Omark actions

[GriMo]

The very first adapters were just barrel stubs.

Not knowing the actions that well, what improvements would a different adaptor offer?

[mick_762]

The very first adapters were just barrel stubs.

Not knowing the actions that well, what improvements would a different adaptor offer?

The ability to buy off the shelf Remington barrels I would imagine would be a big plus.

[GriMo]

The very first adapters were just barrel stubs.

Not knowing the actions that well, what improvements would a different adaptor offer?

The ability to buy off the shelf Remington barrels I would imagine would be a big plus.

Sorry, should have been clearer. If the original adapters where machined barrel stubs I'm guessing they could accept more commonly threaded barrels. Just not sure why people would use a Nielsen adaptor over that.

Unless I'm wrong and the stub doesn't allow off the shelf barrels, in which case it makes perfect sense.

[aaronraad]

Maybe the barrel stub didn't have the recoil lug integrated as a single piece? http://shootenstuff.com.au/collections/ ... tor-maddco versus the original
http://www.tsengineering.com.au/firearms/exploded-view/

The main reason was that the machining cost to have those locking lug recesses done for each new barrel wasn't insignificant.

You'll notice most of the quick change barrel systems on European and American rifles use some sort specially machined locking and locking design as part of the barrel. Some lock have their lugs lock directly into the barrel or it's included as part of the received, either way OEM barrels for these systems cost closer to $1,000 locally.

I'm not sure if the HS Precision interrupted thread system was able to overcome this issue but it still ends up being extra machining work for each barrel. Maybe the Savage barrel nut does the job, I see Remington have added the feature to their new budget series 783 rifles.

[Tony Z]

Lets just go back a little here and clarify things. The stock Omark has a recoil lug jammed between action sleeve and barrel where the bolt locking lugs are machined into the barrel like a Blaser. Barrel thread was 1 1/8" x 12 TPI where the problem of tenon wall thickness was completely eliminated. The early stub adapter was the same except the barrel chamber area was cut then bored and threaded to accept another barrel. The often used thread was 7/8" x 14 UNS where the very thin tenon wall led to early sticky cases.

Then there was the Nielson style adapters. No integral recoil lug at first that used the stock Omark recoil plate jammed forward of the adapter and before the barrel like on a Rem 700. Then later an integral recoil lug that was either forward, rearward or mid positioned on the adapter itself. I have seen all four set ups with all kinds of screw locations from regular Omark positioning to bolting through the recoil lug like a Winchester M70. Thread size was inch by 14 or something similar. Tenon wall still thin but way better.
Mine are either no recoil lug at overall Rem 700 configuration that then used the stock recoil plate or the Rem 700 one. Then later forward integral recoil lug again at Rem 700 configuration. All at 1 1/16" x 16 TPI that could accept modified Rem 700 barrels (third ring of steel machined clear to end of chamber). Most were made of EN 29 and some were 420 MFQ stainless steel.
There are other adapters i have seen or heard of that are all to time consuming to mention but the principle is the same. The latter Nielson adapters got a horrible reputation for fracturing during lock up of the barrel. This was most likely due to the lack of drawing back the steel after the hardening stage. Considering the barrels of stock Omarks were just plane Jane 4140, i could not see why an adapter would have ever needed to be that hard. It only led to the bolt head wearing away prematurely.

The point is that with the right adapter that is timed properly for maximum extraction camming and firing pin fall the Omark action can be cheaply converted to a very good if not exceptional single shot action. The very early stock trigger is probably the best of all to do a three lever conversion to as the steel used as well as the one piece machined housing offers very good repeatability.

[Branxhunter]

For years i have used or helped set people up with Omarks for long range BR. With a properly timed adapter and roller cam for extraction they can be quicker to use than many custom actions.

I am intrigued by what you mean by "properly timed adapter and roller cam for extraction". Do you have any photos of the roller cam and how it works?

Marcus

[Tony Z]

Timing simply means the location of the locking lugs far enough forward so the bolt handle is close enough to engage the cam on the sleeve for full extraction while maintaining the cocking helix in a position where the cocking sear on fall does not strike any metal and kick the bolt out of lock. Many adapters did not do this properly and to correct it the bolt handle had to be removed and sweated back on closer to the sleeve. But then the other problem arose where the cocking sear was engaging only when the bolt handle was partially closed leading to a shallow firing pin fall and ignition problems. The job to correct this without replacing the adapter was usually not done. Sometimes a Remington trigger or even cocking sear put in place of the original Omark cured the issue. But not always. The firing pin fall needs to be around 6 to 7 mm minimum on the Omark. Often it is less than 5 and that is where problems occur.

It was easy for me as i made an adapter to fit the action. Most adapters are made for the general fit of all Omarks not taking into account wear or butchered modifications etc and that is where the problems start.
The roller is something i came up with some years ago and is basically a tool steel bearing inner and outer ring placed where the bolt cams through its arch during extraction. As far as i know mine are the only ones in existence. Anyone who has seen either aJRs HG Remroid or albows Omark LG rifle will have seen how it works to speed the actions up. There are pics of it already on this forum somewhere. It is so simple that it astounds me no custom actions do it. I did one on a Savage 12 cocking/unloading sear some years ago and i believe there is now an option for one from a US manufacturer for that model. It should have been a factory off the shelf item (the bearing is obtainable from any supplier of precision skate board wheels} around 30 years ago. For a lousy $7 and the cost of a modified pin it would have made the Savage actions a lot more palatable.