7.9x57 M88 Nil headstamp

I think we agree that bore diameter is the diameter between the lands.
If I understand you correctly, you say that original bore diameter was .3208 (8.15 mm) and was later reduced to .311 (7.90 mm) to make the grooves deeper.
Two Gewehr 88 barrel dimensional tables held in the Bavarian Army Museum (one for the older, thinner barrel shape and one for the newer barrel shape) both list bore diameter as 7.9+0.05 mm (.311-.313). The second dimensional table also contains the change of 1896 to increase groove depth from 0.10 mm (.0039) to 0.15 mm (.0059) and reduce bore diameter tolerance from +0.05 to +0.04.

Have you any German documentation describing the initial bore diameter reduction from 8.15 mm to 7.9 mm? So far, I encountered no source for this type of change.

Gewehr 88 was notorious for immense barrel wear, barrels being totally shot out after much less than 700 (yes, 700) rounds. I do not at all doubt the measurements you obtained from early rifles. But do they still reflect the dimensions as they left the factory?

I am glad we agree on

  • no dimensional change of the bore after 1896 through 1945,
  • the long throat is a relic of round nose Patrone 88.

I tried to be clear . I said the original bore dia was .314 , later reduced to .311 to make the grooves .003 deeper . The groove depth stayed the same at .321 , but with the smaller bore dia of .311 the grooves were deeper . There were a lot of old thin barrels made with the " new " .311 bore . the bore change happened before the thicker barrel change . So barrel shape is not a factor . The second bore size change was in 1896 and the grooves actually were made deeper to .323 [ the Z barrels ] with the bore staying .311 . Yes the original German documents state ’ the groove depth was deepened by .003 " in early 1890 due to wear . That matches my dozen 1889 and very early 1890 produced rifles with the original barrels . When a barrel gets wear it is the lands that wear , not the grooves . The .3188 bullet road the lands , not the grooves , the lands are only 25 ish % of the bore surface . All my bores are in very good + condition , sharp lands and all are .314 - 321 exactly .

To me the main question remains:
Can you quote any documentary evidence that says Gewehr 88 original bore diameter was .314 (7.98 mm) and that in early 1890 “groove depth was deepened by .003” (0.076 mm)?

I am quite willing to accept that the German sources on this matter that I read in the last 50 years did not mention this at all and therefore were wrong. But this in my view would require some sort of credible documentary evidence beyond measuring barrels of unknown history.

Along with many original German documents , it is not hard to find . The originals are still in Germany , but a lot is on the internet . Lately the first bore change has been confused [ by doc av ] by some as the Z barrel change .

Could you please show one of these documents?

Thank you in advance.

You researched original German military documents , or later books on the subject ? A lot of what I am referring to is fairly common , you never saw it in 50 years ? You must have a large collection of Gew-88 rifles built up in 50 years as a real rifle is very good proof of changes and dates . Without real rifles it is easy to misinterpret the meaning of documents , that is how most bad information on Gew-88’s got started . And there is a lot of it , and a lot of it just lately from a few really bad sources . Mechanical proof is also important . My documents and sources are mine .

If this is your opinion, this discussion brings nothing.


It brings the fact that you are incorrect about the bore sizes . Real rifles and German documents both prove it . Even if you do not know it .

dbdog9, I think what dutch is trying to say is that without scientific support of your statements his words are as good as your’s.

Or in German: sein Wort ist so gut wie Deines.

If you do not want to present the full set of documents you have because you have invested a lot of time and money it is very understandable.
But maybe you can cite the names & dates of the documents and show wether single sentences or single sections of a drawing or thelike so people will get your point and take it as a fact.


Well, I started this discussion back on 18 Nov and asked about a clip of M88 Cartridges I have that bear no headstamp.
The discussion has moved off topic a little as these threads tend to do and that’s OK.
I am only a novice in the bore size discussion and only just keeping up with the discussion so far regarding bore sizes varying from .311 up to .323 and everything in between, much of the discussion is academic and opinion based it seems.
Based on the premise that this forum is about sharing knowledge with like minded colleagues,
Anyone that may have documentary evidence please show us what you have and enlighten us with a partial or watermarked photograph to advance our collective knowledge on this subject of bore sizes.

Just my thoughts

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Lets get this question of BORE size settled.

The BORE of a rifle or shotgun is the original diameter of the the drilled and reamed hole in the barrel BEFORE
Rifling or Choking
It is also the universally accepted means of defining the Calibre of a Military Firearm.
(Calibre…thought to derive from the Latin Qua Libra meaning " how many pounds " …What Weight? Of ball; alternative derivations say it is an Arabic word relating to diameter or weight?)

Anything else in a rifled barrel is GROOVE DIAMETER

Which is NOT necessarily BULLET DIameter.

ESPECIALLY where 1880s–1890s Cylindrical Bullets were concerned, just like their Lead BP Predecessors were concerned.
Cylindrical jacketed bullets were made UNDERSIZED
Wrt GROOVE diameter for several reasons…jacket friction, metallic fouling, possible powder fouling (with semi smokeless and early compositions of smokeless)

They utilised the BASE UPSET OBTURATION system, where a concave lead base in the jacket on firing, expanded to fill the Grooves and thus give a gas seal.
( Minie style).
The best example of this is the M1891 7.62mm Mosin Nagant heavy ball bullet…Original drawings (Russian) show a bullet with a max. Shank diameter of .308", with an average .306" for most of the cylindrical part, and a .250" diameter conical impression in the base lead core of the bullet.
Imperial Russian designs in Inches.

