McGowan 280ai barrel distance to lands

[Luke45]

So my McGowan barrel ive had for a while shoots light stuff (140s) great. Never gave much though to coal because the first seating depth I tried worked great. Now I'm on to heavier bullets, and I did a test to see how far out I could seat the bullet to get better case capacity.

With 4 bullets, 110 TNT hp, 140 vld, 168 vld, 168 CH, and 162 amax, I realized that I'm hitting the lands before the cartridge is even to sammi spec length. Not a big deal for lightweights , but I'm sacrificing ALOT of case capacity shooting 168s with slow powder.

What gives? As it sits, a factory round would be into the lands, what am I doing wrong? Or are McGowan barrels normally short throated?

[Luke45]

http://i155.photobucket.com/albums/s319/lukeonderko1/unnamed_zps331b84b9.jpg
heres a print of the chamber to you machinists out there

[Savage6x284]

A generic chamber is almost always the price you pay when buying a prefit barrel.

This seems a dirty word around here but a GUNSMITH could extend your leade and throat to suit the 7mm heavies. I prefer my leade/throat to be cut with the chambering reamer ground to suit my intended projectile but it can be easily and quickly done with just a throating reamer in an existing chamber.

[FW Conch]

"284" is right on..... I use pre fit barrels for hunting accuracy, and they serve me well in that capacity. If I want to use a heavier bullet, I first find the desired seating depth to the lands, determine the available powder space left, then choose the powder burn rate that will work in that space. One cannot always say, I want this bullet weight, with this powder, to work with the chamber lead that I have in this pre fit barrel.

The alternative, as alluded to by "284", and as my BIL does, is select a bullet, seat it in an empty case to the desired COAL, provide his "smith" with the distance off the lands desired, have a reamer made to that specification, provide the "smith" with the desired barrel blank, and let him "do his magic. All this to shoot "little tiny holes in paper" :-))

As "284" said, having a good smith extend the lead with a throating reamer is a solution, but it may not meet the accuracy standards of some of the "purest"?

The question we all must ask ourselves is, how "Excessive/Compulsive" do we want to be?

Just Askin? :-))......Jim

[stomp442]

I have a couple Mcgowen barrels now and they all seem to be a bit short but I have not had any problem getting the velocity either. Personally I like a short throat that way I can chase the lands as the barrel wares and have plenty of room and also get my monies worth before a set back is needed.