6.5x55 Head Measurments

[lgm270]

The correct head diameter for the 6.5x55 is .480".  I have read that American manufactured shell casings  in 6.5x55 are based on the 30-06 diameter of .473" and are actually undersized.  Supposedly Lapua and Norma are manufactured to spec. 

Does anyone else know anything about this? 

[Wynn]

My brand new box of Lapua mikes at .476. Some new Remington brass I have measures .474. I have shot both in two M96,s and my CZ 550 American and my handloads function just fine. A box of factory Winchester comes in at .473. All hold between .5 and 1" groups at 100 yds. The Speer and Lyman manuals call for .480 but the Lee 2nd Edition calls for .479. I had heard that Lapua was .480 but my measurements do not indicate as much.

[R.W.Dale]

 When loading for my semiautomatic AG42 and two Swedish mausers I found case life to be rather brief when I used "domestic" 6.5x55 casings with their lousy 30-06 sized case head.

[AtlLaw]

This is an issue that brings questions to the mind of everyone who owns a 6.5x55; at least at first.  After using nothing but domestic brass in my three 6.5x55's (2 custom cut and 1 military chamber) for some time, I believe the difference in head size specs is a non-issue.   

[lgm270]

Thanks for all of the responses.  I have made 6.5x55's out of 30-06, .270, 7x57, 8x57, 9.3x63 and even .308 Winchesters.   I knew they were undersized so I kept the loads to modest levels.  No maxed out hunting loads. Just mild mannered target rounds.  They did show swelling at the base.  That was before 6.5 brass was available from domestic manufacturers and Norma was scarce and expensive. Since then Win and RP make it and Norma and Lapua is available.


I was rather surprised to read that domestic brass was undersized. Your experiences confirm this fact. 

[Guy Pike]

S&B-.476, Wolf-.479 no problems with factory rounds in my Husqvarna 1640. Have reloaded some S&B cases 5 times for testing with no problems. As a side note I haven't seen huge improvements over these factory rounds which are just under moa at 100yds and work well for our Eastern Whitetails, coyotes{no market for fur anyways} and woodchucks. Guy

[Brithunter]

It's not so much the rim diameter as the case diameter over the web area and more importantly just in front of the web where the case wall thins is where the case diameter matters most and a lot of cases are under-size here for some reason. The smaller the case is at this point in relation to the design specs will determine just how much the case has to expand to fill the chamber. American made .303 british cases are mostly under-size at this point and that is one reason the 303 British has a reputation for short case life. On the other hand this being undersized at the web in the 303 British case is useful when re-forming the brass to make 6.5x53R.

In the 6.5x55 cases most that I use are of European manufacture as that was what was a vailable. I have often wondered why makers cannot keep the cases closer to design specs, for instance Winchester make 30-30 cases are under-size on the rim diameter which I find strange as after Winchester designed the cartridge so you would have thought they could keep the specs. Perhaps it's something to do with Olin owning the ammunition brand?

[muskeg13]

I shrunk my group sizes in half when I went from US manufactured cases to either Lapua or Raufoss (Norwegian) brass.  That alone was enough to justify the extra expense.

[deltecs]

According to Cartridges of the World, the head diameter of the 6.5x55 is .376", or .003" larger than 06 type cartridges.  The only difference in reality is the Swede may not fit the 06 shell holder, but mine does. 

[Brithunter]

Sorry to tell you but COW and Mr Barnes made a fair few mistakes in his book, so quoting figures from COW don't really mean much. Much better is to use sizes from CIP the European proof house group.

[deltecs]

Sorry to tell you but COW and Mr Barnes made a fair few mistakes in his book, so quoting figures from COW don't really mean much. Much better is to use sizes from CIP the European proof house group.

