Freebore in a hunting rifle.

[Trickymissfit]

Nah gary I was just trying to simplify things, actually I still run a 5 speed liberty in a 66 deuce with with a fogger and delay when I get a wild hair up my ***!

The one single advantage of an automatic is the decreased shock on the suspension during launch, but if the suspension is working with a good four speed car the difference is only slight. But on the otherhand it takes a little more horsepower to drive an automatic verses a stick. And there is always slippage with both of them. With the advent of four speed and five speed automatics, it sorta surprises me that nobody has tried the clutch system again. It didn't work as well as they wanted it to with the three speed gear boxes due to the first gear ratio so they had to run something like 5.38's in a Clutchflite (I knew two that ran 5.56's). The new stuff will sorta mimic that concept, but tax the engine for about 50% less horsepower. Hard to believe that guys are running Darts and Cudas in the mid eights at 160 mph!! I always knew that 9.00's were possible, but nothing like the speeds these guys are showing. That's a pure sign that somebody's making about 1050hp out of 426" on gasoline! When you compute that into a 3200lb. car, it is really more efficient than a Pro car at 500" weighing 2350lb. But of course nobody ever thought a 176" four banger could ever go 400mph!
gary

 

[BRIT]

A very interesting thread.

It would seem that Kirby Allen is now the Cartridge designer using the new case designs and powders to further push the envelope. Does Mr Allen use Freebore similar to Weatherby? Is he still getting those impressive results using what we would consider normal Freebore?

I have a desire for a custom built 7mm Ultramag. I note however it has .400" of Freebore! I have read that to spec a short throat Reamer will lead to pressure spikes and all sorts of dreadfull things will happen. This is why Remington went down the Freebore route when designing this cartridge apparently.Is this correct?

Could you just choose a Bullet with a bearing surface of more than .400" and rely on it engaging the Rifling before it leaves the support of the case neck?
Is any particular type or style of rifling any better than another when the Bullet engages it having gained some velocity? My thinking is maybe less stress on the Bullet on impact with the lands.

Thank You.

Brit.

 

[J E Custom]

A very interesting thread.

It would seem that Kirby Allen is now the Cartridge designer using the new case designs and powders to further push the envelope. Does Mr Allen use Freebore similar to Weatherby? Is he still getting those impressive results using what we would consider normal Freebore?

I have a desire for a custom built 7mm Ultramag. I note however it has .400" of Freebore! I have read that to spec a short throat Reamer will lead to pressure spikes and all sorts of dreadfull things will happen. This is why Remington went down the Freebore route when designing this cartridge apparently.Is this correct?

Could you just choose a Bullet with a bearing surface of more than .400" and rely on it engaging the Rifling before it leaves the support of the case neck?
Is any particular type or style of rifling any better than another when the Bullet engages it having gained some velocity? My thinking is maybe less stress on the Bullet on impact with the lands.

Thank You.

Brit.

I can't speak for Kirby but if you are looking for velocity without excessive pressure, freebore
is the way to go IMO.

Of course higher pressure will yield more velocity But at a cost to the brass. There are some
brands of brass that will take more pressure than others, like the Lapua or custom designed
brass like the Excalibur and the Chi Tack. These can be used for a velocity gain but there are
other cost if a regular diet of hot loads are used, like bolt lug set back and more throat erosion.

If you must seat the bullet close or against the lands there is no reason to have freebore.

As to the stress on the bullet with freebore this may have been the case with the old bullets
but the new technology bullets aren't damaged by having freebore. However,the twist rate
if to fast will.

I personally will not build a magnum rifle with less than the standard freebore because of the
potential for problems if a person tries to use Factory loaded ammo.

Even the Short mags have freebore and are limited in length by the magazine. And if you want
longer ammo you must hand load it and extend the mag or single load it in the chamber.

This is a safety feature and should not be altered by anyone without great care and though.

