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7.7-06......has it been done, can it be done?

kidthatsirishkidthatsirish Member Posts: 6,985 ✭✭✭
So...i have a arisaka 99 that was reamed to accept 30-06. While this is very safe and done numerous times espicially on early war rifles like mine, the accuracy suffers as 7.7 jap uses a .311-.312 bullet best.

So..my question is, If I have some 7.7 jap bullets is there a way to neck up a 30-06 case to accept the slightly larger bullet?

I can't imagine I'm the first to try this in the past 70 years....

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    charliemeyer007charliemeyer007 Member Posts: 6,579 ✭✭✭
    edited November -1
    If they just ran a reamer in it, I think the fired cases will have a bulge just ahead of the web.

    I would just change your expander ball to a 303 British size. FL sizing your 06 cases with a larger ball will work your brass harder (same with the lumps), but so what.

    Slug the bore, dad had a 6.5 that a 270 bullet would drop threw. Had nice rifling tho we never found a bullet that fit correctly
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    kidthatsirishkidthatsirish Member Posts: 6,985 ✭✭✭
    edited November -1
    It does not shoot 308 bullets very accuratley....310 0r 311 bullets will fit better i imagine.
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    MIKE WISKEYMIKE WISKEY Member, Moderator Posts: 9,986 ******
    edited November -1
    "I think the fired cases will have a bulge just ahead of the web.".............I don't know why you would think this, the 'head size' is almost identical (.470" vs .472) chamber reamers vary this much. as above, slug the bore and go from there.
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    charliemeyer007charliemeyer007 Member Posts: 6,579 ✭✭✭
    edited November -1
    I think that because I have seen it. Dimensions on paper have little to do with actual war production. I didn't say the bulge was dangerous, just implied full length sizing will likely be necessary.

    Case life will be shorter due to working the neck harder, 06 brass is cheap enough.

    Annealing could be a good skill. Neck sizing only in a 303 Brit might work well too.
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    kidthatsirish,

    First and foremost, cast the chamber before making any rash decisions about which bullet or dies to use. Be smart, know your chamber dimensions first then see if there is anything to be done about improving accuracy.

    The area I question is the neck diameter, especially when recommended to increase the bullet size by as much as 0.004" to 0.006" in diameter. If the neck diameter is a pinch too small for the larger bullets, the case necks can be turned a tiny touch for clearance/expansion also.

    Do the cast, then do the measurements, then do the math. There are no short cuts to safety.

    Best.
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    MobuckMobuck Member Posts: 13,855 ✭✭✭✭
    edited November -1
    Here's a specific instance I found. Not a 7.7 but an Argentine 7.65.
    Chamber had been reamed to 30/06 with no other modifications. Accuracy was poor with .308 bullets which is likely the reason the rifle was for sale. In an atempt to improve accuracy, I simply forced .312 bullets into sized 30/06 cases-not that difficult. UNFORTUNATELY, the 30/06 chamber neck would not accept the rounds loaded with the .312 bullets. I turned the 06 case necks thinner and was able to make the rounds fit. BUT then realized that meant they'd also chamber in a common 06 chamber and decided the possibility of forcing .312 bullets down another rifle's .308 bore wasn't worth the gain.
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    SoreShoulderSoreShoulder Member Posts: 3,136 ✭✭✭
    edited November -1
    quote:Originally posted by Mobuck...BUT then realized that meant they'd also chamber in a common 06 chamber and decided the possibility of forcing .312 bullets down another rifle's .308 bore wasn't worth the gain.That's not the end of the world. You could just use a slightly milder load and if those rounds find their way into an '06 it won't blow up.
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    navc130navc130 Member Posts: 1,216 ✭✭✭
    edited November -1
    You do not say what the accuracy is. Are the bullets keyholing? I would try some different bullets to see if some worked better than others. If you can get a three to four inch group at 100 yards you have a satisfactory deer rifle up to that range. I loaded a 170 grain 30-30 bullet in my 7.7mm Jap and as I recall it shot OK and was stabilized. If you try loading a .311 bullet, Nononsense's comment is appropriate. YOU MUST HAVE PROPER NECK RELIEF TO RELEASE THE BULLET. Catastrophic pressures develope with a too tight neck condition that does not allow the case neck to expand and release the bullet. If you are not familiar with that issue please read a good reloading manual on that subject. A follow-up report of your tests would be interesting.
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    quote:It does not shoot 308 bullets very accuratley....310 0r 311 bullets will fit better i imagine.

