Swampy
Well their is so much choice these days for rebarrelling a rifle, especially if your prepared to look overseas. Their are now a number of specialist importers of all kinds of barrels from the USA. We must not forget our very own border barrels who produce high quality barrels one of their top customers is accuracy international need I say any more. For barrel manufacturers please see this link:
http://www.6mmbr.com/barrels.html
Their are a number of good articles that will help you understand what their is available. I shall try and sum up some of it for you.
1st thing is you can have a new barrel cut to any size you want, someone once suggested that 21 and 3/4 inches was the best length I have yet to see any backup to this statement, for reference this length came from the famous warehouse in the USA.
You can have the Manufacturer screw cut the barrel for you, Border Barrels will do this and have it proof tested for you, any imports I believe will have to be proofed in the UK, dont quote me on this.
Their are various ways of manufacturing a barrel and reasons for carrying it out. Please bare in mind that when I say inaccurate we could be talking about the difference between sub moa groups and sub 1/2 moa groups and a drop in accuracy as your barrel shoots out initially may only go from 1 moa to 2 moa. The level of accuracy you need and the type of manufacturing technique you choose are really dictated by the what you are shooting at; Varmints, Deer , targets etc
Cold hammer forged barrels
This manufacturing technique is used by sako, remmington, etc. It involves extruding a piece of steel pipe over mandril using a series of small hammers. The mandril actually imparts the rifling as the barrel is extruded. The barrels come out red hot and have to be cooled before handling them. This process produces good barrels quickly, but imparts alot of flaws in them, namely stress which can create an inaccurate barrel and a rough finish which can effect intrinsic accuracy. These barrels will last a good 3000+ rounds and providing you keep the shot strings fairly short to avoid unnecessary throat erosion.
Button rifled barrels
These are usually at the lower end of the price spectrum. That does not necessarily mean they are not very good. Shilen barrels are credited with lots of benchrest records and these are button rifled. This process involves either pushing or pulling a button manderil through a length of steel bar to produce a rifled barrel of the appropriate diameter. This method was developed to cope with the mg42's need for barrels, it ate them alive during WW2 due to the high rate of fire. This process can put stress into the barrel due to the high forces involved and can be a little rough, lapping is usually carried out to smooth the rifled surfaces. These barrels regularly shoot 1/2 moa and are very popular in the benchrest game. Again these barrels should last a good 3000+ rounds providing you keep the shot strings down.
Cut rifled barrels
This is the oldest and to most precision shooters best way to make a barrel. It involves using a machine designed specifically for the task. Border barrels are quite rightly very proud of their old pratt and whitney machines. The machines effectively drills the rifling through a piece of appropriate steel bar. This process produces very little stress in the barrel, clean rifling and long life. The main providers of these type of barrels are Krieger and Border. They are considered to be the most accurate barrels available. These barrels are very strong and for the AI system they had to pas the military test of 25,000 rounds before losing their accuracy but to what level I am not sure. Keep the shot strings short and allow the barrel to cool while zeroing will help the life, you should expect to get 5000+ rounds out of cut rifle barrel.
Most barrel manufacturers will ream your barrel blank to a specific chamber, border offer a number which are listed on their site:
www.borderbarrels.co.uk
Krieger on the other hand will do it but its a request, they usually provide a barrel blank to your gunsmith who will then ream the chamber.
Shilen have probably the widest selection of reamers I have ever seen, anything from standard chamberings to a whole host of unusual factory chamberings to wildcats.
Obviously if you by a barrel blank from either Border or Krieger then you can have your gunsmith ream whatever you wish. Pacific tool and gauge can provide you with virtually any chamber reamer you wish.
I am not sure about thread size and thread length but remingtons thread length is 0.70 inch, I am not sure this is an industry standard or not. Obviously custom actions can have longer for example surgeon have a thread length of 0.95 inch. Your gunsmith or the barrel manufacturer should be able to help you with this one.
You can have a number of finishes to your barrels the most common is stainless steel, but moly can also be had. You can then have an outside company or your gunsmith apply a finish such as blueing of teflon.
You should make sure that the barrel is lapped for a top class finish and that the barrel is lapped into the action, this increases the contact area between the action and barrel threads. This leads to better accuracy.
Border will fit your barrel to your action and proof the rifle for a moderator before sending it back to your RFD of choice.
All of the custom barrel manufacturers recommend shooting your barrel in for a variety of reasons.
remember custom barrels are like custom actions you can have whatever you want if your prepared to pay for it and reload if you request something strange or a tight necked chamber, so heres one 257 banshee, a very rapid offering from one of the USA's top gun writers, its flat shooting varmint come deer cartridge based on the 6.5x68 cartidge. It regularly shoots sub moa at 300 yards, but barrel wear may be excessive as it pushes a 110 grain bullet at around 3900fps. Sounds like alot of fun but your barrel will remain intrinscally accurate for about a 1000 round. For a more unusual factory chamber try 7mm STW about as fast a you can get with a 7mm bullet again see above for barrel life.
The world is you oyster when you start rebarreling and customising watch out it can be highly addictive and like everything that so much fun in life it aint cheap. I hope this helps, but for a more detialed understanding see the 6mmbr website it should help.
