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View Full Version : Case Length Shortening Myth Or Reality



BOOM BOOM
05-23-2005, 01:05 AM
HI,
I just got through measuring a batch of 50 7MM MAG. brass I fired this sat. w/ cast squib loads. had to trim 2 but the rest had not changed at all,Over the yrs. I have had to trim many 7MM/06 & some 7MM MAG. that I had shot w/ cast.
So the old adage that shooting cast shortens cases my be a myth.
Or it may be only occuring under certin special conditions occasionly.
I have had to trim brass every once in a while.
I've shot alot of stright walled cases .38,.357, .44 special, 44 mag., & .444 marlin and never noticed any shortening w/ cast bullets.
So what do you guys think?

Bass Ackward
05-23-2005, 06:33 AM
HI,
So the old adage that shooting cast shortens cases my be a myth.
Or it may be only occuring under certin special conditions occasionly.
So what do you guys think?

Boomer,

Please don't confuse your cases getting shorter with headspace issues. Cases reduce in size during squib loads in cast because the blow of the firing pin drives the case forward, thus setting back the shoulder. This is corrected if the pressure of the load is capable of expanding the brass back out to fill the chamber and you never notice it. But this is only with rimless designs because belted and rimmed actually headspace there.

That is another reason I favor pistol primers in my shooting. They offer less resistance to the blow of the firing pin.

One cartridge that you hear about having problems all the time is the 35 Whelen because it has very little shoulder to fight back against the firing pin. I have some 35 Whelen brass around that has been shot 20 times at nothing more than 34,000 psi and they show no signs of reduced headspace. And I full length resize religously.

Now as far as your brass lengthening, dies will do this. That is why they always advised cleaning and lubing the inside of the case neck. But they will actually increase in length during the sizing down stroke. RCBS's new X-die series has a hole in the body of the die that they claim will prevent this.

So under certain conditions is applicable here, as in most other areas of shooting.

joeb33050
05-23-2005, 07:12 AM
Boomer,

Please don't confuse your cases getting shorter with headspace issues. Cases reduce in size during squib loads in cast because the blow of the firing pin drives the case forward, thus setting back the shoulder. This is corrected if the pressure of the load is capable of expanding the brass back out to fill the chamber and you never notice it. But this is only with rimless designs because belted and rimmed actually headspace there.

Cases that headspace on the shoulder sometimes develop excess headspace when used with light loads. About 10-12 grains of Unique in a 30/06 has increased headspace pretty reliably. I measure headspace increase with one or more pieces of paper and/or cellophane/saran wrap on the bolt face. I've heard the firing pin explanation above, and heard alternatively that the primer backs out of the case, acts as a piston against the bolt face, pushes the case forward and increases headspace.
I've tested the firing pin theory with an empty oily case and primers deadened with oil. Firing 20 times gave NO increase in headspace. This is an easy test to do. The firing pin theory doesn't hold water.
I don't know how to test the "primer backs out of the case" theory.
Whatever the reason or mechanism, headspace of the cases does increase=shoulder does move back when firing light loads.
This is minimized in rifles with claw type mauser type springfield type extractors; at its worst with Remington type extractors.
I don't shoot real light loads in guns that headspace on the shoulder, check headspace of cases now and then, keep cases clean = not oily which helps, like to shoot cast in guns that headspace on the rim or belt.
joe b.

Willbird
05-23-2005, 09:09 AM
Well another interesting thing to think about, if the primer acts like a piston (makes sense to me) then is this going on all the time, and only stays that way when the pressure is not high enough to reverse the process ? IE blow the case back out to fit the chamber again ?

It would be interesting to try firing a primer in a pocket that has no hole, Phil Sharp had a picture of a ctg. that was mfg. that way by mistake, it shortened the case up quite a bit when the primer fired with no place for the energy to easily escape.

Bill

JDL
05-23-2005, 09:30 AM
Primers will back out of a case. John Garand's first semi auto was based on this principal but, the military started staking the primers in to prevent the machine guns from jamming because of this. Now, if only the slight movement of about .031" is sufficient to operate the mechanism of a semi-auto, doesn't it seem likely that applied in the opposite direction, it will have enough force to shorten the case? -JDL

StarMetal
05-23-2005, 10:02 AM
No way no how do I buy that .031 will operate the mechanism of semi auto. How about substantiating some proof that Garands first M1 rifle operated on the primer backing out.

Bass

You're Wrong, the firing pin's blow doesn't shorten the brass. First a primer isn't seated all the way all the time till it's cup is up against the case. Second that cup is softer then the case. Third most firing pins don't have enough force to pound that primer in all the way and still size down the case. Those that do are very far inbetween and if they all did we'd have pierced primers galore.


I just disagree with some of the theories here, need some explanations to help me swallow them.

Joe

StarMetal
05-23-2005, 10:13 AM
Well you don't have to prove the primer blowback first Garand expriments, I have been digging into it and THAT is true. Amazing, also amazing that it didn't work well too.