Excuse me, in a previous post I had the 6.5x55 head dimensions as .376".  That was a typing error that I did not catch, it should have been .476".  According to Handloaders Manual of Cartridge Conversions by John Donnelly, the 6.5x55 Swede has a head dimension of .476" also.  Now according to COW without regard to dimension errors, is the CIP European proof house group using the dimensions from the 6.5x55 Swede or the newer 6.5 SKAN, which can be chambered in 6.5x55 rifles without any changes.  This round has been redesigned to a fixed set of Standards that vary slightly from the original 6.5x55 Swede cartridge.  The new 6.5 SKAN cartridge is generally referred to at the 6.5x55 Swede.  If I am in error on any of this info, please enlighten me with your corrections.  Either way, the head dimensions of the Swede would not have any difference in cartridge strength, effectiveness, or inconvenience to the hand loader.

[Brithunter]

All I did was point out that COW has quite a few errors in it and so is not a good source of information really.

   I do find it strange that the cartridge manufactures cannot seem to maintain specs on head and rim size when making cases, even thos cases which they designed themselves. As I have never used any American made cases in 6.5x55 I cannot comment on problems, or lack of them whe using such cases. As to the 6.5 SKAN? never heard of it.

[Siskiyou]

I have to agree with AtlLaw I think it is a none issue.  Last year I loaded a bunch of new WW cases to published maximum using two different powders behind 140-grain C-L bullets.  After firing each round I carefully examined the case for any issues; I did not discover any. 

I measured a couple of cases heads at the time of loading and did not find a problem.  I did not find any significant difference with the military ammunition I have.  I do not recall the measurements at this time, if any difference would have been significant I would have documented it. 

My final selected load gives me approximately 50-additional feet per-second over the military surplus ammunition I have.  The rifle is a sporterized M96 Swede.  There were no extraction difficulties and the ammunition provide to accurate.  I was loading H4831 and WMR powder which in theory give lower pressures, and higher velocities then some of the faster burning powders loaded in the 6.5X55.

In this day-and-age of consumer safety and manufacture liability I rather doubt that WW would market cases that are likely to be loaded more then once to the consumer if there were a safety issue.

From examining the cases after firing I expect to get a number of loads out of those WW cases.  Most likely the cases will provide more loads then new cases I have loaded for the .270 Winchester or the 7MM Remington Magnum load to the maximum.  The lower operating pressure of the 6.5X55 being the reason for better case life.

Visually the cases from my Golden State .303 British Jungle Carbine show greater changes after firing, with the shoulder blown out to fit the chamber, as designed for muddy battlefield conditions, and slight ring just above the head.  I always check these cases for incepted case separation.  I do not expect to get many loads from my .303 cases.  I use a wire with a fine hook to feel the inside of cases for the beginning of separation (incepted).

I have also seen the bright ring above the case head in some once fired 30-30 and .32 Winchester Special cases fired from Winchester M94’s.  I have heard about short cases life from 30-30 ammunition fired in a lever action; it has not been unexpected or an issue as some have made of the head size of 6.5X55 cases.

While I have been loading for fifty some years, my experience with the 6.5X55 is more recent and limited.

Has a member loaded a number of different cases of European origin, and U.S. manufacture in 6.5X55 and record the life span of the cases using the same load?

[deltecs]

All I did was point out that COW has quite a few errors in it and so is not a good source of information really.

   I do find it strange that the cartridge manufactures cannot seem to maintain specs on head and rim size when making cases, even thos cases which they designed themselves. As I have never used any American made cases in 6.5x55 I cannot comment on problems, or lack of them whe using such cases. As to the 6.5 SKAN? never heard of it.

In 1990, the National Rifle Associations of Denmark, Norway and Sweden agreed on a standardized set of drawings and specifications, renaming the 6.5x 55 Swede to 6.5 SKAN.  These standardized set of drawings and specifications permitted these countries to continue using the 6.5x55 as their active military round interchangability until recently.  Commercial ammo followed these changes in brass manufacturing.

[Brithunter]

Hmmm interesting. Have not seen cases marked so and this is the first i heard of it.

