260 chamber help please...

[LongRange]

So monday i called shilen and they had a blank in stock so i ordered it as they said 8-10wks plus i wanted a custom 260 barrel chambered for the long 140g bullets i shoot with slower powders and not have such compressed loads.

Ive already sent shilen some dummy rounds but im wondering.... is there such a thing as to much free bore?
The dummys i sent in are 139g lapuas seated at 2.405 off the ogive for a COAL of 2.955 touching the lands which leaves .250 + seated in the neck not counting the boat tail...with these measurements i will have no problems with seating any of the 3 bullets as i spent a couple of hours checking and rechecking...so what are your thoughts?

[44magleo]

Yes, too much free bore can be an issue.If your rifle likes to have the bullet touching the rifling and you have the free bore too long the cartridges may not fit in the magazine. It has advantages too. Weatherby uses a very long free bore, this reduces pressure some so they can load heavier charges to get more velocity.Leo

[LongRange]

Yes, too much free bore can be an issue.If your rifle likes to have the bullet touching the rifling and you have the free bore too long the cartridges may not fit in the magazine. It has advantages too. Weatherby uses a very long free bore, this reduces pressure some so they can load heavier charges to get more velocity.Leo

this will be in a single shot target action so no worries about COAL...the only bullets ive shot out of my current barrel that like more than .009 jump are the 140g hornadys which is third on my list of bullet choices for the new barrel. my plan with this barrel is to chamber it around 3 different bullets and slow burning powders that will fill the case 98% to about 105% and produce velocities in the 2850-2950 area and most important keep chamber pressures low.

[BillPa]

Ya did good.

[LongRange]

thanks Bill...ive done a bunch of research and asked a lot of questions about this and from all the info ive gathered over the last 9mos this barrel should...in theroy...be very accurate,produce high velocities with less pressure,run cooler,less throat erosion as most of the powder burn should/will be farther down the barrel not in the chamber/lands and have a better round count in the end...powders of choice in order are norma MRP,RL-22,IMR7828ssc...ive run the RL-22 and 7828 in my barrel now and they both produce fantastic velocities with no pressure signs if i adjust for ambient temps but the loads are VERY compressed...ive split a redding seating stem once already...i havent tried the norma MRP yet but have an 8lber on the way. as best as i can figure the MRP should be the best powder in the new barrel.

[foxx]

Just wondering... why not the same throat deal but 260AI?

[BillPa]

thanks Bill...ive done a bunch of research and asked a lot of questions about this and from all the info ive gathered over the last 9mos this barrel should...in theroy...be very accurate,produce high velocities with less pressure

I did they same thing when I built my 250Imp sporter, throated it so the heel of 100 isseated .010" out of the neck-shoulder junction and .010" off the lands to allow full use of the useable case capacity and still have some wiggle room.
http://i56.tinypic.com/23igfns.jpg

Cute little bugger, huh?

Bill

[LongRange]

Just wondering... why not the same throat deal but 260AI?

that is a good question and ive been thinking about this as well....biggest reason is i have the redding 260 comp dies and wanted to see how this chamber works out before i invest in another set of dies. i have a 110BA in 300 win mag thats about due for a barrel and if this barrel shoots as well as im hoping it does the 300 will become a 260AI that i will build a complete bolt for so i can switch from 260 to 300 without having to mess with bolts.


I did they same thing when I built my 250Imp sporter, throated it so the heel of 100 isseated .010" out of the neck-shoulder junction and .010" off the lands to allow full use of the useable case capacity and still have some wiggle room.
http://i56.tinypic.com/23igfns.jpg

Cute little bugger, huh?

Bill

YES IT IS....id even say SEXY as hell!! i also thought about chambering around 1 bullet but thought what if the barrel dont like that bullet so i spent a couple of hours at the bench and came up with a number that should work well with all 3 bullets i listed...the 139g lapuas have the longest bearing surface of the 3 and will seat just a bit deeper than the SMK and the hornady...funny thing is i havent had much luck with the hornadys in my current barrel but included them in the mix because my buddies riffle shoots 1 hole groups with them.

[BillPa]

.funny thing is i havent had much luck with the hornadys in my current barrel but included them in the mix because my buddies riffle shoots 1 hole groups with them.

Barrels tend to shoot what they want to shoot, not necessarily what "you" want them to shoot. I have a 700 VSSF in 308 w/12 barrel. It shoots 155 Amaxs' into a little ragged holes, not so much a 155 SMK.

Its guys like us who keep bullet manufactures in business and yard sale shoppers happy!:p

Bill

[LongRange]

Barrels tend to shoot what they want to shoot, not necessarily what "you" want them to shoot. I have a 700 VSSF in 308 w/12 barrel. It shoots 155 Amaxs' into a little ragged holes, not so much a 155 SMK.

Its guys like us who keep bullet manufactures in business and yard sale shoppers happy!:p

Bill

LOL...this is very true...i cant tell you how many times i wanted to just leave my 300wm in the hills....that is the most finicky riffle ive ever owned the smallest change in anything throws it all outta wack. the 260 is much more forgiving and i havent found any combo that wont shoot well in it with a little adjusting. my problem is my short attention span...once it shoots bug holes im bored and start playing around with new loads and then it turns into a challenge,but i enjoy the tinkering as much or more than the shooting...im pretty sure im powder valleys number one customer LOL!!

as a matter of fact im going out right now to see what effects seating depth has with 2 loads.