Joe

NVcurmudgeon
05-23-2005, 10:49 AM
I don't know about the exact mechanical cause of headspace shortening in rimless cases fired with low pressure loads. What I do know, because it has happened often to me, is that .35 Whelen cases will shorten headspace to the point of some of the cases having misfires after ten firings with LP loads. I bought a Wilson case gauge to satisfy myself on this point. These cases had been partially full-lengthed resized. Changing to sizing in a genuine neck sizing die made the misfires go away. Cases that have always been neck sized show no evidence of shortening in the gauge after twelve firings. OTOH, the famous gun writer who badmouthed the .35 Whelen and .358 Winchester over "cushioned firing pin blows" with full power loads a few years ago is as full of excrement as a five pound sparrow. I have shot a LOT of .35 Whelen and .358 Winchester with never have a headspace shortened case or a misfire when shooting full pressure loads.

StarMetal
05-23-2005, 12:13 PM
Wonder if: Let's say you start with a full lenght sized case. You load a reduced pressure cast load. When the round is fired, maybe because it's a reduced pressure load, that the case doesn't get blowed out to the chamber wall as much as a high pressure load. We all know that sizing low pressure fired cases are much easier they say a jacketed high pressure one. So the case isn't getting expanded out, which wouldn't we assume that the metal expanding out has to come from somewhere and that being the lenght of the case. Maybe Curmudgeon's 35 Whelens didn't shrink after neck sizing only because the case is already out to the chamber walls.

I neck size only everything when possible.

Joe

Willbird
05-23-2005, 12:38 PM
Well I do know that many sources have advocated drilling flash holes larger for true squib low pressure loads, to prevent primers from backing out.

This could lead to some interesting experiments.


Bill

JDL
05-23-2005, 01:18 PM
Joe,
Oh, yee of little faith. It was not the M1 but Model T1920. Let's see, this is from Hatcher's "Book of the Garand" starting on page 29: "This gun operated the breech on a rather novel principle: the primer of the cartridge case moved back a short distance on firing, driving the firing pin th the rear with force enough to unlock and open the bolt." He goes on to explain in detail and then on page 31: "One other novel thing about this gun was that it really worked and that its construction plainly showed that the designer knew exactly what was about and had a thorough grasp of advanced machine design."
So wheather you agree or disagree, believe or disbelieve, if I tell you a rooster dips snuff, you can take it to the bank 'cause I don't make statements without supporting facts!:-) That's why I posted that if the primer had enough energy to operate a semi-auto mechanism, it could probably shorten the brass as well.-JDL

P.S. Almost forgot to add that Hiram Maxim in 1883 patented a primer actuated action that used special cartridges, but it didn't work very well. Garand's models of 1920, 1921, 1922, and 1924 were all primer-operated.

StarMetal
05-23-2005, 02:56 PM
I Believe Brother! I Believe Brother! hahahaha, learn something new everyday. Although I didn't know that, I knew it wasn't the Garand that got fielded in WWII. That is amazing that the primer could do that. I guess the rest of the action opening was from the gases of combustion.

Joe

44man
05-23-2005, 08:10 PM
Whew, I was right in the middle of answering this when we had a power outage. Blew my video all out of whack and it took all day to fix.
Anyway the case shrinking problem is caused by a larger chamber. The brass will expand to fill it and it will shorten a few thousandths. Brass has to go somewhere and when it moves sideways the top comes down. Now if you were shooting real hot loads, the brass will flow foreward also and it will come out the same length you started with or maybe a little longer. Continued use of hot loads will make the brass longer and longer so it will need trimmed, but if you just shoot light loads, the brass will not grow and it can stay shorter then a new, unfired case for a long time.
This is common in revolvers where a new case will shorten when fired. Most will lengthen a little when resized, but since I don't full length mine, they stay short.
A benchrest chamber that is tighter will not do this, neither will a tight chambered revolver. It all depends on where the brass has to go. It is nothing to worry about because it only happens on the first firing of new brass. It will never get any shorter then that and from that point on, it can lengthen if hot loads stretch the brass.

Slowpoke
05-23-2005, 08:39 PM
[QUOTE=joeb33050]I've tested the firing pin theory with an empty oily case and primers deadened with oil. Firing 20 times gave NO increase in headspace. This is an easy test to do. The firing pin theory doesn't hold water.


Ha, I bet you would have hard time convincing Tom Gray that the firing pin theory doesn't hold water.

He did a write up in the CBA journal #135 about an experiment he did with a O3A3, after 6 hits he wound up with .030 increase.

Good luck

NVcurmudgeon
05-23-2005, 09:38 PM
Joe, "Maybe curmudgeon's .35 Whelens didn't shrink after neck sizing only because the case is already out to the chamber walls." That makes as much sense as any other explanation, and more than some. I do know one thing for sure, my little experiment in neck sizing vs. partial full-length sizing has made a real believer in using a genuine neck sizing die. Once I had the third die for my .35 Whelen set and saw how good it was, the next bottleneck case rifle to show up around here (.260 Rem.) got a Redding three-die set to start with. Then I had to get a neck sizing die for my favorite NRA sporter Springfield. Somewhere in that aquisition of NS dies, I improvised a NS die in .303 British. Set up a 7.65 Belgian/Argentine die for FL sizing, then back it off enough to allow a 1/32" shim between the lock ring and the top of the press. This will exactly size the whole neck of a .303 British case without touching the rest of the case. What it does for case life can be seen on the .303 page.

