Std neck dimension of .260 Rem chamber?
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243winxb
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260 Remington
Click the links at the bottom of this page > http://thehighroad.us/showpost.php?p=4939758&postcount=10 Afy shoots the 260. Do a search using Afy. For factory chambers, the loaded neck diameter is listed in the link. The loaded neck diameter listed is the maximum allowed. The neck wall thickness in most cases is undersize, giving a smaller neck diameter of the loaded rounds. Afy said , loaded maximum outside neck diameter is>
Click the links at the bottom of this page > http://thehighroad.us/showpost.php?p=4939758&postcount=10 Afy shoots the 260. Do a search using Afy. For factory chambers, the loaded neck diameter is listed in the link. The loaded neck diameter listed is the maximum allowed. The neck wall thickness in most cases is undersize, giving a smaller neck diameter of the loaded rounds. Afy said , loaded maximum outside neck diameter is>
A custom chamber/neck could have a tight neck, requiring neck turning. The factory chamber should measure .002" to .003" larger than .2970" Just a guess on my part. Afy's 2nd rifle had a custom chamber. I think he just installed a new barrel also. You could PM him.
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Different factories will have dimensions vary a bit, but they're all pretty close to specs. You should measure them for exact numbers. Here's the specs for cartridge dimensions:
Diameter differences between case neck and chamber neck vary all over the place. Some folks believe that the smallest difference is best for accuracy 'cause it "centers" the bullet best in the bore. Others have proved it can be several thousandths and still shoot the smallest groups.
But few folks know why it doesn't matter how much clearance there is for rimless bottle neck cartridges. The front of the round perfectly centers in the chamber when it's fired. The tapered case shoulder centers in the matching chamber shoulder when the firing pin drives the case forward setting the case shoulder back a few thousandths of an inch before the powder burns.
If the case neck's not perfectly centered on the case shoulder, it won't be centered in the chamber neck when its fired. This happens even with only 1/1000ths inch clearance around the chambered round's neck.
Diameter differences between case neck and chamber neck vary all over the place. Some folks believe that the smallest difference is best for accuracy 'cause it "centers" the bullet best in the bore. Others have proved it can be several thousandths and still shoot the smallest groups.
But few folks know why it doesn't matter how much clearance there is for rimless bottle neck cartridges. The front of the round perfectly centers in the chamber when it's fired. The tapered case shoulder centers in the matching chamber shoulder when the firing pin drives the case forward setting the case shoulder back a few thousandths of an inch before the powder burns.
If the case neck's not perfectly centered on the case shoulder, it won't be centered in the chamber neck when its fired. This happens even with only 1/1000ths inch clearance around the chambered round's neck.
Here are chamber and cartridge drawings for the 260. Keep in mind tolerance will cause slight variation from the figures here. The 260 Rem is on pg 78.
http://www.poliisi.fi/intermin/images.nsf/files/AE55118F4B9B6506C2256FBE0032C6DE/$file/TABIcal.pdf
http://www.poliisi.fi/intermin/images.nsf/files/AE55118F4B9B6506C2256FBE0032C6DE/$file/TABIcal.pdf
I will post up my neck dimension for my barrel tomorrow. Wont get home until late tonight. But about .2970 for non neck turned cases seems about right. I also have some Federal ammo so will measure that as well.
I have switched barrels recently and am playing with 6mm Norma BR currently...
I have switched barrels recently and am playing with 6mm Norma BR currently...
Clark
Member
Measuring with pin gauges:
The Douglas factory long chambered 98 Mauser barrel is .299" rear of the neck and .298" forward.
Why someone would care so much about the neck size of the 260Rem is because many of us have a closet full of 308 brass and would like to use it.
The trouble with 308 brass, is that after necking down and seating a .264" bullet, the neck O.D. [outside diameter] is then ~ .298" and may often interfere with the chamber.
Much better is necking down 7mm-08 brass.
I have necked up 243 brass, but that is not as good.
The Douglas factory long chambered 98 Mauser barrel is .299" rear of the neck and .298" forward.
