Recently bought a Remington 760 pump that was rebored to 9.3x62 mauser. Beside the fact that I haven't been to get it to group with factory ammo... The spent Remington ammo cases have mangled primers? Never saw such a thing and I'm hoping someone can tell me what's going on and maybe how to correct it.
Thanks.

What does the bolt look like?
A pic of the bolt face would be helpful, I suspect it is being done by the extractor, it's probably broken or damaged.

Cheers.

The ejector makes sense. I've noticed the primers have gradually gotten worse after ~20 shots.

If you look close the pock mark is curved like the
ejector.

Looks like a pressure issue. Tool marks of boltface embossed on primer, primer flattened and cartridge ID info on case head distorted/flattened. As stated, ejector mark on primer. Looks as if brass is flowing into the gap between the ejector plunger and the bolt face. Cartridge rotation during extraction may be tearing this off. Also a significant expansion ring on case head.

looks more like headspace to me. the primer is getting nail-headed - it backs out on ignition, wedging into the ejector, then the case shoves back onto the primer. the primer tears against the ejector as it is squashed.

the rounded shoulder on the FP divot do not indicate pressure flattening, to my eyes.

Looks to me to be too MUCH pressure and the brass is flowing into the ejector.

The pressure does look high but I have seen higher with factory ammo (7x61 S&H) and the same type of ejector but no problems such as on these cases. It does not look like brass flowing into ejector as although the primers are reasonably flattened, they are not at the point of cratering around the firing pin or flowing out of the primer pocket. To me it seems the cases are sticking tight in the chamber on firing and as the bolt face rotates against the case head the ejector edge is gouging the primer. It has nothing to do with the extractor as that is out on the rim of the case.

Try dropping the pressure of the loads but also a careful stoning of what looks like a sharp edge on the ejector pin may stop it picking up the edge of the primer.
The ejector on my 7x61 S&H rifle had a flatter profile which 'filled' it's pocket in the bolt face.

I don't think it is the ejector itself, but the edge of the ejector mortise that is shearing brass that has flowed into an apparent gap between the two. Look at the bolt face pic closely. There appears to be a gap between the plunger and BF on the FP side, right where the tear starts.

The primers are indeed flattened to 50% of the pocket radius(observe the unfired case). They are deeply impressed with the boltface machining marks. This is apparently not dangerously high, but enough to push primer brass into a gap. I frequently see case heads like that fired from bolt guns, but not with the primer issue. Cratering is not always indicative of high pressures, but often observed. If a bolt has a tight FP clearance with the FP hole, then there is nowhere for brass to flow. It will take the path of least resistance; in this case into the plunger hole gap.

This fellow's problem is he may be restricted to shooting factory loads and may not be able to reduce the pressure except by going to another brand of ammo. Since the primers are expendable, unless the issue causes case sticking, it may just be a cosmetic problem and not a safety one.

Perhaps having the ejector hole trued and a fabricated over-sized ejector installed would cure it. A simpler cure might be to lightly stone the offending edge of the ejector hole. Maybe that would let it ride over the brass instead of tearing it.

Bobster, I would certainly agree the ejector seems to be a sloppy fit in the mortise, unfortunately the photo is a little blurred. I think you are correct in that the primer brass must be flowing into the mortise and then being hooked by the sharp mortise edge as the bolt rotates and the case is held in the chamber. A harder primer in other factory ammo brands may cure the problem in this case, the firing pin indentation looks quite deep so maybe the R-P primers are soft?

Here is a factory ammo fired case which gave no problems in my rifle (mentioned in my earlier post) as it had a properly fitted ejector in the mortise with a flat profile nose.

Thanks to everyone for all the great information!
I managed to get a decent zoom-in shot of the bolt face and can really see what you're talking about.
I will be trying some different factory ammo for comparison. I intend to reload as soon as I can get some bullets...and eventually get this rifle shooting groups.
Are there any primers ("soft primers") that I should avoid when reloading for this rifle?
Do you think it's necessary and/or possible to adjust the ejector for a better fit?

Whoa, great shot. It looks to be a burr on the bolt face next to the ejector. If you stone that down it should cure the problem.

Looks like the drill might have walked with the ejector hole was drilled.
It could be repaired by several methods or just replace the bolt head.

Remove the ejector and clean up the hole; and stop using those primers; go to CCI which are harder. Ejectors are not designed to hold any pressure so the actual fit is not important in this case. You will always have a hole there, won't you?