StarMetal
05-23-2005, 11:10 PM
Curmudge

I've always been a believer and follower of neck sizing. I honestly feel I have improved the accuracy on alot of my rifles by doing so. I know for certain that it has extented the life of my brass.

Joe

sc03a3
05-24-2005, 12:32 AM
hello folks,when i started using cast boolit loads in my 03a3[years ago] i had problems with shoulder set-back after a few firings, i enlarged the flash-holes to .098 dia and no more set-back. in fact, the brass i use for match and practice is 100 rds of lc-53 that ive been shooting for about 5 years now, i just opened my 6th box of hornady gas checks for this 100rds of brass.....dick

joeb33050
05-24-2005, 06:05 AM
[QUOTE=joeb33050]I've tested the firing pin theory with an empty oily case and primers deadened with oil. Firing 20 times gave NO increase in headspace. This is an easy test to do. The firing pin theory doesn't hold water.
Ha, I bet you would have hard time convincing Tom Gray that the firing pin theory doesn't hold water.
He did a write up in the CBA journal #135 about an experiment he did with a O3A3, after 6 hits he wound up with .030 increase.
Good luck
Rather than read about it, why not DO it. Preferably with a rifle having a mauser type extractor. Remove the extractor, take a case that won't allow the bolt to close (with normal force) with a piece of paper or 2 on the bolt face under the case head. Deaden some primers with oil or wd40 or anything oily. Or leave the primers alone and do this outdoors. Prime the case, put it in the rifle, pull the trigger. Check the headspace with the paper. Do it again. And again. You'll be done in half an hour, then tell us what happened when YOU did it. I got no increase in headspace in 20 tries.
I'll try it this week with my M721 in 30/06.
joe b.

Willbird
05-24-2005, 06:31 AM
Slowpoke brings up something very interesting, an 03A3 has a long heavy striker fall....it and other older rifles designed to work under all conditions will all sorts of ammo may well have twice the striker energy of say a 700 remington.


Bill

Bass Ackward
05-24-2005, 06:36 AM
Bass

You're Wrong, the firing pin's blow doesn't shorten the brass. First a primer isn't seated all the way all the time till it's cup is up against the case. Second that cup is softer then the case. Third most firing pins don't have enough force to pound that primer in all the way and still size down the case. Those that do are very far inbetween and if they all did we'd have pierced primers galore.

Joe

Joe A,

Ha! You think that scares me? I am wrong all the time. Enough so that I quit keeping statistics like Rush Limbaugh does.

Well, you didn't like my first theory. But it doesn't happen to rimmed or belts. So I give up what causes it? When I asked another guy that he told me that rimless cases were superior cartridge designs and that high velocity of the bullet exiting the tube created a vaccuum that contracted the shoulder. Now there is a theory for ya. I guess that was the purpose for that belt to keep your brass in the chamber and not let it get sucked out the gun.

Even Joe B says it isn't the firing pin blow but then he says it doesn't happen with Mauser like extractors. Maybe this is an American phenom?

Oh and Joe A, I never neck size unless it's pistol brass using undersized, jacketed bullets that result in slop in the chambers. Bass ackward again.

joeb33050
05-25-2005, 03:07 PM
I just got back from the range. I took 15 new primers and put a drop of Marvel Mystery Oil in each one. Took a FL sized case, put it in the Rem 721 30/06, it fit fine. My first try at paper was .0036" thick with micrometer; a piece on the clean bolt face, cur to miss the extractor and ejector, made bolt movement after the first few degrees very hard. That's what I call measuring headspace on the cheap-headspace with that case was something under .0036". Paper out. Fired the primed case-same case- twice. No change in headspace. Three more, no change. Five more, no change. Five more, total of 15, no change-still lots of resistance after the first few degrees with the paper in. All fired without paper, allo measured with the paper on the bolt face. The oil didn't kill the primers, most went off with a pfft noise. Much crap in the barrel. WD40 generally kills primers, or has for me in the past. The case was oily. No primer was above the case head before or after firing.
I have the case if anybody wants to check it with a Wilson type headspace gauge.
The extractor holds the case, I won't remove it cause I'm told they aren't made any longer.
Once again, folks-it ain't the firing pin driving the case forward.
Maybe it's that primer-is-a-piston theory-I dont care why, I know that LV loads = excess headspace, at least it has in the past for me.
I'm interested n hearing from somebody doing this experiment with other rifles.
joe b.

