I just rebarreled a Rem700 (factory 24" lightweight barrel for a 20" heavy tactical) and set the headspace with Forster gauges and got to test fire her this afternoon. I fired some factory 7.62x51 ammo as well as some .308 and 2 of the 7.62 rounds started to separate that the top of the case web and some of the .308 shows stress in the same place. I got home and double checked the headspace and it's exactly where I set it at (closes on "go" gauge, just starts to cam on "no-go" before stopping) so I'm at a loss why I'm getting this problem. This isn't my first rebarrel job, but again I haven't seen this in a properly headspaced barrel. Any ideas?
Gunsmithing Case head seperation Remington 700 help
- Thread starter Mattitude
- Start date
How much bolt nose clearance do you have? Maybe a bit too much and there is to much unsupported case. Your go gauge can still check good.
Break the receiver off of the barrel. Measure the thickness of the recoil lug. Then measure from the receiver face to the top of the bolt lug Then measure the top of the receiver face to the top of the bolt nose.
Formula:
lug face to receiver face dimension+recoil lug thickness - Breech Clearance ='s Total tennon length
Bolt nose to receiver face +recoil lug thickness - Breech Clearanc - Total tennon length = Counter bore depth.
If your counter bore is too deep then your chamber is leaving too much case exposed.
Also too large of a chamfer on the breech can be suspect.
When I set clearance for the bolt nose I will leave .010 plus .002 for crush when I torq the barrel on. Measure the rounds that didnt have a case head seperation around the web and measure an unfired one just for shits and giggles.
Kc
Kc
Big Toby, thanks for the explanation. I'll break it down tomorrow and make some measurements. What specs should I be seeing and when does it become too much? I'm only asking because I'm still learning and have been going off headspace gauges and last thing I want to happen is to lose body parts when my luck runs out with missed measurements. The barrel I'm using is a Remington take-off that I bought from a member here, so I know it did work on its original receiver just fine...now if I can get it to work on mine is the big question.
I got .466 with an unfired case and .471 with a fired one w/o separation.
When you set this clearance then how do you set your headspace while maintaining this clearance?
When you set this clearance then how do you set your headspace while maintaining this clearance?
More than likely you have an issue due to change of components. Different Lug, receiver, bolt nose protrusion, and so on. These are things that need to be looked at before you chamber. This is a big reason why take off barrels are not always a good idea.
JWP
And please do not take these measurements with calipers. Calipers are just a tape measure with a Tach. Make sure you are using a depth mic for the receiver measurements and a good 0-1 micrometer to measure your lug.
Ok, I think it's sinking in now and realizing that take-off barrels are a bigger roll of the dice than I previously thought and is just better to finish chamber a barrel. Also thanks for noting to take depth measurements with a proper depth gauge.
How terrible/crappy are the case web measurements that I gave on the fired cases?
How terrible/crappy are the case web measurements that I gave on the fired cases?
For a quick measurement you can use a piece of soft solder. Partially flatten out a short pc of solder about 5/8" flatten it to about .020" put a small dab of grease on both sides of the solder. Place the solder on the bolt nose and close the bolt carefully the solder will squash down to reflect the clearance between the bolt nose and counterbore just remove the solder and mic it. You have to be a little carefull to get the solder in the right place while you close the bolt. Works for a quick measurement without taking it apart
When measuring while cutting a chamber I will put the go gauge in and spin the action on with the bolt in the closed position. when the action is snug, I measure the gap between the shoulder on barrel and the lug. I adjust my MARS kit just short of where I would like to be and check it again and make my final cut +.002-.003 for when I torque the barrel down. The difference between a go gauge and no go is .004 (please correct me if I'm wrong)
This is how I do it and it has worked well for me. It does not mean its the only way to do it.
This is how I do it and it has worked well for me. It does not mean its the only way to do it.
Easiest way is to remove the firing pin or close the bolt in the fired position. If the front of the handle contacts the back of the rear receiver ring when you push it forward, you have too much clearance.
Ok, so I did this test with the bolt that originally came with this donor rifle (ADL that was stripped for the bolt & action strictly for this build) and the bolt handle isn't touching the rear of the receiver ring...but it's very close and I also get slight lateral movement. Then I took another bolt from my other Rem700 and I not only had plenty of daylight between the handle and receiver ring but I also had zero movement. I tried the suspect bolt in my good rifle and not only did the handle touch the receiver ring but I had slight lateral movement as well. I'm thinking that I got an out of spec bolt. Does that sound plausible???
I'd guess Rem's spec window is big enough to drive a truck through. Paint the front of the offending bolt with a Marks-a-lot and push it forward and work it to verify that it's hitting the barrel.
You don't need to pull the gun apart to measure breech clearance. In fact imho you should leave it assembled as this gives a real world dimension. Here's how:
Get a sliver of soft solder. Just cut a snip from a roll of .04 stuff from radio shack.
Stick it to your forward side bolt lug with a dab of grease.
