Slugged my O3-A3

[Slick Pilot]

Slugged the barrel of my O3-A3 Springfield tonight. Apparently it is a two groove bore.

When I miked the slug, it measured .3085.

Then when rotated 90 degrees, it measured .3005.

Does that sound right? I figured the bottom of the grooves, therefore are .3085 and the top of the lands are 3005.

This leads me to believe that, if I size my bullets to .309, they should be about right.

Someone sound off if I am off base.

Thanks!

[Buckshot]

..............You're gold! Those 2 grooves do really well with the bore riders, since they're 50% bore

..............Buckshot

[Slick Pilot]

Great! Now I'm going to go slug everything I have!

Thanks!!

[Dale53]

Slick Pilot;
I size to the ball seat (area just in front of the case mouth) size. I use the largest bullet that will allow me to seat in a fired case from THAT particular rifle with fingers, only. That will be somewhat larger than groove diameter (often as large as .311". This generally gives the best accuracy as the bullet is aligned by the fit in the ball seat (again, the straight portion of the throat just in front of the case).

These rifles will SHOOT. I have had excellent results with the two groove barrels back when I was shooting big bore rifles and experimenting with cast bullets in them.

Dale53

[bkbville]

I picked up a mint 2-groove at auction cheap because they thought the bore was shoot-out...

Turns out they just didn't know of 2 grooves - the bore is mint
Darn nice rifle that's for sure

[mike in co]

Slugged the barrel of my O3-A3 Springfield tonight. Apparently it is a two groove bore.

When I miked the slug, it measured .3085.

Then when rotated 90 degrees, it measured .3005.

Does that sound right? I figured the bottom of the grooves, therefore are .3085 and the top of the lands are 3005.

This leads me to believe that, if I size my bullets to .309, they should be about right.

Someone sound off if I am off base.

Thanks!

i would think more like 310/311...than 309..thats only a half over.......

[Bob S]

When I miked the slug, it measured .3085.

Then when rotated 90 degrees, it measured .3005.

Thanks!

You have an unusually tight one, and that's good. That one should also shoot jacketed stuff very well, too.

The groove diameter could be as much as .3095, and bore .3015 and still "pass". The vast majority of several hundred two-groove barrels that have come across my bench in the last 43 years have been .309+ and .301+.

Resp'y,
Bob S.

[docone31]

I paper patch mine at .309.
Out shoots jacketed.

[Ben]

And yes, THEY WILL SHOOT !!!!!!!!!!!!!!!!!!!!!!!!!!!!

[sundog]

I'm with Dale. Slip fit of a sized boolit to the fired case is a good way to set it up.

I go one step further. I outside neck turn a batch of good brass for each rifle and neck size only. I also weigh my match boolits (cull the light weights for barrel warmers or recycle) which has reduced flyers to zero. Two groove barrels can be very accurate. It's normal for a .311 boolit to work quite well in all of the 03s I've the pleasant honor of knowing. In fact, I've never slugged a single one of them (don't like beatin' on a gun), just size to the fired case and set length to lands.

The 03A3 I'm currently using as my match gun for military bolt matches is 'as issued'. I named her "Ole 98". That gun will consistently shoot 98s on the SR21 at 100 yards with just about any 180-210 grain boolit and 21.0/4227. When I study real hard it will do 99s and 100s, also. I shoot a 1.820 inch group at the state shoot off a couple weeks ago. This is not bragging, as I get my butt soundly whipped on a regular basis. I'm just trying to convey what these fine old rifle are capable of. My buddy's 03A4 is well capable of sub MOA with 168 BTHPs. It does almost as well with real boolits.

[sundog]

Looks like we have some 03 fans. Nice shooting, Ben. Here's another one.



50 yards with a 4X scoped sporter, 311291, 10 rounds. The paster is 3/4".

[Char-Gar]

As others said, those specs sound just fine. As others said, .310 or .311 would probably be better than .309.

You made me curious about the new Remington 2 groove 03A3 barrel on the Krag I am building, so I got up and went to the vise and using a Starrett small hole gage measured the lands. Two inches down from the muzzle and got .3003. I have not sluged it yet and figure .310 bullet should do the trick. A .301 nose or even a .300 nose (depending on bullet design) should work fine.