BOOM BOOM
05-25-2005, 03:10 PM
HI,
Well just measured 100 fired brass. 50 were R-P, trimmed , primer reamed flash holes, 30/06 cases necked down to 7MM/06. load 10.1 to 13.5grs., 700X w/ 1/2gr dacron filler (SQUIB LOADS). 50 others were exactly the same except load was 22 to 25grs. IMR 4198 w/ 1/2 gr. dacron filler. Bullet was 168gr. gc. lyman cast WW H2O quenched.
Then 6 standard j-rounds. All 6 J rounds lenthened & needed slight trimming.
1 of the 100 cast bullet cases needed slight trimming.
Also found slight lead/lube deposits on the cast bullet cases on neck & shoulder. Found alot of same deposits on the 6 J bullet cases used as bore cleaners.
From this I'd say that cast squib & medium vel./ pressure (2000'/s) rimless cases don't lengthen much.
The pressures are low enough for some lube & lead to be blown back into the chamber around the case neck & shoulder.
I'll try some more next week.

Scrounger
05-25-2005, 03:20 PM
It's probably a mistake for me even to post this as I'm way over my head as far as knowledge here. But, is it possible that the "low' pressure, maybe 20,000 PSI, failed to blow out and seal the neck, BUT had sufficient force to push the shoulder back a bit? Just a thought, I won't argue the point...

joeb33050
05-25-2005, 03:44 PM
HI,
Also found slight lead/lube deposits on the cast bullet cases on neck & shoulder. Found alot of same deposits on the 6 J bullet cases used as bore cleaners.

If you bell the case necks, you'll eliminate the blowback. More precisely, if you don't bell the case mouths and eliminate the blowbach, your accuracy will suffer.

From this I'd say that cast squib & medium vel./ pressure (2000'/s) rimless cases don't lengthen much.


I don't think that we think that rimless cases lengthen with CBs-we know that LV loads in shoulder-headspacing cases get increased headspace. I don't know why. The cases don't get longer.

Jacketed bullet cases get longer, I don't know why. Brass-is-extruded-longer or bullet-pulls-neck-forward-making-case-longer and pulling-that-neck-expander-through-the-neck-makes-it-and-the-case-longer are three theories. I suspect that the last-resizing and that neck expander, may be the reason. Those using the Lee collet dies claim no/less case lengthening.

With CBs I see the case necks get uneven over time, so that they're not square. Then I may trim, to make them square. But I shoot dozens to hundreds of CBs out of each case. Today a case failed, a piece of the neck about 1/8" X 1/8" disappeared. That's mostly how my cases fail.
joe b.

I guess I don't know how to do this quote stuff. The comp[uter wins again.

StarMetal
05-25-2005, 04:47 PM
Art

That's a pretty interesting theory and I like it. I can see that happening. The gas slips by the neck then is confronted with a shoulder, which it can push on, by that time the bullet and the pressure is gone..

Joe

Ed Barrett
05-25-2005, 05:16 PM
Art

That's a pretty interesting theory and I like it. I can see that happening. The gas slips by the neck then is confronted with a shoulder, which it can push on, by that time the bullet and the pressure is gone..

Joe

If that's true the shoulder on a rimmed case should have the shoulder moved back also. Has anyone tried this with a rimmed case vs. a rimmless 7mm mauser and a 7x57Rmm are supposed to be the same case except for the rim. I don't own a rifle in either one but if someone has both rifles it would prove the theory. Just a thought.

StarMetal
05-25-2005, 05:20 PM
It would be kind hard to measure a shoulder move back on a rimmed case as it headspaces on the rim. That is unless you headspace off the shoulder on a rimmed case as is suggested in TC Contenders.

Joe

Ed Barrett
05-25-2005, 05:40 PM
If you took a case guage and opened up the bottom so the rim didn't interfere and work with a depth micrometer to see how far the shoulder changed on the rimmed and rimless case using the same case guage.

BOOM BOOM
06-08-2005, 11:12 AM
HI,
Well when using my lacmiller max. case length gauge on the 1st inspection it gave the impression that no case lengthing occured on the squib & mild loads.
But when I put the cases in my trimmer I found some differances.
The 50 R-P cases loaded w/ 10.1 - 13.5 grs. of 700x + a dacron filler (1200-1500'/s) did not lengthen at all.
The 50 R-P cases loaded w/ IMR 4198 + dacron filler midrange loads ( 1500-1950'/s) trimmed just a hair. So they may have lengthened slightly.
The 6 j-bullet R-P brass laoded w/ IMR 4350 (hot) at about 3050'/s did need trimming clearly both buy the max. case length guage & by my trimmer.

Willbird
06-08-2005, 12:55 PM
I do know from personal experience that a "tight" bolt handle as the benchrest shooters call it greatly accellerates the wear on a rifle action..it is not designed to work with ctg. that are a tight fit...it WILL deal with them, but it is not ideal.

What is desired is minimal resizing, and I think a .002" shoulder bump...this is about impossible to achieve perfectly with saami brass, chambers, and dies, but one can strive towards it.

also the necks should be sized .002 smaller than the expander button with the thinnest neck in the batch of ctg., several dies in differant calibers (green box dies even) I have checked sized the neck down as much as .008" smaller than the expander ball...bushing dies are the answer there.