Checked out another Remington 760 at a local gun shop... ejector is identical to mine with the thin gap on the bolt face next to the ejector... Also bought some PPU factory ammo while I was there to compare with factory Remington ammo I've been using. I will clean-up the bolt head/ejector before heading to the range.

I have never seen a hole under a primer before.
That is a guaranteed primer flow on each shot.

I just checked my 1952 760 and it does not have that eye brow on the ejector hole.

quote:

Originally posted by dpcd:
Remove the ejector and clean up the hole; and stop using those primers; go to CCI which are harder. Ejectors are not designed to hold any pressure so the actual fit is not important in this case. You will always have a hole there, won't you?

My 760 and the one I inspected at the gun shop are late '70s vintage with the plastic ejection port cover and stamped wood. The ejector/bolt assembly may be another (lesser known) reason why earlier 760's (like your 1952) are more desirable for their craftsmanship.

Of course, the ejector hole can't be under the primer and yours is oval shaped and is. Use harder primers and or re-bush the ejector hole. Your primers are backing out into the slot and then when the bolt rotates, it tears off the protrusion.

That photo is awful showing up some poor gun making. The ejector is far too big for what is needed and off course the drill has run off bring the ejector mortise out into the primer area. A harder primer may cure the problem but I would be opening out the ejector mortise and then bushing down to a smaller ejector pin so any ammo can be used.

quote:

Originally posted by dpcd:
Of course, the ejector hole can't be under the primer and yours is oval shaped and is.

DPCD nailed it. Your ejector is moving under the primer surface when a round is chambered. A real simple cost free way to make it stop is to remove the ejector and remove a very little bit of metal from the frontal, inward edge of it to keep the ejector surface away from the primer. But I would suggest trying Numrich for a replacement bolt.

Thanks for the insight. Tried a different fatory ammo with similar results... PPU ammo primers didn't flatten-out as bad as the Remington ammo primers but it's still marking the primers.
Because this Remington 760 rifle was rebored and rechambered from a 270 to 9.3x62...any thoughts on the possibility there's a headspace issue that is creating high pressure with factory ammo and, in turn, creating the primer issue?
I'll probably stop by the local gunsmith with the information you guys have provided.

The .270 is a way higher pressure round than the 9.3. It was probably causing bigger divots in .270 than the 9.3 does.
Those bolt heads are easy to replace if you can find another. Check Ebay & gunbroker.
If no luck that hole or the firing pin hole can be bushed to fix your bolt.


[QUOTE]Originally posted by Triple4:
Thanks for the insight. Tried a different fatory ammo with similar results... PPU ammo primers didn't flatten-out as bad as the Remington ammo primers but it's still marking the primers.
Because this Remington 760 rifle was rebored and rechambered from a 270 to 9.3x62...any thoughts on the possibility there's a headspace issue that is creating high pressure with factory ammo and, in turn, creating the primer issue?
I'll probably stop by the local gunsmith with the information you guys have provided.

quote:

Originally posted by Triple4:
Thanks for the insight. Tried a different fatory ammo with similar results... PPU ammo primers didn't flatten-out as bad as the Remington ammo primers but it's still marking the primers.
Because this Remington 760 rifle was rebored and rechambered from a 270 to 9.3x62...any thoughts on the possibility there's a headspace issue that is creating high pressure with factory ammo and, in turn, creating the primer issue?

If the re-chambering job has created some head-space for the new cartridge, then potentially on firing the primer backs out slightly (as they can do with excessive head-space) and the unsupported edge of the primer can flow into that enlarged ejector hole creating a divot on the primer edge as one of your photos show clearly. Once the case is seated back against the bolt face as the pressure builds to maximum the primer is reseated in its pocket but the divot remains to be gouged as the bolt is opened.

Perhaps it was okay in the original 270W chambering with correct head-space and the issue has only shown up with the re-chambering to the new cartridge?

My bad with my original reply, meant to say ejector, not extractor.
The primer flowing into the ejector hole should pose no problem, unless they pierce.
Is it hard to cycle after firing?

Cheers.

Check the ACTUAL headspace on that rifle using a mangled fired case...with a Hornady headspace gauge or make on one.

That will tell you how MUCH excess there is...then adjust your sizer to set back the shoulder about 1-3 thou...just enough for easy/correct cycling.

IF excess headspace is your problem, and I think it might be, fitting your sizer to the actual amount of excess headspace will cure the problem...no more primer back out.

