308 to 307

[ranger 76]

has anyone changed a 308 to 307 so that it would have a rim.
or neck the 307 to 243 i would think it would be easy to do
mite be something to play with.  Lorne

[BCall]

I asked the same question, it can be done easily by cutting a lip for the rim, and possibly changing the extractor. Not sure about the necking down to 6mm, but that might not be a bad idea. 307 can be reloaded in 308 dies, so necking one to 6mm and using 243 dies could be an easy conversion if someone wanted a rimmed 6mm. There was a former forum member that used the 307, so it has been done, and I think it is a worthy conversion personally. Rimmed cases and single shots go hand in hand if you ask me. Billy

[FW Conch]

A guy on another site & his gunsmith built a 25-307 , stub barrel , on a TC platform.  The work is beautiful

& he says it shoots like a dream & has the targets to prove it !  "I" am up in the middle of the night with

compulsive delusions of a 6.5-307 , or a 6.5-444 , or a  6.5 Krag Improved  - why can't I just go to

"TEASERS" & hang around brass poles instead of " brass cases" ?            Jim

[watsisname]

I've been shooting a Winchester Big Bore .307 for well over 20 years. It is by far my favorite to shoot and reload. Basically a .308 with a rimmed case (same rim as 30-30) it has thicker brass than the .308 so you can reload over and over. Such a rimmed cartridge would be the perfect match for a break open single shot rifle. It would be extremely easy for Remington to build... a .308 barrel, cut out for a 30-30 rim and use a 30-30 ejector. Now how do we get the right person at Remington to listen??? I would buy the first one 

[Mitch in MI]

We had a regular here by the name of John, I think his handle was Deadeye47, who shortened a .308, I think it was a survivor, put a big aluminum muzzle brake on it, and cut the rim to make it a .307. John is dead now, but here's some info on his gun:

http://www.gboreloaded.com/forums/index.php/topic,65949.0.html

http://www.gboreloaded.com/forums//index.php/topic,48840.0.html

[carbineman]

I've been shooting a Winchester Big Bore .307 for well over 20 years. It is by far my favorite to shoot and reload. Basically a .308 with a rimmed case (same rim as 30-30) it has thicker brass than the .308 so you can reload over and over. Such a rimmed cartridge would be the perfect match for a break open single shot rifle. It would be extremely easy for Remington to build... a .308 barrel, cut out for a 30-30 rim and use a 30-30 ejector. Now how do we get the right person at Remington to listen??? I would buy the first one 

While I have chased this idea as well, the 307 would probably be a real slooooooow mover from a sales standpoint, and I doubt it would ever be introduced from the factory. I have toyed with the idea of using a 30-30 Topper barrel and going to 307 to really lighten things up. My 30-30 topper is my favorite whitetail rifle and it goes to northern Minnysodas with me every year on my annual rifle hunt. Having one in .307 would complete my rifle battery.

watsisname, What performance do you get out of your handloads for your Winchester lever in .307?

[NFG]

Other than the fact that 307 ammo cost 2-3 times what 308 ammo costs, if it can be found...all you have to do is insert a 307 into a 308 chamber and check the headspace is within limits and go shooting.  I think it's a step backwards for all intents and purposes as far as economics are concerned and other than the fact you can find 307 reloading components and some like rimmed cases better than rimless for single shot rifles, both cases are SAAMI spec'ed at the same pressure, use the same reloading dies and the same bullet size.  Both are basically interchangeable.

I have a Marlin 336 in 356 Win and I can use 307/308 (necked up to 358 cal) - 356/358, 7 and 8 x57 cases, and several other cartridge cases without any problems other than the case forming mess...interchangably...mix and match...I did it just to prove it could be done and to blow away all the "old wives tales" that were running around for a while concerning conversions in the Marlin 336...didn't help much...the unbelievers are still unbelievers.... ...as long as I used the same set of dies 356/358, adjusted to the headspace of the rifle.

As far as going up or down in calibers, the same thing applies...it is highly arguably "better" to use a rimmed cartridge case in single shot rifles than a rimless case...I think it depends more on personal preferences than anything else.

The reloadability of a case also depends on the pressures used...the 307 has a slightly thicker base but the neck was slightly thinner...we're talking thousandths of an inch here...and there are a bunch of ways to deal with that problem and it also depended on the case maker and case metal composition as to which was actually "stronger".

