Needed help with reamer pilot size...

[stgw77]

Hi all,
please help me out: I have Bartlein 5R barrel with .300" and .308" bore and groove dimension. My gunsmith will chamber it into .308WIN. I have .308 Palma Bisley finish reamer in my hands. On the reamer print it says that pilot size is .298" and bore size should be also .298" (groove size is .308"). Question is if this reamer will be OK to make perfect chamer? What about clearance between pilot size and actual bore size (0.002" difference)? Need some kind of bushing to fit this clearance or not?
Thank you a lot for your help.

 

[Rustystud]

Most piloted reamers come with one pilot. In years past Palma rifles have shot what is called a tight bore .297"-.298"becaues they shoot 155 grain bullets in rather long barrels and need a good gas seal. Reamer manufactures can make you pilots in your selected size or sell you a set of progressive sizes. You can buy pilots in incremental sizes ie: .0001", .0002", .0005". The cost of additional pilots varies between manufactures. The more you buy the better the price. Being a gunsmith I own approximately 50 different sized pilots in each caliber from 17 through 50 you can imaging the investment. Most 30 caliber hunting and F-Class barrels are .300/.308 or some slight variation. Thirty caliber bullets with longer bearing surfaces generally have pressure issues when shot in tight bore barrels.

Call Pacific Tool and Gauge and they can make you precision ground pilots that will fit theirs and any other manufactures reamers.

Nat Lambeth

 

[Preacher]

I would use a bushing that just barely turns in the bore, not a tight fit because I want it to turn in the bore a little... .002 seems to be a bit on the loose side to me..
If the bore numbers are dead on @.300 then a bushing that was .299.5 should give you a good fit..

 

[stgw77]

I found out that my friend has reamer from the same company (PTG). His reamer is 2013 F-TR reamer that has .2998" pilot. Pilots should be removable so I can use his pilot for my reamer in my .300" bore? Sounds like a perfect match to me.
What is your opinion, what are "perfect" .308WIN remaer dimensions using strictly Lapua brass at web and at base? How does .4731" at web and .4708" at base sounds to you?
I appreciate your help!!!

 

[Erik Cortina]

Your gunsmith should have more than one bushing. You need to try different bushings to see which one fits best. If your gunsmith is not aware of that nor knows how to fit a bushing to the bore, it's time to find a new gunsmith.

 

[stgw77]

Hi Eric,
you are right, I agree. But I havent asked him about bushings yet. I guess I want to make his homework Want a perfect chamber allready in first try.
This forum is great to get good info.

 

[Erik Cortina]

Hi Eric,
you are right, I agree. But I havent asked him about bushings yet. I guess I want to make his homework Want a perfect chamber allready in first try.
This forum is great to get good info.

If you want a perfect chamber, leave it up to your gunsmith. You'll have a better chance of success if you provide the reamer to your gunsmith and walk away and let him work.

 

[butchlambert]

Ain't no such thing as a perfect chamber!

 

[shortgrass]

Ain't no such thing as a perfect chamber!

+1 on that.

Hi Eric,
you are right, I agree. But I havent asked him about bushings yet. I guess I want to make his homework Want a perfect chamber allready in first try.
This forum is great to get good info.

If you want a perfect chamber, leave it up to your gunsmith. You'll have a better chance of success if you provide the reamer to your gunsmith and walk away and let him work.

The worst customers are those who think they need to help! If your 'smith is worth his salt, he'll cut a good chamber first time. He won't have to 'try' several times.

 

[Eddie Harren]

C'mon now Butch!

 

[Rustystud]

You started this thread off asking about reamer pilots. Then you switched to talking about web diameters.
You mention a web of .4731" and .4708" at the base.

I will say a virgin 308 Lapua is .466' at the web. SAAMI Specs fall .468" to .473".

Working your brass is your worst enemy. I personally like chambers that are tight enough not to work your brass and not too tight to cause extraction issues.

Good luck on you adventure...
Nat Lambeth

 

[jscandale]

You gunsmith should either have the pilot for the application or have the capability of making a pilot if need be. They are pretty easy to make and it beats waiting several days for one to arrive.
I have made several out of ampco bronze when I have needed to and they work quite well.

Perfect chamber, heh, they are about as common as .0000 runout that so many claim. That's a good one.

JS

 

[butchlambert]

Bushings have to have at least .0002 clearance to slide on the reamer and also the same amount to slide in your rifling. You can't put a .250 pin in a .250 hole without force.

 

[Eddie Harren]

JS, what type of grinder do you use?

 

[jscandale]

JS, what type of grinder do you use?

You can't grind bronze.

JS

 

[Eddie Harren]

So, you turn these pilot bushings on a lathe?

 

[jscandale]

Yes, on a lathe.

JS

 

[Eddie Harren]

To the fourth decimal?

 

[Gundoktr]

That comment doesn't even deserve an answer.

 

[jscandale]

I just checked it with a tenth mic, and yes, it has a 4th decimal point.

JS