excessive headspace

D

drover

Member
First of all let me clarify that I am not a gunsmith nor do I consider myself one, but I have worked on my own rifles for many, many years and have full understanding of the dynamics involved with them.

Now for the question - at what point do you consider headspace as excessive?
I do not have a set of headspace gauges for my Rem 700 22/250 Varminter but the issue is that it is a brass eater even with mild loads. This is an older "C" series action that has been fired less than 200 rounds and never hot-rodded, 35.5 gr of H4895 with 50 gr Nosler BT seated .005 off the lands is my preferred accuracy load.

It doesn't matter if I full length size or just neck-size, brass life is limited to about 3 reloads and I am showing enough stress at the base of the brass that I toss it. In an attempt to determine if the headspace may be a little long I used new full-length sized brass, removed the ejector from the bolt face and placed shims on the bolt face and chambered the F/L new cartridges to get a rough idea of what is going on. Using a .003 shim the cartridge will chamber, using a .004 shim I begin to feel enough resistance that I must force the bolt to start closing it, using a .005 shim I cannot close it.

I realize that this method is somewhat crude and subjective however running it to the nearest gunsmith to have it checked is not an option since he is over 200 miles away.

So do I have a "brass-eater" or is the headspace a bit excessive??

Be gentle, but give me your honest opinion or if more info is needed let me know.

p.s. - The rifle is an honest 1/2" rifle day in and day out so I may end up just living with it irregardless of the issue.

I have also posted this in the General Discussion Forum.

drover
 
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If you are getting 1/2 MOA accuracy from your factory built 22-250, congratulations; you've got a winner!

It sounds as if your only problem is oversizing your brass and bumping the shoulders excessively. The secret is in the way you set up your sizing die. To do this properly, you need a good dial caliper and a comparator nut or some type of headspace 'thingy.' Both are available from Sinclair, Bruno, Russ Hayden or most any benchrest supplier. You should be pushing your shoulders back no more than .001. Do this and it will greatly extend your case life. If you have any questions, get back to us.

Gene Beggs
 
My reply from the General forum.
You're wasting time if you don't check with headspace gauges. Using brass won't work because it is all over the place. If you use sized brass you could be even further off.
Gene is correct, you can probably use the brass many times if you don't oversize it.
Butch
 
I already replied to this on the general forum, but forgot to ask, how is the brass failing?

If it's head separations and you're neck sizing you've got the die set to where it's bumping the shoulder which could mean a die problem, but if it's neck splits the chamber neck is likely too large in diameter. This problem can be made worse if you're using non-bushing dies because conventional dies size the case necks way too small, then expand it back up so that they'll take a bullet. Bushing neck and FL sizing dies can have a bushing selected that will size the neck of the case the minimum required so that the neck expander isn't being forced to open up a way undersized neck. Even then if the chamber neck is way too large you will end up having neck splits unless you anneal the necks every other firing or so.
 
I am showing enough stress at the base of the brass that I toss it
Click to expand...

We need to know what you mean by this statement...........What exactly is the brass showing? Is the base separating? Are there cracks in the brass? Are the primers falling out or extended from the primer pocket? Or is the brass just a little bulged at the base?

Pictures would be great if possible..............
 
Gene,

Yes, I agree that I have a winner, it does consistent 1/2" - three shot groups, with boring regularity. It is an older "C" version action of the Remington Varmint Special (think BDL wood sporter style stock with a Varmint contour barrel). This rifle has been a great shooter from day one, however it is not quite box-stock. I have done an action glass bed on it, free-floated the barrel and adjusted the trigger to 1 & 1/2 lb pull.

For neck sizing I am using a Lee Collet Die and have it set so that I am sizing the upper 2/3 of the neck so I don't think that I am pushing the shoulder back in my neck sizing step. For my full-length sizing I set my F/L die by smoking the shoulder of the cartridge and then setting the die so that it just contacts the case enough that it will chamber with a slight resistance.

Butch,

I am in total agreement with your statement but at this time since I do not have access to a set of gauges and it is cold and snowy here, and I am bored to tears since I can't get out to do anything I thought I would run this past the folks on here for feedback. It is currently 5 degrees and tonight is forecasted for -20 and I have been housebound for too many days.

