Help me improve the accuracy of my Remington 798

[rainydayshooter]

Haha, I took my 3-9x off this rifle.
Having access to a good range and being a passionate shooter I couldn't resist.
Making the 1,000 is on my bucket list now.

I haven't considered the sticks because they're foreign to me, but might look into it.

I put a cap on my collection after me and a buddy bought and traded as many firearms as we could. A pistol, bolt action, semi-auto, and shotgun is all I need.

So I have this evolution...
I could hunt with my semi-auto but prefer my bolt.

Maybe I will compete one day, but after seeing someone shoot a 7" group on the 1,000.
I think it will be wayyy out.

[rainydayshooter]

So an update. I bought a new barrel but can't find a Smith that can do it. Something about metrics and European threading tpi/pitching or something. Sent it to 4 gunsmiths just to have each one return it saying they can't. Didn't think rebarreling this would be so difficult.

[Jim Watson]

The 798 is a '98 Mauser made by Zastava. I would expect it to have Mauser standard threads which are metric but have been cut by any gunsmith worthy of his lathe.

[Clemson]

Find yourself another gunsmith. That rifle has 1:12 Whitworth threads like almost every other Model 98 Mauser.

Bill Jacobs

[Scorch]

That rifle has 1:12 Whitworth threads

That's 12 tpi (threads per inch). I just rebarreled a Zastava Mauser last summer, it's pretty easy. If your so-called smith can't rebarrel a Mauser, what can he do?

[Clemson]

Amen!

[Unclenick]

The Mauser threads are not metric in pitch. They use the old British Whitworth thread, as mentioned by Clemson, so it has a 55° thread profile instead of the 60° profile used most of the time these days. When I was messing with Mausers, I bought a special 55° profile threading tool from Brownell for the barrels. I later concluded I could have worked around it as the lathe's toolpost can be set to angle a 60° threading tool 5° tailward and the top slide under it may be set to the 55° angle, then the 55° threads produced by turning the cross slide in a little at each threading pass until the depth of cut is adequate. You don't get the ideal radiused peaks and valleys of the Whitworth profile without modifying the tip of the threading tool, but you do get something that fits, and it is something any gunsmith with a lathe should be able to do.

Other than that, if you buy your barrel from Douglas, McGowan, Hart, Shaw, they offer rebarreling services to include installation. I'm sure some other brands do as well.

[HiBC]

While I agree threadform is important, i have a lot of years in the macine trades and some experience with threading tools.
The manufacturing industry uses almost exclusively carbide insert tooling.
Threading tools,too,and I'm sure 55 deg inserts are available.That system has advantages,one being if you chip a tip the replacement insert will be essentially identical.
A disadvantage is the cost of buying the tooling.Figure the lathe tool "bit" around $100 ,plus or minus,and the inserts $10 each,plus or minus.

I've cut a lot of threads with hand ground high speed lathe tools.A "pocket comparator" can be very helpful.Ists sort of a jewelers loupe with scale reticles.A thread gauge and loupe can be used. Final shaping can be done with a hard,fine India stone.
I'd certainly communicate with the number of fine USA barrel makers who can fix you up,but there is one other barrel maker that I might look at the website.
No,I'm not saying its better than the fine American companies! Among those,if you have Kreger,Bartlein,Lilja..I have not been disappointed by Douglas Premium or Criterion. There are oher good ones I have not tried.

But for pre-chambered,pre threaded.contoured Mauser barrels, ten years ago,I got a good price and a nicely machined barrel from Lothar Walther. It might be something to look at.
I would think your smith would have a Mauser receiver mandrel. If he doesn't, I'd buy one from Brownells. You want a skinny facing cut taken off the receiver ring. That surface is the foundation of your barrel/receiver fit. It needs to be square and flat.

Good luck!

[Unclenick]

HiBC,

Thanks for the website suggestion. I don't think I've ever looked there before, and they do have some things other barrel makers don't catalog that I recall; polygonal rifled pistol barrel blanks, five chamberings for the M1 Garand, hammer-forged 223 barrels.


Rainydayshooter,

One part of your group size puzzle (though not the whole thing) is you should expect some growth in moa with distance from a rifle, even if it is fired from a machine rest. This is because some portion of the error in the group is due to radial drift way from the mean trajectory path. Because the bullet slows down as it goes downrange, each successive 100 yards will have a longer time of flight than the previous 100 yards, and that gives the drift more time to carry the bullet away from the center of the group.

If you could fire in still, unchanging air from a perfect machine rest and every round departed with the exact same velocity and barrel time, you would expect the following effect from bullet slowing:



Since you don't have still, unchanging air or zero velocity spread, you can expect the increased moa with range to be greater. That table is the minimum expectation.