Given that the BORE of the 7.62 MN is .300" ( trelinaya), and the GROOVES average out ( Given Russian production) at .310 to .312 on New rifles…the system seems to have worked fine.

The same applied in theory to the Gewehr 88. BUT with a BORE 7.9MM( .311) WITH 8.05 GROOVE AND A 8.05 BULLET…hence wear, barrel failure, overheating, etc.
Then rifling Deepened, 8.15mm( .320-321");, barrel and receiver steel changed and better controlled ( “n.m.”)
Bullet diameters varied with manufacturers, but Military
Bullets remained in the .316-318" diameter area.

Civilian barrels and projectiles were a totally different matter. BORES WENT DOWN TO 7,8, EVEN 7,75, AND GROOVES WERE .315-319" (many variations).

Then the 1903-5 change to the spitzer flatbased bullet…no more need for base upset, as the contact surface area of jacket to barrel was much reduced, the Bullet was made to approximate a new Groove diameter…8.2mm or .323" the S barrel…to match the S diameter Spitzer bullet The actual average Groove diameter was .3225" but rounded to .323" for tolerance and convenience. Gew 98 barrels are marked with BORE dia. for armourer wear gauging (7.90 to 7.94) at throat and muzzle.

Now the older Gew88s were found to be able to fire the S-munition, if the larger diameter case neck was allowed for in the chamber, compared to the smaller.
Diameter Gesch.88 and P88 case.
Once this neck and throat relief was done, the Gew88 could safely chamber and fire the S-munition.
The BORE was 7.9-7.92mm, same as for the G98, and the Grooves of the improved G88s were .320-321", and the shorter S bullet could draw down to the tighter groove diameter safely…a fact shown in WWI, when Austria rechambered 7.62 Mosins to Fire 8mmAustrian ammo without any ill effects!!!. ( DRAWING DOWN A CYLINDRICAL .324" BULLET TO A .300 BORE AND .310 GROOVE…QUITE A REDUCTION COMPARED WITH THE GEW88 S RIFLES!!!

Those are the basics leaving out misconceptions and misinterpretations and what may or may not have occurred between 1888 and WWI.

K.I.S.S. Our Sgt-major used to drum into us at Officers
Training .


It would seem logical that this would only be factaul if none of the rifles had actually been shot and have the original factory new tolerances.

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Please cite your actual sources, either scans or photographs, which, when shared, go a long way here to proove whay you say.

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Doc is a major source of 88 mis information . He has dates and meanings all mixed up . There are NO real rifles that match what he says . S is not a bore size . The Z is a bore size , it is .323 . It was started in 1896 , so NO Gew98’s have a groove smaller than .323 . All you have to do is measure a real rifle , all Z’s will be .323 , all 98’s will be .323 . By measuring rifling depth , you can tell if there is any wear .

[quote=“dbdog9, post:55, topic:30757”]
“S is not a bore size . The Z is a bore size , it is .323 .”

Interesting that you are the ONLY person I have EVER heard refer to a “Z” bore size, when all the manuals, articles, references, and stampings ON rifles I have seen over the past 50 + years have an “S” reference, and never a “Z”, .

Again, PLEASE cite your references, and supply scans or photos as provenance, as that is the ONLY way to prove your claims.

To be exact Z is not a bore size; it is a groove size. The Z represents the German word Zug, which refers the grooves of the barrel interior. Jack

Be that as it may be: I have never seen it mentioned in 50+ years, many working in the firearm industry, in any reference to a bore size/diameter/width/depth/groove/land/etc. in any way, SO, I am still requesting copies of documentation for provenance, which is said to be written references, as mentioned several times in previous replies.
I am sure I am not the only one who would like dbdog9 to add provenance to his comments.

My source was Die Handwaffen des brandenburgisch-preussischen-deutschen Heeres 1640-1945. That book was written in the years immediately following the Second World War by Eckardt and Morawietz, both former ordnance officers of the German army. My copy is of the Hamburg, 1957 edition. It is not a primary source but is a solid secondary reference in much the same way as Julian Hatcher’s tome Hatcher’s Notebook is. Jack

Thanks, but I am still wondering WHY you so adamantly refuse to post scans, or photos, of the references you mention… it would make many members happy to SEE the provenance you claim.

BadgerJack and Jack,
the book by Eckardt/Morawietz describes the matter only in German language, no drawing or photos. And the text gives the wrong impression that grooves were re-cut to make them deeper.
In fact, a “Z” on a Gewehr 88 shows that its original barrel was replaced with a factory new barrel which had the deeper grooves adopted in 1896. Nothing more, nothing less.
These new barrels indeed had 8.2 mm (.323") groove diameter, but the Z was not used in Germany as an indicator of groove diameter, but simply as an indicator of a new barrel.

Edit: The by far best factual sources on German military rifles 1869 to 1918 are the three volumes written by Dieter Storz of the Bavarian Army Museum at Ingolstadt. They are available also in English and can be found on the publisher’s website www.militaria.at