[beemanbeme]

Perhaps I shouldn't even be in this discussion but the Lyman 48th specifically cautions against the use of 30-06 brass in reforming for 6.5 Swede cases and then I've read the domestic brass --Rem/Win/Etc-- for the 6.5 Swede is made the same head size brass as 30-06 brass and the shell holders won't interchange between domestic and imported so how much caution should be used if any?
Anyway, sounds like a mind boggle to me with the easy answer being the .260 unless you already have a 6.5 Swede. 

[Siskiyou]

I am not advocating the use of cases with a smaller head (rim) then the .480 as a standard practice, but it is an option for the 6.5x55 shooter when the big brass crunch of 2009 occurs.  While I prefer to use brass with the correct head stamp, I would not hesitate to use some of the late military –06 brass I have for remanufactured 6.5x55 cases.

Time-out:

I trotted down to the reloading bench and checked a couple of cases that were handy.  The Swedish military case head measure out at .480, and the new, never loaded WW case out of the factory bag measure approximately .475 or .005 inches less.  I feel fortunate to still be alive.  I also have loaded ammunition from a couple of European manufactures; I will pull those out later for examination. 

Looking for the correct answer many times leads one to shades of gray.  I have a three of Lyman manuals and I respect the data in them.  But like lawyers, one will find a difference of opinions in published material.  In an older NRA Handloader's Guide, which was put together by the NRA Technical Staff and with ballistic data supplied by the H.P. White Laboratory, I found the following information:

“Also, cases can be die-formed from several U.S.-made cartridges, including 8mm. Mauser, .270 Winchester, .280 Remington, .30-06 etc.  Nominal head diameter of such reformed cases will be less that that of factor-made 6.5X55mm. cases, the difference being about .007.  This will result in a slight swelling of the case body forward of the head.  Neck reaming may be required.”

I am not a 6.5X55 purist, it has proven itself in the field in my hands, but my go to rifle is a .270 Winchester.

But I have a responsibility to my family and myself to manufacture safe ammuntion.  I expect that this discussion will be rehashed at my reloading bench with a newer family member who “might” end up with my 6.5X55.    I try and follow best practices for a safe product.  This includes a detailed inspection of a case.  Without a doubt inspecting for case separation is a critical part of the pre-loading process. 

One of the worse things that can happen to the reloader is to have a round fail in the hunting field. 

Based on field results I have no problem using loads based on my newly load Winchester-Western cases.  If I was a 6.5X55 “purist” I might go for the more expensive European brass from Norma or Lapua.  Will case life be 33-percent greater with the more expensive brass.  Will hunting accuracy be improved, in a rifle that is more accurate then I can hold, in my rifle is the smaller diameter head a safety issue when good loading practices are followed?  I think each reloader will need to decide the issue for himself.

[deltecs]

The military brass that measure .480" is probably one of the SKAN specifications.  The WW cases are probably those of commercial manufacturers with head size of .476" or as you measured .475".  Like I related in a previous post, the 6.5x55 was slightly standardized for military use with commercial rounds may still be slightly different with regard to head diameter as originally manufactured.  It is too bad that the military standardization did not just go along with the existing commercial standards instead of changing an original military round again.

[CapoWard]

I believe the Scandinavians did correctly when they updated the 6.5x55mm to the 6.5 SKAN.  They have been manufacturing firearms and ammunition for the 6.5x55 for more than 100 years.  Why should they change the cartridge’s original specifications comport with manufacturing short cuts implemented by major US ammunition manufacturers?      

We (the US consumers) should be demanding that US ammunition manufacturers comport with the original and updated SKAN cartridge design specifications for the 6.5x55mm cartridge.  It is they (US ammunition manufacturers) who have created this problem inclusive of any hazard it may pose…the solution is simple for all but their bean counters to understand.       

I don’t have a 6.5x55mm but have always liked them so I really don’t have a dog in the fight.  If I did own one, I would purchase Lapua or Norma ammunition over US manufacture ammunition unless the cases are true to specification and the cartridges are loaded to modern European pressure and performance standards.   

Jim