    His accuracy really doesn't matter because he does NOT know what's going on in the chamber. Anything done before knowing what size the chamber is has the potential for being dangerous.

    Be smart, cast your chamber then tell us what the dimensions are and we can then make sensible suggestions.

    Best.
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    charliemeyer007charliemeyer007 Member Posts: 6,579 ✭✭✭
    edited November -1
    Post some pic's of the fired cases.
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    kidthatsirishkidthatsirish Member Posts: 6,985 ✭✭✭
    edited November -1
    quote:Originally posted by nononsense
    quote:It does not shoot 308 bullets very accuratley....310 0r 311 bullets will fit better i imagine.

    His accuracy really doesn't matter because he does NOT know what's going on in the chamber. Anything done before knowing what size the chamber is has the potential for being dangerous.

    Be smart, cast your chamber then tell us what the dimensions are and we can then make sensible suggestions.

    Best.




    I know it was a 99 arisaka reamed to accept the 30-06 cartridge. I intend at this point to load the 180 grain 7.7 bullets into a 30-06 case(not primed or powdered by the way). If they fit i will then load the dud rounds into the rifle. If they load and eject as smooth as they should then I will pull and load with a starting load of powder and see how they shoot.
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    sandwarriorsandwarrior Member Posts: 5,453 ✭✭✭
    edited November -1
    I've seen a number of 7.65 Argy's and some 7.7 Japanese 99's converted to an '06 case. None were worth the money spent to get at best an average shooting rifle. Save some pennies and get the right barrel put on there. If it's already chambered, do as nn said and figure out where you're at with the chamber. Nothing dumber than having a gun accident that you knew could have been a problem from the get-go.

    I will also say, I've seen a number of 8mm-06 conversions just like above. The best were hunting capable at best. and yeah, they work alright for that, just as the above will when you get the chamber and bore figured out.

    I saw one however that started as a new replacement barrel chambered in 8mm-06 that shot outstanding. IMO, that's because it started as a single cut with a modern reamer. My .02$
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    Hawk CarseHawk Carse Member Posts: 4,373 ✭✭✭
    edited November -1
    I recall we rechambered a number of captured Arisakas to .30-06 for the ROK. Wonder if they used many against the DPRK.
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    kidthatsirishkidthatsirish Member Posts: 6,985 ✭✭✭
    edited November -1
    quote:Originally posted by Hawk Carse
    I recall we rechambered a number of captured Arisakas to .30-06 for the ROK. Wonder if they used many against the DPRK.


    Would be interesting to know. The one in question here is a early war production model that was captured during the battle of Okinawa by my grandfather. He brought it home and had it reamed by his hometown gunsmith to 30-06. It was given to my father, who, on my 16th birthday gave it to me where I asked my grandfather to recount how he got it. He did so reluctantly, and I appreciate him doing so as I know it brought back some painful memories.

    I fire it once a year...which is why the 18 bullets I have for it will do just fine for the foreseeable future. I hope that someday in the future my son will be happy to have it passed to him.
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    charliemeyer007charliemeyer007 Member Posts: 6,579 ✭✭✭
    edited November -1
    I have a bring bring back from my uncle Dutch. It's a 6.5. The story goes this one would clip weeds/branches off from point blank to as far as he could see them. There were piles of rifles and foot lockers full of ammo so he shot lots of them and picked a good shooter.

    While an occupation troop, he ask guy about the rifle on his back. It was some kind of 11 mm something bolt gun. The guy wouldn't take it back - it was honorably surrendered. He always called his weasel gun - a weasel could run down the bore.

    His other one was an 8 mm Murada. I made ammo for it. We gave it to a nephew.
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