Stick it in the action and close the bolt up in the receiver. Pull the bolt and find the sliver. Measure its thickness. When you close the bolt use a light "forward and down" tapping action with the palm of your hamd. This will aid in getting it shut w/o damaging anything. (Some actions -aka customs, are prone to galling and this simple procedure can gall a lug on them. Your pretty safe with m700s though)
This is a real world, no bs way to check breech clearance. The same can be done w/headspace. Just move the solder to the bolt face and plop the go gauge into the chamber. Cam it over and you'll see exactly where your at. Strive to be at no more than "GO+.003" and no less than +.001"
This will deliver good brass life so long as you don't hammer the snot out of your case shoulders when reloading.
Hope this helped, good luck.
C.
Get a sliver of soft solder. Just cut a snip from a roll of .04 stuff from radio shack.
Stick it to your forward side bolt lug with a dab of grease.
Stick it in the action and close the bolt up in the receiver. Pull the bolt and find the sliver. Measure its thickness. When you close the bolt use a light "forward and down" tapping action with the palm of your hamd. This will aid in getting it shut w/o damaging anything. (Some actions -aka customs, are prone to galling and this simple procedure can gall a lug on them. Your pretty safe with m700s though)
This is a real world, no bs way to check breech clearance. The same can be done w/headspace. Just move the solder to the bolt face and plop the go gauge into the chamber. Cam it over and you'll see exactly where your at. Strive to be at no more than "GO+.003" and no less than +.001"
This will deliver good brass life so long as you don't hammer the snot out of your case shoulders when reloading.
Hope this helped, good luck.
C.
Mattitude, I'm no gunsmith and I'm pretty new at LR loading, but I had a similar problem with case web expansion just above the head after doing a prefit swap on a savage. Different gun I know, same possible solution though? My problem was I had my FL dies bumping my shoulders back too much, then when fired, there was too much area for expansion. I originally though it was my chamber but it was my lack of knowledge on properly setting headspace on my reloading dies. Also, I found if I didn't wipe off ALL sizing lube from cases the head and web would be really bad! I was bumping 8/1000, soon as I got down to only 2 or 3/1000ths on my sizer, my case web and head brass problems wen t away.
Chad, I appreciate you explaining that technique and I'll give it a try but what measurement range should the solder piece be when I'm done...and I assume that I should check it on both lugs as well?
Chad, what would be considered excessive space between the bolt nose and counter bore? How much space would it take to cause what Matt is experiencing (if that is the problem).
Kc
Kc
We run .02" for breech clearance. I have a gaggle of milled cartridges that have the head/web cross section exposed so that I can visually reference that the case is fully supported. It takes awhile to buzz up a dozen or so, but once you have them they are well worth the hour or two investment.
Mattitude,
I would be more than happy to inspect the rifle, document all the measurements and let you know what the issue could be at no charge for labor, just cover the shipping. We had JGS make us up a set of 308 gauges in Go -.002 all the way to Go +.002 and then a No go. So we can accurately measure your headspace this way as well as documenting all the correct clearances and measurements of your Rem 700 and barrel combination.
I would be more than happy to inspect the rifle, document all the measurements and let you know what the issue could be at no charge for labor, just cover the shipping. We had JGS make us up a set of 308 gauges in Go -.002 all the way to Go +.002 and then a No go. So we can accurately measure your headspace this way as well as documenting all the correct clearances and measurements of your Rem 700 and barrel combination.
Mark, that's incredibly generous of you and I'll be sending you a PM today with some questions and whatnot.
This is interesting. I just checked two of my rifles using the solder method that Chad described. The first, a 700 action with a Shilen barrel mic'd at .007 and the second, a custom job (TAC30 with a Broughton Barrel) mic'd at .011
I guess they're both OK unless I get some debris in the chamber.
I guess they're both OK unless I get some debris in the chamber.
Interesting thread.
Yep. Too bad most of the pertinent info went totally ignored.
and with this test, what if the bolt lugs are making contact with the breech but the counterbore is a mile deep?
Then I'd say someone needs to go back to measuring school or quit trying to mess around with dangerous things.
The nose recess should be .150" max.
And we shouldn't be having head separation requiring trouble shooting...
Point well taken. I suspect that if the recess was too deep, it would be obvious. Ie blown case or it looking like a flange head bolt.
I'm beginning to think the OP has some issues with bad or overworked brass.
I'm beginning to think the OP has some issues with bad or overworked brass.
Not sure I read in here where he measured anything..... a few minutes with a depth mic and we would all know the story.
OP - if you have a depth mic, measure from the action face to the end of the bolt, not the bolt face. Add the recoil lug thickness to it. Write that number down. Then measure from the shoulder ( on the barrel ) to the end of the breech, and subtract the depth of the counter bore from that. Write this number under the first one you wrote down, and subtract. That is your bolt nose to counter bore dimension. Please share this number if you would, it's possible that is the source of your issues, or at least is eliminating one possibility.
If you don't have a depth mic and/or a set of calipers, then stop working on your own rifles, or buy one and learn how to use it. This stuff can hurt you, if you don't get it right.