Larry,

The stress, or impending separation, is at the juncture of the web of the case where the head and body taper begins - about .325 from the base of the cartridge. The stress mark occurs on the first firing and progressively gets worse, by about the 3rd firing it is bad enough that I toss the cases.

I suspect that the ovesize chamber theory may be correct, I have to go be gone soon but when I get back tonight I will get some measurements posted.

RoyB - pictures

You can see the stress marks just above the base, these are both 3rd fired cases and in good light cracking is apparent on both of them.

There are no overpressure signs whatever, cases extract easily, primer pockets are still tight.

brassfailure.jpg
 
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Do you have any CerroSafe? Perhaps make a chamber casting and measure.

Data is good.
 
I did find a couple of fired cases that had not been resized and they miked at .464 at the web, my Sierra manual shows the measurement at that point as being .467, so it appears to be under that measurement.

If you refer to the pictures the measurement was made at the slightly shiny spot on the circumferance just below the stress marks.

Off to town - I will check back later tonight.

Thanks, drover
 
sound like the "stress marks" are just that marks..not over stress and mayeb you have been tossing brass too soon.

maybe a poorly chambered rifle...a line in the chamber

just guessing from the pics...

mike in co
 
You can buy headspace gauges for around $25. Get a piece of fine stiff wire and reach in the case and if it is separating you should be able to feel it.
Butch
 
I'll attemp to show 4 pictures of a simple gage. I built this one, but all smiths build these similar. This is how you determine how far back you are moving the shoulder when you size brass. You measure new, 1 time fired brass, then you measure as you set up your dies for sizing. .001" is all you need to move it. Once it it close you can go by feel with a stripped bolt.

Shouldergage1.jpg


Shouldergage2.jpg


Shouldergage3.jpg


Shouldergage4.jpg
 
Hard to tell, but it does look like the brass is ready to experience a head separation. The bent thin wire to feel for a ring on the inside does work sometimes.

Here's what I would do. Take a new piece of brass without a primer. Do not size it. Insert it into the chamber, close the bolt. Open bolt and remove the brass. Put a piece of electrical tape on the base of the brass, trim it nice an round so nothing hangs over the edge. Reinsert the brass and try to close the bolt. If the bolt closes without resistance, you have a headspace issue. Remove the brass and put another layer of tape on top of the first. Reinsert the brass and attempt to close the bolt. If it closed on two layers of tape you have a BIG headspace issue.

In either case, you will need a real headspace gauge and a qualified smith to fix the issue.

There are ways to use long bullets or a false shoulder to fireform your brass to that long chamber..............but that's a whole other issue!
 
Drover,
Domestic 22-250 brass is also notoriously undersized at the case head. So it might be a case of stacking tolerances - undersized brass in a chamber that's on the large size of "normal."

Why WW and Rem make them undersized, who knows? Perhaps Lapua is bigger, otherwise you may need to make your brass from 308, etc.

Regards,
Ron
 
Brass Marks

My experience and expertise is not near those that have posted, but I can offer $0.02. Lee Collet die rang a bell with me. My cases, all of them, have similar brass marks after firing and collet neck sizing. I could feel nothing with a bent wire paper clip. I finally took one to work and had the shop cut one case length wise. No thinning near the base where the brass shine marks were. Everything A-OK. Take a look !!:)
 
Gentlemen,

Thank each and everyone for their responses.

I have used the bent wire trick and I can feel the crack inside the case at the same place the shiny spot is. Using the magnifer on my inspection lamp (I am unsure of the magnification but it is a typical mounted desk lamp with a magnifer and a built in light) I can see the impending separtion on the case, at the shiny ring just forward of the web area. I have tried going beyond 3 to 4 firings with a few of the cases and invariably I have had head separation.

I am using Lee Collet dies which are set to resize the top 2/3 of the neck, I have determined this by smoking the case neck and setting the collet die so that it is only resizing the top 2/3 of the neck, it is definetly not hitting the shoulder.

I did do some more measurements of the fired cases, in comparing the fired cases to new WW brass, the web area is .002 to .003 larger in diameter. Measuring the impending failure area (shiny ring above the web) it measures .002 larger.