You have good ideas...the 307 case necked up or down makes for an excellent conversion for a single shot or lever gun and the case has been fondled over and over again since it first came out...I remember reading about a 22 cal once way back.  There are just so many rimmed and rimless cases that came before it that were wildcatted up and down for the 307 case to gain much of a following.

happy holidays

[FW Conch]

   NFG , I don't think you meant to say we can take a stock NEF 308  Survivor , open the action , & chamber a .307 WINCHESTER round in it ?   

[ranger 76]

When I asked the question about changing a 308 to 307 I thought if someone had a 308 or 243 that wouldn't shoot they could try changing it to a rimmed case to see if that really solves the accuracy problem.                           Thanks Lorne

[LaOtto222]

For the most part - all cases do better accuracy wise if you head space off of the shoulder, rimmed cases included. Cutting a groove for head space will not increase accuracy, unless there were head space issues before the rim cut and the rim was cut to minimum depth. Once you cut the rim in single shot, the only other mod you have to make is the extractor/ejector. I think if the 307 did not work or you could not get cases/ammo you could still replace the ejector and shoot 308 cases in the chamber with out blowing out the head. The rim groove would still fall into the heavier part of the web and should not blow out the head. I am not 100% on this, because I have not sectioned a case to be sure.

[Slufoot]

LaOtto222 you are 100% correct!
I just remembered that the Competitor Corp. offers a barrel chambered for 307/308.
A 308 Handi barrel with the rim cut made properly in a lathe to allow 307 Win to be chambered would have no problem shooting either cartridge as long as the proper extracter was installed.
An extracter for the 444 Marlin is a perfect fit for the 307 Winchester cartridge. They both have .470" base diameters and you can even make 307 brass from 444's if you are so inclined.

GOOD SHOOTING!
Slufoot

[FW Conch]

LaOtto-Slufoot, this is consistant with the posts I have read on the subject.Asfaras ejecting the 308 shell I

could just pop that sucker out of there with my trusty pocket screwdriver, same as I used to do with my

childhood hand me down 410, when the ejector broke !     Jim

[R.W.Dale]

For the most part - all cases do better accuracy wise if you head space off of the shoulder, rimmed cases included.

w


While true for every other action under the sun I feel this rule goes out the window with the break action. Or not that it doesn't apply but rather your headspace must be very tightly controlled within a very narrow range for constancy a break action cannot crush a shoulder back to a minimum headspace as the powerful camming action of a bolt gun can, with a rimmed cartridge this variance will only be how much the rims vary in thickness.

I would love to get my hands on a 308 bbl that doesn't shoot good and expiremnt with the original chamber VS being reamed to 307 or 7.62x54r with the same loads and bullets

[LaOtto222]

"Or not that it doesn't apply but rather your headspace must be very tightly controlled within a very narrow range for constancy a break action cannot crush a shoulder back to a minimum headspace as the powerful camming action of a bolt gun can, with a rimmed cartridge this variance will only be how much the rims vary in thickness."

I agree that head space is very critical in a break open action. A little too long and the action will not shut completely or repeatably. Too much and accuracy will suffer or you will have misfires or failure to fire. The rims are the same way. Rims can be cut too deeply giving you too much head space just like too much head space in the shoulder. That is why I suggested that if a rim is to be cut, to make sure that it is cut to the bare minimum. But even if you are using a rim for head space, you can get better accuracy if it is properly head spaced off the shoulder. Many people looking for top accuracy in a break open, custom adjust their dies to their chamber to ensure proper head space. There are lots of rims cut too deeply. They were cut to max specifications to ensure every case will fit. Case manufactures make thier rims to the thin side to ensure they will all fit into every chamber they may go into. You end up getting a sloppy fit. I think that is one reason the 22 Hornet does not get the accuracy as many other cartridges. You are head spacing off the rim because the shoulder is just too sloping to reliably head space off of. The 22 Hornet can do well enough if the rim has been properly cut into the barrel, but will not be as accurate as a comparable cartridge. Do not get me wrong, I like the 22 Hornet and own three of them. I like rimmed cartridges in break open actions. I have 6 barrels for my H&R frames and all but one of them are rimmed. Many people ream a 22 Hornet to K-Hornet and find their accuracy goes up. Good luck and Good Shooting

[cwlongshot]

Very good read with lots of great information!!!

Tim can this be added to the FAQ's so all this great info doesn't get lost?

I too am a firm believer in rimmed cases for break barrels. I do have a couple rimless handis. My 223 and 243 Ultra Varmint have been shot without a single incident. But my 25-06 Ultra is the opposite end of the spectrum. Giving me fits of frustration at times. it shoots great, just enough stuck cases to frustrate you. Lastly my 308 & 280, are somewhere in the middle. The 307 conversion is of intrest if only because its different...

