head space and accuracy

[BoydAllen]

F Class has become benchrest shot from the ground. The rifles have become very sophisticated, as have the reloading methods. I wrote to the OPs situation.

 

[CatShooter]

..... I always keep my brass bumped to a point to where my bolt (with firing pin removed) will fall half way down before meeting light resistance. This way my case will always be pushed back against the bolt face but not offer enough resistance to upset the rifle on the rest when closing the bolt.
...

I read of this approach of removing the firing pin a lot. One thing puzzles me, what about the ejector plunger? Does that need to be removed too?

Thanks

JCS

The ejector and spring should be removed - that spring is a pushy little booger, and will keep the bolt handle from dropping of it's own weight.

 

[jcampbellsmith]

..... I always keep my brass bumped to a point to where my bolt (with firing pin removed) will fall half way down before meeting light resistance. This way my case will always be pushed back against the bolt face but not offer enough resistance to upset the rifle on the rest when closing the bolt.
...

I read of this approach of removing the firing pin a lot. One thing puzzles me, what about the ejector plunger? Does that need to be removed too?

Thanks

JCS

The ejector and spring should be removed - that spring is a pushy little booger, and will keep the bolt handle from dropping of it's own weight.

Thanks very much. JCS

 

[bigedp51]

So what happens when your bolt closes with resistance with zero head clearance with a case that is warped and banana shaped and bullet is forced out of alignment with the bore.

And how many brench rest shooters buy 100 cases looking for 10 to 15 perfect cases before starting their case prep work.

This is where the .001 to .002 head clearance/shoulder bump gives you a little wiggle room to eliminate any case misalignment with the bore. Meaning getting to use all 100 case you bought and not looking for the "few" perfect cases in that batch.

I'm not knocking bench rest shooters, "BUT" how many shooters here have custom made rifles with custom form fitting chambers using "perfectly selected" cases.

The OP asked what does headspace have to do with accuracy and this covers many type rifles and the quality of your brass. And you will not find any AR15 competitive shooters using ammo with zero head clearance in a National Match.

 

[mikecr]

Banana development seems self induced and self perpetuated to me.
That is, thickness variance not culled out + heavy FL sizing = heavy FL sizing(rat turd in a violin case) to resolve banana chambering,, repeat..
I guess I'm one of the few, the proud, who does chamber & reload with a plan that never exceeds 1thou TIR off bullets. The plan is not directly pointed at accuracy, but consistent case life(same H20cap -forever), and I'm also hoping to compete in a 'Reloading World Championship' some day..

But w/regard to standard headspace settings(~1-2thou), I've never heard an accuracy claim with it other than very excess being detrimental. Especially when best bullet seating is off but near the lands.

 

[CatShooter]

Jon I believe Donovan is correct on this because in the process of bumping the shoulder, the body also needs to be resized at least somewhat or the brass would be pushed outward making the case difficult to chamber. I learned it the hard way.

The Forster Bump die does NOT support, or even touch the case walls - it only touches the shoulder (and neck if there is a bushing installed).

 

[LHSmith]

The ejector and spring should be removed - that spring is a pushy little booger, and will keep the bolt handle from dropping of it's own weight.

Well I just tried that theory on some custom and factory actions , and that isn't the case, the handle drops the same whether on a properly sized case or an empty chamber with the pushy booger.

 

[Tim Singleton]

The ejector and spring should be removed - that spring is a pushy little booger, and will keep the bolt handle from dropping of it's own weight.

Well I just tried that theory on some custom and factory actions , and that isn't the case, the handle drops the same whether on a properly sized case or an empty chamber with the pushy booger.

This is my experience as well. The ejector doesn't play into things for me

 

[LHSmith]

And how many brench rest shooters buy 100 cases looking for 10 to 15 perfect cases before starting their case prep work.

This is where the .001 to .002 head clearance/shoulder bump gives you a little wiggle room to eliminate any case misalignment with the bore. Meaning getting to use all 100 case you bought and not looking for the "few" perfect cases in that batch.

I'm not knocking bench rest shooters, "BUT" how many shooters here have custom made rifles with custom form fitting chambers using "perfectly selected" cases.

Your responses show you are very much misinformed about Benchrest Shooting load techniques - and we are talking Registered Match shooting, Benchrest with a capital "B". I know of no one who shoots for zero H/S, nor anyone who sorts through a box of 100 cases to get 15 usable.
F-Class is commonly referred to as belly Benchrest because much of the equipment used- actions, barrels, optics, and rest are the same. Input from Benchrest shooters most certainly is valid to this thread.

 

[LHSmith]

Mr. Boyd Allen

And judging from what Mr. Salazar and Mr. Thomas of Team Lapua USA said they do not share the partial sizing and zero head clearance of the bench rest fraternity and prefer the rat turd in the violin case method for better accuracy and reliability.