Why someone would care so much about the neck size of the 260Rem is because many of us have a closet full of 308 brass and would like to use it.
The trouble with 308 brass, is that after necking down and seating a .264" bullet, the neck O.D. [outside diameter] is then ~ .298" and may often interfere with the chamber.
Much better is necking down 7mm-08 brass.
I have necked up 243 brass, but that is not as good.
counterclockwise
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I've been downsizing Mil .308 to 7mm-08. RCBS and I am sure others like Sinclair make the necessary neck peelers and reamers to finish the neck after size reduction for the 6.5mm, just like they do for 7mm. The neck needs to be peeled on the outside and reamed on the inside to the required material thickness after reduction, and trimmed to length of course.
Next comes the question about neck annealing. I have not explored this avenue yet, but will be looking for any potential work hardening effects of the downsizing.
Next comes the question about neck annealing. I have not explored this avenue yet, but will be looking for any potential work hardening effects of the downsizing.
Thanks for the replies guys. Been busy, and am just catching up.
My question originated from my first loads. I have a couple hundred once fired Winchester factory .243 cases, so have used them. I trimmed to about .010"- .015" under listed length after necking up. First loads which should have been several grs under max showed fairly high pressure. One culprit, I didnt weigh the bulk bullets, and assumed, incorrectly, what the weight was. Still should have been OK loads. I used 129 gr data (which I thought the bullets were), and they were actually 144 gr FMJBT. First loads were 40 grs IMR 4350 w/ standard CCI LR primer. These were also the first loads I've shot in the rifle. I rough sighted in @ 30 yards, then went back to 100 yards, ran a few rounds, and looked at primers,......a little warm. 41 grs was fairly flattened primers, and some cratering. Gun is a Ruger M-77 with a custom barrel of some sort, it isnt factory. I don't know who barreled it or anything about it, and the guy I bought it from didnt either. A bullet would not enter the neck of a fired case with an unturned neck. I turned a few necks and shot a few more rounds @ 40 grs/4350. A bullet would barely enter a neck on some fired cases after that, but not freely.
I Cerrosafe cast the chamber, it showed .298"-.299" at the front of the neck measured 15 minutes after the cast was made. My unturned rounds showed approx .295" OD and turned necks were .293". Until I made the cast a couple days ago, I had no idea what the chamber dimensions were, so was entirely in the dark. I was hoping to be able to load rounds without the neck turning. I borrowed a tool and find it rather tedious.
At this point, I think I will abandon the 144 gr FMJ bullets and go to a better grade commercial bullet and start over, looking at primers and accuracy. First loads with the 144 gr FMJ's weren't very good. I was hoping they would be good enough for general plate shooting (300 and 600 yds) and practice rounds.
My question originated from my first loads. I have a couple hundred once fired Winchester factory .243 cases, so have used them. I trimmed to about .010"- .015" under listed length after necking up. First loads which should have been several grs under max showed fairly high pressure. One culprit, I didnt weigh the bulk bullets, and assumed, incorrectly, what the weight was. Still should have been OK loads. I used 129 gr data (which I thought the bullets were), and they were actually 144 gr FMJBT. First loads were 40 grs IMR 4350 w/ standard CCI LR primer. These were also the first loads I've shot in the rifle. I rough sighted in @ 30 yards, then went back to 100 yards, ran a few rounds, and looked at primers,......a little warm. 41 grs was fairly flattened primers, and some cratering. Gun is a Ruger M-77 with a custom barrel of some sort, it isnt factory. I don't know who barreled it or anything about it, and the guy I bought it from didnt either. A bullet would not enter the neck of a fired case with an unturned neck. I turned a few necks and shot a few more rounds @ 40 grs/4350. A bullet would barely enter a neck on some fired cases after that, but not freely.
I Cerrosafe cast the chamber, it showed .298"-.299" at the front of the neck measured 15 minutes after the cast was made. My unturned rounds showed approx .295" OD and turned necks were .293". Until I made the cast a couple days ago, I had no idea what the chamber dimensions were, so was entirely in the dark. I was hoping to be able to load rounds without the neck turning. I borrowed a tool and find it rather tedious.
