F T/R Competition .299/.308 Bore

[tsweetsam]

Do anyone have an experienced of using .299/.308 bore in FTR?

Do they need longer freebore for the same coal when compare with .300/.308 bore?

I read that German Salazar recommend to use .114" fb for 175gr to 185gr projectile.

So, how about the minor number in little tight bore of .299 vs .300?

 

[tsweetsam]

One of my friend try using this reamer ( .342"nk, .114" fb with 1-30 ) chamber his new Bartlein 5R 1:11.25"tw .299/.308 barrel. The headspace was correctly. But during testing break-in barrel with factory ammunition (Federal Gold Medal 175smk), it was over pressure. So, any suggest with this tight bore barrel?

 

[l115a3]

Those tight bore may proper for lighter projectile like 155.5 Fullbore.


Not good choice for heavier projectile 185gr

 

[Graham]

Not good choice for heavier projectile 185gr

Why not?

 

[XTR]

Why not?

Someone may know more than I on this one but, FWIW, I'd never use one in F-TR today.

Those were developed for shooting the 155s in fullbore competition. The tighter bore keeps the pressure up so that you can get consistent powder burn. Guys shooting 45-70s with smokeless and smokeless muzzle loaders run into a similar problem trying to get efficient powder burn from slower powders with light for caliber bullets (like 250s in a 50cal) . The light bullets accelerate very quickly and the pressure drops off too fast. Shooting a 175 or heavier pressure is not your problem, at least low pressure. I have not shot one, but I think you would find that your max loads and MV would be lower than with a .300.

 

[Frank Green]

Do anyone have an experienced of using .299/.308 bore in FTR?

Do they need longer freebore for the same coal when compare with .300/.308 bore?

I read that German Salazar recommend to use .114" fb for 175gr to 185gr projectile.

So, how about the minor number in little tight bore of .299 vs .300?

I did reply to your previous post last night on a different thread but will add some here.

For the most part I don't see a problem with pressures and the .299" bore. Changing the groove size will have more of an impact on pressures than changing the bore size.

We make a ton of .299" bore barrels and even (.298" bore barrels for the palma shooters) and I've got a .299" bore on my .308win. and have shot both box ammo and handloads with no issues.

Changing the reamer spec. on the throat diameter and throat length can change your pressures as well.

The reamer I've got in my .308win. is the Obermeyer. .3085" diameter throat with a 2 degree 30 min. lead. depending on where you measure the free bore length (end of case mouth of the chamber chamfer) it's a .085"/.102" free bore length. If you load 175" Sierra's to a 2.800" o.a.l. your only about .010"-.015" off the lands.

I off hand wouldn't use the .299" bore on .300win. mag. type calibers and would use a standard .300 bore. Just more room for powder fouling/carbon build up. If you don't clean the gun properly the carbon build up can lead to pressure issues also.

You don't say how many rounds are thru the barrel but I'm guessing it's basically new from what it sounds like.

How are you cleaning it?

You didn't leave solvent or oil in the bore/chamber when you shot it did you? If so this can lead to pressures going up/hard bolt lift also.

Going back to my other posts on the other thread.....did you try a different lot of ammo? Different maker ammo like Hornady, Copper Creek, Black Hills etc....as it could be that particular lot of ammo as the ammo is another variable besides the barrel, besides the chamber etc....

Later, Frank
Bartlein Barrels

 

[gstaylorg]

Frank also posted a very informative write-up regarding this issue a while back for anyone interested:

http://www.snipershide.com/shooting...ale-two-guns-tight-bore-vs-standard-bore.html

As far as not using a .299/.308 barrel with heavier bullets, that is internet nonsense. I have several GAP .308 bolt guns with .299/.308 Bartlein barrels. These are GAP's standard .308 dimensions, along with .085 fb, .142 nk, 1deg30. Two of these rifles have re-barreled more than once (they now wear 30" pipes) and I have always gone with Bartlein 5R barrels in .299/.308. I also purchased my own reamer with the same specs from PTG to keep them consistent.

I use Berger 185 Juggernaut handloads out of these rifles, which shoot extremely well. Even having only .085 fb and jumping them 20 thousandths, the bearing surface is well above the neck/shoulder junction. I'm getting 2770 fps avg using Varget for these loads with no pressure issues whatsoever. In fact, I still have enough room left in the case that I'm certain I could easily be pushing the 185s on the high side of 2800 fps with Varget. However, it really didn't make much sense to do that because the load I developed showed great accuracy with very low ES/SD and no pressure signs. Neither the tight bore nor the short fb of the chamber has limited accuracy or MV with the 185s. Neither do the tight bore and short fb result in pressure issues with the heavier 185s. If the rifles are ever shooting poorly, it's solely the fault of the wretched wind reader that's lying behind them .

 

[jsthntn247]

I had a Obermeyer with a 298 bore and had no problems with any bullets.