Unless it is a neat older rifle I have given up on wasting time on factory bbls and chambers....it is better to thread them off the action, fit a decent quality bbl with a nice snug chamber,.....otherwise work up a load that shoots 3/4 moa and work on the shooter not the rifle.

Bill

Scrounger
06-08-2005, 01:06 PM
I do know from personal experience that a "tight" bolt handle as the benchrest shooters call it greatly accellerates the wear on a rifle action..it is not designed to work with ctg. that are a tight fit...it WILL deal with them, but it is not ideal.

What is desired is minimal resizing, and I think a .002" shoulder bump...this is about impossible to achieve perfectly with saami brass, chambers, and dies, but one can strive towards it.

also the necks should be sized .002 smaller than the expander button with the thinnest neck in the batch of ctg., several dies in differant calibers (green box dies even) I have checked sized the neck down as much as .008" smaller than the expander ball...bushing dies are the answer there.

Unless it is a neat older rifle I have given up on wasting time on factory bbls and chambers....it is better to thread them off the action, fit a decent quality bbl with a nice snug chamber,.....otherwise work up a load that shoots 3/4 moa and work on the shooter not the rifle.

Bill

Some target shooters I knew had their chamber necks cut on the small side, thinned their case necks to one or one and a half thousandths smaller than chamber size, and their sizer dies honed to that one and a half thousandth smaller than chamber size, and removed the expander ball completely, or turned it down so it wasn't in contact. It helps, no doubt, but don't bother unless you, your rifle, and your ammo, are top notch.

fourarmed
06-08-2005, 01:23 PM
I shot a Wichita International pistol in silhouette for years. It was chambered for 7mm Int-R, which is a necked down .30-30. I used a very light charge of SR-4759. I always had protruding primers after firing. I initially set the FL sizer so that the barrel closed with "feel". This indicates that the barrel may have had excessive headspace at the rim, but also that the shoulder got set back a little.

Scrounger
06-08-2005, 01:41 PM
I shot a Wichita International pistol in silhouette for years. It was chambered for 7mm Int-R, which is a necked down .30-30. I used a very light charge of SR-4759. I always had protruding primers after firing. I initially set the FL sizer so that the barrel closed with "feel". This indicates that the barrel may have had excessive headspace at the rim, but also that the shoulder got set back a little.

Probably because of very low chamber pressure.

BOOM BOOM
06-08-2005, 03:35 PM
HI,
My last post on 6/8 was ment as an update of the 5/25 post. Where I just used the lachmiller max. case gage as a quick methode to try & see if my 106 cases had lengthened. When I set up my forester case trimmer to my trim to case things came out a bit different than I first reported on 5/25.
The squib loaded 50 cases 168 gr. gc lead bullet w/ 700X 10.1- 13.5 grs. w/ dacron filler did not lengthen.
The hi power 145gr j-bullets loaded 6 cases w/ IMR4350 (hot) needed trimming .
The mid power IMR 4198 , 168gr gc lead bullet, w/ dacron filler needed trimming just a hair. Just enough that I had to recampher them.
Now this was w/ only 1 firing & doesn't address belted or rimmed cases,
however I don't think that should make much difference as pressure is pressure.

BOOM BOOM
06-17-2005, 11:40 PM
HI,
Well the result of my last shoot at the range w/ 24 cases w/ 168gr. pb bullets & IMR 4198 at about 1800'/s is:
8 cases needed triming.
16 did not need trimming but still touched the cutter blades of my trimmer.
I set my lacmiller trimmer for a set length below max case length & origanally trimmed ,inside neck reammed, then neck sized over 500 r-p 06 brass.
1/2 the brass is loaded w/ 13.5 grs of 700X, the other 1/2 is loaded w/ 24.5 grs IMR 4198.

BOOM BOOM
07-05-2005, 02:23 AM
HI,
Well , happy 4th of july everyone. Over this weekend I shot off another 100 rounds of squib loads in my 7MM/06 in a Mauser Mark X action w/ a claw type extractor.
So here are my results:
4 did not touch the trinner blades
30 touched & trimmed part of the camfer area
40 touched & trimmed off all of the camfer
26 touched & trimmed even more leaving a ridge
So to sum up my results so far the totals are:
50 cases fired in a Rem mod 700 7MM Mag (button extractor). All cases trimmed to a set length, & inside neck reamed,camfered, then FL resized . Then loaded w/ a squib load of 700X & a 168 gr cast bullet.
2 needed trimming
48 had no change.
150 cases fired in a 7MM/06 Mauser action (claw extractor). All cases trimmed to a set length,inside neck remmed, camfered, then neck sized.
Then loaded w/ a squib load of 700X & a 168 gr gc cast bullet.
53 did not touch the trimmer blades
30 touched & trimmed part of the camfer area
40 touched & trimmed off all of camfer area
27 touched & trimmed off even more brass.
74 cases fired in the 7MM/06 . Case prep the same except load was a mid range load of IMR 4198, 1/2 gr dacron, & same cast bullet, but H2O quenched.
65 touched & trimmed out the camfer area
9 touched & trimmed out more brass.
OK THIS IS NOT CLEARLY SHOWING CASE SHORTENING.
I WILL CONTINUE GETTING A BIGGER SAMPLE SIZE.

