Headspacing REMAG Belted Magnum

[RonAKA]

I think I have thought this thing through, but I need to bounce this off some knowledgeable folks to be sure I have this right. I'm replacing the .264 WM original barrel on my 700 Remington with a REMAGE prefit barrel, chambered in 6.5 Rem Mag. The barrel does not exist yet, but will just be a SAAMI spec prefit, and my Remington brand 6.5 RM brass is on the way to me, and I still need to check it when it arrives. So I am at the planning stage.

My thinking on headspacing it is to get as tight a fit as possible while still reliably chambering my brass in my barrel. You can't buy new loaded 6.5 RM so that is not a worry, and more new brass only is unlikely. I think I have a lifetime supply. If I sell it, I likely will sell the brass and dies along with it. My original .264 WM cases have lasted up to 20 reloads, and I have never suffered from the case separation just above the belt issue. I want this new gun to do the same or better. That is my reasoning for getting the headspacing tight. And I realize it will probably shift to headspacing on the shoulder anyway after firing.

In looking at the 6.5 RM SAAMI drawing I see it is similar to .264 WM and many other belted magnums. It shares their dimensions in the head, and headspaces on the belt, at least with new brass. The belt cavity is 0.220" min and 0.227" max, while the cartridge belt depth dimension is 0.220 max and 0.212 min. For that reason I believe a go gauge will have to be 0.220" minimum to ensure factory ammo and factory chambers always let the bolt close, and possibly 0.221 for a little extra tolerance.

However, I have been measuring some of my .264 WM brass and while measurement accuracy is not the greatest, I am getting belt depth readings in the 0.215 to 0.218" range. This would suggest if I get a minimum chamber depth of 0.220, I still will have 0.002 to 0.005" headspace if I set up with a go gauge, depending on my actual brass dimensions. If they unfortunately are at the brass minimum of 0.212, headspace will be 0.008". I think that is too much.

So, my plan is to do that dirty evil deed, and headspace with the new unfired brass and some transparent tape. I have measured the tape as a very consistent 0.0012". I would measure a bunch of the brass and pick out 10 I think are the thickest (closest to 0.220" belt), and set the headspace with the REMAGE nut to close on them all when they have one layer of tape added to them. That would give me a minimum actual headspace of 0.0012. A no-go check would be to add two extra layers of tape to them all (0.0036" total), and make sure the bolt will not close on any of them.

What do you think? Will it work? I've tested the idea out with my .264 and it looks like it would work when the ejector is removed.

 

[hoz53]

I think I have thought this thing through, but I need to bounce this off some knowledgeable folks to be sure I have this right. I'm replacing the .264 WM original barrel on my 700 Remington with a REMAG prefit barrel, chambered in 6.5 Rem Mag. The barrel does not exist yet, but will just be a SAAMI spec prefit, and my Remington brand 6.5 RM brass is on the way to me, and I still need to check it when it arrives. So I am at the planning stage.

My thinking on headspacing it is to get as tight a fit as possible while still reliably chambering my brass in my barrel. You can't buy new loaded 6.5 RM so that is not a worry, and more new brass only is unlikely. I think I have a lifetime supply. If I sell it, I likely will sell the brass and dies along with it. My original .264 WM cases have lasted up to 20 reloads, and I have never suffered from the case separation just above the belt issue. I want this new gun to do the same or better. That is my reasoning for getting the headspacing tight. And I realize it will probably shift to headspacing on the shoulder anyway after firing.

In looking at the 6.5 RM SAAMI drawing I see it is similar to .264 WM and many other belted magnums. It shares their dimensions in the head, and headspaces on the belt, at least with new brass. The belt cavity is 0.220" min and 0.227" max, while the cartridge belt depth dimension is 0.220 max and 0.212 min. For that reason I believe a go gauge will have to be 0.220" minimum to ensure factory ammo and factory chambers always let the bolt close, and possibly 0.221 for a little extra tolerance.

However, I have been measuring some of my .264 WM brass and while measurement accuracy is not the greatest, I am getting belt depth readings in the 0.215 to 0.218" range. This would suggest if I get a minimum chamber depth of 0.220, I still will have 0.002 to 0.005" headspace if I set up with a go gauge, depending on my actual brass dimensions. If they unfortunately are at the brass minimum of 0.212, headspace will be 0.008". I think that is too much.

