Help identifying 30-06 IMP rifle

[antelopedundee]

Simply take a empty and open rifle case and place a primer and a few grains of pistol powder in it and try shooting it. You will see

Quite likely to happen if you don't use ENOUGH Bullseye.

Here are other thoughts about the matter.

https://forum.accurateshooter.com/threads/forming-ackley-brass-with-a-new-barrel.4007763/

 

[Remington92]

Dragging this up from the past but I finally got around to mailing some brass off to Redding for examination. This was their reply

I've had a chance to examine the fired cases you had sent. Unfortunately we do not have any dies that are suitable for this chambering but I can give you some information anyhow. These cases have a 35° shoulder angle which surprised me given the "imp 30" marking on the barrel. The major issue that I see is that the base diameter is rather large which makes me leery about the potential safety hazard posed by firing this rifle. As you mentioned, one of he cases appears to have split or is very near splitting. For obvious reasons this could be extremely dangerous. I would suggest consulting a gunsmith about this to see if the chamber could be set back and fixed or maybe consider re-barreling the rifle. In any case - I would advise not firing the rifle until it has been evaluated/repaired by your gunsmith.

So given this what can y'all recommend for possible rechambering? Or with the oversized chamber diameter am I forced into a rebarrel?

 

[jdyoung]

Dragging this up from the past but I finally got around to mailing some brass off to Redding for examination. This was their reply

I've had a chance to examine the fired cases you had sent. Unfortunately we do not have any dies that are suitable for this chambering but I can give you some information anyhow. These cases have a 35° shoulder angle which surprised me given the "imp 30" marking on the barrel. The major issue that I see is that the base diameter is rather large which makes me leery about the potential safety hazard posed by firing this rifle. As you mentioned, one of he cases appears to have split or is very near splitting. For obvious reasons this could be extremely dangerous. I would suggest consulting a gunsmith about this to see if the chamber could be set back and fixed or maybe consider re-barreling the rifle. In any case - I would advise not firing the rifle until it has been evaluated/repaired by your gunsmith.

So given this what can y'all recommend for possible rechambering? Or with the oversized chamber diameter am I forced into a rebarrel?

In the pictures you included, I didn't see any Imp 30 marking on the barrel. Is there such a marking ?

 

[Remington92]

That was a screw up on my part I meant to put imp 30/06

 

[jdyoung]

Still, from my understanding of the stamping, it's a 30/06 IMP (Improved). Have the chamber cast to verify the cartridge and shoulder angle.

 

[Frog4aday]

If the gunsmith thinks the barrel can be set back enough to clean up the loose chamber fit, I'd just ask if he can recut with a standard .30-06 reamer at that point. Path of least resistance & cost.

If it has to be re-barreled, then you have a lot of options to choose from! But a classic rifle warrants a classic cartridge. I'd go .270 Win or .30-06 Sprgfld again, but I do so love .25-06 Rems!

 

[Sage70]

Mashburn Arms Company had their business located on Pennsylvania Avenue in Oklahoma City back in the 1960's and they were building many custom rifles for Mashburn improved chambers. I had them build a 25-06 Mashburn improved in 1965 on a FN Mauser DeLuxe action and it was a real shooter. I had this rifle built before Remington introduced the 25-06 with the standard 30-06 shoulder. My rifle used a 30 degree shoulder and my reloading dies were made by RCBS. Your rifle could have that same 30 degree shoulder. Also, the Mashburn case has a straight taper so the diameter of the case is the same from the web to the shoulder. That explains the comment in post 59 about the base diameter being large. Mashburn load data was quite hot and that explains the split cases but after all the increased case capacity was intended for higher velocity and case life was short. In 1965 quality rifles were not known to blow up and no one was concerned about shooter safety. I fire formed many cases in that rifle just like you would do with the Ackley chamber today but the shoulder was not blown out quite as steep. Your rifle is very strong and can handle the fire forming without any problem. I think even today you could fire form a cartridge case and send it to RCBS and they would make you a set of dies.

 

[Remington92]

A crush fit help hold the case and allows it to stretch properly. It'll let you shoot standard/ factory 30-06 ammo like you did with good accuracy and less cases lost. If the case isn't properly support you could have poor accuracy and lose case due to case head separation.

The rifle is hopefully going into the shop this week to get chamber cast but could this be what I'm actually looking at? Case head separation due to lack of crush fit. Not sure what I did wrong with the dummy round before but I dissembled the bolt and dropped a live round In and there's no resistance.