Doing this is safe AND desirable for accuracy... I have several "gunsmithed" rifles with excess headspace up to 0.0250" that once the sizer was adjusted properly have been shooting without problems for over 30 years.

Reducing the load or going to a different burn rate powder might also help...those primers are WAY too flat for my taste, but may be a function of soft primers combined with a stout load AND the excess headspace.

quote:

Originally posted by 416RigbyHunter:
My bad with my original reply, meant to say ejector, not extractor.
The primer flowing into the ejector hole should pose no problem, unless they pierce.
Is it hard to cycle after firing?

Cheers.

No problems cycling.

As I understand it...Maximum overall specified length for the 9.3x62 is listed as 3.29".  I measured the Remington ammo at 3.14"overall length.  The Prvi factory ammo at 3.27".  Then, to check the amount of headspace/throat, I took an empty case and seated a bullet by hand a short way down the case neck...chambered the round...closed the bolt to seat the bullet directly on the lands...reopened the bolt and measured 3.47" overall length on the dummy round.  I'm not sure if this is the correct way to do it but the difference between the dummy round overall length and the factory rounds is .2" headspace for the Prvi factory ammo and .33" headspace for the Remington factory ammo..  If there is excessive headspace, I'm guessing there's not much that can be done with a 760 and how the barrel attaches.  Plus, I have to figure out what length will fit in the clip and cycle properly. I may have try your suggestion to compensate for the excessive headspace but I don't know if it will do much for my situation...but Thanks for the info.

quote:

Originally posted by NONAGONAGIN:
Check the ACTUAL headspace on that rifle using a mangled fired case...with a Hornady headspace gauge or make on one.

That will tell you how MUCH excess there is...then adjust your sizer to set back the shoulder about 1-3 thou...just enough for easy/correct cycling.

IF excess headspace is your problem, and I think it might be, fitting your sizer to the actual amount of excess headspace will cure the problem...no more primer back out.

Doing this is safe AND desirable for accuracy... I have several "gunsmithed" rifles with excess headspace up to 0.0250" that once the sizer was adjusted properly have been shooting without problems for over 30 years.

Reducing the load or going to a different burn rate powder might also help...those primers are WAY too flat for my taste, but may be a function of soft primers combined with a stout load AND the excess headspace.

quote:

Originally posted by Triple4:
As I understand it...Maximum overall specified length for the 9.3x62 is listed as 3.29".  I measured the Remington ammo at 3.14"overall length.  The Prvi factory ammo at 3.27".  Then, to check the amount of headspace/throat, I took an empty case and seated a bullet by hand a short way down the case neck...chambered the round...closed the bolt to seat the bullet directly on the lands...reopened the bolt and measured 3.47" overall length on the dummy round.  I'm not sure if this is the correct way to do it but the difference between the dummy round overall length and the factory rounds is .2" headspace for the Prvi factory ammo and .33" headspace for the Remington factory ammo..  If there is excessive headspace, I'm guessing there's not much that can be done with a 760 and how the barrel attaches.  Plus, I have to figure out what length will fit in the clip and cycle properly. I may have try your suggestion to compensate for the excessive headspace but I don't know if it will do much for my situation...but Thanks for the info.

No you are not checking the headspace, you are only checking the overall length of the cartridge (COAL) which can vary depending on bullet weight and style and has nothing to do with headspace. The COAL is usually limited by the magazine or the amount of freebore (aka throat or leade). The headspace in your rifle is measured from the bolt face to the start of the shoulder in the chamber so your cases have to conform to this. With a fired case you should set your FL die to just size the neck i.e. back the die off the shell holder in your press and size a case until only the neck has been sized, easy to see this. If the case is a little tight to chamber wind down your FL die just a fraction, resize the case and try in the chamber. Best result is when you feel a very slight drag on closing the bolt, this indicates the case is properly headspaced for the chamber.

I appreciate the headspace explanation. At least I figured out how much throat the rifle has. I'll report back when I figure out more...

This is a picture of two calipers...the top one with a Hornady headspace gauge and the bottom one with a Hornady bullet ogive gauge...both do the same thing...and some "home made" gauges...I make gauges out of brass, steel, alum, plastic, use nuts or ANYTHING as long as it has a ID slightly larger than the case neck OD and an OD slightly smaller than mid shoulder and is square and parallel...I use 1" scrap stock, old barrels and alum mostly just for handling. I've been making these types of gauges of over 50 years.

