The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Wildcats And Their Development Chamber bigger than case, how much?Go | New | Find | Notify | Tools | Reply | |
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Hi all. I have a question about how much bigger the chamber can be than the case and still be safe to fire. I bought a 325 WSM finish reamer from PTG and I think it may be too large. I have a few basic questions. 1. How much larger(than the case) can the chamber be and still be safe to shoot? 2. How much larger than the reamer will the chamber be? My reamer's base is .558" and the chamber is .559" 3. How much longer should the reamers neck be? The reamer cuts a .326" long neck. The prints I've seen show a .300" neck for the 325 WSM. TIA Below is an e-mail I sent them. 325 WSM Reamer dimensions correct? Hello, I bought a 325 WSM finish reamer w floating pilot from you. I cut a chamber and noticed that the case wiggled around at the base. The reamer fit the chamber snugly. I did a chamber cast and measured the reamer. The reamer measured .558" at the base(2.1" back from the end of neck). The cases are .545". The chamber prints I've seen show the base at .550". Your site says you make the body -.0035" under. My chamber cast is .559". Is the chamber too large? Will I have a problem with cases splitting with .014" difference? Or should I wrap a piece of masking tape around the base to center the case and fire form? I measured several of my rifles and noticed that most have a .008" difference and one at .004". I also have a question about the neck length. The 325 WSM print I looked at showed a .300" neck. The reamer cuts a neck length of .326". Is this normal? Thank you for your time. | ||
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lar The difference between a minimum chamber and a maximum cartridge is usually around .002 to .003 for most dimensions. Obviously, the difference between a minimum cartridge and a maximum chamber is much more, probably about what you are experiencing. The best way to avoid this situation is to have a reamer custom ground to the dimensions of the brass you intend to use. All brands of brass is not the same. As far as a .558 reamer cutting a .559 hole that means either that the reamer is not .558 or the operator let a little off-center play take over. But I wouldn't consider .001 as being a big deal. Having said that, even the best reamer makers sometimes make mistakes. You are perfectly right to ask the questions that you did. JMHO Ray Arizona Mountains | |||
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So does anyone know if it will be safe to fire if the base of the case is .545" and the chamber is .559"? .014" difference. I was just reading in the new Handloader mag about the 9.3x62 and to not form cases from 06 brass as their is a .012-.014" difference at the base. The mag says "Anytime case expansion above the web approaches wall thickness, case failures become almost certain." I have some 300 RUM and 375 RUM cases that all measure .545" at the base. Does anyone have any RUM or WSM cases that measure larger than that. I may have measured the chamber cast after it sat for abit and expanded. The reamer is a tight fit in the chamber with no slop. | |||
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The ultramag and short mag cases I've measured are 0.550-.555" at the case head. The 404 Jeffrey is 0.542-.545 at the case head. I have to confirm my refrences, but I believe a chamber should be 0.003" to 0.005" larger in dia than the nominal sized case. __________________________________________________ The AR series of rounds, ridding the world of 7mm rem mags, one gun at a time. | |||
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What brand and caliber are your ultra mag cases? I'm trying to make a 325x2.55" to use surplus 8x57 barrels and have a loaded round that will still fit in the stock magazine. The idea is to have a big boomer with minimal effort. I'm going to try one of the 29.5" barrels also. I have some Hornady 125 spitzers that should be able to go around 4000fps. I want to try a case that is 2.25" long also to just clean out the 8x57 chamber. The 2.55" case has about the same capacity as the 340 wby. I had to cut down a 338 RUM size die to form cases and then run into the 325 size die to get the neck the right size. I tried forming cases with the 325 size die, but the sholder and body angles were too steep and it just buckled the cases. So the ones formed with the 338 die will need to be fireformed to get the body and sholder correct. The cases I have are Remington 300 and 375. | |||
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As I recall it was a remington 300 ultra case that measured .555" at the head, and winchester 300 WSM measured .550" at the head. The 300 Rum case was fired. I also believe a new 338 u/m rum case I had was .550" at the head. I'll have to measure the cases when I get home. That's an interesting concept, and it should be a screamer in the long tube. Getting it to feed properly will require the mag box to be widened and the feed rails to be widened and worked as well. __________________________________________________ The AR series of rounds, ridding the world of 7mm rem mags, one gun at a time. | |||
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Paul, i am getting .547 on the rum and .550 on the wsm, but, of course, ymmv. Lars, on the 416, 458, and 470 ar, with the .540 shoulder, the cases at 2.55 are about 4percent larger than the hh bases cases with the same bullet. jeffe opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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Well I guess theres one way to find out. I'll wrap the rifle up in a blanket, tie it to the bench and pull the trigger with a string. For feeding, it looks like I might be able to get away with opening up the front just a little bit. It looks like it wants to feed, but the sholder is too wide at the front when it tries to pop up. I think I'll fire form the cases with cast bullets seated out to engage the rifleing and be a force fit to keep the case head back against the bolt face. | |||
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In the world of wildcats, it's all been done before. https://forums.accuratereloading.com/eve/forums/a/tpc/f/...=420103682#420103682 | |||
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I don't know how big is too big, but the string test should tell. It'll be interesting to measure the case produced. Big Edit: How about an 8 mm - 376 Steyr?  ______________________________ DT | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Wildcats And Their Development Chamber bigger than case, how much?
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