 Thank you for all who contributed, this really is a great read!!

 Merry Christmas all,
 CW

[NFG]

FW...you notice I said..."CHECK THE HEADSPACE"..."..."BOTH CASES ARE SAAMI SPEC'ED TO THE SAME PRESSURE"...you can check that for yourself..."FOR ALL INTENTS AND PURPOSES, THE 307 AND THE 308 HAVE IDENTICAL CASE SPEC'S"...except one has a rim and the other is rimless.

I don't advocate ANYONE doing ANYTHING unless they thoroughly understand all the ramifications, I just responded to a question from the perspective of "been there, done that".

As I said I shot 356 W/358 Win (nothing but 307/308 cases expanded to 35 cal without any other mods) loaded ammo interchangeably and intermixed in my 356 Win, Marlin 336 levergun...and have use all the other listed cases with the required forming.  This is not to say I have a magazine full of intermixed ammo in my 356...doing so causes a big ruckus with accuracy...just that it can be done with minimum problems as long as you follow good reloading practice and understand the inherent problems and do the require things to solve them...


I use one set of Lee dies marked 356/358 to load the rounds and do much of the forming.

I don't have an NEF 308 Survivor to test so I can't say for certain if I could be done or not...I didn't specify a gun maker other than my Marlin 336 in 356 cal...but I have shot 307 W cases loaded in three different sets of 308 dies...RCBS, REDDING AND LEE, in two different 308 cal bolt guns/barrels while I was working through the 356/358W process just to see...I didn't have ANY problems with using the 307/308 cases as long as the sizing die was adjusted to fit the chamber of the particular rifle/barrel I was shooting at the time.  The rimmed and rimless cases fed, extracted and ejected without a hitch.

It may be as simple as just resizing or it may entail a more lengthy process...information on the "how to" aspect can be extracted online, in many reloading manuals or by experience...I've been doing this "reloading thing" for over a half century and the internet isn't a substitute for self education...I can't and won't try to reduce that level of experience to a few lines of print on a forum...if you don't quite understand or want to learn more, break out the books and start the long process.

I also continue to say..."don't ever use ANY data or information you find on the net unless you are a very experienced reloader and understand the whole process...reloading, case forming, SAMMI specs, headspace, chambering, receivers and pressure...to just name a few.

There are several good forums that have dealt with this same 307/308 - 356/358 conversion at length...Beartooth, Accurate Reloading, LeverGuns, etc...if you are interested, do a search on those sites for additional information.

The best way to insure consistent accuracy and ammo quality for break action guns is to adjust your sizing die so the action has a nice snug closure on the reloaded ammo...this insures minimum headspace and takes up any slop in the hinge pin.  The best way to insure the cases stay within that narrow window is to keep the pressures down...I garontee none of my breakaction shooters respond well to high pressures and that includes NEF, T/C Contenders and Encores.

One case in point...a 22-243 Midd...Ive had both bolt guns and a rechambered Encore in that wildcat...while I can get higher velocities than the 22-250 in the Encore, and the rechamber was done to correct an over length throat, I can't get anywhere near the velocity in the Encore that I could get in a Ruger M77 without the action locking up.  As long as I kept the pressure and velocity down around the 50 KCUP range in the Encore I still got higher velocity that with the OEM 22-250 and once the dies were adjusted correctly the accuracy and case longevity increased by a factor of 10.

Another case in point is to headspace on the shoulder for belted cases.  Different brands of belted cases have different headspace.  To ensure case longevity headspacing on the shoulder eliminates this problem...but how many bother with it...I use only once fired cases for hunting anything larger than a coyote, but try to extend the life of cases used for hunting varmints...but then again I only shoot a few rounds of larger caliber rounds a year while shooting 1,000's of rounds at varmints.  

Again this points to the fact that many reloaders have no clue when it comes to "benchrest prepping" there ammo and many don't want one...Not a problem...each person has different requirements when it comes to his fact of shooting and each will work through the problems or not as their needs dictate.

This sport is as bad as golf...some enjoy just whacking the ball around and enjoying a day out...some get wrapped up in the nuances of all aspects of the game...and the rest fall somewhere on the line connecting the two extremes.  

It's all fun and enjoyment no matter where you end up.


Luck on your projects.

[NFG]

One other thing I constantly remind shooters of...that each individural rifle is as individual as the owner...some can be pushed around more than others...some have no tolerance for the slightest hint of being thought "wrong" or disagreeing with them.