I, like most seasoned shooters have tried all of the "tricks" and found the trouble not worth
it in any way.

There are many ways to gain velocity, A larger case and a longer barrel is a simple solution.

As to the rifling type; The three groove rifling seems to have a slight edge in the velocity area
because of bearing surface and is reported to last longer (I cannot verify that yet because
I have not shot a 3 grove barrel out). I have used them on ultra high velocity cartriges (4500+
ft/sec) and found with a slow twist rate (1 in 15) that accuracy was good and velocity was
achieved without excessive pressure.

Sorry for the long winded explanation. In truth, there is no free ride.

J E CUSTOM

 

[WyoElk2Hunt]

One thing I have found is that a rifle with deep freeboar will not shoot a Serria boat bullet accuratly the flat baces
yes but boat tails no. I have nothing against WBY. I own a WBY rifle.

The same with my 300 WBY it likes flat base bullets. Boat tail bullets just don't work as good as flat base bullets.

 

[backwoods83]

Well I do not own many weatherby rifles but I have quite a few barrels chambered in wby calibers and never have any trouble with bt bullets and I have used several sierra, berger, hornady, nosler, swift, etc. As I stated before a friend of mine shoots a 300wby in 1k IBS light gun and has shot over a dozen screamer groups ( 3" or less, 5 shot) with a 2.318" best with 210 berger vlds. I have found in my experience most weatherby calibers are like a 308win, its sometimes hard to make them inaccurate. If you reload, a no throat 300wby (.060" freebore) is about like your standard 300WM, just more potent, but you should not use wby ammo, and is a very accurate setup that will do just about anything any of the rest of the big 30s will out to 12-1300yrds and the barrel will last twice as long as a 300RUM or 4 times longer than a 300 Pegasus.

 

[meatyrem]

I don't mean to get in the middle of a thread, but my question kinda fits in.

I was wondering about my 7rum: remmy bdl with a measured coal of: 4.00" using a 150gr scirocco. Now, this only has the bullet seated About .211" into the case mouth.

Any suggestions as to where I might need to seat to. That is to get enough bullet base into the case mouth for proper seating?

Do I need to try say maybe; 160 or higher? Probably the AB so it will provide enough bullet in the case?

Just need some thoughts or suggestions cuz it looks as if I've got a long throat. To fully eject a round, I need to hit my bolt release and slide the bolt out more to be able to eject the round.

 

[backwoods83]

You'll do better with a 160 AB or 162 SST and a good rule to go by is to keep atleast .125" of the bullets bearing surface in the case, absolutely no less than .100" but you will probably have the best results with the bullets bearing surface/boatail junction seat at the cases neck/shoulder junction. Good luck.

 

[BRIT]

Ankeny.
Apologies for Piggybacking your thread.

J E Custom.
Excellent answer,thank you.

Brit.

 

[BRIT]

Meatyrem
Looks like you have the .400" freebore i eluded to in my previous post.

Brit.

 

[meatyrem]

I measured a factory round just for comparison. 150gr scirocco seated to canulure.
The factory round-----3.57"

my round 150gr scirocco seated to touch the lands----4.00"

a difference of .430"
I tried a 140gr balistic tip, and I couldn't even come close to lands.
I had measured that 150 scirocco bullet and from the base up past the to where it was seated to measured .211" and did not measure the bearing surface only. I can't say what that is, only, not much.
My original thoughts for my 7rum was to push the 160 AB through it or maybe a 160 tsx? Thinking my best bet is to stick with my first thought, and go with the 160 ABs.

Very green here. Don't have any experience with handloading, but am starting up. So to say the least, pretty new.