So, my plan is to do that dirty evil deed, and headspace with the new unfired brass and some transparent tape. I have measured the tape as a very consistent 0.0012". I would measure a bunch of the brass and pick out 10 I think are the thickest (closest to 0.220" belt), and set the headspace with the REMAGE nut to close on them all when they have one layer of tape added to them. That would give me a minimum actual headspace of 0.0012. A no-go check would be to add two extra layers of tape to them all (0.0036" total), and make sure the bolt will not close on any of them.

What do you think? Will it work? I've tested the idea out with my .264 and it looks like it would work when the ejector is removed.

So we agree we want to headspace on the shoulder and not the belt if you want to get decent brass life right. I think your plan would work but before I used the tape and if your size die will size your case shoulders down at least .002 more than they are unfired I'd just use a piece of brass for a headspace gauge and size your fired brass to what you need for your gun. You could then check with a headspace gauge if you're worried about factory loads fitting and adjust a little if need be. I wouldn't want the belt to touch the front of its recess in the chamber if I could help it. There will be a little unsupported case wall when you do this but I've never had a problem with it in my 7mmRM

 

[kendog]

Set your barrel with a go gauge, and set your resizing die to set the shoulder back to a zero or .001" clearance and your brass will last much longer. Ignore the belt. Even set to a absolute minimum with a go gauge, you will have too much headspace from bolt face to shoulder datum with most factory ammo and resized brass from a die set up like most manufacturers advise (shell holder touching the bottom of the die). This is quite common with almost all of the belted "Magnum" cases. You can either size a case and try it in your chamber, or use something like the RCBS precision case micrometer to set your die properly. Also, chances are the new brass will be a bit short in the base/shoulder dimension but it will be fine after the first firing.

 

[BoydAllen]

In the past on cases like the 7mm Remington Mag, and .300 Weatherby, using a Stoney Point (now Hornady)headspace gauge, I have found a around a .021 difference between the head to shoulder dimension of new brass and fired. Because of the belt, the case cannot be shoved forward to the shoulder of the chamber on the first firing, so the situation is different than with a rimless case. I have seen no problems caused by the first firings of belted magnum cases. I prefer to set bump using a tight case as a reference rather than one that is once fired, the reason being is that it takes more than one firing for cases to reach their maximum head to shoulder dimension. If I have to work with once fired brass to set a FL die, the first thing that I do is to set the die to duplicate the head to shoulder dimension of the fired case, which I measure after either removing the primer, or re-seating it well below the head. With the reduction in case body diameter that the FL die produces, and the clearance that is usually preset, head to shoulder, with once fired brass, you should be able to operate your bolt smoothly. There is one other issue to consider, inconsistent bump caused by differences in the hardness of new brass. I have seen this, and you have two options, learn how to anneal properly, or sort your brass after sizing and redo the ones that are too long, head to shoulder, after making a slight adjustment to the die. Generally, the .001 bump specification can be increased for big cases that are primarily used for hunting applications. I would not exceed .0025. In any case, if you are going to pay to shoot a match, or there is much expense involved in a hunt, I would suggest removing the striker assembly from your bolt, and cycling your loaded ammo through the rifle to make sure that you did not miss a beat somewhere along the way. Do not do this without removing the striker assembly first.

 

[Ggmac]

When you say pre fit barrel , what exactly do you expect ? Is it adjustable with a barrel nut ? If not , it needs to be installed by someone with experience . Chances are it will need either the chamber cut or the barrel cut to headspace correctly .
Sorry if you already know this .

 

[hoz53]

In the past, using a Stoney Point (now Hornady)headspace gauge, I have found a around a .021 difference between the head to shoulder dimension of new brass and fired. Because of the belt, the case cannot be shoved forward to the shoulder of the chamber on the first firing, so the situation is different than with a rimless case. I have seen no problems caused by the first firings of belted magnum cases. I prefer to set bump using a tight case as a reference rather than one that is once fired, the reason being is that it takes more than one firing for cases to reach their maximum head to shoulder dimension. If I have to work with once fired brass to set a FL die, the first thing that I do is to set the die to duplicate the head to shoulder dimension of the fired case, which I measure after either removing the primer, or re-seating it well below the head. With the reduction in case body diameter that the FL die produces, and the clearance that is usually preset, head to shoulder, with once fired brass, you should be able to operate your bolt smoothly. There is one other issue to consider, inconsistent bump caused by differences in the hardness of new brass. I have seen this, and you have two options, learn how to anneal properly, or sort your brass after sizing and redo the ones that are too long, head to shoulder, after making a slight adjustment to the die. Generally, the .001 bump specification can be increased for big cases that are primarily used for hunting applications. I would not exceed .0025. In any case, if you are going to pay to shoot a match, or there is much expense involved in a hunt, I would suggest removing the striker assembly from your bolt, and cycling your loaded ammo through the rifle to make sure that you did not miss a beat somewhere along the way. Do not do this without removing the striker assembly first.

