6mm TCU reamer with short freebore?

[Douger40]

I'm looking for a 6mm TCU reamer that is set up with short freebore for lightweight varmint bullets. I had a barrel maker build a barrel chambered in 6mm TCU, but the reamer he rented had the standard freebore for long bullets. So I've now got a 1-12" twist barrel that won't stabilize any bullet long enough to seat close to the lands.

The barrel maker will cut my barrel back and cut a new chamber if I can provide the reamer. I can't be the first guy to try to build a 6mm TCU rifle set up for 58-80 gr varmint bullets. Does anybody have a 6mm TCU reamer set up for lightweight bullets that they would be willing to rent? I thought that I would check here before ordering a custom reamer from PTG. Thanks much.

 

[jscandale]

is a 6mm TCU the same as a 6x45?

JS

 

[Douger40]

Not sure. The 6mm TCU is kind of an improved case with a 40 degree shoulder made from .223 necked up to 6mm. I think that the 6x45 has a different shoulder.

 

[jscandale]

The 6x45 is just a necked up .223 and no other changes to body taper. If the TCU has a 40°, I am not aware of other changes. I am certainly no TCU expert, I just know that it's a cartridge you hardly hear of anymore. Don't know what advantages it gives over the 6x45. Maybe a 100 fps...sound right??

JS

 

[TominSWNY]

I had one like that and it was frustating. I took a nec reamer and extended the neck out and used 222 mag brass. The Next best thing to the 6 TCU is the PPC

 

[Douger40]

The 6mm TCU also has less body taper than the .223. It was designed back in the 1970s for metallic handgun silhouette for use with 90-100 gr 6mm bullets. Which is why the standard reamer is set up for long freebore. Brass is cheap and very easy to make. One pass through a 6mm TCU full lenght sizing die then fireformed with either a light load with a real bullet or 10 grains of Bullseye with a case full of Cream of Wheat behind a wax plug.

It tends to be very accurate with bullets seated close to the lands. However, with light weight varmint bullets and the long freebore you have to push them very fast before you get much accuracy. I was getting 3200 fps with 65 gr V-max and AA 2460 in a 24" TC Carbine with a standard chamber, but wasn't getting near the accuracy I could get using heavy bullets. So my goal is to build a bolt gun with less freebore to see what it would do as a varmint gun.

 

[jscandale]

I chambered 3 Bartlein barrels for a friend for his 6x45 bolt gun and he claims that it's the most accurate match rifle he has ever had. It shoote very well at 600 yds. It launches the 107 Sierra around 2550, but it is very accurate. Most guys are after speed, I used to be, but accuracy is all that I care about anymore.

JS

 

[Lumpa]

 

[Lumpa]

There are small differences between the two cases as the drawings show.

 

[shortgrass]

Before I just "ordered one from PT&G" I'd call the other reamer makers. Someone may have one on the shelf they can alter for you.

 

[Ggmac]

The 6mm TCU also has less body taper than the .223. It was designed back in the 1970s for metallic handgun silhouette for use with 90-100 gr 6mm bullets. Which is why the standard reamer is set up for long freebore. Brass is cheap and very easy to make. One pass through a 6mm TCU full lenght sizing die then fireformed with either a light load with a real bullet or 10 grains of Bullseye with a case full of Cream of Wheat behind a wax plug.

It tends to be very accurate with bullets seated close to the lands. However, with light weight varmint bullets and the long freebore you have to push them very fast before you get much accuracy. I was getting 3200 fps with 65 gr V-max and AA 2460 in a 24" TC Carbine with a standard chamber, but wasn't getting near the accuracy I could get using heavy bullets. So my goal is to build a bolt gun with less freebore to see what it would do as a varmint gun.

Where do you live ? I've got 3-4 different 6 TCU reamers , most were made for 68-70 gr flat base bench rest bullets . It's a very forgiving cartridge. Easy to find accurate loads for with a wide range of powders .

 

[Dusty Stevens]

Every tcu reamer ive ever heard of was set up for 65-68gr bullets. Thats about all it can handle and what it was made for

 

[AckleymanII]

I got into this here lately. I bought up some new Winchester brass. Measurement at the web is .370 and reamer print is .377. So, I will order a reamer smaller in the web so hopefully I will not get premature primer pocket expansion.

I also think that I may go 22/204 & 6/204 due to feeding out of a repeater. You don't hear much on guys shooting the 22/204 or 6/204 in as far as extremes in accuracy.

 

[JSH]

Forget the gents name, but there is a 6-204 called the 6mmRR or somthing like that. One of the guys from Hodgdon or Sierra I believe.

As to the 6TCU and 6x45/6-223. A cartridge that is highly over looked by many. It will do over what most think. I also found it to be very forgiving.
H335 and a 70-80 grain bullet has given me a lot of grins over the years. I am going to try some of the “newer” powders when I get a chance.

 

[Ggmac]

I got into this here lately. I bought up some new Winchester brass. Measurement at the web is .370 and reamer print is .377. So, I will order a reamer smaller in the web so hopefully I will not get premature primer pocket expansion.

I also think that I may go 22/204 & 6/204 due to feeding out of a repeater. You don't hear much on guys shooting the 22/204 or 6/204 in as far as extremes in accuracy.

Do what you want but no case head is supported so primer head opening on base size is just , well let's say , words for discussion. I'd stay with std size . If you've measured any Winchester , Remington or federal 308 based cartridge for the last 20 yrs or so you'd see them at .467-.469 . With that said the only difference is Lapua brass and the common US brass companies already mentioned . Good luck and keep us posted . With the small base dies available, you will not be needing another reamer if it goes wrong with the tight diam .

 

[AckleymanII]

Thanks, Ggmac!