SmallCaliberCentral

Rick,

I have been kicking around the idea of rebarreling my Model 12 Savage, with a Mcgowen barrel with the same reamer you used on your last 204 rifle project.
I was wondering how you came up with the .015 freebore, and what what you was trying to accomplish.
I was also wondering if you would give me the stock number of the reamer that you had made at PT&G.

Thanks, Billy

Billy,
As most SAMMI 204 Ruger reamers I've seen have in excess of .065" of freebore, and many of the guys over at Saubier use reamers with zero freebore for other 'accuracy rounds', it was my thought that the .015" freebore would eliminate excess peak pressure spikes at ignition, and so far, the targets, fired cases, and fired case measurements after firing bear this out to be true.

To me, in an high intensity round like the 204R, zero freebore may be asking for trouble in very warm weather, especially with temperature sensitive powders.

My friend and writer, Ken Howell (former editor of Rifle and Handloader Magazines) in his excellent book, "Designing and Forming Custom Cartridges", also agrees with the practice. We all know that if you jam a bullet into the lands, you will increase pressure at ignition. The BR guys all do it, but they are looking for extreme accuracy in neck sized cases (or not sized at all), and portability of the loaded ammo is of no concern to them, as they load and shoot right there at the range. Their loads are worked up very carefully too.

My reamer allows the bullet to be seated to about the base of the neck, fully supported, and reach the lands if wanted. It basically sets up the 204R like any other high intensity rifle round intended for both speed and accuracy. You can also "chase" the lands over time due to throat erosion, and has worked extremely well in all the other rifle calibers I've chambered that way.

I'll not go public with the reamer number, but if you're interested, I'll share the Print No. with you via PM.

Rick
Can you give us a COL to lands using any bullet you prefer.
This should give us a good idea on what .15 freebore really means.

jo: It's .015" freebore, NOT a whopping .150". I'll have to dig into my ammo boxes later to give you guys a Comparator Overall Length to lands, but the way my 39 SBK's are seated now, they are just "kissing" the lands; about .001" from touch point. Like most smallbore CF rifles, it shoots like a house afire set up properly this way, and I can seat a tad deeper if wanted for pressure relief as discussed earlier. (Yes I know that deeper decreases powder space and CAN raise pressure)

I'm just home from surgery and back on the mend (one more in January, then done), so it will be a day or two till I'm ammo box lifting worthy (.50 Cal cans stuffed = too heavy right now).

But basically, if loaded to SAMMI spec at 2.260" Overall Length (or perish the thought, shoot factory ammo... ), my bullets would have right at .015" to travel out of the case prior to encountering the lands. There is an older post that shows the reamer drawing a few pages back.

Thanks Rick.
Yeah I knew the correct freebore. Just a little to tired today to get it right
So roughly 2.275 is on the lands. Sounds just right to me. Thanks. My turn to ream a custom is coming up and this info will help greatly. I did purchase a one time used .0 freebore reamer. I'm certain I'll desire a throater to shoot the 40's.

Get well and stay well. I hope you feel better soon.

No worries jo; I figured you already knew that. Now it's back to the couch....no full .50 cal cans for me then any time soon. Good luck on the new build, and I know you'll fix us up with pics when she's done.

Rick I sent you a PM on this last week. I do not know if my PM was the one that you accidently deleted, but I resent it today.


Thanks, Billy

Well, I had my first zero free-bore done, it's a .223 AI with a .250 neck, match chamber, Rock barrel. It's a Savage single shot action in a VLP stock. I wouldn't change a thing, shoots good!

Tom

Ohlsen: The only reason I went with the minimal freebore (.015") with my 204RM reamer was to give a small margin of pressure relief, as virtually all factory 204R chambers are cut with as much as .065 - .070" freebore, which to me is far too excessive.

If the rifle had been intended for any other caliber than the 204R, it would have been like your 223AI; zero freebore, as both my custom Holland rifles are cut. They are a set of matched M700's in 223AI and 243AI. Like yours, they shoot like a house afire cut with zero freebore.