At this point, I think I will abandon the 144 gr FMJ bullets and go to a better grade commercial bullet and start over, looking at primers and accuracy. First loads with the 144 gr FMJ's weren't very good. I was hoping they would be good enough for general plate shooting (300 and 600 yds) and practice rounds.
counterclockwise
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interesting...
When downsizing the neck material gets thicker as one might expect. And, yes, neck peeling and reaming does get tedious.
I am surprised that the neck of the .243 (6mm) does not get thinner when expanding to the .260 (6.5mm), thus eliminating the need for peeling or reaming.
When downsizing the neck material gets thicker as one might expect. And, yes, neck peeling and reaming does get tedious.
I am surprised that the neck of the .243 (6mm) does not get thinner when expanding to the .260 (6.5mm), thus eliminating the need for peeling or reaming.
You tend to get a doughnut at the shoulder junction when upsizing from .243. Generally you would need to inside neck turn.
One way to get rid of neck turning is to use .260 brass. I have had decent luck with RP .260 brass.
If you have difficulty closing the bolt, it could also be that the bullets are getting jammed into the lands, which would also push the pressures up.
I have never tried the 144 grain bullets, but had good results with the 139 Scenars.
One way to get rid of neck turning is to use .260 brass. I have had decent luck with RP .260 brass.
If you have difficulty closing the bolt, it could also be that the bullets are getting jammed into the lands, which would also push the pressures up.
I have never tried the 144 grain bullets, but had good results with the 139 Scenars.
Buying some 260 brass was the another thought, but already having a couple hundred 243's sitting around gathering dust, wanted to use them.
The bolt was snug to close when I first seated the bullets. Cases chambered freely, so figured it was the bullets touching the rifling when I first tried the bullet seating depth. I reseated until they were clear. No marks on the bullets after I turned the seating stem in a half turn, and the rounds chambered easily.
The 144 FMJBT's were hopefully going to be inexpensive practice/plinking bullets. They were about $12/100 in bulk. A friend had ordered a thousand and I got some to try. If the Sierra's and other standard commercial bullets I have work better, without the pressure signs, then I'll scratch the 144's. The friend I got them from had used them in 6.6 x 55, and 6.5 x 284 and was happy with them for practice loads.
Thanks for all the input. Hopefully within the next week I'll have time to work on loads again. Work gets first priority, grouse season just opened, it gets second place, and black bear is also open now. Still want to get a round ball load worked up for the .375 H&H for grouse. A grouse load for 35 Whelen would be nice, but I don't know of anyone selling .360" round balls.
The bolt was snug to close when I first seated the bullets. Cases chambered freely, so figured it was the bullets touching the rifling when I first tried the bullet seating depth. I reseated until they were clear. No marks on the bullets after I turned the seating stem in a half turn, and the rounds chambered easily.
The 144 FMJBT's were hopefully going to be inexpensive practice/plinking bullets. They were about $12/100 in bulk. A friend had ordered a thousand and I got some to try. If the Sierra's and other standard commercial bullets I have work better, without the pressure signs, then I'll scratch the 144's. The friend I got them from had used them in 6.6 x 55, and 6.5 x 284 and was happy with them for practice loads.
Thanks for all the input. Hopefully within the next week I'll have time to work on loads again. Work gets first priority, grouse season just opened, it gets second place, and black bear is also open now. Still want to get a round ball load worked up for the .375 H&H for grouse. A grouse load for 35 Whelen would be nice, but I don't know of anyone selling .360" round balls.
Clark
Member
I have eaten a grouse killed with size 9 shoe.
Doesn't that just s***!
If I am doing a long post I will copy and paste it into a word doc as I go. Then I can get it back if something happens, like a power blip the other day, when I had NOT done that. :banghead:
I would have never thought to use a # 9 shoe for grouse.