I did try the tape trick but the bolt will not close on a piece of electrical tape, I measured the tape thickness afterwards and it was .007, so since I cannot close on a .005 piece of shim stock that was no surprise. As mentioned a piece of .004 shim stock will require forcing the bolt over while a piece of .003 gives just a touch of resistance, just enough to know that I am chambering a cartridge.

pbike - thanks for the pictures and very clear instructions on how to build the gauge, building one of these just went to the head of my to-do list.

My loading procedure has been to prep the brass by an inital neck sizing, check for trim length and then load it. At the time that I can see failure traces beginning to occur the brass is starting to give a slight resistance to chambering.

Failures do not occur like clockwork at 3 firings, in a few instances I have had 5 firings before failure but more often than not at 3 is when the cases are starting to show external signs of separtation. In some instances at 3 loadings the stress cracks are visible with the naked eye using a bright light or in sunlight.

More thoughts - After looking at all of the answers and suggestions and with the measurements I have taken I do not think I have a headspace issue but the next time I am in the city I will find a smith and have it checked. I am beginning to wonder if the chamber is oversized after taking the measurements of the body. In the few instances of brass life that lasted long enough to require F/L resizing (usually after 3 firings) then failure occured within the next 1 or 2 firings.

I do not have a shoulder bump die but have set up my F/l die so that I am just bumping the shoulder, so perhaps I am fooling myself there and instead of just bumping it I am forcing it back further than I believe. To be sure of this I intend to build a gauge as illustrated by pbike.

My next step is to take 20 pieces of new WW brass, neck size them, check them for trim length, number them 1 through 20. I will fire them and only necksize them until such time as they give too much resistance when chambering, at that point I will F/L resize them by doing a minimal shoulder bump on them. I will keep a log of each piece of brass, by number, and the times necksized and F/L resized and number of times each before impending failure.

I have been reloading for over 45 years, not as a caual reloader but as an active high-power competitor and varmint shooter on average I go through 2000 to 3000 centerfire rounds per year. I suppose the fact that I have never had something like this occur before is why I am so frustrated with it. Although I have owned this rifle for a long time this is my first real go-round with 22/250 loading and I know they have the reputation of being hard on brass but I have to believe that it is something more than that in this case.

After all of the ideas that have been posted I am to the point where it appears as though it is something that I am doing that is causing the problem.

Thanks again and any more thoughts pop up please post them.

drover
 
Just for grins, expand a few unfired cases to 6mm, and then adjust the FL die down till you feel a little resistance as you close the bolt, then load and fire them, and tell us the result.
 
One thing that hasent been mentioned, How does the bolt lift after firing feel ?
Reciever lug set-back will give the impression of correct head space with gauges or shims.
I've never seen reciever lug set-back on a Remmy,,,, but you never know.
 
The brass is being damaged on the very first firing because the rife has excessive chamber headspacing. You need to fire form the brass on the first firing as if you are blowing out the brass to fit a wildcat chamber. Shooting factory ammo, then reloading that brass will not work, as the cartridge headspace is already to short for the chambers headspace. Seating the bullet to jam into the rifling might keep the head against the bolt face on firing. Some put a light oil on the brass to help also.
 
I would not recommend oiling the brass for full power loads. This could cause excessive bolt thrust. Also, I have read that seating bullets hard into the rifling is not a reliable method to hold the case on the bolt face. That is why I suggested the false shoulder method, which is reported to be reliable for doing so.
 
Boyd,

If I understand correctly what you are saying is this - using new cases expand the necks up to 6mm and then using the 22/250 F/L sizer resize the neck down until such time as I can chamber the case with a slight resistance. In essence I will probably end up with a sort of a 2-step neck with a lower portion still being expanded to 6mm but the upper portion being resized back down to 22 caliber. Is this correct?

If so, I assume that the intent is to make a false neck to hold the case firmly against the bolt face at the time of the inital firing. Would you expound on this a bit since I am somewhat unsure of just exactly what I am looking for after doing this. It is supposed to be 0 or below here for the next couple of days but as soon as it warms up I will give it a try and post pictures.

yooo vinny - the bolt lift is normal, no drag, no hitches, lift is easy with no clicks. There is no sign whatever of excess headspace, I have chronographed the load and it is right in line with the loading manual data, primer pockets are not loose and primers (I have tried various ones but have settled on Federal since they give the best accuracy) do not show any pressure signs.

Thanks to all - drover
 
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