This is to say that for all the millions of reasons one rifle will take a load that will munch up and spit out another...same brand...same caliber...same load.

The only way to get the best performance for each individual rifle is to treat it like a balky mule...speak gently but have a 4 ft long, 2x4 handy just to get it's attention.

[FW Conch]

The original question was "308 to 307" ?  Assuming that all 307 rims were the same thickness then we could
make the rim cut out .001" deeper than rim thickness = rim headspace.  Once the 307 was fired in the chamber the case would be "fire formed" &  if it were neck sized & reloaded the next time it was fired it would be headspaceing off the "rim & the shoulder" !    Yes?  No?  Maybe?     Jim

[FW Conch]

NFG - point of order ?  You said " all you have to do is insert a 307 into a 308 chamber and check the headspace is within limits and go shooting".   I contend that before we can insert a 307 into a 308 chamber & close the action the chamber has to have a cut out for the 307 rim. Then it is possible to close the action & check the headspace for both rounds. ?     Jim

[LaOtto222]

The original question was "308 to 307" ? Assuming that all 307 rims were the same thickness then we could
make the rim cut out .001" deeper than rim thickness = rim headspace. Once the 307 was fired in the chamber the case would be "fire formed" & if it were neck sized & reloaded the next time it was fired it would be headspaceing off the "rim & the shoulder" !   Yes? No? Maybe?     Jim

Yes- Cutting the rim .001" deeper than the rim thickness would be ideal. If you neck sized only it would head space off of the shoulder, but only if it was less than .001" other wise it would head space off the rim still. Most factory cut rims are deeper than needed to ensure ALL cases will fit, so to get to .001: head space involves cutting a custom one.

NFG - point of order ?  You said " all you have to do is insert a 307 into a 308 chamber and check the headspace is within limits and go shooting".   I contend that before we can insert a 307 into a 308 chamber & close the action the chamber has to have a cut out for the 307 rim. Then it is possible to close the action & check the headspace for both rounds. ?     Jim

Of course the rim would have to be cut to fit the 307, then both could be shot in the same single shot break open gun. This will not work for a bolt action for instance because the bolt head and extractor would need modified to fit the head diameter of the 307 which is larger than a 308 head. They would not be interchangeable.

Good Luck and Good Shooting

[Badnews Bob]

From what I've read the .307 head spaces on the shoulder not the rim. Thats why it will chamber in a bolt gun or auto loader, the base of a .308 actually protrudes out of the chamber on my FN FAL and  my Mauser M48, so a .307 would to, I can't see how the bolt would close on the 307 because of the rim.  Now on a handie rifle if you cut the sammi .308 chamber a .307 will not work, The action could not close because of the rim. The .308 would chamber just fine in a chamber cut for the .307, the extractor would not work thou.

I understand what you guys are saying about rimmed cartridges, but how can it improve accuracy if its not head spaceing on the rim? As the .307 dose not do.

It also has a smaller capacity than the .308 so you would probably lose a little speed.

The only benifit I see is it should aid in extraction.

I am just speculating here as I am a card crrying member of the Just Because Crowd.

Thats why I am going to build a .22 Reed Express as soon as I can afford it.

[cwlongshot]

I haven't read that, its rimmed, so as it comes from the factory its headspacing off that rim. Whats being suggested here is that once a case if fireformed in a firearm and loading procedures do not move that shoulder. The newly loaded case is in effect headspacing off both head and shoulder...
 Personally, I have deal with HS problems for many many years, some problematic calibers are the 35Rem and the 357 Herrett. Mostly because they have small shoulders, the Herrett is of higher pressure and works best HS of both shoulder and rim.

What has been said here about higher pressures and rimless cases in SS actions is spot-on and IMHO the crux of the "issue" with them. Think on it, the only other variable that jives is the case's rim. Most rimmed cases are of lower pressures and these are by far the LEAST problemattic to handi shooters.. When the pressure spikes in a forward hinge action the action "stretches" a bit and returns to position it was in before firing. The brass case will remain at or damn near the expanded size. In a perfect world these two sizes are the same, in our world they are not. The brass flows to become the chambers size. This size is not only determined by the depth of the chamber but its legnth as well. SO, setting up dies to not move the fired cases shoulder is making that case headspace off both its rim and its shoulder simultaneously. This coupled with keeping the pressures down should be a good thing.

Ooh, the 307 is not of the same case cap as the 308. and the 307 does not equal the 308 in ballistics, but its is close. A better analogy for ballistic comparison might be the 300 savage.

