Question regarding free bore

[stef]

Apparently speed sells - like 4200 fps or the fastest loaded factory cartridge.

I have 2 stainless super match PacNor barrels and like them very much.

I have yet to load a .204 Ruger but I have been playing around with the "free bore" question for some time. I like to use long heavy bullets, 140 gr. 6.5mm, in some of my rifle for shooting at steel targets and these rifles have long leades, so long that the loaded rounds won't fit into the magazine. Yet these rifles, 2 6.5-.308's also shoot the stubby 95 gr. 6.5 Hornady VMax very well. I make sure the 95 gr boat tail bullets are securely held in the neck of the brass at a depth somewhat more than one caliber (.264 in) and check bullet runout of loaded rounds. I turn my necks to ensure uniformity as I neck down .308 Win cases to 6.5 mm and .264 bullets just fit with little resistance inside unsized fired rounds. My rifles have minimal neck size chambers. Lee collet dies and the Lee seater work just fine and I full length resize when needed with a 7mm-08 full length die with no decappper or expander. I usually seat long bullets out to just touch the rifling.

Using the same thinking I am about to launch a .204 Ruger project and plan to provide a dummy round to the gunsmith who will cut the chamber - it has to fit inside the magazine, close enough to contact the rifling if I want it to, able to launch either the 39 gr Sierra BK or 40 gr H VMax (1-11). Speed is secondary to function and accuracy. I may or may not turn necks. I will know more when I get into things.

The comments and questions have been real valuable.

[goosebrown]

Wanted to post an update. I am getting happier.

I added a Limbsaver Sharpshooter Xring. (http://www.limbsaver.com/2011/firearms/41.php) and it brought the groups down significantly. They are $8 so why not try them out was my thought. They really do make the rifle look ugly, like a sci-fi raygun, but I am going to be laughed at for the lousy groups or the raygun thingy and I did the math there... (FWIW, It cut down group size on my .308 as well, I got two, one for each rifle.)

The last of my Varmint Grenades were well under an inch which is a lot better than they were and no bad fliers that aren't blamable on me as the shooter. The real prize though is with the 39gr Sierras and H4895.

I loaded 20. The first 10 were at 25.5gr Benchmark and the bullet seated to OAL of 2.36" and the OAL to the bearing point of the bullet was 1.977". They shot pretty well, under an inch at 100 (remember this is a good group for me at this point with this rifle). Also each group had 3-4 that were one largish hole with a flier or two which I ascribe to me. If you discount the fliers, I am at 1/2" or so.

The real joy was when I shot the last group. I loaded an Audette Ladder, which I discovered in a thread here, from 26.7gr to 27.6gr with H4895 and the bullet seated to OAL of 2.36" with the OAL to the bearing point of the bullet remaining at 1.977".

For info on the Audette Lader if you aren't familiar...(http://www.desertsharpshooters.com/manu ... edload.pdf)

I fired them in 2 groups of five at identical targets rather than at one target because at 100 yards it is hard to differentiate the holes to determine order because they are so close.

The results from the first five rounds were "goodish" with the bullets being more spread out than in a line, but the second group was great with the bullets going down as one flier and the next four in one .3" hole. According to the documentation that is where the sweet spot is and I need to start doing more detailed work in my loads there between 27.1 and 27.5gr.

The Rl10x is coming from Midway sometime this week and I will try that out too.

I am still a little miffed about the freebore because that seems wrong to me, but the rifle is starting to shoot a better so I can at least not do drastic change to the rifle for now.

Thanks everyone for the comments, they were VERY helpful and I appreciate everyone's time.

[GaCop103]

Not to hijack your thread but, where did you find the 204 modified case for the Hornady OAL tool?

Most places that sell these supplies usually have a 204 Modified Case on the shelf with the other calibers. The Nosler Pro Shop usually has them in stock most of the time, as does Sportsmans Warehouse.

OR........use a 5/16"-36 tap with "I" letter size tap drill and chuck it up in the lathe and make it yourself. Most of mine were made that way, just use a fired case and a Univesal Decapper and you're set.

Finally got an answer from Hornady. Now they're saying they won't have any until August "they're having a hard time getting 204 brass". What!? They make brass and test production runs, why would they have a hard time getting brass? Sounds like pure BS to me.

Tom

[sharptailhunter]

This freebore was designed into the cartridge to reach the manufacturers wish to exceed 4,200 fps with factory ammunition with the associated claim to speed fame. With a two-fold combination of special blend of non-canister powders AND this excessive freebore, this high velocity was possible.

Sorry to be talking about an older topic, I've been way too busy lately. Anywho, Rick, could you enlighten me, and others I'm sure, how free bore relates to velocity? That is, why would the factory barrels need the generous free bore to reach their desired velocities? Is it an attempt to keep throat erosion to a minimum?