BOOM BOOM
07-05-2005, 04:37 PM
HI'
Well i went up to the clearing on Squaw peak above Provo, & shot off another 50 rounds.Saw a moose & 5 wild turkeys just before I started shooting.
So here are the results to date W/ a squib Load of 13.5 grs 700X, 168gr gc cast bullet in my 7MM/06 mauser mark X.
200 cases shot so far.
61 cases did not touch the trimmer blades(no lenthening)
46 " touched & trimmed off part of camfer(lengthened)
53 " " & " " all of the camfer( " )
40 " " & " " " " " " & more( " ).
THIS IS NOT WHAT I EXPECTED TO HAPPEN! I EXPECTED CASE LENGTH SHORTENING. THEY SEEM TO BE LENGTHING MORE CONSISTANTLY. I'll increase the sample size & report back.

old gunner
07-05-2005, 08:43 PM
More reasons to like the 30-30, 45-70, the cast shooting with rimless has been confined to the 30-06. With moderate to heavy loads there has been no problems.
I agree that lubing the inside of the neck will almost eliminate case stretching, many years ago I did a simple test, I picked a new Norma 30-06 case at random, cleaned the mouth of the case on my trimmer, then fired the case 20 times with a full power load. The case did not get any longer,and I was carefull to lube the inside of the neck with moly powder mixed with acetone. Then the test was repeated with dry necks, it grew so much that after 5 loadings the case needed trimming.
Bill

BOOM BOOM
07-07-2005, 04:07 PM
HI,
Well went up to shoot this A.M. Saw 6 wild turkeys , a doe & a spotted fawn. Clocked the fawn at 25mph for a ways. I've clocked adult deer at 30, adult moose at 30+, & wild turkey at 30mph on the road ahead of my truck.
today 1 turkey walked up to where I set my 150yd. plate while I was shooting!
Well here are the new totals W/squib loads:
250 cases
66 " did not touch the trimmer blades
55 " did touch & trimmed part of the camfer off
58 " " " & " all of " " "
71 " " " & " " " " " " & more leaving a ridge.
I'll try another 50 cases for a bigger sample later.

BOOM BOOM
07-08-2005, 04:26 PM
HI,
Well went shooten steel plates today, saw a yearling muley on the road up Squaw peak.
Here is the totals to date:
300 cases fired W/ squib load
75 cases did not touch the trimmer blades
71 " " touch & trimmed off part of the camfer
68 " " " & " " all " " "
86 " " " & " " " " " " & more leaving a ridge.
THE RESULTS DO NOT APPER TO BE CONSISTANT.
I will increase the sample size by 50 cases.

drinks
07-08-2005, 10:42 PM
I make shotshells for .45acp and .44mag. the pressure is quite low, I have no idea how low.
I have to drill the flash hole out to 7/64 or 1/8" or the primers will back out and lock the cylinders up, obviously shooting revolvers, not sl's.
The best info I have come up with on this is that when the cartridge is fired, the pressure backs the primer out some, the recoil of the bullet leaving pushes the case back and reseats the primer, some how, drilling out the flash hole stops the primer from backing out, do not know the reason, just know it works.

GEO 41
07-10-2005, 02:10 PM
HEY BOOM BOOM,
IT'S GEO 41, YOUR FAVORITE BROTHER. SEEMS LIKE YOU GOT ALOT OF INPUT TO YOUR POSTING. I DONT THINK I HAVE HAD ANY PROBLEMS WITH MY RELOADS AS I STAY WELL WITH IN THE CONFORT ZONE FOR EACH CAL AND LOAD. LIKE MY 7MM MAG (JACKETED 139 GR,162 GR) RIGHT AT 3000 '/S. ALL LEAD 200 GR, 240 GR IN MY 41 MAGS AND 44 MAGS RIGHT AT 1000 '/S. ALL LEAD 9MM, 38 SP RIGHT AROUND 800-900 '/S. STILL DON'T MAKE MY LEAD BULLITS YET, SOME DAY WHEN WE SEE ONE ANOTHER YOU CAN TEACH ME HOW, LIKE YOU DID RELOADING.

JUST A THOUGHT, RELOADING WITH A FAMILY MEMBER WAS SOME OF THE BEST TIMES I CAN REMEMBER WHEN I WAS A YOUNG'N. :twisted:

BOOM BOOM
07-10-2005, 09:52 PM
HI,
Well basicly I load rifles for accuracy w/ j-bullets. pistols for power w/ j-bullets. As my only focus w/ a j-bullet is hunting & the unlikely self defence situation. Velocity & bullet wt. + power.
I'm v. lucky that both my 7MM/06 & 7mm mag. shoot thier tightest groups w/ max. loads.
Cast bullets are a whole different animal.
Most of my pistol loads for 30+ yrs. have been as hot as the Wheel wt.(WW) metal could be pushed w/out leading. This pluse case extraction have been the gov. factors. But lately accuracy is a factor as I am trying to seriously shoot long range w/ the hanguns.
Cast in the rifles started out as a safe way to shoot economicly W/ fair accuracy. But Now I'm trying to streach my range w/ them too.

