357 Max reamer question

[Tioal]

Does the reamer alter the first bit of the original land and grove ? I just got a stock 357 Mag and it has a very deep chamber. It is about 1.430 and does not shoot swc lead bullets well. I feel this is due to the bullet being totaly free and un supported for .050 and then it slams into the rifling that has only a small bevel to center the bullet. It does well with jacketed  but they are more round nosed and self centering. Or is the fact that the grooves are only .0035 deep letting the lead bullet strip the rifling? There are reports of the Max shooting 38spl well and this if useing swc should be an even bigger jump. I am thinking 360 Dan Wesson brass but it is very hard to get now. I have ordered some 357 truncated cone to try. May even try round nose.My goal is to shoot home cast lead to keep cost down to lowest I can. I need to find a good bullet shape size ect before buying more moulds. Thanks for any thoughts Tioal

[Lon371]

 What kind of accuracy are you calling not so accurate? Have you slugged your barrel to find the true size to match your bullets to?
 
 Doubt your bullets are stripping the rifleing. Maybe bullets are to soft and filling the grooves. Or maybe pushing them a little to hard?
 
Lonny

[Dinny]

Welcome to GBO!!


  I would venture to say you're having accuracy issues due to the "forcing cone" H&R calls a throat. Yes the jump is far, but, as you have read, a Maxi chamber shoots the shorter cartridges much better than the OEM chamber did. I believe that to be the result of a proper throat. The rental reamer is made for cutting chambers on a rifle barrel. You will see a marked increase in accuracy after using it. If you're not up for the task, there are a few good 'smiths out there that do a great job. One of my Max chambers was cut with a throat specific to my preferred bullet. I'm not a very good shot nor am I an expert reloader, but Handi rifle shoot just over 1/2" groups at 100 yds.


Thanks, Dinny

[gcrank1]

Are you an experienced cast bullet shooter? If not, there is a cast bullet forum here on GBO that has a wealth of info. My point is that there is no reason to have to 're-invent the wheel'; the principles of cast bullet accuracy are well established. As to the 'jump' theory, look at the jump a .22Short makes in a LR chamber, and most shoot really well.

[jackddavis]

The bullet is NOT unsupported until it reaches the riflings as you suggest. There is a tapered section at the end of the case (commonly called a forcing cone) that decreases to the diameter of the bullet.  I measured the throat length in my .357 Handi with a split case and 140 gr. FTX. The bullet just touches the rifling lands at a cartridge OAL of 1.96". With a SAAMI COL of 1.59" the bullet jump is ~.37" with the FTX and should be similar with other bullets. However the bullet is still supported during that "jump" (at least with my FTX load with a COL of 1.86" it is).
 
http://www.cactustactical.com/reloading/tips1.pdf

[Tioal]

First thanks for your thoughts. I think Dinny told me what I most wanted to know. The reamer cuts a differnt style lead forcing cone throat what ever you wish to call it. To answer some of your thoughts the bore slugs .3575 The 2 swc bullets are sized .357 and are hard so that they barely take a fingernail mark.In 70 years of life 55 of them shooting I have learned I know very little but seek to learn all I can. The chamber is long as I said. To hit the lands the oal would need to be about 2.050. As the case is 1.290 and the bullet is .710 total 2.00 it is free float for .050. I do not wish to do a chamber cast which would show real dimensions .When I measure with a telescoping tool the chamber is atleast .360 just in front of the forcing cone or slight bevel to the lands. My guess is that the swc presents a sharpe full caliber sholder to that bevel and if it is even slightly tiped the it enters the lands and grooves out of center. this causes bullet yaw that only get worse in flight.My thought was either a more funnel like throat or use of a rounder nose bullet would help. The accuracy was not as big a concern as the 6 that cut a profile rather then a circle. Others showed oval or key hole.As I said the jacked soft point do well but they are almost round nose and will self center far better then a square full caliber sharp sholder. And the learning and guesswork go on. Tioal

[parson48]

Tioal,

Something to think about: cast bullets need to be at least .001 over bore size. If I understand correctly, your swc bullets are actually less than your bore. This can account for keyholing, as well as result in significant leading of your barrel.

I size to around .359 and have had good results with my maxi.

parson

[gcrank1]

The key is the bullet fit in the 'all critical' throat. The reason the old adage of 'at least .001 over bore dia. is that it results in a cast bullet that better fits most sporting gun throats.
The easiest way to get the best throat fit is to use as large a cast bullet as comfortably fits in a fully fire-formed (and necessarily unsized) case neck. Make sure you chamfer or slightly flare  any remaining lip edge from the case. If your supply of bullets falls into that case mouth, they are too small, regardless of the alloy. With proper bullet/throat fit even soft alloys will shoot accurately to some pretty stout velocities without leading.
Where this doesnt work is when a barrel's groove dia. is actually larger than the throat (as in most of the H&R 38-55s),but a simple throating job will solve that. Happily this is not the case in the majority of chamberings.
You may find referencing 'The Cast Bullet Assoc.' informative and useful.