7x57 to .284 win

[southernman]

Has anyone converted a 7mm Mauser to .284 win with out doing a barrel set back, I realize that the throat will be a bit further forward than normal and the Mauser case being 2mm longer, will likley never have to trim brass,
Will the .284 reamer clean out fully the old Mauser case chamber.
I have an old M70 push feed and thinking about converting it to .284 and choping it short about 17" and buffing on a Suspressor, (it's in NZ,) there is plenty of data for the .284 with a faster powder, still push a 140 gr at 3000 fps. Just use a faster powder than normal.

 

[Ltbull01]

Give some thought to a 7x57AI? No need to set back I believe unless throat dimensions needed work. Couldn't say if setting back needed for rechamber to 284. Doesn't look like you would need to.

 

[guntech]

Some 7x57's have very large neck diameters and long throats. A chamber casting of your rifle would be helpful in making a decision. Chambering to an AI version always requires setting back as all AI versions have a shorter headspace than the original version.

 

[Ltbull01]

Some 7x57's have very large neck diameters and long throats. A chamber casting of your rifle would be helpful in making a decision. Chambering to an AI version always requires setting back as all AI versions have a shorter headspace than the original version.

Interesting info re: Ackley. Good to know.

 

[c-fbmi]

Dennis is absolutely correct, the AI has a shorter headspace than the original case. HOWEVER any gunsmith can run the reamer in an extra roughly 20 thou to clean up the original chamber and make it an improved chamber but not technical an AI chamber. To answer your original question the answer is yes, a 284 rechamber will completely clean up the old 7X57 chamber except for the last bit of the neck without setting back the barrel. The neck/shoulder junction is 1.855 on the 7X57 and is 1.885 on the 284..............

 

[Sun_and_Steel_77]

I have an old M70 push feed and thinking about converting it to .284 and choping it short about 17" and buffing on a Suspressor, (it's in NZ,) there is plenty of data for the .284 with a faster powder, still push a 140 gr at 3000 fps. Just use a faster powder than normal.

3000 FPS with a 17" barrel is never going to happen no matter what you read on the intranets about Reloder 17.
My NULA chambered in .284win just barely makes 2950fps with 4831 and almost makes 3000fps with 4350 with a 22" barrel and near book maximums.

I experimented with RE17 after reading internet tales and picked-up 75fps but dealt with unsatisfactory accuracy.

Moly-coat your 140's and sprinkle them with fairy-dust, whisper a prayer to the God(s) of your choice, and shoot with a gale-force wind at your back and you just may see 2900 with your 17" barrel.

 

[pete dobinson]

No point in re chambering to 284 if your going to shorten the barrel to 17". I've got a 20" barrelled 284 and with 139 gr hornady and a hot charge of imr 4831 velocity will run around 2800 fps. RL 17 will be faster but accuracy might suck.

 

[southernman]

3000 FPS with a 17" barrel is never going to happen no matter what you read on the intranets about Reloder 17.
My NULA chambered in .284win just barely makes 2950fps with 4831 and almost makes 3000fps with 4350 with a 22" barrel and near book maximums.

I experimented with RE17 after reading internet tales and picked-up 75fps but dealt with unsatisfactory accuracy.

Moly-coat your 140's and sprinkle them with fairy-dust, whisper a prayer to the God(s) of your choice, and shoot with a gale-force wind at your back and you just may see 2900 with your 17" barrel.

You are correct, I miss read and have given incorrect infomation, 3000 fps is with the 120 gr
Can get 2700-2800 with 140 gr, plenty for a bush carbine.
Know several mates now, with chopped 16-18" 7-08 and .284 with suspressor, short hand carbine, and not hard on ears For man and dog,

Have my finlight 2506 fitted with a suspressor, but it's still 22" as 2506 really needs longer barrel, (New Zealand). Bit long to push bush.
Currently have two rifles, I am looking at reworking to a short suppressed carbine, 7x57 M70 and a sako finlight .260. Not sure witch yet.
Think you might be right, not enough gain over the 7x57... Over .284,