BOOM BOOM
07-11-2005, 03:19 PM
HI,
WELL went shooten agien.
Here is the totals to date:
350 cases fired out of the 7MM/06 W/ squib load
94 " did not touch the cutter blades
85 " " touch the cutter blades & trimmed off part of the camfer
80 " " " " " " & " " all of camfer
91 " " " " " " & " " " " " & left ridge
Will increase sample size tomorrow.

GEO 41
07-11-2005, 06:50 PM
:twisted: HEY BRO,
I WHISH I COULD SHOOT EVERYDAY. IN ALL THE TIME THAT I HAVE RELOADED I DON'T THINK THAT I HAVE HAD TO TRIM SHELL CASINGS. REMEMBER THAT MOST OF MY RELOADING HAS BEEN FOR PISTOLS, BOTH REVOLVER AND SEMI AUTOS. I HAVE NEVER HAD ANY PROBLEMS WITH RIFLE BRASS IN MY SEMI AUTOS OR TURN BOLTS. I MAY HAVE ONLY RELOADED RIFLE BRASS 2 OR 3 TIMES MAX, WERE AS PISTOL BRASS I HAVE RELOADED UNTILL I SEE DEFECTS. AS YOU CAN SEE I USED TO SHOOT HANDGUNS A LOT MORE THAN MY RIFLES, MAYBE AN 8 TO 1 RATIO.

YOUR TRAINING IN BEING A BRASS HOUND HAS MEANT THAT I HAVE PICKED UP THOUSANDS OF PISTOL CASES FROM EVERY PLACE THAT I HAVE SHOT. I HAVE 5 GAL BUCKETS OF BRASS I HAVENT EVEN THOUGHT ABOUT RELOADING YET. I HAVE BEEN ABLE TO GET FACTORY AMMO VERY CLOSE TO COST THROUGH M.P.S. (LONNIE) WHEN I WOULD BUY IN THE THOUSANDS.

HOW LONG WILL PRIMERS LAST IF STORED IN A COOL DRY PLACE ? I HAVE SEVERAL HUNDRED THOUSAND IN DIFFRENT SIZES (STANDARD AND MAG).

IF I EVER GET STARTED RELOADING AGAIN I COULD HAVE AN AMMO DUMP THAT WOULD MAKE YOU CRY.

TAKE CARE BRO, PLEASE BE SAFE WHEN YOU SHOOT! :evil:

BOOM BOOM
07-12-2005, 04:06 PM
HI,
Well this is a large enough sample size , 390 cases.
97 cases did not touch the cutter blades
91 touched & trimmed off part of the camfer
89 " & " " all " " "
113 " & " " " " " " & more leaving a ridge of brass.
Now I realize this is only 1 firing.
But I am getting case lengthing W/ squib loads which is contrary to what most people believe happens.
In order for the trimmer to touch a previously trimmed case, which was afterwards further shortened by camfering, the case must have lengthened.
This happened to 293 of the cases, or 75% of the cases which is a significant #.
Now if someone wants to take 50 micked cases & fire them 8 times then remike them to check I'd pay close attention to his point of view.
Right now that is the only possible flaw that I can see in my experemental procedure.

BOOM BOOM
07-12-2005, 04:25 PM
HI,
Well I can't go shooting everyday, but I'd like to!
AFTER 3 FIRINGS OF RIFLE BRASS YOU SHOULD CHECK ALL BRASS W/ A MAXIMUM CASE GUAGE. YOU COULD GET DANGEROUSLY HIGH PRESSURES AS A RESULT OF CASE LENGTHING.
I have never trimmed revolver brass. But the real good shots ,I believe, do so for accuracy reasons, it insures a uniform crimp.
For autoloader pistols it might need to be done for the same reason. But if I remember right a 1/32" seating diff. in a 9mm can triple pressures. So there is a 2nd reason. I am not a autoloader shooter so I'm no expert. This is a factor of the 9mm's small case capacity. Smaller cases are even more sensitive.

Bullshop
07-12-2005, 08:22 PM
Boom Boom
I think the culprit your looking for is shortening of the criticle head space dimensions between the datum line at the sholder and the base of the case. Case length could increase while at the same time the sholder is being set back and causing an excessive head space issue. Case length is not the criticle issue. I havent followed this entire thread so I may have missed something, if so just apply my usual foot in mouth condition.
BIC/BS

BOOM BOOM
08-01-2005, 11:47 PM
HI,
As I'm sure you know overall case length is an issue if one gets too long.
The 50 case test on 7MM Mags is documented above no datum line issue there.
Unfortunatly I have no means to accuratly measure a change in the shoulder datum line or I would have done so.
I suppose it might be possible for the overall case length to increase while the shoulder datum line to be set back while firing, but I think it unlikely.

