.243 Win/ 115gr DTAC seating depth ? / QL request

[memilanuk]

I was checking the seating depth on my new .243 Win barrel,Pac-Nor 1-8" twist, 28" stainless SuperMatch) last night. Looks just a wee bit short... heel of the bullet extends down to the bottom of the shoulder. C.O.L. length using a Stoney Point tool shows 2.272",using digital Mitutuoyo calipers that had been 'zeroed' on the SP tool) as an average for three reads each on three bullets.

Is this 'normal' seating depth, or is my barrel throated too short? Could someone run some QL tests on this for me? Cases are Winchester, averaging 157-158gr, and whatever the regular dimensions are of a 115gr DTAC.

Thanks,

Monte

 

[DTubb]

Monte,
I cut and pasted this from the sight- I figured you cold interpolate just how long your 243 should be throated from these dimensions.

Water capacity of the Superior Shooting Systems Inc.,DTAC) 6mmXC case is just under 50 grains capacity. Case neck length is .305 inches so a 115 gr. DTAC bullet seated .015 inches in front of the neck-shoulder junction will have .290 inches of neck support at the start of use in a newly chambered barrel. This allows one to keep seating the bullet outward as the throat wears and yet have plenty of case support for the bullet over the life of the barrel. I have used less than .170 inches of neck support with good results when feeding out of the magazine. Seating the 115 gr. bullet approximately .015 inches in front of the neck-shoulder junction gives an approximate overall length,OAL) of 2.750 inches, which will allow you to grow your round,for magazine feeding) more than .100 inches when using a T2K magazine.
DTubb

 

[chuckw2]

Monte,
I just checked the jam on my new Pac-Nor a couple of days ago.
These numbers are an average for 10 different bullets in each sample. SP tool used..

105 Laupa 2.2635
107 SMK 2.2641
115 Tubb 2.2763


Chuck

 

[joesr]

Chuck,

If those measurements are OAL you have a short chamber. You should be able to load to an OAL of well over 2.820" Say 2.840 to 2.845.

Joe H

 

[memilanuk]

Thanks all for the responses.

Based on those numbers DTubb provided, if I were to seat that 115 out to where the shoulder of the boat tail just clears the neck, it's at an OAL of ~2.937"... pretty dang long. Maybe that is where it needs to be. The OAL on the rounds at 'jam' length,i.e. firmly pressed into the lands w/ the SP tool) is about 2.836" ,Joe, I think the numbers Chuck listed were measured off the ogive, using the SP tool like I did originally)

Seated to the lands

Seated to where the boat tail junction just clears the neck/shoulder.

Not sure it comes across to well in the photos. Gotta send the stock and whatnot in to get everything assembled; might see if the gunsmith has a throating reamer as well. Either that or just wait for the .243 Win to 'do its thing' to the throat

Thanks,

Monte

 

[chuckw2]

Monte and Joe, right my measurements were taken off the ojive not the bullet tip.


Chuck

 

[rhino]

Now all I need are the specs for a tight neck .243 AI for the DTacs.

RHINOUT!