When the op said he had a lifetime supply of brass I thought he meant new brass. Not sure now. Anyway I had in mind using new brass for a gauge. And to the OP don't turn the barrel in tightly when you set headspace with brass because you can actually push the shoulder back on the case.

 

[BoydAllen]

I made a change to the first sentence of my post. I was writing early in the AM and got ahead of myself. Although the rest of the post makes reference to belted cases, the first sentence did not make that distinction. It should have.

 

[RonAKA]

So we agree we want to headspace on the shoulder and not the belt if you want to get decent brass life right. I think your plan would work but before I used the tape and if your size die will size your case shoulders down at least .002 more than they are unfired I'd just use a piece of brass for a headspace gauge and size your fired brass to what you need for your gun. You could then check with a headspace gauge if you're worried about factory loads fitting and adjust a little if need be. I wouldn't want the belt to touch the front of its recess in the chamber if I could help it. There will be a little unsupported case wall when you do this but I've never had a problem with it in my 7mmRM

Thank you for the response. Good thoughts. Don't you think that the new unfired brass will be way off the shoulder even without sizing?

 

[RonAKA]

Set your barrel with a go gauge, and set your resizing die to set the shoulder back to a zero or .001" clearance and your brass will last much longer.

Thanks for the response. That is exactly what I plan to do. I wish I could resize the neck and bump the shoulder only with a Forster Bushing Bump Die, but from what I can see there is nothing they have that will work. Will have to use the FL RCBS die I got with the brass. With a little luck I may be able to partially resize the neck and not bump the shoulder for a few reloads before having to go all the way with a shoulder bump. I have been able to do it with my .264 WM.

 

[RonAKA]

In the past on cases like the 7mm Remington Mag, and .300 Weatherby, using a Stoney Point (now Hornady)headspace gauge, I have found a around a .021 difference between the head to shoulder dimension of new brass and fired. Because of the belt, the case cannot be shoved forward to the shoulder of the chamber on the first firing, so the situation is different than with a rimless case. I have seen no problems caused by the first firings of belted magnum cases. I prefer to set bump using a tight case as a reference rather than one that is once fired, the reason being is that it takes more than one firing for cases to reach their maximum head to shoulder dimension. If I have to work with once fired brass to set a FL die, the first thing that I do is to set the die to duplicate the head to shoulder dimension of the fired case, which I measure after either removing the primer, or re-seating it well below the head. With the reduction in case body diameter that the FL die produces, and the clearance that is usually preset, head to shoulder, with once fired brass, you should be able to operate your bolt smoothly. There is one other issue to consider, inconsistent bump caused by differences in the hardness of new brass. I have seen this, and you have two options, learn how to anneal properly, or sort your brass after sizing and redo the ones that are too long, head to shoulder, after making a slight adjustment to the die. Generally, the .001 bump specification can be increased for big cases that are primarily used for hunting applications. I would not exceed .0025. In any case, if you are going to pay to shoot a match, or there is much expense involved in a hunt, I would suggest removing the striker assembly from your bolt, and cycling your loaded ammo through the rifle to make sure that you did not miss a beat somewhere along the way. Do not do this without removing the striker assembly first.

All good comments. I have not totally sorted out what I will do to size the cases. I have had some success with my .264 WM with doing a partial resize of the neck (about 2/3rds) with a FL die, and not bumping the shoulder at all. That will be my first attempt as I will have a FL die to work with. Then I may just bump the shoulder with the FL die. Measurement will be a problem, and I will have to consider the Stoney Point gauge. I currently do not have one. With my 6BR I just use the body from my Forster Bushing Bump Die to measure the amount of bump I get. Even a fired case just drops into the body with the deprimer and bushing out of the way. I will have to do some more careful measurements to see if the case continues to grow longer with more firings. It seems I never need to trim my 6BR cases with this method, but the bigger magnum case could be totally different...