Larry Gibson
08-02-2005, 07:10 AM
Well I do know that many sources have advocated drilling flash holes larger for true squib low pressure loads, to prevent primers from backing out.

This could lead to some interesting experiments.


Bill
__________________

hello folks,when i started using cast boolit loads in my 03a3[years ago] i had problems with shoulder set-back after a few firings, i enlarged the flash-holes to .098 dia and no more set-back. in fact, the brass i use for match and practice is 100 rds of lc-53 that ive been shooting for about 5 years now, i just opened my 6th box of hornady gas checks for this 100rds of brass.....dick
__________________
if it ain't broke don't fix it


The two above quoted posts have it nailed. I shoot many thousands of squib loads in various calibers but mostly in .30s every year. Many of these are rimless cartridges; 30-06, .308, .308 CBC, 7.65, 7.62x39 etc. The squib load I shoot most often is a Lee 314-90-SWC-TL over 2.7 to 3.2 gr of Bullseye depending on the cartridge. Velocity is around 800 – 875 fps. I found a long time ago the shoulders do in fact get set back with light loads such as those. With many cast loads that use normal weight bullets in the 1600 to 2000 fps range there was little setback. Measurements of shoulder set back or increase/decrease of headspace are easily measured with a Stoney Point tool.

There have been basically the two theories regarding the cause of this setback or increase in headspace; the firing pin blow theory and the primer theory. I ran the same tests with a fire formed case and inert primers and found headspace was not changed. I then used the same fire formed case with live primers. In as little as two firings there was a measurable decrease in headspace. After five live primers the fired primer was noticeably backed out after firing. NOTE: this increase in headspace was with case taking LR primers. I never experience the problem with the .222 Rem or the 5.56 Nato.

Using #d drills I gradually increased the flash hole diameter with a progressively larger drill. Using a different fire formed case with each larger size drill and firing 5 primers I then measured the headspace before firing and after. As the size of the flash hole increased the headspace decreased or lessoned. With a # 29 drill I no longer got any decrease in headspace. I dedicated five .308 cases and five 30-06 cases that were well fire formed to their respective rifles chambers and drilled the flash holes with the #29 drill. Over the next few days I fired 50 shots with each case. There was an indoor 50' range where I was stationed so it wasn’t all that bad. After the 50 firings there was negligible change in headspace with any of the five cases of each cartridge.

The results of my test firmly demonstrated to me that it was the force of the primer explosion that drove the case forward and set back the shoulder. The squib load does not have the pressure to expand the case out to fit the chamber. By drilling out the flash hole the force of the explosion mostly went directly into the case as there is little rim left to contain it. Two other side benefits that were unforeseen; the extreme spread and standard deviations of the velocity readings improved and the case position sensitivity of the small charge was greatly reduced.

As a result of the above tests I dedicate fire formed cases for squib loads for each rifle in rimless cartridges and drill out the flash holes. I have fired them many, many times now with no change in headspace. Besides the squib load mentioned I also use 311631 (# may be wrong but it’s the 118 gr GC 32-20 bullet) with Unique in the above .30 cal cartridges loaded to 1400 fps or so for a little more powerful small game load. The flash hole drilled cases work just fine for those. I now use the flash hole drilled cases for all my rimless cartridges with squib and really light loads.

Caveat; I still use normal sized flash hole cases for loads with medium to heavy (for caliber) cast bullets with velocities from 1600 fps and up. The flash hole drilled cases may or may not work but I have not tested that so I won't conjecture. It is on my list of things to test when I get back home. Good shooting to you all.

Larry Gibson

felix
08-02-2005, 10:28 AM
Larry, your description of your testing process is excellent. Very enjoyable to read. Besides that, I have often thought of this problem, and have concluded the same. There are exceptions, though, such as strongly annealed brass and strongly-firing firing pins, due to whatever firing pin reason. I have encountered both situations many times. Still, for accuracy, IGNITION characteristic is everything. Bigger flash holes means your "timing" is considerably "advanced" and powder selection as "octane" must be made commensurate. ... felix

BOOM BOOM
08-02-2005, 02:07 PM
HI,
Thanks guys, all brass used was fire forned, at least 100 were annelled, all inside neck reammed,all trimmed to the same trimmer setting, all had the primer pockets uniformly reammed w/ a wire drill dit by hand.
This means the cases can & do lengthen while the shoulder is set back.
So cases should be segergated not only for accuracy , But also for safety reasons.

BOOM BOOM
08-02-2005, 02:09 PM
HI,
Thanks guys, all brass used was fire forned, at least 100 were annelled, all inside neck reammed,all trimmed to the same trimmer setting, all had the primer pockets uniformly reammed w/ a wire drill dit by hand.
This means the cases can & do lengthen while the shoulder is set back.
So cases should be segergated not only for accuracy , But also for safety reasons w/ squib loads.

BOOM BOOM
06-09-2006, 04:46 PM
HI,
Have shot 227 rounds of squib loaded 7MM/06 this yr.so far all needed to be trimmed as the cases lenthened.
I was hoping someone had preformed the datum line test, but have not seen any mention of it.