 

[fj40]

Hello Guys
I have a Ruger 22-250 M77 MkII. I love the gun but it will not shoot tight groups unless the bullets are seated .010 off the lands. This doesnt leave much of the bullest in the neck. The gun also doesnt like hot loads. I only us the gun for ground squirrels. The average range is 100-350 yards but I have had several kills out at 500 yards. I dont believe the freebore is helping me especially since nonlead bullets are becoming manditory in some areas here in California. I have to go to a 35 grain bullet and they are shorter than leaded bullets in a 50-55 grain. But this is not a hunting rifle it is more of a target/bench rifle. So is freebore important in bench/target rifles? Just trying to learn more about freebore in different types of rifles.
Thanks

 

[velocity-is-key]

There are several things that I would recommend for you Application/Need.

I would set the chamber back just enough to clean it up with a new reamer with these dimensions.

3/16 to 1/4" freebore, the freebore should be bullet diameter(NO More),The big issue for accuracy
is head space in a chamber with Lot's of freebore (On belted cases I head space .0005 to .001 max,
And on shouldered cases .000 to .0005 max) On the shouldered cases the bolts camming action will
compress enough to close the bolt with no movement of the case during firing.

I do not recommend this to an inexperienced re loader or if factory ammo is to be used, because of
inconsistencies.

The other option is to fire form and neck size only 90% of the neck.

To also reduce the pressure have the reamer cut to allow the neck to expand .002 to .003
thousandths more than loaded rounds. Or turn the necks down for the same clearance.

The tight head space and 10% of the neck that was not re sized will align the cartridge perfectly
for greater accuracy and the freebore will allow for larger powder charges with no more pressure.

I have my 30/378 Weatherby setup this way and using 126 grs of 50 BMG and a 200 grain partition
velocity is off the charts, and case extraction is easy with no signs of pressure. The best 5 shot
group to date at 100 yards has been .092 (Less than 1/10 of an inch).

And all of this with a belted case, and lots of freebore And a Mark 5 Weatherby action.

J E CUSTOM

Thank you JE that sounds like a sensible solution that I will try and I guess one could in all practical procedures "taylor" the curve by varying this "freebore" and recording the results which I am sure you have done to get the staggering velocity from the big weatherby.
My neck is a average .276" and my loaded rounds are a .274" with a unloaded neck of .273" after the brass is cleaned up all the way..With my bushing dies I really don't need to neck size as after the brass spings back its pretty dare close to .273 again.. I typically have gotten 15 reloads on the same brass with annealing if I feel a increase in seat tension...
I am betting that those performance figures for the big Weatherby were also had using a aftermarket barrel rather that the factory hammer forged setup, but never the less it does make me want to design another gun off that cartridge even if I have a perminent neck problem after all that research I did years ago with the factory set up minus the muzzle brake...
Thank you again for any and all input...
velocity

 

[velocity-is-key]

Thank you JE that sounds like a sensible solution that I will try and I guess one could in all practical procedures "taylor" the curve by varying this "freebore" and recording the results which I am sure you have done to get the staggering velocity from the big weatherby.
My neck is a average .276" and my loaded rounds are a .274" with a unloaded neck of .273" after the brass is cleaned up all the way..With my bushing dies I really don't need to neck size as after the brass spings back its pretty dare close to .273 again.. I typically have gotten 10 reloads on the same brass with annealing if I feel a increase in seat tension...
I am betting that those performance figures for the big Weatherby were also had using a aftermarket barrel rather that the factory hammer forged setup, but never the less it does make me want to design another gun off that cartridge even if I have a perminent neck problem after all that research I did years ago with the factory set up minus the muzzle brake...
Thank you again for any and all input

velocity

Do you use a throat reamer to /and talyor throat length till max velocity with max pressure is reached?

 

[backwoods83]

Fj40 if your seating a 55grn .010" off the lands in a saami spec 22-250 chamber you do not have enough bullet in the case, that is not really safe. I use the 53 grain vmax at 2.505" oal its a lot longer than 50 or even 95% of the 55s .023" longer than a 55grn NBT and I have about .115"s of bearing surface in the case and I'm still .055" off the lands. I don't know what your twist is but you may have to go to a 70grn Barnes TSX.