Thanks for your wealth of knowledge, it helps dummies like me learn

[Rick in Oregon]

sharptail: Here's a good an explanation of freebore as any, and describes it well from someone who builds custom rifles:

http://www.predatorwild.com/topic/4059- ... free-bore/

This, along with the Primex SMP746 non-canister powder made 4,225 fps possible in their lab. I suppose most of us found out early that it's folly to try to produce field handloads that reach this speed, but the 204R gets along just dandy with slightly lower 'real-world' velocities for everything I use mine for. I doubt that Skippy has noticed that my handloads do not match factory advertised velocity.....



BTW, just for info sake, I'll add that my custom "no-turn" 204R Match reamer used on my SPOD 11-twist is set up with .015" of freebore, which compared to my zero freebore rifles has worked out well so far. I was a bit hesitant to spec a zero freebore 204 Ruger chamber with all the other chamber dimensions tightened up from SAMMI that was to be used in the field at full throttle and not babied.

[sharptailhunter]

BTW, just for info sake, I'll add that my custom "no-turn" 204R Match reamer used on my SPOD 11-twist is set up with .015" of freebore, which compared to my zero freebore rifles has worked out well so far. I was a bit hesitant to spec a zero freebore 204 Ruger chamber with all the other chamber dimensions tightened up from SAMMI that was to be used in the field at full throttle and not babied.

Thanks for the explanation. It makes a little more sense now. When you say zero free bore rifles, does that mean that a SAMMI (factory) cartridge would not have any free bore? So with your above mentioned SPOD (love that moniker btw) barrel, what distance off the lands do you load for? I have found that most of my loads prefer to have the bullet seated about .040" off.

[Rick in Oregon]

When you say zero free bore rifles, does that mean that a SAMMI (factory) cartridge would not have any free bore? So with your above mentioned SPOD (love that moniker btw) barrel, what distance off the lands do you load for? I have found that most of my loads prefer to have the bullet seated about .040" off.

sharptail: The amount of what we're calling freebore exists in almost all factory rifle calibers to some degree or another, just varying amounts. The Weatherby and 204R are two of the more excessive examples I'm aware of, but I'm sure there are others out there as well.

Most of my custom rifle chambers that I've spec'd for the reamer usually have zero freebore. I load SPOD with Nosler 40gr BT's .005" off the lands, and run her with RL-10X right at 3,980 fps. That rifle really turned out exactly as planned, and is a pure laser in the field, especially when the ranges are stretched a waaaays out there with a rat arrogantly sitting on his mound in perceived safety at 500 yards.......THWOP!

Seriously though, all my rifles have their own seating depth preferences; some like being right at or "kissing" the lands (my Cooper 223), others like anywhere from .005" all the way to .090" (my Sako 204). But with most factory 204's, being near the lands is usually not an issue, nor is it possible. Good thing they shoot as well as they do with all that jump in factory chambers. But when set up like a 'normal' varmint rifle caliber (like SPOD), they really shine. BUT, once this is done, factory ammunition should not be fired in a chamber so designed; another reason to handload.

[stef]

Free bore is somewhat of a controversial subject.

Weatherby rifles were chambered with a good amount of free bore with the thought that allowing the bullet to get a running start to allow more pressure to develop enabled higher velocities to be attained. Apparently the current factory .204 Rugers are chambered this way to help with getting the most velocity.

Lee precision doesn't like free bore -- they like to seat bullets close to or even touching the rifling with the thought that pressures will be rapidly attained and more uniform giving greater accuracy. Lee has carried this further with their thinking that crimping also contributes to greater accuracy through more uniform pressures. I know of more than one 1000 yd match that has been won using loads having bullets seated so they just touch (kiss) the rifling -- less variation in velocity.

My preference is to have a chamber that will allow bullets to be seated close to the rifling. The chamber throat dimensions can be controlled by use of a chamber "throater" (a rod like reamer that just makes the throat deeper) machining operation after cutting the chamber or by using a reamer that cuts both chamber and throat to some specified way.

Some rifles that have long throats (leade) shoot quite well. I have a 6.55X55 M96 that was chambered for bullets longer than 140's and it shoots the 155 Sierra 6.5 MK at the heavy end to 107 Sierra 6.5 MK at the light end very well (about 2 moa @ 400 yds). Looking through the bore of the 96 that was made in 1903 the rifling appears to start about 5/16 inch from the end of the chamber. I also have a 6.5-06 with a 1-8 twist that can shoot 140's down to 95's real well (about .5 @ 100 yds). When loading for these I make sure the bullets are securely and uniformly seated into brass that has uniform neck walls and check for bullet "run out" -- does the axis of the bullet line up with the center of the case neck and are the walls of the neck uniform. The 6.5 - 06 chamber is tight enough so the 95 gr bullet has no room to wobble before it runs into the rifling.

I think that factory .204 Rugers that have lots of freebore and shoot really good groups have good chambers and use good ammo in respect to bullet seating and run out . Trying to load a normal weight bullet (up to 40 gr. in a .204 Ruger) in a chamber with freebore so it touches the rifling may not be possible because the bullet is just not long enough.