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Type 38 bore diameter

 
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Halfabubble



Joined: Dec 03 2009
Posts: 3

PostPosted: Thu Dec 03, 2009 7:24 pm    Post subject: Type 38 bore diameter Reply with quote

Hey, new here...just stumbled on the forum while searching for an answer.

I have a Type 38 with a 6-groove barrel. Two things I'm wondering:

1. For those of you who have slugged the bore, what was the groove diameter?
2. Have any of you shot oversize bullets (i.e. Hornady's .268)

The reason for my question is that my handloads are are running ~300 fps slower than published data. I slugged the barrel and it's around .269 across the grooves. Not being familiar with the Metford rifling on this thing, I'm wondering if this is normal, or if maybe I'd get better velocity and accuracy with a slightly larger bullet.

Thanks
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gwsiii



Joined: Aug 21 2003
Posts: 2207
Location: Hayden, AL

PostPosted: Fri Dec 04, 2009 9:27 am    Post subject: halfabubble Reply with quote

H...Welcome to the forum. I'm not up on this sort of question, but I've asked a couple others, hopefully they'll chime in when they get a chance, Trey
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DEFUC



Joined: Aug 17 2004
Posts: 200
Location: UP of michigan

PostPosted: Sat Dec 05, 2009 8:53 am    Post subject: Reply with quote

Ive used .268 bullets in slightly oversized bores,not uncommon in early arisaka (and if its got the 6 groove its early,pre 1918 I belive) .Ive also found flat based bullets to work best.Im not sure what loading or round your using,but structural design and base can effect speed somewhat ( I mean not all 140gr ,for instance, bullets will perfom the same or even close from differnt makers or patterns) .I think you'll end up using 160's if you move to a .268 ,I havent found much for 140s or 120's in that dia. but the round nosed 160's meant for the carcano work nicely.Id try a couple and see how they perform thru your gun. faster isnt usually better in the arisaka and similar rifled guns,the design doesnt stabalise a really fast moving round ,generally,so if you find a consistent load thats accurate thats what counts.
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Halfabubble



Joined: Dec 03 2009
Posts: 3

PostPosted: Sat Dec 05, 2009 10:39 am    Post subject: Reply with quote

Thanks, DEFUC. At least I know I'm not crazy for thinking about it. I guess I'll try the Hornady 160 first. Also found these 140 gr bullets at Buffalo Arms.

Not being familiar with Metford rifling, I guess I'm still unsure what constitutes oversize in these rifles. Would a "perfect" bore be .264 across the grooves?
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gwsiii



Joined: Aug 21 2003
Posts: 2207
Location: Hayden, AL

PostPosted: Sat Dec 05, 2009 10:48 am    Post subject: article Reply with quote

See Shannon's reloading article, in the first post one of the later images/pages mentions bore dimensions from various rifles of the 6.5 family. Trey
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DEFUC



Joined: Aug 17 2004
Posts: 200
Location: UP of michigan

PostPosted: Sat Dec 05, 2009 5:35 pm    Post subject: Reply with quote

Shannons article is one of the best on loading for the arisaka,we use the same base specs ,tho I play with mine constantly to match the particular rifle (he does too Im sure for precision shooting) but the 31.5 load of 3031 is really decent in almost every gun and a great starting point.His research is top notch (has to be Mikes work ) .Mag is another good source of info for the arisaka ,should he wander thru,I know he has done some oversize loadings,but dont recall the details he posted elsewhere.
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Smokey



Joined: Sep 07 2006
Posts: 60

PostPosted: Sun Dec 06, 2009 4:18 am    Post subject: Reply with quote

I use 160gr 0.268 bullets in a 6-groove Type-38 with good results. I use IMR-4831 and get good, usable accuracy and adequate power for hunting.
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Halfabubble



Joined: Dec 03 2009
Posts: 3

PostPosted: Tue Dec 08, 2009 11:54 am    Post subject: Reply with quote

thanks everyone. Great info!
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