Custom Rifle

deepforks · January 7, 2014, 07:39 PM

so my hart barrel just arrived and my gunsmith is getting ready to start my project. he's asking for a couple dummy rounds and here lies my question. when seating a boat tail bullet, should you seat to the bullet diameter in total or include the boat tail? so for my 270, should my minimum seating depth be .277 or .277 + the boat tail measurement? hope that makes sense. thanks.

lefteye · January 7, 2014, 07:53 PM

Seating depth is not directly related to bore diameter. The bore diameter for a .270 Win is .277. Assuming a magazine does not limit seating depth, the bullet should be seated to provide the best accuracy - a trial and error procedure. One technique is to seat the bullet out far enough for the ogive of the bullet to contact the lands of the rifling. The ogive is the surface of the bullet closest to the point of the bullet that measures same as the maximum diameter of the bullet, i.e., .277 for a .270 bullet, and it is the surface of the bullet closest to the point that actually contacts the rifling. If necessary, then seat the bullet slightly deeper to achieve the best accuracy with the load you are using. A boat tail may affect the best seating depth but, at least in my experience, no part of the boat tail should be in the neck of the cartridge case.

James K · January 7, 2014, 09:08 PM

He is probably either working on the magazine and wants to make sure it will accept the rounds you use or he wants to be sure the throat is right to handle the bullet and seating depth you have chosen. Alternatively, he would simply make the magazine to SAAMI COAL spec (3.340", same as .30-'06), and use a standard reamer.

If he uses the SAAMI spec and standard throat, you could be limited if you want to seat bullets long.

Jim

Lucas McCain · January 7, 2014, 09:50 PM

Question #1. Did Hart chamber the barrel or is your smith chambering it?
Question #2 They sometimes order the barrel where the chamber is not completely finished and then the smith finishes it when he gets the barrel? I've never liked that method.
When I have a gun rebarreled, the smith chambers the rifle with his reamer, he always orders the barrel longer than I want it. He cuts the barrel to my specified length. The piece he cut off, he takes the same reamer and makes me a bullet seating gauge. All it is is the shoulder, neck and throat.
Now when I reload I can tell if the bullet is against the lands or not. It also gives me a baseline which will tell me if I am having any throat erosion occurring down the road.
I have never had to furnish a dummy round to chamber a barrel. As previously said about the magazine being modified, thats possible, but that would depend on the donor action was made for a different cartridge family than what the new chambering is. If you were planning on using VLD bullets would be a concern on how much throat it should have.

coalroller · January 8, 2014, 11:27 AM

Who do you have building your rifle?

old roper · January 10, 2014, 09:58 PM

Read early post building 270 on Rem action and not sure what you talked to gunsmith about on your build but most gunsmith would ask few question on the chamber. Only time I furnished rds is for custom throating and checking magazine length but this is all done when he get the rifle and we've talked about seating depth prior.

If it was me I'd call him back and get a clear understanding why and purpose make sure your both on same page.

Well good luck

January 7, 2014, 09:50 PM	#4
Lucas McCain Senior Member Join Date: March 7, 2013 Location: Callaway, MN Posts: 361	Question #1. Did Hart chamber the barrel or is your smith chambering it? Question #2 They sometimes order the barrel where the chamber is not completely finished and then the smith finishes it when he gets the barrel? I've never liked that method. When I have a gun rebarreled, the smith chambers the rifle with his reamer, he always orders the barrel longer than I want it. He cuts the barrel to my specified length. The piece he cut off, he takes the same reamer and makes me a bullet seating gauge. All it is is the shoulder, neck and throat. Now when I reload I can tell if the bullet is against the lands or not. It also gives me a baseline which will tell me if I am having any throat erosion occurring down the road. I have never had to furnish a dummy round to chamber a barrel. As previously said about the magazine being modified, thats possible, but that would depend on the donor action was made for a different cartridge family than what the new chambering is. If you were planning on using VLD bullets would be a concern on how much throat it should have. __________________ If you have time to do it twice, then you have time to do it once right and put your name on it

January 10, 2014, 09:58 PM	#6
old roper Senior Member Join Date: June 11, 2007 Posts: 2,155	Read early post building 270 on Rem action and not sure what you talked to gunsmith about on your build but most gunsmith would ask few question on the chamber. Only time I furnished rds is for custom throating and checking magazine length but this is all done when he get the rifle and we've talked about seating depth prior. If it was me I'd call him back and get a clear understanding why and purpose make sure your both on same page. Well good luck __________________ Semper Fi Vietnam 1965 VFW Life member NRA Life Member

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January 7, 2014, 07:39 PM	#1
deepforks Member Join Date: October 15, 2011 Location: Southwest Idaho Posts: 89	Custom Rifle so my hart barrel just arrived and my gunsmith is getting ready to start my project. he's asking for a couple dummy rounds and here lies my question. when seating a boat tail bullet, should you seat to the bullet diameter in total or include the boat tail? so for my 270, should my minimum seating depth be .277 or .277 + the boat tail measurement? hope that makes sense. thanks.

January 7, 2014, 07:53 PM	#2
lefteye Senior Member Join Date: January 30, 2006 Posts: 1,433	Seating depth is not directly related to bore diameter. The bore diameter for a .270 Win is .277. Assuming a magazine does not limit seating depth, the bullet should be seated to provide the best accuracy - a trial and error procedure. One technique is to seat the bullet out far enough for the ogive of the bullet to contact the lands of the rifling. The ogive is the surface of the bullet closest to the point of the bullet that measures same as the maximum diameter of the bullet, i.e., .277 for a .270 bullet, and it is the surface of the bullet closest to the point that actually contacts the rifling. If necessary, then seat the bullet slightly deeper to achieve the best accuracy with the load you are using. A boat tail may affect the best seating depth but, at least in my experience, no part of the boat tail should be in the neck of the cartridge case. __________________ Vietnam Veteran ('69-'70) NRA Life Member RMEF Life Member Last edited by lefteye; January 7, 2014 at 08:36 PM.

January 7, 2014, 09:08 PM	#3
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	He is probably either working on the magazine and wants to make sure it will accept the rounds you use or he wants to be sure the throat is right to handle the bullet and seating depth you have chosen. Alternatively, he would simply make the magazine to SAAMI COAL spec (3.340", same as .30-'06), and use a standard reamer. If he uses the SAAMI spec and standard throat, you could be limited if you want to seat bullets long. Jim

January 8, 2014, 11:27 AM	#5
coalroller Junior member Join Date: August 9, 2013 Posts: 25	Who do you have building your rifle?