 

[RonAKA]

When you say pre fit barrel , what exactly do you expect ? Is it adjustable with a barrel nut ? If not , it needs to be installed by someone with experience . Chances are it will need either the chamber cut or the barrel cut to headspace correctly .
Sorry if you already know this .

Some barrel manufacturers are using the Savage barrel nut method of headspacing a barrel instead of using the custom machined shoulder on a Remington 700. The nut/method they use is called REMington SavAGE, or REMAGE. Here is an article on how a Remington 700 is converted to the REMAGE system. I will basically follow this method, except I am questioning the use of the GO gauge to set minimum headspace. I would like to go tighter, if that is reasonable...

 

[RonAKA]

When the op said he had a lifetime supply of brass I thought he meant new brass. Not sure now. Anyway I had in mind using new brass for a gauge. And to the OP don't turn the barrel in tightly when you set headspace with brass because you can actually push the shoulder back on the case.

Yes, it was sold to me as new unprimed Remington brass. Will physically see it until next week. I have devised a somewhat crude method of measuring the base to end of the shoulder dimension, and will try to refine that at bit and measure this brass to see where it sits in the SAAMI tolerance range as a first step. I planned to select a few cases, add the 0.0012" tape and use that as the GO gauge, especially if the brass measures toward the 0.212" range. Thanks for the comment on going easy screwing the barrel back on the brass when used as a gauge.

 

[RonAKA]

A followup question for everyone, now that I have read the initial comments. Do you think there is any disadvantage to having a tight fit (headspace) on the belt, as well as at the normal shoulder after I get into using fired cases? It seems to be that the belted magnum case failures must be due to case stretching, one way or another. And, if the case is held within a thou or so at both ends, belt and shoulder, that it really does not have anywhere to go, and case stretching should be eliminated or at the very least greatly reduced? I have never had these kind of failures with my .264 WM but a friend using a Remington 700 in 7mm RM has had a number of them. Part of his reloading process is to check every case with a bent wire to look for the thining above the head which seems to start from the inside.

 

[Ggmac]

If you load your first loads at jam , then size using the shoulder as your headspace , you can use the go / no go gauges . It will only stretch once if you don't keep pushing it back .
A pre fit is completely dif then a Remage .
Another option is to find your shortest belt distance and use that to set your headspace , then you'll have to cut all longer cases ( belts ) to that length .
I've done it both ways , but did only do the jam method for customers .

You will have to watch how much you screw your barrel in to get to where you want to be , the bolt nose to barrel clearance may be an issue . Usually there's .005 nose clearance , but each is different .

 

[RonAKA]

1. If you load your first loads at jam , then size using the shoulder as your headspace , you can use the go / no go gauges . It will only stretch once if you don't keep pushing it back .

2. Another option is to find your shortest belt distance and use that to set your headspace , then you'll have to cut all longer cases ( belts ) to that length .
I've done it both ways , but did only do the jam method for customers .

3. You will have to watch how much you screw your barrel in to get to where you want to be , the bolt nose to barrel clearance may be an issue . Usually there's .005 nose clearance , but each is different .

1. When you say jam, are you suggesting a bullet jam? I wonder if that is enough to hold the case in place when the firing pin hits? I know there are all kinds of discussions about that issue, and what the case really does on an initial firing or form firing. It can be done, and I in fact jam all my 6BR loads. They are very lightly seated though. I suppose these basic RCBS dies will likely give me a much tighter fit, and may take some force.

2. That sounds like it needs a lathe or case trimmer. Have neither...

3. Yes, I wondered about that issue. The SAAMI drawings leave out the bolt (other than the face), so I guess each manufacturer is on their own as to how much clearance they leave. And if my new barrel is chambered deep in the belt area, that tolerance is going to eat up nose clearance too.

 

[Ggmac]

Yes bullet jam , if you don't turn your necks , you'll be ok . Plenty of cases have been fireformed this way .
A case trimmer or small lathe is necessary for the case belt trimming . Your basically making your own little wildcat , in being non Saami anymore . That's why I could never do it for customers .
I shot , shoot the 6.5 rem mag a lot , I've got 6-8 dif reamers just for that case . All are slightly dif in leade angle , neck . I use to shoot it at 1000 in Pennsylvania . Seems like a lifetime ago , 30 plus years , I guess it is .

