I've recently gotten it in my mind that I need to "upgrade" to a rifle with a coned bolt for better feeding. Is their really much benefit to coned bolt faces? Rifle would likely be a 6mm BR for shooting at the range. No competition shooting in my area.
Coned bolt faces. Are they worth it?
- Thread starter Markus
- Start date
gstprecision
Regular
- Location
- Frankford, On
+1 On Guntech comment.
You won't get better feeding in general unless you go to a controlled feed.
GST
You won't get better feeding in general unless you go to a controlled feed.
GST
If a rifle needs a coned breech to feed, there is a problem with the action. If the cartridge is missing the chamber mouth, the issue is with the feed ramp or magazine lips.
The one place where a coned breech is beneficial is in a single shot bolt action where the cartridge may not lie at the right angle to feed in otherwise.
The one place where a coned breech is beneficial is in a single shot bolt action where the cartridge may not lie at the right angle to feed in otherwise.
The action or the cartridge you're feeding ? Tough to feed a fat a short necked cartridge.
I had A PTG coned bolt installed in a single shot Remington 700 in 223. It makes loading longer 80 grain tipped rounds a breeze compared to feeding with a standard bolt face. Just drop the round in the action and close the bolt like it’s empty.
That said it does negate some of the safety features built into a Rem 700 but I load conservatively and always wear eye protection. Mick McPhee did the install and rebarreling ( with the breach face also coned to match of course!) so I am confident in the workmanship.
Feeding isn’t an issue in any of my other rifles but this conversion is nice for the 223.
I don’t think you can get them from PTG anymore though, apparently people were installing the cone bolts and leaving the breach of the barrels factory with no matching cone! Yikes!!
That said it does negate some of the safety features built into a Rem 700 but I load conservatively and always wear eye protection. Mick McPhee did the install and rebarreling ( with the breach face also coned to match of course!) so I am confident in the workmanship.
Feeding isn’t an issue in any of my other rifles but this conversion is nice for the 223.
I don’t think you can get them from PTG anymore though, apparently people were installing the cone bolts and leaving the breach of the barrels factory with no matching cone! Yikes!!
Some additional trivia that may be helpful. The Tikka M55/LSA55 has a ‘reverse’ cone on the barrel face. The ‘cone’ protrudes from the barrel face like a small volcano (I have a theory why this was done fwiw).
The actual bolt face is recessed like a Remington and flat at the firing pin face. When a round is chambered only a small amount of the case protrudes above this ‘cone’ and is unsupported ... just enough to expose the rim and let the extractor catch it.
Despite this design my .223 HB Sporter M55 feeds without an issue both from the magazine and when a single round is placed on top of the magazine feed lips. OTOH when you try to manually place a round into the chamber it is tricky ..BUT drop the round on top of the empty mag ... and it feeds very slick. Also a .223 (or smaller) calibre is probably a worse case as bigger chambers are a bigger ‘target’ for the round to find.
The actual bolt face is recessed like a Remington and flat at the firing pin face. When a round is chambered only a small amount of the case protrudes above this ‘cone’ and is unsupported ... just enough to expose the rim and let the extractor catch it.
Despite this design my .223 HB Sporter M55 feeds without an issue both from the magazine and when a single round is placed on top of the magazine feed lips. OTOH when you try to manually place a round into the chamber it is tricky ..BUT drop the round on top of the empty mag ... and it feeds very slick. Also a .223 (or smaller) calibre is probably a worse case as bigger chambers are a bigger ‘target’ for the round to find.
As is the case with most magazine fed rifles the magazines feed from a strait inline position, there is very very very little to do with the breech shape, the bullets line up perfectly with the waiting chamber mouth.
When we are talking feeding from the rails as is the case with most non mag fed bolt actions perfect geometry is required for reliable feeding. I do not agree with the opinions that the cone breech face has no advantage, in my opinion it is a superior design with no negative attributes, Enfields, winchester Pre 64 M70's and the grand daddy of them all the Mauser M98 among others have a cone breech for good reason it is done for reliable feeding no other reason, silly to claim otherwise.
IMHO
BB
98 Mauser does not have a coned breech. Barrel face is flat. Pre-64 70 is coned, as is the M54 and the '03 Springfield from which the Winchesters were derived. The Mauser has significantly superior breeching, from the standpoint of the amount of unsupported casehead protruding from the barrel.
I am afraid you are wrong about your Mauser statement, the Mauser M98 does indeed have a coned breech. The primary shoulder is flat on the front side where the barrel torques upon but the feeding side is very well coned, It is very well seen in this cutaway.
https://www.youtube.com/watch?v=FrTAOeNjdhc
Cheers
BB
We are making reference to the breeching system that is what is refered to as a coned breech, the barrel face on a 98 is flat but it is not part of the breeching system, what you like to refer to as the collar has two functions, primarily it acts as the primary torque shoulder for the barrel secondly it in fact is what acts as the breeching system since it is what guides the cartridge into the chamber, the barrel face never sees the cartridge or guided by it in any way. It has been documented that when some of the Europeans decided to go with the H type of breech due to easier(cheaper) manufacturing due to being able to pass the broach strait through, it was shown to be less reliable and tended to increase failures to feed, the C type with it's full cone breech was always more reliable but more expensive to manufacture.
BB
On any Mauser which is working as it should, the cartridge does not even touch the "cone" or barrel seat. While it is an important part of the breeching system, it's purpose is to block off the left locking lug raceway. On newer actions where the seat was cut through, this is compromised and gas or debris could pass freely into the left locking lug raceway. Combine this with the elimination of the "thumb cut", which allowed gas to escape, and gases could be directed back to the shooter.
Cartridge guidance is taken cafe of by the ramp exiting the magazine. The opening at this point is exactly the same size as at the inside of the barrel seat since, at both points, the bolt has to be able to pass so the diameter is , roughly, .705" or so.
When MRC designed their action with an Mauser-like barrel seat, they did not make it like a mauser but like a Model 70 or a Springfield. In other words, they made a cone. The ID was reduced, since the bolt didn,t fit inside the collar as on a Mauser and the breech was coned as is a Model 70. A P-poor system IMO.
Cartridge guidance is taken cafe of by the ramp exiting the magazine. The opening at this point is exactly the same size as at the inside of the barrel seat since, at both points, the bolt has to be able to pass so the diameter is , roughly, .705" or so.
When MRC designed their action with an Mauser-like barrel seat, they did not make it like a mauser but like a Model 70 or a Springfield. In other words, they made a cone. The ID was reduced, since the bolt didn,t fit inside the collar as on a Mauser and the breech was coned as is a Model 70. A P-poor system IMO.
One of the worst injuries I ever saw was incurred by a biologist up here who had a 7X57 Ackley built on a pre 64 Model 70. One of his cases failed in a handload, and the escaping gas really worked him over good, most of it on his face.
Peter Paul Mauser got it right!
Ted
Peter Paul Mauser got it right!
Ted