If I am doing a long post I will copy and paste it into a word doc as I go. Then I can get it back if something happens, like a power blip the other day, when I had NOT done that. :banghead:
I would have never thought to use a # 9 shoe for grouse.
I dont even know what happened, it just popped back to the log in page when I was about 2 seconds from posting,......I often just copy the post if it takes more than a couple minutes before I send it. I type so slowly that I sometimes get timed out before I can post, then I can just paste it back in if it doesnt take on a long one.
Try this again,.
The grouse aren't too big, its more about what you may bump into when looking for grouse. The best grouse country around here is also good grizzly country. There's been 2 or 3 contact level bear encounters per year recently in the general area, and a few "interesting" non-contact encounters per year. So far, I've not had any trouble with them in the 20+ years I've been roaming around here. I like to tent camp, and sometimes sleep out on the ground up above timberline, not to mention just exploring trails and scouting for game.
The .375 H&H will likely work well with a .375" round ball w/ about 3 or 4 grs Red Dot for grouse and small game. I've used .310"-.315" round balls in 30-30 w/ 3 grs Unique for grouse, works great, and with about as much noise as a 22 LR std vel (not high vel). A .350" round ball w/ 4 grs Red Dot also works great in the .348. Neither ruin any meat, less than a .22 LR hollow point. Good for camp meat when hunting larger game, but they have become my favorite grouse loads. Nice to have a real rifle in hand instead of a .22 when roaming around in the woods. You're on your own up there. It's a long ways to any help or towns, and no cell signal in most of the mountains.
Grouse shot with the 30-30.
Try this again,.
The grouse aren't too big, its more about what you may bump into when looking for grouse. The best grouse country around here is also good grizzly country. There's been 2 or 3 contact level bear encounters per year recently in the general area, and a few "interesting" non-contact encounters per year. So far, I've not had any trouble with them in the 20+ years I've been roaming around here. I like to tent camp, and sometimes sleep out on the ground up above timberline, not to mention just exploring trails and scouting for game.
The .375 H&H will likely work well with a .375" round ball w/ about 3 or 4 grs Red Dot for grouse and small game. I've used .310"-.315" round balls in 30-30 w/ 3 grs Unique for grouse, works great, and with about as much noise as a 22 LR std vel (not high vel). A .350" round ball w/ 4 grs Red Dot also works great in the .348. Neither ruin any meat, less than a .22 LR hollow point. Good for camp meat when hunting larger game, but they have become my favorite grouse loads. Nice to have a real rifle in hand instead of a .22 when roaming around in the woods. You're on your own up there. It's a long ways to any help or towns, and no cell signal in most of the mountains.
Grouse shot with the 30-30.
Here's a good link to look at, be sure to go to his link about "using pistol powders in rifle cartridges". There is also data on the sidebar of the first page.
http://www.gmdr.com/lever/lowveldata.htm
Using very light bullets and very light loads is an old practice, but seems to have fallen from common use in recent years. Winchester used to load "gallery" and other types of lighter loads in the early 1900's. I have an NRA reloading manual from the very early 60's that has a chapter about ultra light cast or round ball loads, trying for the lightest possible loads that burned cleanly. They were in the 1-3 gr range for most rounds, going down a tenth at a time until poor ignition, then back up a tenth or two until it was consistant again. I've long loaded jacketed loads in centerfire rounds in the 1200-1600 fps range, using the Hornady .338" flat point (33 Win) bullet in the .338 Win Mag for small game and close range varmint loads, using I believe 4756 powder. Groups were about 1/4" for 4 shots @ 30 yards. Same for 30-06, using a light for caliber jacketed bullet in that vel range. I try to use a bullet thats easily identifiable at a glance, so there's no mix up when you need a full power load. Jacketed takes a little higher load level, as the bullets have more resistance in the bore, and can stick if they are too low.
Going to the lowest level thats functional and usable is nice though, you can shoot in places you wouldnt normally be able to, or they make good fun rounds for hunting small game with your big guns. With the increase in the price of .22 ammo, the ultra light centerfire loads aren't bad as far as expense either. If you cast, the main cost is the primer. At 2-4 grs per shot, a pound of pistol powder goes a long long ways.