 

[hoz53]

A followup question for everyone, now that I have read the initial comments. Do you think there is any disadvantage to having a tight fit (headspace) on the belt, as well as at the normal shoulder after I get into using fired cases? It seems to be that the belted magnum case failures must be due to case stretching, one way or another. And, if the case is held within a thou or so at both ends, belt and shoulder, that it really does not have anywhere to go, and case stretching should be eliminated or at the very least greatly reduced? I have never had these kind of failures with my .264 WM but a friend using a Remington 700 in 7mm RM has had a number of them. Part of his reloading process is to check every case with a bent wire to look for the thining above the head which seems to start from the inside.

Like I said in an earlier post I would prefer to headspace on the shoulder and not have the belt touching at all. Otherwise all your belts are probably a little different and so some cases might headspace on the belt some on the shoulder ect. -- I would full length resize and adjust the shoulder as necessary. A bump gauge would help a lot. You set the shoulder of the barrel to the new unfired brass. Don't use a headspace gauge since for belted magnums, that only sets headspace by the belt and you don't want that. If you do set your headspace by the belt your cases will stretch more than necessary. That said I never had problems with belted magnum cases I let stretch only on the first firing but no need to let that happen in your case. Set your headspace by screwing the barrel in gently against a new piece of brass like you would with a headspace gauge made for a caliber that headspaces off the shoulder. You don't sound like you're going to shoot any factory loads so you don't have to worry about headspace being a little to tite to chamber them. The way your barrel is chambered will determine how this will all work.

 

[hoz53]

I made a change to the first sentence of my post. I was writing early in the AM and got ahead of myself. Although the rest of the post makes reference to belted cases, the first sentence did not make that distinction. It should have.

You provided the OP with plenty of good info for him to get his question answered Boyd. The .021 is something I learned. Thanks

 

[kendog]

There can be as much as .026" difference in minimum factory ammo and a maximum SAMMI chamber in the bolt face to shoulder datum dimension. This holds true for 300 Win Mag, 7 Rem Mag, 264 Win Mag, and 6.5 Rem Mag., and probably many other belted cases. The simple solution is to size to YOUR shoulder and ignore the belt entirely. The belt is a hold over from adapting flanged H&H mag cartridges to feed in a bolt action. A factory load (or equivalent hand load) in a max chamber will fire form the first shot, then size accordingly.

 

[BoydAllen]

Some time back, a friend, who is very good about small details and careful about procedures asked me to design a tight necked shorter throat .300 Weatherby reamer. It was set up so that 180 gr. hunting bullets could touch the lands and fit in the magazine of the German Mk. V action. I moved the shoulder so that there would only be a .006 difference between the head to shoulder dimension of unfired brass and the rifle's chamber. Based on experience, I avoided tight clearances for the body diameter at the shoulder and .200 from the head, and used the standard Weatherby dimensions. We also ordered a FL die reamer. Because we had not data for the chamber design, the first thing that we did after the rifle was together was to do some pressure testing, using belt expansion and other indicators to judge pressure levels. The last load tested expanded the belt a second time and was well past the point where an ejector mark appeared. We had moved up by half grains. loading at the range. Sizing was done with a one piece neck die, that just happened to give very straight sized brass (Remember, tight neck.) All the way through the test, seven shots I believe, the bolt close was OK, at the end, after the case had cooled, but without sizing, it chambered easily. There are issues involved in reamer design that are not commonly understood, or discussed. I will not digress into why I decided to use the body dimensions that I did, but it was not a wild guess. It was based on a friend's experience, and it worked. The first time that the rifle was used on a hunt, my friend's son shot a 4x4 elk, high in the shoulder, at 600 yd. dumping it on the spot. End of story. PS Yes I know that it wandered a bit off of topic, for the curious, after our exploration to the outer limits, we stepped back from the edge and designated the max load at what appeared to be a sane pressure level. The testing was purposely done in warm weather to avoid the kind of surprises that cold weather testing can result in when things warm up. This has to be the longest example on record to back up the idea that while it may or may not be necessary to reduce body diameters slightly after the first firing, it is highly unlikely that the shoulder would need bumping, which is why when I don't have a tight case to use as a reference, I set FL dies to give sized cases the same head to shoulder dimension as it had after firing. Try it; you might like it, and you can always reset the die if you don't.