[Bart B.]

Regarding the effects of crosswind, those closest to the firing line have the greatest effect of drift at the target. See post #2 in:

https://thefiringline.com/forums/sho...ght=wind+drift

[BornFighting88]

Originally Posted by Unclenick

The Mauser threads are not metric in pitch. They use the old British Whitworth thread, as mentioned by Clemson, so it has a 55° thread profile instead of the 60° profile used most of the time these days. When I was messing with Mausers, I bought a special 55° profile threading tool from Brownell for the barrels. I later concluded I could have worked around it as the lathe's toolpost can be set to angle a 60° threading tool 5° tailward and the top slide under it may be set to the 55° angle, then the 55° threads produced by turning the cross slide in a little at each threading pass until the depth of cut is adequate. You don't get the ideal radiused peaks and valleys of the Whitworth profile without modifying the tip of the threading tool, but you do get something that fits, and it is something any gunsmith with a lathe should be able to do.

Other than that, if you buy your barrel from Douglas, McGowan, Hart, Shaw, they offer rebarreling services to include installation. I'm sure some other brands do as well.

Last I remembered, Mauser 98’s used 1.100”x10 TPI, and a standard 60 degree tool will cut them just fine. I think the compound adjustment at the 60 degrees is 0.087” (.866/TPI, hence .866/10 = 0.0866”). I have found when single point cutting threads, it is best to start by making your last pass about .005-0.010” shy of your calculated depth. Only cutting a max of 0.001” per pass until you have seated your threads to a satisfactory fit.

I digress. Usually glass bed, free floated barrel, and properly torqued action screws go a LONG way to starting you on your accuracy journey.

[HiBC]

Just to list a back up reference source, I searched "98 Mauser Barrel Shank Thread data"

One of the sources that came up was a "Practical Machinist Forum". They had a thread on the subject.

It verifies 55 Deg Whitworth thread form, 12 threads per inch, 1.100 major

You may do your own search,or look here:

https://www.practicalmachinist.com/v...-specs-175198/

Note one post confirms truing the receiver face face using a mandrel.

Consider most (if not all) Mauser Military barrels did not have a shoulder that seated against the forward surface of the receiver ring. The largest diameter of the barrel was the major diameter of the threads.

The extreme end of the barrel,at the level of the chamber mouth,stopped against the diaphram within the receiver ring.

At least on a Military 98,nothing rested on the forward surface of the receiver ring. I have no idea what the original machining strategy was for the 98 Mauser, but they had no real good reason to make the face of the receiver a precision surface.

The common way of fitting barrels to Mausers today,the forward face of the receiver ring is THE foundation surface the barrel extends from.

Since the scope (line of sight) is attached to the receiver,and the axis of the bore is the barrel, how the barrel seats to that foundation is CRITICAL to accuracy. We want it square,straight,and solid.

Anything that amounts to a high spot or out of square condition introduces play,or a "cracked baseball bat" into that joint.

I might be wrong, but IMO, some "bedding solutions" such as a pressure point,worked because they provided a preload to push the barrel to take the rattle out of the barrel receiver joint. A rattling free float barrel won't work so well.
But flat,square fitup of precision surfaces will likely make full free float the most consistently accurate bedding method.

Other folks ,I'm sure may disagree, but when I tighten guard screws,I want the flat bottom of the receiver to be the one and only surface (think horizontal datum plane "A") the screw is loading. The floor. On a Mauser,depending on the bedding strategy,it might be the guard screw bosses, or the sides of the receiver rails that provide a vertical datum plane "B" to align the receiver . The fence. And the recoil lug,Datum "C", or the "Stop".
Just like a machine setup.

I DO NOT want two surfaces arguing over which is in control. Like tang versus recoil lug. Or sides of guard screws contacting the stock.

And I DO NOT want torquing up the guard screws to put a side load on the breech end of the barrel!! You do as you wish.

[Scorch]

Mausers are a little bit different to bed than a lot of rifles. Flat bottom keeps them from torquing when fired. The rear of the recoil lug, the flat bottom of the front receiver area, the rear pad, and slight shoulder areas at the front ring and rear tang are the only places that should contact the stock. If the rear of the tang touches the stock it will split it eventually.

Do the barrel any way you want, free-floated or bedded, but put a shoulder on the barrel that contacts the front of the receiver ring. Original Mausers were barreled that way, the barrel had a shoulder that seated against the front of the receiver and the breech seated against the internal gas ring. We used to go to a lot of trouble to make sure both the receiver ring and the internal gas ring made contact when the barrel was seated, but I have seen a lot of them that were not done that way that shot just fine as long as the threads were tight.

And yes, Mauser threads are 12 tpi, both on small rings and large ring Mausers.