Mushials info got me started on using Red Dot. Unique has long been the ultra light powder of choice, and it works pretty well in that use, but I've had erratic consistancy unless a small amount (as in about the size of the end of my little finger when loose, I ball it up and poke it in with a pencil) of dacron pillow stuffing is poked in to keep the powder near the primer. This bothers some people, tho I've never had the slightest trouble with it. It does, however, make an extra step in the loading process. Mushial wanted to eliminate that step, and has found several powders that work well without the fluff.
There have been some interesting threads on Shooters Forum on light loads. I'll see if I can find some.
http://www.gmdr.com/lever/lowveldata.htm
Using very light bullets and very light loads is an old practice, but seems to have fallen from common use in recent years. Winchester used to load "gallery" and other types of lighter loads in the early 1900's. I have an NRA reloading manual from the very early 60's that has a chapter about ultra light cast or round ball loads, trying for the lightest possible loads that burned cleanly. They were in the 1-3 gr range for most rounds, going down a tenth at a time until poor ignition, then back up a tenth or two until it was consistant again. I've long loaded jacketed loads in centerfire rounds in the 1200-1600 fps range, using the Hornady .338" flat point (33 Win) bullet in the .338 Win Mag for small game and close range varmint loads, using I believe 4756 powder. Groups were about 1/4" for 4 shots @ 30 yards. Same for 30-06, using a light for caliber jacketed bullet in that vel range. I try to use a bullet thats easily identifiable at a glance, so there's no mix up when you need a full power load. Jacketed takes a little higher load level, as the bullets have more resistance in the bore, and can stick if they are too low.
Going to the lowest level thats functional and usable is nice though, you can shoot in places you wouldnt normally be able to, or they make good fun rounds for hunting small game with your big guns. With the increase in the price of .22 ammo, the ultra light centerfire loads aren't bad as far as expense either. If you cast, the main cost is the primer. At 2-4 grs per shot, a pound of pistol powder goes a long long ways.
Mushials info got me started on using Red Dot. Unique has long been the ultra light powder of choice, and it works pretty well in that use, but I've had erratic consistancy unless a small amount (as in about the size of the end of my little finger when loose, I ball it up and poke it in with a pencil) of dacron pillow stuffing is poked in to keep the powder near the primer. This bothers some people, tho I've never had the slightest trouble with it. It does, however, make an extra step in the loading process. Mushial wanted to eliminate that step, and has found several powders that work well without the fluff.
There have been some interesting threads on Shooters Forum on light loads. I'll see if I can find some.
counterclockwise
Member
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- Jan 17, 2008
- Messages
- 176
Thanks for the great photograph! It belongs in Field & Stream. Got any more like that?
A couple,....
I've posted some of them on other threads. This is a 1927 Winchester 94 carbine I had an extra barrel cut to 16" for. Pic was in June of this year out at one of my dog walking spots.
A Browning 1886 carbine leaning against a tree with some bear bites in it, and some bear hairs from rubbing.Grizzly hairs I believe. Not as spectacular scenery as some other shots. it was back from the edge on a trail. 100 yards farther out it looks like the edge of the world.
This is a cabin I used to live in a few years ago. 94 carbine second from top in the rack is the same gun as in the first pic.
I've posted some of them on other threads. This is a 1927 Winchester 94 carbine I had an extra barrel cut to 16" for. Pic was in June of this year out at one of my dog walking spots.
A Browning 1886 carbine leaning against a tree with some bear bites in it, and some bear hairs from rubbing.Grizzly hairs I believe. Not as spectacular scenery as some other shots. it was back from the edge on a trail. 100 yards farther out it looks like the edge of the world.
This is a cabin I used to live in a few years ago. 94 carbine second from top in the rack is the same gun as in the first pic.
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Seedtick
Member
^^
Wow! Beautiful photos.
ST
Wow! Beautiful photos.
ST
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