CW

[FW Conch]

  First of all let me say MERRY CHRISTMAS to all ! 
   222, thanks for your input & conformation, I didn't think I was too far off on my thinking on the subject & your extensive knowledge is always well received.
   Bob & 222, I feel I am on the verge of making a point that I have been trying to make on several sites for some time. This is the NEF/ H & R forum so my focus is on the break action firearm. As has been stated,
if the cut out for the 307 rim into the 308 chamber is done accurately & to a nice tight headspace tolerance
when the 307 is fired, the case is driven forward against the front of the rim, the charge ignites & the case fire forms to the chamber reducing the shoulder headspace to zero, & as the case comes back against the breach face it can only move the amount allowed for the minimal headspace provided, & the case is (theoretically) perfectly formed to the chamber. That case can then be neck sized, trimmed to length, reloaded, & when chambered & refired, provide the maximum accuracy possible in a break action firearm, as far as the case to chamber fit is concerned. My thinking is, when this is achieved, the case is headspaceing of the shoulder & the rim @ the same time, providing maximum case to chamber stability & the only movement that can occur is within the dimension of the rim headspace originally provided. Of course, eventually, the case will grow enough to where the shoulder would have to be bumped back enough for the case to fit back into the chamber.
   I feel if this were applied to any rimmed case in any break action rifle that accuracy could be maximized as far as case to chamber to headspace is concerned.  When this is achieved it could contribute to the reasons that rimmed cases perform so well in the Handi, I feel.
   Weather these thoughts have validity or I am totally off base I would like to hear from anyone interested in the subject.   Thanks for Listening        Jim   CW, you posted while I was typing but I think we are of one mind on this?

[R.W.Dale]

From what I've read the .307 head spaces on the shoulder not the rim. Thats why it will chamber in a bolt gun or auto loader,.

What bolt guns or semiautomatics are chambered for 307win? Whilst neat for us handi guys the rim on 307 was purely a fashion statement and an aide to prevent confusion with 308win

.308 actually protrudes out of the chamber on my FN FAL and  my Mauser M48, so a .307 would to, I can't see how the bolt would close on the 307 because of the rim.

your comparison is flawed in that the rifles you cite are not break actions and do not chamber rounds in the same manner. The sngle shot action is as far as I know the ONLY rifle where a case head is flush with he breach face, to that end a cartridge with a shoulder bumped back beyond the minimum headspace created by the rim will ALWAYS headspace there.

Look into old world European cartridges for break action firearms single shots, drillings and doubles, there was an entire line of "flanged" and "rimmed" cartridges for these firearms, and in my opinion for very good reason

[FW Conch]

& krochus, isn't it true that when you acquire your 7.62 x 54 R the case could be fit to the chamber so that it headspaces off the rim & the shoulder assuring great stability & arruracy ?  Jim

[R.W.Dale]

& krochus, isn't it true that when you acquire your 7.62 x 54 R the case could be fit to the chamber so that it headspaces off the rim & the shoulder assuring great stability & arruracy ?  Jim

That's the theory anyhow. I would likely bump the shoulder back .002" so the actual headpace will be controlled by the min thickness rim relief that I'll cut.

I may yet go with 307 since I won't have to buy new dies for this rimmed vs rimless experiment. Either way it'll be a few weeks as my handi is at remington getting a couple bbl's fitted. Then I'll have to find a problem child "tomato stake" 308win barrel to experiment on.

[FW Conch]

Thanks very much, I for one will be standing by waiting for your results !     Jim

[Fred M]

so that it headspaces off the rim & the shoulder assuring great stability & accuracy ?  Jim

What are you talking about Great stability? What are you stabilizing? You can't both head space on the shoulder and rim at the same time. Nor should you ever head space on the the rim since all rims have a great deal of
variation, 0.015" I measured on different 303 brass.

Besides the Handi works best with "ZERO" headspace.
Converting a 308 to 307 serves no practical purpose and is a waste of time, since the Handi operates just fine with a 308 rimless case. Is the nut behind the butt loose?

[R.W.Dale]

Handi operates just fine with a 308 rimless case. Is the nut behind the butt loose?

Except for when your handi decides it want's to give you fits and start shooting 14" groups. You of all people can attest to that phenomena

There's nothing wrong with a little bit of experimentation, unless your the kind of guy who greatly fears the risk of proving himself wrong in the face of others

[FW Conch]

  Never headspace on the rim ?  That's bad news for the 45/70, the .444 Marlin, etc. ?