Another assumption that's incorrect. I don't know of anyone successful in Benchrest comp ever advocated partial sizing. Neck sizing in the early years, yes.

 

[LHSmith]

I'm not knocking bench rest shooters, "BUT" how many shooters here have custom made rifles with custom form fitting chambers using "perfectly selected" cases.

Who else better to determine what reloading methods and techniques work or don't work. We have the equipment and condition reading skills that can give trusted results because we start experimenting only after we have gained confidence in a rifle/scope/rest and can use that as a baseline.

 

[bigedp51]

[size=12pt]Your responses show you are very much misinformed about Benchrest Shooting load techniques - and we are talking Registered Match shooting, Benchrest with a capital "B".
I know of no one who shoots for zero H/S, nor anyone who sorts through a box of 100 cases to get 15 usable.
F-Class is commonly referred to as belly Benchrest because much of the equipment used- actions, barrels, optics, and rest are the same. Input from Benchrest shooters most certainly is valid to this thread.

Apparently you have not followed this posting or know anything about Tony Boyer and his "ZERO" head clearance method and felt resistance the last half of bolt closing.

The following is from his book that "YOU" as the misinformed should read since you missed it the first time.

Quote

The techniques in this book have been learned and perfected over decades of competition and are sure to benefit benchrest shooters, handloaders and hunters. Become a better shooter and gain much more from any aspect of the shooting sports. ABOUT THE AUTHOR:Tony Boyer is a living legend among benchrest shooters. He has competed against the world's top accuracy shooters for decades, winning 12 World Championships and earning the Shooter of the Year designation 11 times. Tony Boyer has been inducted into the prestigious United States Benchrest Hall of fame, and holds more points than any other competitor.

As you can see below the bolt face of Tony Boyer's rifle is resting on the rear of the case and the bolt is only half closed meaning "ZERO" head clearance and "ZERO" head space. :

In closing LHSmith I will stick with "The Rifleman's Journal" website by Germán A. Salazar and Kevin Thomas of Team Lapua USA. And both of these gentlemen quoted the late Jim Hull of Serra bullets "I get the best accuracy when the cartridge fits the chamber like a rat turd in a violin case" which I take to mean the case having approximately .002 shoulder bump and head clearance.

And thank you for your misinformed tunnel vision postings above about headspace.

 

[LHSmith]

As you can see below the bolt face of Tony Boyer's rifle is resting on the rear of the case and the bolt is only half closed meaning "ZERO" head clearance and "ZERO" head space. :

Where did you get the idea it was Zero H/S.....you don't have closed quotes, so I don't know if that is in the book or your assumption.
A fit that close (essentially a line-to line fit) would leave absolutely NO room for error and would completely destroy T.B.'s ability to "run 'em" when HIS condition comes around due to disturbing his rhythm and the bags. There's many vids of TB on You-tube, watch and you may learn something new.
Myself, I was taught to size till the bolt drops which is ~.002" H/S , but who can argue TB's techniques.
From my experience, what is described in the book gives .001" H/S as measured with the appropriate H/S gauge, not zero.

 

[bigedp51]

Another wrong assumption , no where does the book claim this method yields zero H/S...... a fit that close (essentially a line-to line fit) would leave absolutely NO room for error and would completely destroy T.B.'s ability to "run 'em" when HIS condition comes around due to disturbing the bags. There's many vids of TB on You-tube, watch and you may learn something new.
Myself, I was taught to size till the bolt drops which is ~.002" H/S , but who can argue TB's techniques.

Quote from photo above in Tony Boyer's book.

“Checking headspace in rifle (firing pin assembly removed)"

Quote above photo.

"This resistance is caused by pushing the shoulder against the chamber. If the bolt handle falls all the way down you have sized the case too much and need to increase the shims and try again on a second case. If it takes too much effort to close the bolt, then you have not yet sized the case enough and need to take another .001 off and try again."

I know of no one who shoots for zero H/S, nor anyone who sorts through a box of 100 cases to get 15 usable.

Does "misinformed" mean not reading all the free information on the main webpage of Accurate Shooter, like sorting and prepping cases.

Complete Precision Case Prep
http://www.accurateshooter.com/technical-articles/reloading/complete-precision-case-prep/

Step 8

Weigh the cases and separate by lots not greater than one grain in weight difference or about 0.5 percent.

Reason: We know that the outside dimension of each case is the same as all other cases. A weight difference between cases means that the interior is different in volume or the head is different in size. A case that is heavier than the others indicates less interior volume, and the pressure will be greater than for those cases that weigh less. Differential pressure results in variations in velocity and larger long-range groups.
Method: Weigh each case on a reasonably accurate scale such as this RCBS electronic scale. Pay close attention to ensure that the scale is reading accurately.

