Primer backing out ?


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HOWARD J
May 3, 2014, 07:37 AM
On my new to me ( used once) Marlin 336C 30-30
I am using 28.5 gr of H335 with a Hornady 160 gr bullet ( one with plastic tip)
Looking at fired cartridge--the primer is backed out a little less than 1/16".
Any idea why this is happening ?
This is a super accurate load.
Thanks,
H

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jwrowland77
May 3, 2014, 07:42 AM
I'm going to say too low of pressure and it's not fully reseating the primer as the case stretches.

Just looking at the Hodgdon website, you're only .3gr above a starting load for the 160gr FTX Hornady bullet. The starting is 28.2 and goes up to 30 using that powder. I would continue to workup the load if it was me. You'll most likely see this problem disappear and find an accurate load.

fguffey
May 3, 2014, 08:42 AM
Howard J., I believe reduced loads are cute, there are those that used your method of reloading to determine the difference in length between the chamber from the shoulder of the chamber and bolt and the difference in length between the case when measured from the shoulder/datum and case head, or the amount of the protrude from the case head.

They say" The protruding primer can be measured from the end of the primer to the case head to get case head clearance, or the difference in length between the chamber and case when measured from the usual places. Problem, someone else says the case can shorten .005" with the impact of the firing pin, I ask "How do you measure that?

Question, have you fired these cases with recommended loads as in starting and maximum loads? I believe recommended loads would solve your problem and at the same time allow you to determine the length of the chamber from the shoulder/datum to the bolt face if you are in the habit of measuring before and again after with a comparator.

F. Guffey

HOWARD J
May 3, 2014, 10:02 AM
This is mid load data from Hornady's #9 manual
I hate to give up this load if it is not dangerous as I hit the bullseye 98 times out of 100 shots
I don't deer hunt anymore--target only

jwrowland77
May 3, 2014, 10:06 AM
Hornady is notorious for being lightly loaded.

Are you using the Hornady FTX 160gr? If so, I would go with the load data Hodgdon has. Hodgdon used that bullet for their data.

That's just what I would do. You can normally find two accurate loads. One on low end and one on high end. I normally always find two loads that shoot great. Who knows, you might find that load that gives you 100 out of 100 in the bullseye.

454PB
May 3, 2014, 11:41 PM
You've got some excessive headspace.

It can be verified (and even measured if desired) by placing a resized empty case in the chamber and then inserting shims between the bolt face and case until the action won't close.

In lever guns, it's not at all unusual and can be mitigated by "partial sizing" rather than full length resizing. What you're really doing is neck sizing with a full length resizing die so that the case headspaces on the shoulder rather than the rim.

I do this with all my rifles, the downside is that partial sized brass may only fit the rifle it was fit to.

I've owned rifles that would produce case separations in as little as three firings if the cases were full length resized......belted magnums are one of the worst for this.

HOWARD J
May 4, 2014, 12:05 AM
I will let you know what happens after & increase the powder charge & polish inside the breech area.

gamestalker
May 4, 2014, 01:57 AM
Although there are other possible culprits, this sounds typical of a sub pressure load. I would bump the load up, and according to Hodgdon's data, considering they're data was developed around that bullet.

Years ago while still engaged in the learning curve, I managed to separate .270 win. brass on the first resizing by over bumping the shoulders as far as my die would bump them, I didn't know any better. I'm not implying your problem has anything to do with your resizing step, but I would pay attention to shoulder's in this respect, could extend the life of your brass.

GS

amlevin
May 4, 2014, 09:30 AM
I'd pay attention more to headspace than loading.

If the case is tight between shoulder and bolt face, there's no room for a primer to back out. If you just increase the loading to cure the problem then you run the risk of increasing the likelihood of case head separations. Yes the extra pressure will re-seat the primer but it will also stretch the case just above the case head web.

Get a case gauge and set your sizing die so you aren't bumping the shoulder back more than .002" or so. If your primer is backing out " a little less than 1/16" " then that's almost .0625" and way more than it should under any pressure loading.

HOWARD J
May 4, 2014, 10:48 AM
I'm not worried about case head separation as I have 40 guns & this Marlin will be lucky if it gets used more than once a year.
Thanks for all the info
H


BTW: I will fire a new cartridge & see what happens----the ones I have used so far are my old stock from my old 30-30 Win 94

blarby
May 4, 2014, 12:47 PM
Well, you have both the probable causes from folks better than I !

Let us know which one it was- or maybe both !

gamestalker
May 4, 2014, 01:35 PM
I was under the impression that sub pressure loads can actually bump the shoulders back some, thus allowing the primer to get backed out. I've witnessed this with some 7mm RM mag that was significantly under charged, not by me, but none the less, the shoulders did get pushed back in the chamber, and quite a bit as confirmed by pre, and post firing measurements.