He stated that he installed a factory bbl. Unless he made a cut that he shouldn't have, it should be right. It's not likely that his headspace gauges are out of spec.
can't argue with that.
Mattitude .....
The problem is that your handloads have excessive shoulder clearance. If you minimize chamber clearance (at the shoulder), you'll never get a case head separation. This Digital Headspace Gauge makes it easy to check any rifle caliber. Check it out.
The problem is that your handloads have excessive shoulder clearance. If you minimize chamber clearance (at the shoulder), you'll never get a case head separation. This Digital Headspace Gauge makes it easy to check any rifle caliber. Check it out.
I wish it was that easy to diagnose but the cases that were splitting were factory loaded ammunition. My handloads showed signs of stress, but no separation.
Op stated he used factory ammo in his first post
No cuts and my headspace gauges are pretty new Forsters. I do know how to properly use them and also how to properly care for them. I've conversed with Mr. Gordon and I will more than likely be sending him the rifle for a proper diagnosis and also accurate measurements. Once that's done I'll update the thread with the findings. I'm really thinking that I got a Monday/Friday made bolt and will work best with a barrel blank so that it can be properly fitted.
Have you tried diff ammo?
I only tried 1 type of factory ammo and 1 type of handload. I only fired 10 rounds total as I didn't want to experience a hard failure and/or break something. It's easier & cheaper to just stop, re-evaluate and ask some questions. I've gotten great responses here and in some PM's as well. I'm grateful to everyone here for not only the advise but for not making me feel stupid.
Did all 10 cases fail?
Most folks on here are here to help. You only have to worry about a'holes like me that might be in a foul mood. That said, even I won't try to make you feel stupid if you're genuinely seeking help.
Only 2 of the 10 cases split, but the other 8 showed near-catastrophic stress right at the case web. Yes I really need help with this project and y'all have been extremely helpful. I've got enough things wrong with me medically...I don't need to add anything to the list by pushing my luck.
Wish you could post some pics.
That'd be good. Never seen even a sloppy chamber that couldn't support a single firing.
Sorry for the delay...I got lazy with the pics. Anyway, here are some of the cases. The 2 on the left are the factory rounds and the others are my reloads. It's hard to see the stress on the reloaded cases, but the splits are visible on the factory cases.
And for giggles here is the rifle in question if anyone is interested.
I did shoot it again yesterday evening and I used a different bolt (it's the one pictured in the rifle above) and I didn't experience any splitting or even any stress. They appeared to have been fired by the average rifle.
And for giggles here is the rifle in question if anyone is interested.
I did shoot it again yesterday evening and I used a different bolt (it's the one pictured in the rifle above) and I didn't experience any splitting or even any stress. They appeared to have been fired by the average rifle.
usually factory ammo have MORE clearance than the handloads, because F.A. are intended hopingly to perform well in all the average factory rifles_ that's the reason behind the failure of your F.A._ for sure the actual headspacing in your rifle is wrong, if we mean headsp. as the result of the interaction between the closed bolt & the chamber_the proof of that is that changin'bolt,the problem has disappeared : easy that the new bolt,once closed,allow less clearance_ (if interested, is possible treat even new brass ,even before the first shoot, to avoid this problem, before a mayor redone of your gunsmith's work_
(p.s.: have you paid some attention to the primers in your picure, too?)
(p.s.: have you paid some attention to the primers in your picure, too?)
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It's interesting that the factory loads don't show the bulge at the web that your reloads do. I'd measure the dia. at the head in front of the extractor groove on both. If you have any of the factory unfired, measure it also. If the head/web is swelling I'd say your brass is soft. The bulge on your reloads doesn't look excessive. Typical of most factory chambers.
Note; If those factory cases are from the same lot, I would try some other stuff. The diff. in the extractor grooves makes me think it is 2 diff. mfg's or it is crap.
Note; If those factory cases are from the same lot, I would try some other stuff. The diff. in the extractor grooves makes me think it is 2 diff. mfg's or it is crap.
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Have you measured the large end of your chamber and compare it to saami specs? One of the pros can tell us but I think it should be 4.714 at the mouth of the chamber. I guess another way to check that is to place a sized case or loaded cartridge into the chamber and see if it wiggles around on the breech end.
His reloads are surely going to wiggle unless he neck sizes.
This is true. My consideration was how the barrel was reamed. I wasn't clear on if the barrel was a factory chamber or if it had been set back etc... If it was rechambered or set back incorrectly and the back end of the reamer was off center, That could possibly open the mouth of the bore an extra .XXX and not support the area just above the web. Some of theose cases look large above the failure. Whatever the issue is it affected both resized and factory brass. So I'm thinking the cases are not the problem. It headspaces good. all of the other dimensions are good. Maybe the bolt head and the counter bore diameters need to be compared, if that has not already been dismissed. What else can it be?
Edit. After looking at the print it would be .010 loose. But it should not be say .020.
Fish
Edit. After looking at the print it would be .010 loose. But it should not be say .020.
Fish
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