To use...look at the picture...first measure a fired case, then size it and measure it again...SUBTRACT THE SMALLER NUMBER FROM THE LARGER MEASURE AND DON'T WORRY ABOUT THE OVERALL LENGTH...IT DOESN'T MATTER...BELIEVE ME.

In this case I used the upper caliper...I could have used the lower caliper as in the pic or just the gauge alone...it doesn't matter as long as you only use ONE GAUGE AT A TIME.

The top caliper indicated 4.125" sized...4.129" fired...using the bottom caliper the measurements were 3.125" sized and 3.129" fired...and the subtracted lengths for BOTH SETS OF MEASUREMENTS IS 0.004"...the only difference is the upper gauge is 1" LONGER than the bottom gauge. (my dies are also adjusted for minimum shoulder setback and sizing which helps in the accuracy and case life department.)

If I had used a 1" piece of steel with the correct size neck hole the measurements would be about the same as the bottom gauge because the bottom gauge is about 1" long also.

Are you getting the picture??? You want to measure the SHOULDER SETBACK DIFFERENCE...THAT IS THE ACTUAL HEADSPACE OF EACH INDIVIDUAL RIFLE. It isn't the actual total length of the measured case/gauge, it is the DIFFERENCE between the lengths. My COAL with 270-320 gr bullets is still ~3.29-3.35" to fit my modified mauser 98 magazine.

HOW to do this (and MANY other "secrets" that are now blabbed all over the net) was taught to me by my shooting/reloading/rifle building mentors back in the day when I still had mothers milk on my breath.

All you have to do to get your rifle working correctly is to follow these steps to find out WHAT the actual headspace is, then correct by adjusting your sizer or buy a Redding competition shell holder that will reduce the amount of headspace to about 0.002"....AND REDUCE YOUR LOAD A BIT...IT'S TO HOT!!

GOTO Hornady and look up the directions on how to use their headspace gauges, buy or make a gauge, measure a fired/sized case and start making good ammo.

lUCK

THATS BETTER!!

I really appreciate you taking some time to pass along your secrets...I'm all ears.
You mentioned reducing my loads. That's one of the oddities that brought me to you (and the others who've offered information)...Although I intend to reload for the rifle at some point, both pictures I posted above of spent cases are from two different factory loads. Remington and Prvi Partisan...?! Which is why I started down the path of headspace, etc.
Thanks again for the help!

Solve the "headspace" problem...if that is the actual problem, first...the flat primers might go away or not be of concern at all...pumps and autos can be a bit finicky with what they digest...and sometimes need a dose of tums.

THEN...LET US KNOW...what your results were. Many times problems are presented but the actual solution is never forthcoming...a bit disconcerting....makes one think suggesting solutions is wasted and the solution is always useful to someone and for the future.

Luck

I will be sure to let you know how the "project" goes. I really appreciate everyone's help and information!

What we actually know:

1. This chap has already stated that he is restricted to using factory loads, so handloading is not an option for him at this time.

2. The burr on the primer does not impede function or safety.

3. Headspace has nothing to do with brass flow into the ejector mortise, pressure and brass hardness does. It may however be an issue if he reloads (casehead sep) which he does not at this time. It probably should be checked since this is a rebore/rechamber. Properly headspaced chambers allow the primer to back out a thou or two and be re-seated during the firing cycle (otherwise semi-autos couldn't cycle). That is normal. The only exception to this is in zero headspace target bolt guns.

4. There are visible signs of high pressure on the brass case heads involving brass flow of the primer and case.

5. There is a visible burr on the bolt face above the ejector mortise and it is likely the prime suspect for the primer damage.

6. The positioning of the ejector mortise over part of the primer is a bad design and invites brass flow and primer damage.

Options:

The logical course is to eliminate possible causes (re: burr and mortise) by stoning and test. Check headspace for safety. If still a problem, alter boltface as previously described to move ejector away from primer radius.

quote:

Originally posted by Bobster:
What we actually know:

1. This chap has already stated that he is restricted to using factory loads, so handloading is not an option for him at this time.

2. The burr on the primer does not impede function or safety.

3. Headspace has nothing to do with brass flow into the ejector mortise, pressure and brass hardness does. It may however be an issue if he reloads (casehead sep) which he does not at this time. It probably should be checked since this is a rebore/rechamber. Properly headspaced chambers allow the primer to back out a thou or two and be re-seated during the firing cycle (otherwise semi-autos couldn't cycle). That is normal. The only exception to this is in zero headspace target bolt guns.