So again thank you for your misinformation you posted above, and if you find other methods of sizing for the other venues of shooting offensive, then you should spend all your time at Benchrest Central and not get upset.

And for your information I have received more than a few PM about "Pompous Benchrest shooters" in this posting.

So again try and see the big picture on headspace and the different type venues of the shooting sport, and seriously try and look past your one sided tunnel vision.

 

[BoydAllen]

Boyer's book was written for benchrest shooters, not as a general reloading manual, and while he is the shooter that has the most hall of fame points, by a wide margin, he is not the only one that wins matches consistently. If you want to see how a lot of winning benchrest shooting is done, take a look at this video of Charles Huckaba shooting a dot at 200 yards at the Worlds Benchrest Championship in Sydney Australia. https://www.youtube.com/watch?v=2Bjs96PsbXI
Note the smooth and speedy gun handling, and lack of disturbance of the rifle on its bags. This cannot be accomplished with ammunition that is a tight fit in the chamber. There has to be some clearance, but certainly not the rat turn in the violin case variety. The rifle's stock; the joystick front rest; super slick bag material; right bolt, left port, right eject action, to facilitate running a group when the opportunity presents it, are all current state of the art in benchrest. If one is going to make statements about how benchrest is done, it is probably a good idea to have seen some up to date examples. Successful shooters do not,by any means do everything the same, but there are some significant trends that are one might wish to be aware of.

 

[bigedp51]

Boyer's book was written for benchrest shooters, not as a general reloading manual, and while he is the shooter that has the most hall of fame points, by a wide margin, he is not the only one that wins matches consistently. If you want to see how a lot of winning benchrest shooting is done, take a look at this video of Charles Huckaba shooting a dot at 200 yards at the Worlds Benchrest Championship in Sydney Australia. https://www.youtube.com/watch?v=2Bjs96PsbXI
Note the smooth and speedy gun handling, and lack of disturbance of the rifle on its bags. This cannot be accomplished with ammunition that is a tight fit in the chamber. There has to be some clearance, but certainly not the rat turn in the violin case variety. The rifle's stock; the joystick front rest; super slick bag material; right bolt, left port, right eject action, to facilitate running a group when the opportunity presents it, are all current state of the art in benchrest. If one is going to make statements about how benchrest is done, it is probably a good idea to have seen some up to date examples. Successful shooters do not,by any means do everything the same, but there are some significant trends that are one might wish to be aware of.

Are you saying you know more than Germán A. Salazar and Kevin Thomas of Team Lapua USA.

And AGAIN this website is NOT "Benchrest Central" and this website covers all venues of shooting. (Tunnel vision strikes again)

 

[LHSmith]

As usual you mis-quote.....again where does it claim ZERO, nadda H/S? What they describe will yield .001" H/S.
Another wrong assumption is that point blank BR competitors weigh cases...most DO NOT. Read Tony's Book and re-read if at first you don't comprehend the info. If you would actually read posts here on Accurate Shooter, you would know that almost all Long Range BENCHREST Competitors weigh and segregate cases.

 

[Tim Singleton]

I don't even weigh powder much less cases

 

[bigedp51]

As usual you mis-quote.....again where does it claim ZERO, nadda H/S? What they describe will yield .001" H/S.
Another wrong assumption is that point blank BR competitors weigh cases...most DO NOT. Read Tony's Book and re-read if at first you don't comprehend the info. If you would actually read posts here on Accurate Shooter, you would know that almost all Long Range BENCHREST Competitors weigh and segregate cases.

More BS, if the bolt face is pushing the cartridge case against the shoulder of the chamber as described by Boyer in the last half of bolt downward movement you have zero head clearance.

And I'm not misquoting you I copied you word for word, and your the one bobbing and weaving around your own quotes. :

 

[BoydAllen]

I do not believe that either German or Kevin shoot benchrest, so yes, since I have shot competitive benchrest, and have written professionally reporting on equipment that is use in that sport, I believe that it is very likely that I know more about the specifics relating to the sport of short range CF group competition than they do, and that they know a lot more about those areas of competition that they have frequented than I. One thing that needs to be understood, the kind of shooting that is done at Camp Perry has very different realities than benchrest. Within each, their truths are valid, but there may be areas where there is significant difference. It has been my pleasure to know accomplished shooters in both types of competition, high masters who have won national matches in across the course and prone shooting, and several NBRSA record holders in short range benchrest, as well as a number of the very top gunsmiths in the latter field, all of which I have enjoyed asking a lot of questions of about what they do, and how they do it. It has been a real pleasure.