Tag Archives: chamber

5.56 x 45 (Nato) vs. 223 Remington; The Ongoing Saga

The subject of 223 Remington vs. 5.56×45 (5.56 Nato) is a popular source of discussion.

Probably one of the best blog posts on this subject can be found at http://www.luckygunner.com/labs/5-56-vs-223/

One item this and most of the discussions seem to overlook is headspace.  Since this blog leans more toward gunsmithing subjects, I wanted make sure this subject was discussed.   I often hear from clients that the 5.56 and the 223 differ in headspace.  The truth is, when I checked the various gauge makers they are all working to the same standard.

Why is this important?

Mainly because educating the shooting public minimizes accidents and makes life easier for all concerned.  None of the articles I looked at mentioned headspace.  Most of the chamber dimensions being shared do not include headspace dimensions.  This may be in part because they are so hard to locate for the 5.56 Nato.

Forster Products publishes the data for their 5.56 gauges.  Minimum headspace (Go gauge) is 1.4636” according to their specifications with a tolerance of -.0003”.  With the Maximum (Field gauge) measuring 1.4736”; that’s 10/1000s of an inch longer than the go gauge.  Most No-go gauges would be set .004” to .006”  longer than the Go gauge.  The Pacific Tool & Gauge print shown here uses a Go gauge that measures 1.4636”.

5.56 Nato Print

Look at the Minimum Headspace dimension listed on this print, it is identical to the dimension used on the 223 Remington.

SAAMI specifications for the 223 Remington show a Minimum headspace (Go gauge) of 1.4636” identical to the military spec for the 5.56×45.  The Nato round is not a SAAMI cartridge, so they do not provide prints or specification for it.

My curiosity as to why so many shooters think there is a difference between the gauges for these two, led me to do an Internet search to see what people are reading.  I consider all material on the Internet to be of dubious quality until I can confirm the data through trustworthy sources.  What I found was interesting; you have to dig deep to find anything that pertains to headspace and the 5.56 Nato.

What is easy to locate are drawings which purport to show why the two cartridges are not the same.  The dimensions  they are concerned with mostly have to do with the junction of the body and shoulder plus the shoulder and neck.  In the real world the camming action of the bolt closing would be more than sufficient to deal with the tiny difference that might exist in the brass.  Frankly there is more variation in tolerances allowed that these drawings account for, in short, it’s all smoke and mirrors.

One Internet source shows the Military gauge .001” longer than is found in the prints mentioned above.  Even if that were the case, that is only 1/5th of the difference between a standard Go and No-go gauge for the 223 Remington.  To be totally clear, it would make NO difference.

Conclusion:  Headspace gauges for the 223 Remington and the 5.56 Nato are identical.  The differences between the cartridges has to do with case wall thickness and how they are loaded.  If you want to shoot either type of ammo in your gun, rechamber it to 223 Wylde.  The Wylde chamber is designed to work safely with both types of ammo.

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More Calibers in Savage Drop-in Barrels Than Any Other Source

Any contour you want.

4D offers a wide variety of barrel tapers.

4D Reamer Rental LTD. has expanded what they offer for shooters and gunsmiths once again.  Not only do they offer Savage pre-fit barrels in most any caliber, or twist.  They also stock a small supply of barrels on the shelf.  See:  http://www.4-dproducts.com/sales.php?category=Barrels+on+Hand

Here is what’s really new:

Recently, they started a new offering of chamber work.  4D will rechamber your barrel for Savage barrels as well as many single shots, like NEF rifles, TC Contender or Encore barrels, Rossi single shot rifles can all be reworked to new larger chambers.  If you have some other barrel be sure to check in before you ship it.   4D will be glad to answer your questions about this service option.  They will not accept a complete firearm, this is barrel work only.  For $99 they will rechamber your barrel.

If you have always wanted to try out an Ackley chambering, or wanted a caliber the factory does not offer then this service is right up your alley.  With over 600 reamers on the shelf it’s likely that 4D will have a chambering that will interest you.  The gunsmith doing this work for 4D has over 30 years of experience in chambering and barrel work, so you know the work will be done right, no guessing.  For the complete list of calibers go to the 4D web site.

Barrels can be blued or coated, 4D currently offers CeroCoat.

Barrels in both Blue and Stainless material are available if your placing an order. Custom orders take more time than barrels on the shelf.

Fred at 4D tells us that this service came about because they often get calls from folks who want to rechamber a gun but do not have any experience with chambering barrels.  So it seemed natural to help out such potential clients who were either short on time, or worried about the process.  “We offer more chamberings than any other Savage barrel vendor out there, and we can extend that to the single shot barrel market too.”

The barrel blanks offered by 4D are made by three makers, McGowen, Green Mountain, and Criterion.  Delivery times vary by maker, and prices vary a little as well so check in with them for a quote. 406-752-2520 hours are 9-5 Mountain time, Monday to Friday.

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What is Cerrosafe™ and How to Make a Chamber Cast.

Cerrosafe from 4D Reamer Rentals LTD

CERROSAFE™ alloy was originally made for toy soldier castings. One of its most popular uses today is casting to check gun chambers. Cerrosafe shrinks during the first 30 minutes and at the end of one hour is EXACTLY the chamber size. Some other uses are casting cavities such as threads, dies, molds, blind holes, duplicate patterns in foundry matchplate making, support work pieces while machining; spray coating wooden patterns, dental lab techniques, masks for electroplating. Cerrosafe is a non-eutectic alloy with a yield temperature of 162.5º F.

To make a cast, clean the chamber thoroughly and apply a very thin film of oil or graphite. Plug the bore immediately ahead of the throat with a small cleaning patch – but not so tightly it cannot be driven out. If possible, pour the molten alloy through a small tube into the bottom of the cast, gradually removing the tube as the chamber fills.  We recommend that you warm the barrel to just above room temperature before making the cast. When cooled, remove from chamber, using a rod or dowel from the muzzle end of the gun.
Cerrosafe shrinks during the first 30 minutes of cooling and then at the end of an hour, is EXACTLY chamber size. At the end of 200 hours it will have expanded approximately .0025″. This factor is known to reamer or die makers and they will take it into consideration when making dies, reamers, or gauges from your casting – just tell them the cast is of Cerrosafe.
Cerrosafe is reusable, and never wears out.  It provides excellent casts of chambers and will save you from costly guess work.  Identification of chambers is simplified by a clean chamber cast that you can measure and rely on.
Cerrosafe melts between 158° – 190° F. This alloy should be melted in a clean, iron ladle. Source of heat should be removed as soon as the alloy is completely melted, at which time it is ready to pour. Solidified castings should be removed from the chamber before, or when, it cools to room temperature. Cerrosafe should not remain in the mold more than an hour, as it will grip the chamber walls and be difficult to remove.
Just a few minutes work, for reliable results.

4D Reamer Rentals LLC sells cerosafe in 1/2 and 1 pound ingots.

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4D Reamer Rental made it to the Shot Show for 2009

4D Reamer Rental Show Show booth 2009

4D Reamer Rental Show Show booth 2009

If you are not familiar with this service 4D rents chamber reamers, headspace gauges, and many specialized gunsmith tools to the trade.  You can find them on our blog roll.

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