Johnston Ultimate Howa ASG plug

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michiganmuzzy

michiganmuzzy

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I picked up an Ultimate ML on a Howa action a month or two ago. Stainless and laminate thumbhole stock. I Took it completely apart to thoroughly clean and inspect. Loocks pretty good except for the ignition system. It takes a .458 Win Mag primed case. I mean i like using a LRMP but the is CF case a good design for a ML? The breech plug looks weird like it is two pieces, somehow. Since Ive got a lot of ASG modules and plugs for other guns, i figured i would get one of his breech plugs to replace this one. I had heard stories about these Ultimate plugs being hard to get out, but this came out pretty easy and quite clean. Well i went to ASG and looked at plugs, i came to the UML plug and (wrongly) assumed that was the right one and ordered it. I think this was a Saturday or Sunday night. Got an auto reply in my email saying they received my order. I replied saying its for a Howa action, not a Rem action. I got a reply within a few minutes saying i had ordered the wrong plug. Well I went back to the website and sure enough, there was a whole nother page of plugs, including one for the Johnston Ultimate. So i replied back saying yep i screwed up & bill me the additional and send the correct plug please and thank you. Got it today and will be installing it tomorrow as we have our company Christmas party in a couple hours.
But there was something else in the mail. I forgot all about the trigger spring upgrade that i ordered on ebay, from a guy in Australia. Ive got that kit to put in the Howa tomorrow, too. Maybe i can get this beast to the range soon. I need to get a scope on it first tho. Ive got a Burris3-9x40 that should do fine.
Thanks to Luke and ASG.
 
michiganmuzzy said:
I picked up an Ultimate ML on a Howa action a month or two ago. Stainless and laminate thumbhole stock. I Took it completely apart to thoroughly clean and inspect. Loocks pretty good except for the ignition system. It takes a .458 Win Mag primed case. I mean i like using a LRMP but the is CF case a good design for a ML? The breech plug looks weird like it is two pieces, somehow. Since Ive got a lot of ASG modules and plugs for other guns, i figured i would get one of his breech plugs to replace this one. I had heard stories about these Ultimate plugs being hard to get out, but this came out pretty easy and quite clean. Well i went to ASG and looked at plugs, i came to the UML plug and (wrongly) assumed that was the right one and ordered it. I think this was a Saturday or Sunday night. Got an auto reply in my email saying they received my order. I replied saying its for a Howa action, not a Rem action. I got a reply within a few minutes saying i had ordered the wrong plug. Well I went back to the website and sure enough, there was a whole nother page of plugs, including one for the Johnston Ultimate. So i replied back saying yep i screwed up & bill me the additional and send the correct plug please and thank you. Got it today and will be installing it tomorrow as we have our company Christmas party in a couple hours.
But there was something else in the mail. I forgot all about the trigger spring upgrade that i ordered on ebay, from a guy in Australia. Ive got that kit to put in the Howa tomorrow, too. Maybe i can get this beast to the range soon. I need to get a scope on it first tho. Ive got a Burris3-9x40 that should do fine.
Thanks to Luke and ASG.
Click to expand...
Looking forward to your range report!
 
michiganmuzzy said:
I picked up an Ultimate ML on a Howa action a month or two ago. Stainless and laminate thumbhole stock. I Took it completely apart to thoroughly clean and inspect. Loocks pretty good except for the ignition system. It takes a .458 Win Mag primed case. I mean i like using a LRMP but the is CF case a good design for a ML? The breech plug looks weird like it is two pieces, somehow. Since Ive got a lot of ASG modules and plugs for other guns, i figured i would get one of his breech plugs to replace this one. I had heard stories about these Ultimate plugs being hard to get out, but this came out pretty easy and quite clean. Well i went to ASG and looked at plugs, i came to the UML plug and (wrongly) assumed that was the right one and ordered it. I think this was a Saturday or Sunday night. Got an auto reply in my email saying they received my order. I replied saying its for a Howa action, not a Rem action. I got a reply within a few minutes saying i had ordered the wrong plug. Well I went back to the website and sure enough, there was a whole nother page of plugs, including one for the Johnston Ultimate. So i replied back saying yep i screwed up & bill me the additional and send the correct plug please and thank you. Got it today and will be installing it tomorrow as we have our company Christmas party in a couple hours.
But there was something else in the mail. I forgot all about the trigger spring upgrade that i ordered on ebay, from a guy in Australia. Ive got that kit to put in the Howa tomorrow, too. Maybe i can get this beast to the range soon. I need to get a scope on it first tho. Ive got a Burris3-9x40 that should do fine.
Thanks to Luke and ASG.
Click to expand...
I'm looking forward to hearing how your range time goes with it too.
Are you planning on a sabot load in that or BTB?
 
