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Old January 25, 2013, 07:35 AM   #1
UncleGrumpy
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How accurate should my O frame press be?

Hi,

I have been reloading for a few years now, I have been using my fathers O frame press bought in the early 70's. It has not reloaded more than 750 rounds in its entire life.

Last month I started using a Hornady comparator on my mityoyo caliper to measure loading length and realized I was getting upto +/- 3 thou on the bullet seating depth. It was about 50-50 between good and those that varied.

After trying different things including two different calibers, forster & rcbs dies and hornady, berger and sierra projectiles it remained around the same variation.

After scratching my head for a few days, I investigated some more and found that when then press handle was fully down and a side pressure was applied the ram was moving further up and therefore causing the problem.

I reseated the longer cases from the other night but this time made sure that a sideways force was also applied then these matched the good 50% within .0005".

So, my questions are,

Is this issue what I should be expecting in a O frame press that has not had much use?

Am I expecting bench rest quality and need to by something better?

cheers
Jeff
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Old January 25, 2013, 08:23 AM   #2
Bart B.
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Bullet seating depth as measured to some point on their ogive will all have a couple thousandths spread. That's 'cause the ogives don't all have the exact same shape; even being formed by a single pointing die in production. Sierra Bullets acknowledges this happens but they've not seen any issues with it shooting 1/4 MOA test groups with such match bullets at 200 yards.

Don't get concerned about it. There's also a few thousandths spread from the case shoulder to case head and the case shoulder, when against the chamber shoulder when the round's fired, also affects how far the bullet jumps to the rifling.

That small variable may make a 1" difference in your group sizes at 1500 (one thousand five hundred) yards; not much at all.

Most any O frame press will load benchrest quality ammo. The critical thing about them is being able to not spring very much when full length sizing cases so case headspace spread's small. Using the right case lube and putting the same amount on cases helps. But they do have to be used the same way for each case.
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Last edited by Bart B.; January 25, 2013 at 08:28 AM.
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Old January 25, 2013, 09:32 AM   #3
Hummer70
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Bart B is exactly correct. There are gages you can get from Sinclair International where you can segregate bullets by measuring from ogive to base of bullet but proving it works is gonna be one of those things that will cause you to lose hair.
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Old January 25, 2013, 11:32 AM   #4
F. Guffey
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Uncle Grumpy, ‘O’ type press “I have been reloading for a few years now, I have been using my fathers O frame press bought in the early 70' “,

As you can see, without knowing the brand of the ‘Old ?’ O frame press it is a guess, in the beginning before Internet reloading a distinction was made between ‘CAM OVER’ and cram, jam or lock up presses, In the beginning RCBS presses ‘cammed’ over, now they jam over, meaning they jam/cram up before the ram reaches the top (top dead center), a cam over presses reaches TDC and starts back down, the amount of cam over can be measured by a few reloaders with a feeler gage, most deny it happens. In the old days the die was adjusted to the shell holder on a cam over press, the cam over amount, in the old days, was called ‘Bump’. Bump, today, means anytime the shoulder of the sizing die contact the shoulder of the case it bumped. I suppose ad in bumped into the shoulder like some kind of accident. To find ‘Bump’ before the Internet, read RCBS die instructions from 1960 +/- a few years.

Back to RCBS and bind-up/lock-up, the linkage gets tangled up at the bottom when the ram is raised to the maximum, the linkage hits the bottom of the ram, when the linkage hits the ram the ram is kicked forward at the bottom and back at the top. Do not panic, a compulsive giggler posted the effect on YouTube, there was no die and no case, meaning? The case in the die prevents the kick out at the bottom, after the posting the ‘usuals’ posted the claim blaming cheap manufacturing on China and or other countries.

then there is the problem with being able to determine if your press is a ‘cam-over press’, there are not many Herter presses I do not have, all my Herters are cam over presses, two are guaranteed not to flex, with common sense the amount of cam over is a designed limiter to bump.

Back in the old days I listened to a lot of stuff that did not make sense, when sizing and or forming I scribed lines at the case body shoulder juncture, scribing the line convinced me the shoulder of the case did not move, the line did not move, the shoulder was being erases and formed someplace else, I also found by scribing the location of the case body shoulder cases were not stretching between the case head and case body, it was interesting to me part of the shoulder of the case became part of the case body and part of the neck became part of the shoulder, back to stretch and insipient case head separation, insipient case head separation comes from bad habits, not firing the case. Anyhow, I became a fan of knowing the length of the chamber first then sizing cases by length to off set the length of the chamber, I became a fan of cutting down on all that case travel.

Receivers, like presses have different designs, one rule does not apply to all receivers, one rule does not apply to all presses. Again, What brand of press are you using?