What I would try is bumping the charge up with what ever brass you have, and then adjust your FL die such that, the shoulders don't get bumped at all, unless necessary. This way you can get that brass properly fire formed on the first loading, other wise it might just keep getting chamber bumped by the sub pressure loads.

GS

witchhunter
May 4, 2014, 07:41 PM
Sounds more like a headspace issue to me too. You will have problems sooner or later if you have more than 1 30/30. I would get another set of dies and dedicate them to this rifle. The way it is going, it may ruin any brass that is shot out of this rifle.

NCsmitty
May 4, 2014, 08:11 PM
As mentioned, if you move up toward the maximum load, you'll likely see the problem disappear. The pressure is not enough to move the brass back against the bolt face to flush the primer. It's just the difference in the rifles used.
With that old style ball powder, I would use a magnum or BR primer for best complete ignition.



NCsmitty

HOWARD J
May 4, 2014, 08:20 PM
I have 3 sets of dies for a 30-30 & a taper crimp die ( screw this down farther & it gives a nice roll crimp)
H

RainDodger
May 4, 2014, 09:41 PM
Agree with NCSmitty. Too light a load. I would really be surprised if you have a rifle with a headspace problem. Occam's razor... go for the simplest solution first and don't over-think it.

fguffey
May 5, 2014, 09:47 AM
Looking at fired cartridge--the primer is backed out a little less than 1/16".

1/16" is .0625"

http://www.saami.org/PubResources/CC_Drawings/Rifle/30-30%20Winchester.pdf

SAAMI says anything close to that number is tooo much. In the perfect world the primer protrusion would be .005", with a 30/30, .010" would be on the high side. The 30/30 is in the same family of cases that have a lot of tapper and is on the list of cartridges that gain the most by going to P.O. Ackley's Improved chambers.

So, if your wild guess of 'close to 1/16"' is accurate your problem is very serious. If you load your ammo up as in enough pressure to lock the case to the chamber and enough pressure to seat the case head against the bolt face expect the case to stretch .050" (a little less than .0625") between the case body and case head.

I would use a depth micrometer, height gage, dial caliper etc. (feeler gage) to measure primer protrusion from the case head. There is no way the primer can protrude .050". But if did protrude it would be nice if case manufacturers made cases with thick rims, or if reloaders measured case rim thickness when making an attempt to reduce case travel.

F. Guffey

HOWARD J
May 5, 2014, 10:57 AM
When I get around to it I will fire 3 types of new cartridges & a couple of reloads ( with a higher charge of powder)
I will let you know what I find
H

amlevin
May 6, 2014, 11:25 AM
The pressure is not enough to move the brass back against the bolt face to flush the primer.

Yes, it will. But if you have the proper headspace on the sized case then there's only minimal room for the case to move. The proper way to cure the problem is to cure the largest cause which is too short a headspace measurement on the case to begin with.

Upping the powder charge will only cure the symptom, not the problem.

Kp321
May 6, 2014, 12:00 PM
There are a number of things going on here. First let me say in my opinion, some excess headspace in a 30-30 is very common and not as big a deal as in a higher pressure cartridge. The pressure in the cartridge is below the yield strength of the brass so when fired it does not stretch to fill the chamber. The case grips the chamber walls and the result is that the primer backs out. I have seen it happen on factory 30-30 loads so it is not necessarily your loads. The primer protrusion might go away if you give the chamber a mirror polish so the brass doesn't grip it as tightly but if you aren't having any extraction issues, leave it well enough alone.

HOWARD J
May 6, 2014, 12:17 PM
@KP-321
What you said about gripping the chamber walls---I noted that the sides of the fired cases had gripping marks all along the case. I have never noted that on my other rifles.
This gun was given to me by my sister---what I have fired so far is very accurate.
I will miss hunting because I have arthritis of the spine but I can still make it to the gun range.
Have a great summer,
H

spitballer
May 6, 2014, 05:24 PM
I've never encountered the problem you're describing but I read about it in R. Lee's reloading manual. He says it's caused by insufficient pressure. Normally a case will stretch to completely fill the chamber and hold the primer in place, whereas a load with insufficient pressure will instead push the primer out. He goes on to say that this is a dangerous situation that needs to be addressed immediately! Seems to me that cases that are neck-sized only are probably less prone to do what you are describing.

redbullitt
May 7, 2014, 12:45 AM
I have had this happen using reloader 22 out of a long barreled 30-06. No headspace problems on the rifle. Simply a nice slow powder not putting enough pressure to smack the primer back in against the bolt face. Once I got the pressure up with hotter loadings the primers reseated and looked just fine.

IT CAN BE HEADSPACE, but if the rifle shoots factory ammo fine I would lean to low pressure.

amlevin
May 7, 2014, 11:36 AM
I have had this happen using reloader 22 out of a long barreled 30-06. No headspace problems on the rifle. Simply a nice slow powder not putting enough pressure to smack the primer back in against the bolt face. Once I got the pressure up with hotter loadings the primers reseated and looked just fine.