4. There are visible signs of high pressure on the brass case heads involving brass flow of the primer and case.

5. There is a visible burr on the bolt face above the ejector mortise and it is likely the prime suspect for the primer damage.

6. The positioning of the ejector mortise over part of the primer is a bad design and invites brass flow and primer damage.

Options:

The logical course is to eliminate possible causes (re: burr and mortise) by stoning and test. Check headspace for safety. If still a problem, alter boltface as previously described to move ejector away from primer radius.

The burr, if it is one and not just a bit of fluff or something on the bolt face, is outside the diameter of the primer. Where the 'burr' is on the bolt face you would expect to see a mark on the brass case head, I don't see one. The shape of the 'flow' seen on the edge of the primers exactly matches the profile of the ovalled ejector hole in the bolt face.

I can't see how this problem was not cured when the rifle was in it's original 270W chambering as the same ejector hole must have been on the bolt face and factory loads in 270W are no slouch for pressure, I suggest the rifle did not show this problem when in 270W. Remember the 9.3x62 loads being fired in the newly chambered rifle are factory so pressures will be standard and different factory loads have been fired so it is not likely just one out of the box 'high' pressure factory loading.

The only condition that could have changed is head-space?

It ain't excessive headspace.
Here is a suggestion; if you must use only factory loads, shoot it and forget about the little primer protrusion burr. Better, start reloading and use CCI primers. Maybe, get the bolt face fixed.

How much headspace is too much? To get a rough idea of the headspace in this rifle, following what you explained to me, I used a 444 Marlin case as a quick headspace gauge (case mouth diameter falls between Min and Max diameters of 9.3x62 shoulder) and results as follows...

Reminton factory - unfired: 4.275" fired: 4.295" = .020" headspace
Prvi Partisan factory - unfired: 4.280" fired: 4.295" = .015" headspace

I am a reloader but started with factory ammo for this particular rifle because it is available and reload components were tough to find... So, if the solution lies in reloading for this rifle, I can make it happen.

That ejector hole doesn't look out of round to me. I think that dark ellipse you see is the flat cut into the ejector pin that rides on the cross pin to retain the ejector. Normally that flat would not extend that far forward. Moot point because the ejector pin does not support the case and it is abnormal for the ejector hole, be it round or oval, to mark the face of the brass like that, unless there is high pressure.

You sure they rebored the hole all the way through?

Good choice for a gauge. I checked my loaded/fired cases with a 444 M case and came up with 4.264" reloaded in R-P 35 Whelen brass and 4.265" fired.

I built this rifle, M98 action Lothar Walther prefit custom barrel. Just cleaned up the faces and screwed on the barrel and checked headspace with a case sized in RCBS dies I'm now using...couldn't believe how close it was.

Your measurements indicate a H*LL of an excess headspace...it's shouldn't be more than 0.004" to 0.008" MAX. When I build a rifle I try for 0.003" to 0.006" and hope to hit 0.004"-005" when everything is screwed together and torqued. Someone wasn't watching their depth of cut very closely in your case.

I had the very same problem with a 338-06 I had built back in the early 70's. It came back with an excess headspace of 0.022". Originally I made a horseshoe shaped shim 0.018" thick and used it for many years.

I'm still shooting the original 50 cases I made back then and they have at least 20 reloads on them, and probably many more, with the original 225 gr Hornady SP/4320/~2750 fs/5 in one ragged hole, most accurate load...it just won't shoot anything else below 1 1/2".

When Redding came out with their Competition shell holders, set of 5 going from 0.002" to 0.010", 0.002" steps, I got sets in .223 and .308 size...now they also have belted mag shell holders. Later I had them make me one at 0.015" and one 0.020" thick...just call/contact Redding...last one I bought for belted mag ran ~$18.95 I think.

I think my first action would be just getting a shell holder at 0.015"...it certainly won't hurt anything and for a few dollars plus a little time wait, your problem might be solved.

Your magazine should handle ~3.60" plus or minus a bit but your throat a 3.47" still gives you plenty of "seat out" for any bullet you choose over the factory/SAAMI 3.29" length.

I like RL-15 and RL-17 for powders but you can do a search on this thread for 9.3x62 loads and powders...there are LOTS.

Luck