F. Guffey
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Old January 25, 2013, 07:46 PM   #5
wncchester
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Your press isn't going to be "accurate", it's just a tool to push cases into and draw them back out so the ram slop you cite is trivial and meaningless. It's dies, components, load development and user skill that produces high quality ammo. When you have made up maybe 2-4 thousand rounds while experimenting with your methods and loads you MIGHT be ready to go to the high grade dies by Forster or Redding. Until then standard dies will do all you'll need - after all, they're all pretty good!

BR shooters don't normally use threaded dies or presses. They use 'hand' dies and arbor presses and you can't find a looser press than that!
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Old January 25, 2013, 10:03 PM   #6
Hammerhead
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Quote:
Bullet seating depth as measured to some point on their ogive will all have a couple thousandths spread. That's 'cause the ogives don't all have the exact same shape; even being formed by a single pointing die in production.
This.
+/- .003" is very good.
The only time I've done better is with a flat nosed bullet seater and SWC's.
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Old January 26, 2013, 12:33 AM   #7
UncleGrumpy
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Thanks for your help you have all made me think. I believe I may have solved the problem regarding the slop in the press and I believe the problem is me! (go figure)

It is a cam over press in which you are supposed to have the sizing die down tight on the ram and then lift the handle a little screw the die a little more to make sure the slop is gone.

I however turn the die down tight, then unscrew it 1/8th so that I am neck sizing with a full length die. Therefore I am leaving the slop in the presses action.

I also do something similar with the seating dies under the assumption that all dies have a crimping collar and you need to back off the die when using projectiles without the cannelure.

However the last two sets of dies I bought have been forster dies and the seating die instruction says to unscrew the die 1 turn so the spring is not totally compressed. This then is not touching the ram at all.

My procedure I follow has come from reading several books on how to reload from the 70-80's.

So, it seems that either need a few neck size dies for the old press or find a new style press that can handle the old with the new style dies I have.

cheers
Jeff
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Old January 26, 2013, 07:47 AM   #8
Bart B.
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UncleGrumpy procedure:
Quote:
I however turn the die down tight, then unscrew it 1/8th so that I am neck sizing with a full length die. Therefore I am leaving the slop in the presses action.
1/8 turn to move the full length sizing die up changes its height about .009 inch. I doubt that lets one neck size a bottleneck case withthat die. Such procedures with such dies typically ends up sizing the fired case body down a tiny bit which moves the shoulder forward a tiny bit and sizes part of the neck. Which, in the reloading industry, is called "partial neck sizing" with a full length sizing die.

More often than not, when such a sized case is chambered, it binds up a little as the case head to shoulder distance is now too long for the chamber. This causes the bolt to not close back exactly the same for each shot and accuracy suffers.

Reloaders are better off using a case headspace gauge such as the RCBS Precision Mic to measure fired case headspace then adjust the die so it sets the fired case shoulders back no more than a couple thousandths. Doing this usually lets the die's bottom come within a couple thousandths of touching the shell holder. If one of Redding's Competition shell holders of the right height, then adjust the die so when the press cams over a tiny bit, the case is full length sized perfectly and best accuracy is at hand as well as long case life.

Unclenick's great set of labels shown below can be put on sizing die lock rings so one can see exactly how much change in position a given adjustment will make:


Print them so the inside diameter's 7/8th inch. Use a sheet of sticky-back label paper so they can be easily put on lock rings.

wncchester, benchresters have recently started using standard press mounted full length sizing dies with bushings for their specific case neck diameters. The dies set in the press to set fired case shoulders back and case body diameters down a thousandth or a bit more. This method produces more accurate ammo than neck only sizing with arbors pusing neck only dies down on case necks.
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Last edited by Bart B.; January 26, 2013 at 08:02 AM.
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Old January 26, 2013, 11:20 PM   #9
UncleGrumpy
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Thanks Bart B. After reading your post I am starting to understand a little more clearly.

The intention of my current practice of partial neck sizing is to keep the case sized as close to the chamber as possible. But it's using an idea that introduces it own problems such as the loose press when not jammed up hard.

I have just finished looking at the Rcbs Precion Mic and the Redding shell holders and imediately see the advantages for case sizing.

As far as the crimping seating die (ie .303 British) that I do not crimp the projectiles, it takes 3/4 turn before the crimp stops touching the case, this works out at 0.054" using those useful diagrams. The Redding shell holders only go to 0.010" is there a solution to this?

Cheers
Jeff
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Old January 27, 2013, 12:17 AM   #10
F. Guffey
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Partial neck sizing with the versatile full length sizer: Back the die off top prevent the shoulder of the die from contacting the shoulder of the case. .050 thousands gap between the bottom of the die and top of shell holder will prevent the die from contacting the the case body and or case shoulder. I combine neck sizing with minimum case body sizing, I determine the difference in length of the chamber from the bolt face to the shoulder of the chamber then size the case to off set the difference in length between the chamber and case.



