ASSRA Forum › General › Gunsmithing Single Shot Rifles › Chambering a bottleneck round
(Moderator Group: Moderator)
‹ Previous Topic | Next Topic ›
Page Index Toggle Pages: 1 Send TopicPrint
Hot Topic (More than 10 Replies) Chambering a bottleneck round (Read 1228 times)
jhm
Frequent Elocutionist
*****
Offline



Posts: 1440
Location: georgia
Joined: Sep 4th, 2011
Chambering a bottleneck round
May 29th, 2024 at 7:22am
Print Post  
I have chambered many barrels but only one or two bottleneck ones and I just got lucky on those I guess. My question is what is the best method. Do you predrill the chamber area or just take light cuts and let the reamer do all the work. Reason I ask is I will be doing a 7x57 roller for a friend in a few days. 



JMH
  
Back to top
 
IP Logged
 
n.r.davis
Oldtimer
*****
Offline



Posts: 579
Joined: Dec 3rd, 2015
Re: Chambering a bottleneck round
Reply #1 - May 29th, 2024 at 11:20am
Print Post  
The book "Chambering Rifles for Accuracy" from 4D Reamer Rental is a most Informative Book.  You won't be disappointed.  Good luck 👍🏻
  
Back to top
 
IP Logged
 
GunBum
Full Member
***
Offline



Posts: 185
Location: SW Missouri
Joined: Oct 30th, 2021
Re: Chambering a bottleneck round
Reply #2 - May 29th, 2024 at 1:12pm
Print Post  
I never pre-drill.  The reamer cuts just fine.
  
Back to top
 
IP Logged
 
TomKlinger
Junior Member
**
Offline



Posts: 77
Joined: Feb 17th, 2019
Re: Chambering a bottleneck round
Reply #3 - May 29th, 2024 at 4:20pm
Print Post  
Take small cuts, bottleneck reamers will plug up and gouge easier than tapered straight reamers….and of course, plenty of cutting fluid.
Tom Klinger
  
Back to top
 
IP Logged
 
gwahir
Senior Forum Member
****
Offline


Ve gets too soon olt und
too late shmart.

Posts: 414
Location: montana
Joined: Dec 31st, 2005
Re: Chambering a bottleneck round
Reply #4 - May 29th, 2024 at 7:26pm
Print Post  
Depending on the chamber it may not be a good idea to initially run a bit in the full length of the case body. You could be left with the reamer pilot not being able to reach the rifling when you start to use the reamer. Adjust accordingly!
  
Back to top
 
IP Logged
 
jhm
Frequent Elocutionist
*****
Offline



Posts: 1440
Location: georgia
Joined: Sep 4th, 2011
Re: Chambering a bottleneck round
Reply #5 - May 29th, 2024 at 9:55pm
Print Post  
Watched a video by Randy Selby "The Real Gunsmith" and he does everything off the steady rest. He advances about .060 at a time and it takes a LONG time to do a chamber but he swears by this method.



JMH
  
Back to top
 
IP Logged
 
John Taylor
Frequent Elocutionist
*****
Offline



Posts: 1686
Location: Lewiston, ID
Joined: Oct 23rd, 2006
Re: Chambering a bottleneck round
Reply #6 - May 30th, 2024 at 10:30am
Print Post  
I usually pre drill to remove most of the metal. Drill bit should be .020" smaller than the reamer. I usually stop about .1" short of the go gauge shoulder. There are roughing reamers available for most chambers, I only have one.
  
John Taylor   Machinist/gunsmith
Back to top
WWW  
IP Logged
 
beltfed
Frequent Elocutionist
*****
Offline



Posts: 1751
Location: Central Wi
Joined: Dec 20th, 2007
Re: Chambering a bottleneck round
Reply #7 - May 31st, 2024 at 11:17am
Print Post  
FWIW
A Lot of T/C Contender 7x223 (7TCU) factory barrels were
rechambered to 7 International Rimmed which is based on 
the 30-30 case.
So, effectively, the TCU chamber could be considered predrilled for the larger diameter 7 Int R.
Problem is that the 7 Int R reamer Pilot cannot initially reach the bore to start out centered up well.
I have a rechambered 7 Int R barrel here that has the chamber enough off center that fire formed cases have to be
marked as per the original rotational orientation or the gun will not close up.   
Despite that, the barrel was otherwise very accurate as long as you orient the fire formed neck sized brass as you chamber rounds.
beltfed/arnie
  
Back to top
 
IP Logged
 
John Taylor
Frequent Elocutionist
*****
Offline



Posts: 1686
Location: Lewiston, ID
Joined: Oct 23rd, 2006
Re: Chambering a bottleneck round
Reply #8 - May 31st, 2024 at 3:13pm
Print Post  
beltfed wrote on May 31st, 2024 at 11:17am:
FWIW
A Lot of T/C Contender 7x223 (7TCU) factory barrels were
rechambered to 7 International Rimmed which is based on 
the 30-30 case.
So, effectively, the TCU chamber could be considered predrilled for the larger diameter 7 Int R.
Problem is that the 7 Int R reamer Pilot cannot initially reach the bore to start out centered up well.
I have a rechambered 7 Int R barrel here that has the chamber enough off center that fire formed cases have to be
marked as per the original rotational orientation or the gun will not close up.  
Despite that, the barrel was otherwise very accurate as long as you orient the fire formed neck sized brass as you chamber rounds.
beltfed/arnie


Problem caused by the extractor cut forcing the reamer to cut off to one side before the pilot reached the bore. Need to use a boring bar to cut the first part of the chamber till you get past the extractor cut.
  
John Taylor   Machinist/gunsmith
Back to top
WWW  
IP Logged
 
beltfed
Frequent Elocutionist
*****
Offline



Posts: 1751
Location: Central Wi
Joined: Dec 20th, 2007
Re: Chambering a bottleneck round
Reply #9 - Jun 2nd, 2024 at 9:53am
Print Post  
John,
That is a good point re the extractor cut on the T/C barrel.
I leave the extractor in the barrel while cutting the chamber
so as to minimize this factor. The TC extractors are fairly snug in the cut. But also Temporarily glue in with locktite
So, the extractor is also recut without a separate operation.
beltfed/arnie
« Last Edit: Jun 2nd, 2024 at 2:24pm by beltfed »  
Back to top
 
IP Logged
 
wesg
Senior Forum Member
****
Offline



Posts: 274
Joined: Sep 13th, 2004
Re: Chambering a bottleneck round
Reply #10 - Jun 12th, 2024 at 11:35pm
Print Post  
I dial the barrel in and bore the body taper.

Another approach is to drill the body to a depth that still allows the pilot to engage the bore. Ream until you start touching the shoulder, and drill another xx deeper. 'Rinse and repeat '.

Saves some amount of wear on the reamer, but reduces the number of passes just to clear chips.
  
Back to top
 
IP Logged
 
Page Index Toggle Pages: 1
Send TopicPrint
‹ Previous Topic | Next Topic ›
 
  « Board Index ‹ Board Top  

ASSRA Forum » Powered by YaBB 2.6.12!
YaBB Forum Software © 2000-2024. All Rights Reserved.

Valid RSS Valid XHTML Valid CSS Powered by Perl Source Forge

Page completed in 0.6421 seconds.