 

[Timnterra]

If I was you I would make a test case to see how loose the headspace is. To do this take a 30-06 case and expand the neck to something bigger like 338 or 35. Then unscrew your 30-06 die and back it out a turn or so. Run the case back into the 30-06 die leaving a very small false shoulder. Try it in the chamber. It probably will not close. Go back to the press and screw the die in about 1/16 of a rotation and try the case again. Rinse and repeat until it closes with resistance in the chamber. Then you can measure the distance from the false shoulder To the base and get your headspace measurement. It sounds like from the die mfg response that the chamber is oversized at the base which means it was probably not cut well by the gunsmith and needs to be rechambered. If that is the case there may only be two options. The first I'd explore is having the barrel set back one full revolution and rechambering with an actual standard 30-06 ai with 40 degree shoulder. Unfortunately this may not be possible if the base area of the chamber is too over sized. If that happens to be the case I would have it rechambered to 300 win mag and have the bolt face opened to magnum diameter. With the little amount of barrel shank you have It will not be possible to rechamber to 30-06 without replacing the barrel.

 

[xsn10s]

The rifle is hopefully going into the shop this week to get chamber cast but could this be what I'm actually looking at? Case head separation due to lack of crush fit. Not sure what I did wrong with the dummy round before but I dissembled the bolt and dropped a live round In and there's no resistance.

That's my best guess. But after the cast is made you'll have a better idea what's going on. If there isn't a crush fit on standard 30-06 ammo someone might have just ran a reamer in the barrel without setting it back. Let us know what the results of the cast are.

 

[Sage70]

Attached is a poor quality picture of a 25-06 Mashburn which has a 30 Degree shoulder. Mashburn was his own man and completely independent from Ackley so I have no confidence that Mashburn used a 40 degree Ackley shoulder on that 30-06 improved. Note the straight taper of the case. You can bet your barrel was a Douglas premium air guaged barrel because when I visited the Mashburn shop they had a whole rack of Douglas barrels. Most of the busy gunsmiths of the time were using Douglas barrels including Mashburn, Flag's and Paul Jaeger. Mashburn was also using Fajen stocks.

 

[Remington92]

Long shot and I can't find any evidence online but did Mashburn ever strike an M on the bolt handle like this?

 

[Remington92]

If I was you I would make a test case to see how loose the headspace is. To do this take a 30-06 case and expand the neck to something bigger like 338 or 35. Then unscrew your 30-06 die and back it out a turn or so. Run the case back into the 30-06 die leaving a very small false shoulder. Try it in the chamber. It probably will not close. Go back to the press and screw the die in about 1/16 of a rotation and try the case again. Rinse and repeat until it closes with resistance in the chamber. Then you can measure the distance from the false shoulder To the base and get your headspace measurement. It sounds like from the die mfg response that the chamber is oversized at the base which means it was probably not cut well by the gunsmith and needs to be rechambered. If that is the case there may only be two options. The first I'd explore is having the barrel set back one full revolution and rechambering with an actual standard 30-06 ai with 40 degree shoulder. Unfortunately this may not be possible if the base area of the chamber is too over sized. If that happens to be the case I would have it rechambered to 300 win mag and have the bolt face opened to magnum diameter. With the little amount of barrel shank you have It will not be possible to rechamber to 30-06 without replacing the barrel.

I'm assuming if done correctly a 30-06AI would still safely fire 30-06? Or would I still be in a similar situation? Is there any danger to running 300wm in a 1903? It's a fairly light handy rifle so 300wm wouldn't be as much fun on me but oh well.

 

[Sage70]

Remington92, the rifle that Mashburn put together for me did not have the Circle M on the bolt handle. However, Oklahoma is big cattle country and the Circle M brand looks like it could be something out of Okahoma City. I asked them to re-barrel a Weatherby FN Deluxe Mauser which was originally a 270 Weatherby Magnum to a 25-06 Mashburn. Of course, the bolt had the wrong bolt face. The gunsmith doing the job went to a cabinet that contained several new FN actions. He took the correct bolt out of a new action and switched bolts with me at no charge. My new bolt had the FN mark on the bolt handle so that could be why he did not stamp my new bolt. Also, I don't think Mashburn would have been marketing a trigger with his name on it outside of his shop. There was a guy named Warren Page and if I remember it correctly Page had a 7 mm rifle that Mashburn chambered especially for him. The Page rifle increased the notoriety of the Mashburn name and by 1950 the Mashburn shop was on the same level as several known gunsmiths. I think Page's rifle cartridge is still on the RCBS listing of custom dies. Page's rifle was called a 7 MM Mashburn Super Magnum and you can find a Field & Stream write-up on Page on Google. Your rifle has the same bolt handle and the same chamber barrel contour as Page's rifle "Old Betsy," and once you see the stock on old Betsy you'll know who made your rifle.