|
Long Branch 69L Mk 1/3 gets a new Barrel |
Post Reply 
|
Page <1 4567> |
| Author | |
Zed 
Special Member 
Donating Member Joined: May 01 2012 Location: France Status: Offline Points: 6460 |
 Post Options
 Thanks(0)
 Quote Reply
 Posted: March 03 2024 at 4:55am |
|
I'm impressed! that's fantastic shooting Geoff; and a great job fitting the barrel.
well done!
 |
|
|
It's nice to be important, but it's more important to be nice!
|
|
 |
|
|
britrifles
Senior Member 
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: March 03 2024 at 4:59am |
|
To explain what I mean about the LE “long chamber” vs a factory cartridge case, here is an example of a loaded Mk 7z cartridge. This happens to be a 1943 Defence Industries round.
The length from case head to the shoulder datum is 1.817 inches (Hornady Case Headspace Comparator). The case above that in the photo is a new PPU case. It is also 1.817 inches. I measured about 10 PPU cases and they are quite consistent in this dimension.  A fired case in this barrel (which came 0.010 inch short to SAAMI specs) measures 1.839 inches. That gives the cartridge case over 0.020 inch clearance at the shoulder. An additional final finish ream would increase that clearance to 0.030. What you really want for accuracy is zero clearance, or even a 0.001 interference (crush) for accuracy. For reliable rapid fire feeding, I like to have at least 0.001 clearance. Now, the other important dimension is the actual chamber length to the case mouth. That’s harder to measure without taking a chamber casting. But, what I did do is chamber a series of empty cases of varying lengths to see if there was any resistance to bolt locking and any tendency of the case mouth to ride into the step down into the throat. I checked this with pin gages to look for the case mouth closing up. The chamber minimum length should be 2.222 from breech face to front of chamber. With a case as long as 2.229, the case mouth was still not deformed when it was fully chambered (bolt locked). The third check was to determine the cartridge OAL when the bullet touches the lands. Using a Hornady OAL Gage, the 174 Sierra MatchKing touched the lands at 3.098 inches, which is 0.023 beyond maximum cartridge length (3.075). With all of the above and a correct size bolt head to get the rifle to headspace within specification, I felt there was no need to ream this chamber. |
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: March 03 2024 at 5:03am |
Thank you Shaun. It did not go as easy as expected, nor did I get the results I was expecting the first time. But I’m glad I stuck with it. I really appreciate CBI stepping up and replacing that first barrel at no charge. And they did it just based on my measurements of the throat length with the Hornady OAL gage. They knew it would not shoot with a throat that long. I do need to get back with Manson to figure out what was wrong with that brand new reamer.
|
|
|
|
|
Zed
Special Member
Donating Member Joined: May 01 2012 Location: France Status: Offline Points: 6460 |
Post Options
Thanks(0)
Quote Reply
Posted: March 03 2024 at 5:15am |
|
Well it's looking very good for this years competitions Geoff.
Next Saturday is my first competition since last June. I have not shot at 200 metres since then; so just fired a few rounds at 50 metres a couple of weeks ago. Working out the impact over point of aim variations for different distance. Hopefully it shouldn't be too far off; with final adjustments during the 5 test shots.
|
|
|
It's nice to be important, but it's more important to be nice!
|
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: March 03 2024 at 7:51am |
|
Best of luck Shaun, glad to see your getting back out.
|
|
|
|
|
Rossfield
Groupie 
Joined: June 08 2024 Location: Nova Albion Status: Offline Points: 37 |
Post Options
Thanks(0)
Quote Reply
Posted: June 16 2024 at 9:14am |
|
Very impressive all round. Has Criterion made these barrels with the standard chamber dimensions? How do the cases look after firing, typical expansion?
|
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(1)
Quote Reply
Posted: June 24 2024 at 12:52pm |
|
Rob,
The CBI barrels come 0.01 inches short chambered. Theoretically, you need to get a finish reamer to cut the chamber to full depth. That’s what I did on my first CBI barrel. But if you read this entire thread, it did not work out too well for me, resulting in an overly long throat. So, CBI sent me another barrel, free of charge. Outstanding customer service. The second barrel, I did not finish ream. As you probably know, this finish ream has nothing to do with headspace as that can be set by selecting an appropriate bolt head. LE chambers are quite long to the shoulder compared to factory cases and cartridges and I found that Mk 7 ammunition and new PPU cases dropped all the way into the rim as the barrel came from CBI. Cases extracted easily and fairly minimum expansion. I’ve neck sized them a few times, think I have about 200 rounds thru the new barrel now. Very happy with the results, a very accurate barrel indeed. |
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 2:40pm |
|
Update on how the new CBI barrel is shooting in the Long Branch No. 4 Mk I/3, now at a total of 485 rounds.
As this barrel breaks in, mean velocity is climbing and group center to center extreme spread is shrinking. Here is todays result prone at 200 yards, first group was slow fire and second was rapid fire: Gp MV ES SD C-C Score # (fps) (fps) (fps) (MOA) 1 2452 53 15.5 2.5 100-4x 2 2426 62 15.8 2.5 100-7x Standard match load: PPU Case, WLR Primer, 40.0 gr Varget, 174 gr SMK, 3.05” OAL Here is the prone rapid fire group:  I’m very impressed with the Criterion barrels. And excellent customer service as well. I’m really looking forward to getting back in the groove shooting the “wood guns” in vintage service rifle matches. Taking a break from the AR for a while. |
|
|
|
|
Strangely Brown
Senior Member
Joined: April 05 2022 Location: Wiltshire Status: Offline Points: 645 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 2:50pm |
I'm with you on both points there Geoff; and yes that's a stunning group!
|
|
|
Mick
|
|
|
|
|
DarioPirovano
Senior Member
Joined: May 20 2023 Location: Italy Status: Offline Points: 219 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 3:01pm |
|
Great shooting, now I’m pretty curious to see if someone have done barrel change with a lothar walter, and how it went.
based on what I heard, they’re good barrels and the only available in EU. |
|
|
|
|
Strangely Brown
Senior Member
Joined: April 05 2022 Location: Wiltshire Status: Offline Points: 645 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 3:04pm |
Lothar Walther have a good reputation in the UK although I'm not sure I have seen one on an Enfield over here.
|
|
|
Mick
|
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 3:24pm |
I’ve got one of these barrels, and I thought it was made here in the US, but might be wrong on that. Not installed it yet. I may use it on the No. 4 T. |
|
|
|
|
DarioPirovano
Senior Member
Joined: May 20 2023 Location: Italy Status: Offline Points: 219 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 3:54pm |
|
From what I know, they are made in Germany by lothar walther.
Geoff, I’m curious now, have you seen any difference between cbi and lothar walther? I’m talking about bore finish an tooling marks and diameters… can you take a couple of borescope image of the two for comparison please? |
|
|
|
|
Shamu
Admin Group
Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 4:29pm |
|
That's a group to be proud of, mate! From what I'm able to discover they are in Cummings, Ga, USA?
|
|
|
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
|
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 4:33pm |
|
Dario, I’ll dig out the Lothar Walther barrel tomorrow. I know it is not finished, I intend to do a very fine sanding on it then cold blue. Should come out almost black.
The CBI barrel bore is quite nice, and no question it shoots. I did find out that the Lothar Walther barrel was made in the US, there is a US barrel production facility not far from where I live. They shipped it direct to me. Probably should have bought two of them. |
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: February 07 2025 at 4:34pm |
Correct, you beat me to it Shamu. |
|
|
|
|
Post Reply
|
Page <1 4567> |
| Tweet |
| Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |
Topic Options
Zed wrote: