you, the experiment was with a Rem 700 BDL Varmint Special chambered in 7-08!!! The cheap once fire 308 Military brass (slightly more expensive sorted LC Match) and really expensive Federal 308 Nickel clad Match virgin brass had too little neck clearance in the rifle after necking down and seating bullets!!! I only had 0.0005 to 0.001 clearance!!! After safely full fire forming, the experiment proceeded!!! The results of the testing of the turned necks vs reamed necks showed a slight advantage of reaming from target results while maintain ZERO BUMP!!! Plus, the accuracy of the reamed Fed Nickel Match case loads were better than the reamed MIL Match cases!!!

The Engineering at Forster proved themself!!!! What better way to uniform neck thickness is there for fire formed vigrin brass that has not been reformed in the the form dies!!! The Forster reamers are purchased with the tolerance of 0.0010 to 0.0015 larger than bullet diameter!!!! Therefore, reaming the fire form necks creates minimal neck expansion!!!! MINIMAL NECK EXPANSION WAS A CONCEPT IN THOSE DAYS TOO!!! This is why, with the tuned 160 grain, SPBT, SGK bullets, I could get less than 0.1 MOA, 7 shot groups (ragged edged holes) with a factory rifle!!! Cold barrel fired shots from the bipod/squeeze bag prone position no less!!!

Plus, the processes of reaming is much faster with a non work harden Golden smooth surface (the sheared, not cut, chips were really thin small spiralling coils of brass)!!! And another plus!!!! The cases were also trimmed to length while completing the the reaming processes!!!! The added expense of uniforming the neck thickness by buying the reamer was around $16 since I possessed the Forster trim lathe!!!! The base of the bullet was just above the shoulder/body junction and was at 0.002 to 0.001 jump in the chamber (COAL was too long for the box magazine)!!! Some of the cases were fired more than a dozen times and I never had the doughnuts, nor did I anneal!!!!

My late father in law had the doughnut problem in his Rem 700 BDL Varmint Special chambered in 7-08!!! He outside turned his necked down MIL brass!!! He later had over pressure in his 243 too (doughnuts) where the MIL brass necks were turned!! But, he also annealed every other reload too!!!

 

[M-61]

If so, the extractor would only limit or restrict the full case shoulder contact in NO GO GAUGE CHAMBERS or excessive bump back situations!!!!

Generally in the instructions they tell you to remove the extractor and ejector

 

[Wild Bill IV]

Generally in the instructions they tell you to remove the extractor and ejector

I'm old engineer!!! If it's not broke, don't fix it!!! Also, if you can avoid tearing things apart by utilizing another concept, try it!!!

That's why I love Zero bump!!! You don't need to tear thing apart!!!!!

But, for common hunter/shooter, competitive rifle sports, and gunsmiths removal of the case clearing mechanisms can not be avoided!!!!

 

[M-61]

That's why I love Zero bump!!!

Me too. I’m strictly a bench shooter and haven’t shot competition in years. Always against myself unless someone happens by. I consider bumping strictly an operation to correct a case. Absolutely not a step in reloading. When I am done reloading my cartridges I cycle each one through the action. Granted the cartridges I shoot are extremely easy on the brass and the less I ‘work’ them the better. This is not a cost saving adventure for me to reload a case as many times as possible but I’m a nut for consistency. Small groups are my only concern.
As always, anything I write is my experience with my rifles. I guess I must add, this is about my bolt action rimless cartridges.

 

[Wild Bill IV]

Me too. I’m strictly a bench shooter and haven’t shot competavly in years. Always against myself unless someone happens by. I consider bumping strictly an operation to correct a case. Absolutely not a step in reloading. When I am done reloading my cartridges I cycle each one through the action. Granted the cartridges I shoot are extremely easy on the brass and the less I ‘work’ them the better. This is not a cost saving adventure for me to reload a case as many times as possible but I’m a nut for consistency. Small groups are my only concern.
As always, anything I write is my experience with my rifles. I guess I must add, this is about my bolt action rimless cartridges.

That is my philosophy too!!! Take advantage of the best case/chamber geometry and line that bullet up with the bore!!! Find the tuned loads that are the most accurate for that rifle!!! Then, the shooter can improve his/hers shooting skills!!! Thus, the shooter can not blame the rifle, or the reloads, for bad bullet placement!!!

Although, I blame the wind for an East or West flyer on the target at times!!! North and South stray holes are strictly shooters errors!!!! A heartbeat at the wrong time is bad on the target!!! I've learned to control the heart beat and have lowered my blood pressure to 125/85 at age 69!!! Low blood pressure and practicing getting heart beat rate down to near 40 reduces that heartbeat deflection on the target!!!

 

[rr1220]

the distance from case base to ogive of the bullet is not affected by how much you bump the shoulder as stated earlier, though the amount of bullet engaging case neck will change , this is not to say that changing shoulder bump wont affect the performance of the loaded round and this can only be decided by testing. JMO

 

[ELR LVR]

I was wondering why one might want to push the shoulder back any further than light contact, though perhaps using it as a trick to get out of the doughnut with a certain bullet is conceivable. The tradeoff being, of course, more case stretch. I may be the odd man out on this one, but I don't necessarily buy into the bullet remaining unaffected in relation to the bore when the shoulder is moved back, while the bullet is seated the same. The slop introduced between shoulder and chamber provides additional forward and rearward slop of the entire cartridge, bullet included, unless the bullet is jammed. That translates to minute differences in muzzle exit timing? In the end, the target says what is working best - but....

Just offering my experience on this
being that brass is soft compared to the action
I had it in mind to set the shoulder back perfectly to the chamber
IE: you could feel slight resistance closing the bolt on a newly sized piece of brass
------------------------
There were times where occasionally one piece of brass would be harder to close the bolt on than others
I decided while providing good consistency in what you spoke of
maybe that wasn't so good for the bolt lugs in the long run.
I prefer now to be easily able to close the bolt when chambering a piece of brass
so set the shoulder back somewhere in the area of .001" - .002"
(if it is .002" on a newly set up sizing die... I may decide to fool with it later)
any more than that and I would say its more for ensuring a hunting gun can cycle ammo if dirty

 

[M-61]

though perhaps using it as a trick to get out of the doughnut with a certain bullet is conceivable.

IMO an absolutely horrible way to attempt to solve a doughnut situation.

 

[dellet]

There are some things with load tuning that may never be fully understood, they just work. Seating depth, jump/jam may be one of those. It’s still done by trial and error, but with enough people reporting, trends emerge for bullet and cartridge combinations. Most of these debates have been going on since cartridge cases entered the competition shooting world.

Some of the top shooters 125 years ago breech seated their bullets and used a single case for an entire match. Being anal about the process and keeping things consistent are nothing new.
Using a single case and never resizing insured a perfectly fire formed case. Placing an index mark on the case head insured it was in the same place in the chamber every time. If it was a shouldered case it no longer had any real headspace and due to loads being on the lower end of the pressure curve, extraction generally wasn’t a problem. The only work to the case between firings was to flare the case neck to seal the chamber to prevent cases from collapsing.

All bullets were custom made to the chamber and bore. Moulds often made by the gunsmith who made the rifle if it was custom. Again often the mould was marked so that it created a mark on the bullet so that it could be indexed to the chamber.

The bullet chambers independently so as to have a perfect start down the barrel. The distance in front of the case was controlled with a special seating tool and was adjustable, because seated depth changed group size.

There were arguments as to whether the bullet should be seated from the breech or the muzzle. If you seated from the muzzle, the base was more uniform, the lead was pushed forward and the base remained more square, instead of having the fins created pushing the bullet the other direction.

About the only difference between then and now are the arguments over neck tension. All the rest is the same.

 

[M-61]

There were times where occasionally one piece of brass would be harder to close the bolt on than others

Yes. Drove me nuts because I couldn’t understand how this would occasionally happen.
I’d take that stubborn case and resize it and when I got it in the die I’d let it sit there for maybe 5-10 seconds. And then it fit in the chamber and the bolt closed the way I liked. This was not a one time occurrence. When I have this situation every time I let the case dwell in the die for a bit.. no problem.
I realized there was no reason on earth to operate the ram at the speed I was doing. I’m never in a rush and from that day forward I let every case sit for a bit in the die. My guess is? Springback. Each case is different in some manner from the next. Maybe some brass reacts just a small amount differently than the next. Consequently in my reloading all brass sits in the die a short time instead of my arm pumping like a connecting rod.
Of course as all I write, it’s my experience, in my rifle, with my brass.

 

[ELR LVR]

Yes. Drove me nuts because I couldn’t understand how this would occasionally happen.
I’d take that stubborn case and resize it and when I got it in the die I’d let it sit there for maybe 5-10 seconds. And then it fit in the chamber and the bolt closed the way I liked. This was not a one time occurrence. When I have this situation every time I let the case dwell in the die for a bit.. no problem.
I realized there was no reason on earth to operate the ram at the speed I was doing. I’m never in a rush and from that day forward I let every case sit for a bit in the die. My guess is? Springback. Each case is different in some manner from the next. Maybe some brass reacts just a small amount differently than the next. Consequently in my reloading all brass sits in the die a short time instead of my arm pumping like a connecting rod.
Of course as all I write, it’s my experience, in my rifle, with my brass.

Haha, same here, cycling the press too quickly
I learned about "Dwell time" about 3 years ago
it is not really something we give much thought to, until we actually think about it
makes perfect sense, it takes "time" for all things to happen
(In this case, brass flow)

 

[JFrank]

Each case is different in some manner from the next. Maybe some brass reacts just a small amount differently than the next.

All the more reason to set a die to size enough to chamber every case freely. I don’t concern myself too much with dwell time although I can’t see a down side, as a side note .003 set back won’t hurt a thing.

 

[M-61]

All the more reason to set a die to size enough to chamber every case freely. I don’t concern myself too much with dwell time although I can’t see a down side, as a side note .003 set back won’t hurt a thing.

As long as you see a reason to work the brass. .003 + headspace, back and forth.
Purposes?
I’m talking only about target shooting with a bolt action and rimless cartridges.