IT CAN BE HEADSPACE, but if the rifle shoots factory ammo fine I would lean to low pressure.
It's not the headspace on the rifle, it's a matter of the case headspace measurement (from case head to datum point on the shoulder) being excessive. This occurs frequently when people just blindly follow the instructions that come with the die set, screwing the die down until it touches the shell holder then adding another 1/4 to 1/2 turn (depending on the mfr).

This method doesn't take into consideration what the actual headspace is in the rifle. If this is your preferred method, so be it. Just expect the problem described. May not be an issue with low pressure 30-30 rounds but is a BIG problem with others and the leading cause of case head separations.

Again, not headspace IN the rifle, but the headspace measurement of the case itself.

I bring this up because there are those who don't shoot 30-30's reading this thread and might get the wrong idea about it "being no bid deal".

fguffey
May 7, 2014, 05:56 PM
It's not the headspace on the rifle, it's a matter of the case headspace measurement (from case head to datum point on the shoulder) being excessive.

My cases do not have head space, but if they did and the distance from the datum to the case head was excessive the bolt would be difficult to close.

F. Guffey

murf
May 7, 2014, 06:26 PM
this is a rimmed cartridge. headspace is from the bolt face to the front of the rim cutout in the chamber.

low pressure round expands the case body against the chamber wall. not enough pressure to stretch the case head back against the bolt face. primer is already driven against the bolt face upon primer ignition. result: primer sticks out of case after firing.

may want to check chamber with go-gauge, but i don't see a problem here.

murf

fguffey
May 7, 2014, 07:19 PM
Looking at fired cartridge--the primer is backed out a little less than 1/16".

this is a rimmed cartridge. headspace is from the bolt face to the front of the rim cutout in the chamber.

I have 3 sets of dies for a 30-30 & a taper crimp die ( screw this down farther & it gives a nice roll crimp)

I will assume he is a reloader, with 3 sets of dies and all. I will assume he is measuring the length of the case from the shoulder to the head of the case because no one has mentioned measuring the length of the case from the datum/shoulder to the head of the case and no one has suggested measuring the length of the case from the datum to the head of the case before firing new ammo and again after firing and again after sizing.

I have cases with belts, I have cases with rims, I am the fan of cutting down on all that case travel.

F. Guffey

OrangePwrx9
May 8, 2014, 08:55 AM
I agree with Murf on this. .30-30 is headspaced on the case rim. If the rifle was built right and you're using cases of standard dimensions, a too-light powder charge is the more likely culprit.

Might be a good idea to try a box of factory ammo. If the primers back out of it, the gun needs a trip to the gunsmith to determine how severe the headspace problem is and whether it can be corrected. If factory ammo shoots OK with no primer back out, your load is too light.

I had a similar problem with .223; but that cartridges headspaces on the case shoulder, not the rim. My problem turned out to be a sizing die that was pushing the case shoulder back and creating a headspace problem.

ETA: Some rimmed cartridges can be made to headspace on the case shoulder by backing the sizing die out slightly. The idea is to have the shoulder in the case touch the shoulder in the chamber before the case rim touches the breech-face...to force the case head firmly against the bolt face. I've never loaded .30-30, so don't know if there's enough shoulder to do this. If your rifle does have excessive headspace, this might work. You would be creating ammo specific to that rifle, however.

HOWARD J
May 8, 2014, 10:08 AM
I have been shooting for about 67 years
Reloading for about 40 years
I do have many die sets for each caliber
I have never had a case head separation.
I don't really care about headspace or any other krap of why a gun fires.
I want the bullet to come out & hit the bullseye--That's my idea of fun
I cut down loads because this old body is getting tired. Your time will come.
I will shoot factory loads in this rifle---if no primer backout--CASE CLOSED
ENJOY YOUR HEADSPACE
H :neener::neener::neener:

fguffey
May 8, 2014, 11:56 AM
Looking at fired cartridge--the primer is backed out a little less than 1/16".

On the outside chance there are other reloaders that are having the same problem outside of the OP and the choir I will remind the 'outside-others' 1/16" is .0625". Less than .0625" is .050", if the OP chambers a new factory round and pulls the trigger there is a chance the case head will separate from the case body, and if it does not the case will be unfit for reloading.

I've never loaded .30-30, so don't know if there's enough shoulder to do this. If your rifle does have excessive headspace, this might work. You would be creating ammo specific to that rifle, however.

The 30/30, 303 British, 30/40 Crag etc. has a lot of tapper, not much shoulder, in the beginning the belt/rim was designed to hold the case to the rear, what happened in front of the rim/belt was of little importance BUT! the distance the case head traveled forward was, again, .050" is too much primer protrusion.

F. Guffey

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