Guys, I dont really understand how the CF rifle cases are used but can a 338 win mag, a 7mm rem mag and other magnum cases be necked up to make the cases you need. Be easier to find and pay for than 458 cases.
 
snapbang said:
Guys, I dont really understand how the CF rifle cases are used but can a 338 win mag, a 7mm rem mag and other magnum cases be necked up to make the cases you need. Be easier to find and pay for than 458 cases.
Click to expand...
I think the base and length are the important parts.if it has the same base it’ll fit the bolt. If the length is right it’ll fit tight against the breech plug and not leak(too much)
 
The case length itself means absolutely nothing. Its the thickness of the case head that does everything with head spacing. OAL of the case does nothing. It could be 1" long, or only .300" long. Only the case head thickness matters when it comes to head spacing the OEM ignition system.
Head spacing, excluding the new Arrowhead ignition, is only based on the case head thickness, nothing else.

The Ultimate actually uses the 45Win Mag brass and the type of brass makes a world of difference. But the case head thickness is what causes all the problems with the OEM ignition system. Gas leaking has always been an issue, not only with the Johnston, but the RUM also. Not as bad with the RUM, because Remington made the breech plug harder along with changing the breech plug threads.

The OEM ignition system can be made not to leak and requires the breech plug to be set back slightly. Then a TON of work with the brass primer carriers is required. Problem is, even the best possible brass made, varies in head thickness. The Remington brass being the absolute worst. That case head thickness can vary as much as .020". Even Starline brass has case head thicknesses that vary .005". It can be made to work, just too much WORK involved in doing so. Its why Luke designed the perfect system.

I highly recommend the Fury BTB bullets ............ .50 Universal Fit – Fury Custom Bullets
If you will be using BH, 106grs W is a well proven charge.
 
I pretty much know the rifle and system like the back of my hand. Ken and I were close friends and used to have lunch all the time. He was a great guy, but there was a couple things I would have liked to seen him change.

Here is exactly how the ignition system operates........... You could cut the case off and remove the mouth section and it will not affect ignition.
The breech plugs are two pieces, and if you were able to remove yours, you were very fortunate.
Look at the bottom part of the photo. This is how the head space is set. Here again, imagine the case head thickness to be up to .020" different.



1703302422490.png


If you remained with the OEM system, inspection of the primer carriers is a must.
Example........

1703302689165.jpeg


If one wanted to take the time........... the system could be made perfect.
 
Yep, oe system is just too much trouble and too finicky for me and like snapbang pointed out, those cases aren’t always easy to find and ive already got loads of ASGs modules.
 
michiganmuzzy said:
Yep, oe system is just too much trouble and too finicky for me and like snapbang pointed out, those cases aren’t always easy to find and ive already got loads of ASGs modules.
Click to expand...
I shot my old BP Xpress so much, I had 2,000 Win45mag cases, all Starline.
There is no doubt that for those rifles, Luke's system is the savior.

I tried my darndest to talk Ken into setting those breech plugs back further to stop the gas cutting. But his first excuse was that much of the brass wouldn't allow the closing of the bolt. THEN I'd just tell him that he could BS most, but I knew better. He provided an inside primer pocket reamer. All one would have had to have done, was to set the depth and do your brass. He'd just smile, then ask me if I knew how much money he made replacing gas cut breech plugs.

I tried my darndest to get him to stop building all 50cal rifles and build some 45's. I do know that he did build at least one 45cal BP Xpress. I also tried to get him to use Luke's ignition system. Ken was pretty set in his ways as an "old boy".

That was Ken......... may he R.I.P.
 
Words of wisdom, when you set up your scope, use the most robust bases and rings. ENCORE and I both had issues with our UF's eating lesser rings and bases, not to mention scopes. With these rifles and the heavy load/bullet they shoot, expect violent recoil. A good brake is a must if you plan on anything more than a few seasonal shots.
 
michiganmuzzy said:
I picked up an Ultimate ML on a Howa action a month or two ago. Stainless and laminate thumbhole stock. I Took it completely apart to thoroughly clean and inspect. Loocks pretty good except for the ignition system. It takes a .458 Win Mag primed case. I mean i like using a LRMP but the is CF case a good design for a ML? The breech plug looks weird like it is two pieces, somehow. Since Ive got a lot of ASG modules and plugs for other guns, i figured i would get one of his breech plugs to replace this one. I had heard stories about these Ultimate plugs being hard to get out, but this came out pretty easy and quite clean. Well i went to ASG and looked at plugs, i came to the UML plug and (wrongly) assumed that was the right one and ordered it. I think this was a Saturday or Sunday night. Got an auto reply in my email saying they received my order. I replied saying its for a Howa action, not a Rem action. I got a reply within a few minutes saying i had ordered the wrong plug. Well I went back to the website and sure enough, there was a whole nother page of plugs, including one for the Johnston Ultimate. So i replied back saying yep i screwed up & bill me the additional and send the correct plug please and thank you. Got it today and will be installing it tomorrow as we have our company Christmas party in a couple hours.
But there was something else in the mail. I forgot all about the trigger spring upgrade that i ordered on ebay, from a guy in Australia. Ive got that kit to put in the Howa tomorrow, too. Maybe i can get this beast to the range soon. I need to get a scope on it first tho. Ive got a Burris3-9x40 that should do fine.
Thanks to Luke and ASG.
Click to expand...
The original Johnston ML I bought came from Ultimate Firearms with the Burris 3-9x40 Ballistic Plex. Took a beating and maintained accuracy without a hitch. Did the scope come with gun?
 

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