I am building a rifle chambered in 300 BLK with the intention of shooting cast through it. With the a cast bullet being sized anywhere from 0.309 to 0.311 combined with the thicker neck of converted brass from 223/556 chamber becomes problematic. This is a common problem with this chambering and cast. I would like to open the neck area of the chamber 0.004 - 0.006" above SAAMI specs to allow for smoother chambering. Who does this type of work? Dlask no longer does.
Opening up 300 BLK Chamber
- Thread starter gvanzeggelaar
- Start date
Wouldn't it be easier to buy proper factory 300 BLK brass or, alternately, turn the necks on the converted .223 brass to reduced the thickness? You would only have to do it once. Once you open up the chamber neck you pretty much ruin the gun for any resale value as the next owner may not want to shoot cast. Common wisdom is always to alter the part that is going to be the cheapest to replace. A neck turner is a lot cheaper than a barrel.
I have weighed these options and know which avenue I would like to pursue
Even with the turned brass the tolerances are cutting it close with 0.311 cast bullet. I am fully aware brass can be neck turned. Not interested. People make wildcats regularly. This is no different Now does anyone knii or w any reputable gunsmiths that do this type of work.
Size your bullets smaller and use PC..? I know people do silly stuff all the time it won't stop me from pointing it out. Corlane's has been able to pull off several jobs others weren't able to in the past for me, give them a shout.
I suppose it is possible that a 'smith might have a reamer ground to the specs you want. But it isn't likely.
Why not just order a reamer and do it yourself? The amount of metal being cut would not require a lathe - reamer could be hand turned. You wouldn't need a regular reamer - just one to cut the neck, maybe throat, if you choose.
Why not just order a reamer and do it yourself? The amount of metal being cut would not require a lathe - reamer could be hand turned. You wouldn't need a regular reamer - just one to cut the neck, maybe throat, if you choose.
- Location
- Western Manitoba
O.P. - I suspect that you want to find the type of "gunsmith" who will do anything that you are willing to pay him to do, whether it makes sense to do or not.
Your opening post suggests that cast bullets are somewheres between .309 and .311 - I do not know where you got that from, but between PC coating and proper sizing dies, you can have pretty much any diameter that you want - say .3070" to .3145". My own sizer produces .3140" diameter cast bullets.
You presume that reaming out the neck area of a chamber is going to allow "easy chambering" without any consideration of the ball seat area diameter, nor the bore diameter. Good gunsmiths are going to question that stuff, I think, because their name is going to get hung on the finished product.
Your opening post suggests that cast bullets are somewheres between .309 and .311 - I do not know where you got that from, but between PC coating and proper sizing dies, you can have pretty much any diameter that you want - say .3070" to .3145". My own sizer produces .3140" diameter cast bullets.
You presume that reaming out the neck area of a chamber is going to allow "easy chambering" without any consideration of the ball seat area diameter, nor the bore diameter. Good gunsmiths are going to question that stuff, I think, because their name is going to get hung on the finished product.
A custom reamer would likely cost a couple of hundred dollars.
If a 'smith doesn't have a suitable one, it is going to be necessary to order one.
By ordering a custom, the chamber could be configured exactly as you choose.
Make up a drawing with the dimensions that you would want for the neck and throat/leade/freebore, and contact one of the established reamer manufacturers.
If a 'smith doesn't have a suitable one, it is going to be necessary to order one.
By ordering a custom, the chamber could be configured exactly as you choose.
Make up a drawing with the dimensions that you would want for the neck and throat/leade/freebore, and contact one of the established reamer manufacturers.
All you would need would be a "neck" reamer.
You can get one out of Ukraine made up and delivered to your door for around $85C.
Just Google Ukraine reamer builders.
The same folks are on Ebay and they sell pistol caliber chamber reamer kits, which include rifling spuds, for around twice that much.
The UK vendor number is xz2010(807) and has a good reputation.
Any smith that has a 303 Brit, 7.62x54r, 7.62x39 neck and throat reamer should be able to do the job you require.
The only other way to open up that neck properly, would be to remove the barrel if it isn't already off, cut the chambere with a normal reamer and use an inside turning tool to open the neck a few thousandths.
Opening the neck only a few thou can be tricky, especially without a pioted reamer. There are good machinists around most areas that could do the job for you, without a reamer.
I saw a .380acp chamber cut into a barrel blank, without a reamer. The 380acp case only has a couple of thou taper. That chamber was every bit as good as one done with a reamer.
Rotation speed was very fast to keep things very smooth and the cuts were only a few thou deep per pass to stop deflection on the very small inside cutting tool bar.
The throat was cut with the same tool, but it had been ground with an angle for the bullet to feed into the leade.
That little pistol went from prohib to restricted, with a 110mm bbl and actually shoots better now than it did with its original bbl.
Any good machinist should be able to do something similar for you.
In your situation, I wouldn't worry about the throat at all. The tighter the better IMHO
The thing is, are you doing this with a semi auto or bolt action??
You can get one out of Ukraine made up and delivered to your door for around $85C.
Just Google Ukraine reamer builders.
The same folks are on Ebay and they sell pistol caliber chamber reamer kits, which include rifling spuds, for around twice that much.
The UK vendor number is xz2010(807) and has a good reputation.
Any smith that has a 303 Brit, 7.62x54r, 7.62x39 neck and throat reamer should be able to do the job you require.
The only other way to open up that neck properly, would be to remove the barrel if it isn't already off, cut the chambere with a normal reamer and use an inside turning tool to open the neck a few thousandths.
Opening the neck only a few thou can be tricky, especially without a pioted reamer. There are good machinists around most areas that could do the job for you, without a reamer.
I saw a .380acp chamber cut into a barrel blank, without a reamer. The 380acp case only has a couple of thou taper. That chamber was every bit as good as one done with a reamer.
Rotation speed was very fast to keep things very smooth and the cuts were only a few thou deep per pass to stop deflection on the very small inside cutting tool bar.
The throat was cut with the same tool, but it had been ground with an angle for the bullet to feed into the leade.
That little pistol went from prohib to restricted, with a 110mm bbl and actually shoots better now than it did with its original bbl.
Any good machinist should be able to do something similar for you.
In your situation, I wouldn't worry about the throat at all. The tighter the better IMHO
The thing is, are you doing this with a semi auto or bolt action??
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A SAAMI reamer print shows the chamber neck to be .337". An everyday 11/32 chucking reamer could be used to open it to .34375". Your gunsmith probably already has one. So long as you do it between centers in the lathe it will follow the existing neck nicely. It takes a bit of a fine touch to feel the reamer start and from there the depth can be read directly off of the tailstock. It has been done many times.
If you choose to order a custom reamer instead, then it would be wise to consider optimum freebore length and diameter as well.
If you choose to order a custom reamer instead, then it would be wise to consider optimum freebore length and diameter as well.
Update on this:
Barrel has been opened up to suite my 240gr cast hand loads for a cost of 250$. (I kept the reamer) Barrel cost 400$. Some say the barrel is now ruined. I disagree. It would have added value to a fellow caster.
Subsonic rounds are costing 10-15 cents a round and are 100% reliable. Seem decent accurate for plinking but haven’t run accurately tests yet. They chamber and extract with ease. No more sorting brass and dealing with super tight tolerances. 1:8 barrel stabilizes the 240gr cast at subsonic velocities. Payback vs 220gr jacketed is somewhere between 400-1000 rounds depending how you look at it. All in all if you cast 300 blackout I highly recommend going this route. Especially with a firearm that takes a readily available barrel that can be replaced if needed
Barrel has been opened up to suite my 240gr cast hand loads for a cost of 250$. (I kept the reamer) Barrel cost 400$. Some say the barrel is now ruined. I disagree. It would have added value to a fellow caster.
Subsonic rounds are costing 10-15 cents a round and are 100% reliable. Seem decent accurate for plinking but haven’t run accurately tests yet. They chamber and extract with ease. No more sorting brass and dealing with super tight tolerances. 1:8 barrel stabilizes the 240gr cast at subsonic velocities. Payback vs 220gr jacketed is somewhere between 400-1000 rounds depending how you look at it. All in all if you cast 300 blackout I highly recommend going this route. Especially with a firearm that takes a readily available barrel that can be replaced if needed