I am like Sundog/Corky in that I don't like beating on rifles. With most rifles, a little research will give you the nominal specs. A small hole or pin gage will give you the land diameter without banging on the rifle. The body should fit the throat of the rifles and as long as it isn't so large it shaves lead going into the throat, you are good to go. Way to much is made of this standard advise.."slug the bore". If a fellow knows his way around a rifle it isn't necessary in the vast majority of the cases.

A set of Starrett small hole gages, plus a good Starett mike that reads out to .0001 are wonderful things to have on a bench. Pin gages don't require the correct "feel" to be accurate, but a set of small gages cover every thing up to .500 are are very accurate once you get the feel.

You can also measure the inside diamter of a fired case with these gages, deduct .001 and you have your slip fit without shoving bullets in the case neck.

No, I don't own stock in Starrett or any other tool company. I had had my tools for 40 plus years and know how useful they are.

[carpetman]

Slick Pilot-- "Great! Now I'm going to slug everything I have." Are you married by chance?

[Ben]

sundog :

That's some good shooting ! !

Love those 2 groove barrels with cast bullets. A great combination !

Ben

[StarMetal]

Sundog,

Neck turning can be a real enhancement, but I look for the thickest neck brass I can get for cast. For example forming 06 brass for the 6.5x55 Swede. I want to most center the cast bullet as much as I can. Turning is required with the Swede because the 06 necks of military brass are too thick. Boy if you could find some extra thick neck brass that would be the cat's meow for your 06.

To the poster, I'd start off with a fatter bullet then .309 and follow the rest of the stuff mentioned here. You've blessed to have such a tight barrel.

Let us know how it shoots.

Joe

[Slick Pilot]

Slick Pilot-- "Great! Now I'm going to slug everything I have." Are you married by chance?

OOPS! I meant every rifle that I have!

All the advice is greatly appreciated.

I have to point out, though, that there was very little impact on the weapon when I slugged the barrel. I just made sure the bore was very clean, swabbed it with oil, then tapped in a OO buckshot that I had lubricated with Lee case lube. I can't imagine that it was at all hard on the gun.

I have a Mosin Nagant that I am going to slug tonight, then a Krag when I can get to it.

Thanks for all the input.

[sundog]

Joe, that's the idea. Consistent neck thickness and as thick all the way around as the thinest spot in the entire batch. Concentricity. Then load with the thickest boolit that will fit without forcing. There's other ways of doing it, but that way works pretty good in the old milsurp bolt guns. Too much for some folks to mess with, and that's fine. No skin off my nose, more power to them, we're all shootin' and havin' a good time. Hooah!

It ain't rocket science. It's BOOLIT SCIENCE!

[chboats]

I have an 03A3 that the barrel slugs at 311/303. The throat is .312. The guy that sold it to me sold it because it was not very accurate. It took me a while to find a boolit that fit the bore. I tried a 314299 but the nose was not big enough for the throat area. The attached target was shot with a saeco 315 sized .312 and 16 gr of 2400 with issue sights at 100yds.


I have to admit that this is one of my better targets. Too bad about the one in the upper left(operator malfuction) It also shoots great with the 311284 GB that I received a couple of weeks ago. It drops a boolit with a 303 nose and 314 body.

Carl

[Slick Pilot]

Okay, I slugged my Mosin Nagant 91/30 last night. It came out with a groove diameter of .3125 and lands at .3020.

Can anyone recommend a good bullet?

Any suggestions for with and without a gas check?

Thanks.

[chuebner]

Slick Pilot,

You are lucky to get a 91/30 with a .312 bore. My hex 1937 91/30 slugs at .301 X .314 and I've been using a Lyman 314299 beagled to .316. I lapped out a Lee .314 push thru sizer to .316, apply a gascheck with Lee alox and load with 14-16 gr. 2400. Groups about 2 1/2" at 100yd.

By the way, my 03A3 slugs at .300 X .309 and it loves the 311284.

charlie