The full length sizer die is a versatile die, by adjusting the case up or the die off the shell holder I size cases in 26 different length from short chamber by .012"- to .014"+ between the head of the case and shoulder.



"As far as the crimping seating die (ie .303 British) that I do not crimp the projectiles, it takes 3/4 turn before the crimp stops touching the case, this works out at 0.054" using those useful diagrams. The Redding shell holders only go to 0.010" is there a solution to this?"



Backing the seating die off to prevent crimping is necessary, if you acquired a feeler gage for measuring gaps between the die and shell holder you could make repeated adjustments. Most secure the lock ring to the die, I don't, I secure the die to the press with the lock ring meaning I adjust my dies every time I use them. You are correct, Redding Competition shell holders are acquired when used with the seating die. redding Competition shell holders are nice, not necessary, neither is grinding the shell holder or base of the die, and no, the redding Shell holders were not designed to be an alternative to grinding one or the other.



Back to sizing the 303 British, backing the full length sizer to neck size and prevent the die from contacting the case body and shoulder will decrease case stretch. It is possible for some reloaders to determine the length of the chamber from the bolt face to the shoulder/datum then adjust the die to prevent excessive sizing. Again, nothing beats the feeler gage, first I determine the length of the chamber.



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Old January 27, 2013, 12:25 AM   #11
F. Guffey
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Outside of reloading there are many ways to remove slack and play in holes and bores and on shafts, still I do not know what press you are using.



If the slack in caused by the ram loose in the bore the hole can be knurled then reamed or honed back to minimum.



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Old January 27, 2013, 01:29 PM   #12
Bart B.
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UncleGrumpy comments; remarks:
Quote:
The intention of my current practice of partial neck sizing is to keep the case sized as close to the chamber as possible. But it's using an idea that introduces it own problems such as the loose press when not jammed up hard.
You'll get more accurate ammo if you full length size the case and set the fired case shoulder back a bit. That help center the shoulder on the case neck. And it improves feeding and extraction reliability. Loaded rounds don't need to be a "perfect" fit to the chamber anyway as far as diameters are concerned. Only the length from head to headspace point (rim thickness on a .303 Brit) and head to shoulder so there's not too much space between the case shoulder and chamber shoulder for rimmed bottleneck cases. Seating the bullet out to just barely toucn the lands when chambered is a good thing to do for the .303 if best accuracy's the objective.

Quote:
I have just finished looking at the Rcbs Precion Mic and the Redding shell holders and imediately see the advantages for case sizing.
They indeed are great things.

Quote:
As far as the crimping seating die (ie .303 British) that I do not crimp the projectiles, it takes 3/4 turn before the crimp stops touching the case, this works out at 0.054" using those useful diagrams. The Redding shell holders only go to 0.010" is there a solution to this?.
You don't need those higher shell holders to crimp case mouths. They're intended to be used only with full length sizing dies and are optional with seating dies. But I don't think you'll need to crimp case mouths on bullets; that only adds another variable to the round and rarely is needed at all.
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Old January 27, 2013, 04:16 PM   #13
wncchester
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"It is a cam over press in which you are supposed to have the sizing die down tight on the ram and then lift the handle a little screw the die a little more to make sure the slop is gone."

The latteral slop in your ram isn't "removed" or taken care of with 'cam over'. That slop you have actually allows those tapered round cases to self center in that big round hole in the die. High quality (costly) rifle chambering reamers are held in lathe "floating" reamer holders so the reamers can self align with the bore. Meaning we can't MAKE such things go straight but we sure can prevent them from going straight. Unless the alignments of ram-shell holder-case-die-press hole are all perfect (and that is VERY rare!) we actually benefit from less than ridgid ram alignment.
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Old January 27, 2013, 08:15 PM   #14
Bart B.
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UncleGrumpy, regarding your comment:
Quote:
It is a cam over press in which you are supposed to have the sizing die down tight on the ram and then lift the handle a little screw the die a little more to make sure the slop is gone.
You're not supposed to have the die stopping the shell holder's upward movement and the linkage camming over unless you want to full length size a fired case back to the specs the die maker thinks is best. More often than not, that's way too much sizing. The case shoulder's gonna be set back too far every time that case is full length sized and that'll soon lead to incipient head separation. Standard full length sizing dies are made that way so fired in them will fit all rifle chambers made at minimum SAAMI spec and perhaps a bit shorter.

Best thing to do for safety and long case life is to back the die up a few thousandths such that the fired case shoulder's set back no more than 2 thousandths. But you'll need a case headspace gauge to measure the case headspace; once before it's full length sized and again afterwords. The difference is how much the case headspace has shortened.

This is why Redding makes those shell holders with different heights in .002" steps above the standard .125". Use the one that lets the press linkage cam over slightly on the die but not set the fired case shoulder back too far.

There's enough slop in the shell holder's dimensions to let a case well align with the die's center anyway.
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