MAB - 5.56 Conv Kit 1:8" twist

If you shoot full-bore, then you're welcome to use this forum to discuss your sport.

Moderator: Mod

Message
Author
Bart
Posts: 64
Joined: Wed Mar 14, 2007 4:31 pm
Location: Waikerie, South Australia

MAB - 5.56 Conv Kit 1:8" twist

#1 Postby Bart » Wed Mar 14, 2007 4:40 pm

Has anyone had any experience with these conversion kits? I have an old Omark target rifle with a Black Mountain barrel fitted and is a little on the sloppy side after having over 9,000 rounds pumped through it and I am keen to try out 5.56 shooting. Is it worth going with one of these conversion kits or is there a better alternative?

Ken L
Posts: 473
Joined: Tue Aug 30, 2005 6:53 am
Location: Maclean NSW

#2 Postby Ken L » Wed Mar 14, 2007 8:14 pm

They are a reasonably economical aproach to lower recoil shooting but I would sugest going for a 1:7.5 twist for the 80 grain SMK HPBT's and develop a load using 2206H instead of 2208 as is the custom.

Ken L

Malcolm Hill
Posts: 251
Joined: Fri Aug 25, 2006 9:40 pm
Location: Mid North S.A.

5.56 conversion

#3 Postby Malcolm Hill » Wed Mar 14, 2007 10:34 pm

Have been using an Mab 5.56 conversion for about 18 mths now and I am completely satisfied with the 1 in 8 twist for the 80g SMK back to 900yds. The conversion is only available in that twist I think and is a good way to start with this calibre.Once you wear out the barrel you can then buy an adaptor and any barrel you like as you already have the bolthead.Its the least expensive way to get a 223 up and running and mine has done over 3000 rounds now and leaves little to be desired in the accuracy department. As for 2206H vs 2208 I have found 08 produces slightly higher velocity and a little less verticle spread than 06H in all the rifles Ive tested it in Regards Malcolm

rainbow
Posts: 18
Joined: Mon Sep 19, 2005 1:22 am
Location: Warracknabeal R.C. (vic)

#4 Postby rainbow » Wed Mar 14, 2007 10:37 pm

bart
several members at my club have done the conversion on model 44's. (c/m M.A.B barrels, new boltheads) and have now set about working out loads for them. Primarily to allow spouses and some prospective junior members a chance to start shooting a "comfortable" and low cost settup with the hope that they will stick with the sport.
The barrels were from vra stock (sorry I don't recall the spec's) as were a couple of the omark actions. The last time i asked, two were in regular use and showing surprising performance (considering their cost)

Guest

#5 Postby Guest » Thu Mar 15, 2007 7:32 am

Bart,
If you don't want to spend a lot of money setting up, go with the conversion kit--it's good value. Use the 80 grain projectile ( not the 69 ) and you will find performance more than satisfactory.
2208 is OK at around 25.5 gns ( start at 25 and work up )
Be wary of 2206H as it tends toward being unstable at high ambient temperatures---2206 is better.
Malcolm.
Quote " As for 2206H vs 2208 I have found 08 produces slightly higher velocity and a little less vertical spread than 06h----- "
You really need to qualify this as 06h is a faster burning powder that 08 and will inherently produce more speed than 08 all other things being equal.
As for there being a difference in vertical spread between the two powders, this is more a tuning problem than some inherent characteristic of the powders. With all due respects.
Barry

balcom
Posts: 356
Joined: Mon Nov 14, 2005 3:12 pm
Location: ballina

223 conv

#6 Postby balcom » Thu Mar 15, 2007 1:43 pm

Hi Bart,
I have been using a 223 for over 10 yrs, with an Omark action and a Musgrave converted by Kieth Hills, I would suggest you start with only 24 grns of 2208 and then work upwards if using this powder as with an Omark action there are two problems that I know of,
1= the firing pin will put a hole in your primer if the pressure is two high (every barrel chamber has it's own mind).
2= with an Omark the extractor is small and will give you problems ejecting the shell with high pressures.
I use 24.5 in my Omark and 25.5 in my Musgrave but it took a bit of working out also 25.5 is a squashed load in most cases.
You cant be too carefull so I hope this helps.
PeterH

mitchellchandler_au
Posts: 66
Joined: Sun Apr 02, 2006 8:29 pm
Location: MIA

#7 Postby mitchellchandler_au » Fri Mar 16, 2007 7:39 pm

Hi bart,
I had a conversion kit done about 6 years ago, I couldnt be happier with it. Over the last month it has produced scores in the 50.6 -50.9 range. I would think it has done around 3000 rounds by now and still shoots groups around 1/3 moa at 100 metres.
personally I would use 2208 because I got better velocities and better grouping and better ES to boot over the 2206.

Also I was having problems with pierced primers because the hole in the bolt head was too large for the pin. It got to the point where the pin wouldnt even hit a primer because of all the metal chips from the pierced primers in the hole so I rang up MAB to get the poop on the situation. They sent me a new bolt head with a smaller pin hole. I gave them the pin diametre. since then no more problems with the primers busting. At the moment iam having another 223 built on a Omark. MAB sent me a bolt head without the pin hole so the gunsmith can drill it to suit the fireing pin a little better.

Hope this helps.
Firepower usally means an increased number of misses per minute. 50 misses are not firepower. One hit is firepower

Malcolm Hill
Posts: 251
Joined: Fri Aug 25, 2006 9:40 pm
Location: Mid North S.A.

5.56 conversion

#8 Postby Malcolm Hill » Fri Mar 16, 2007 10:46 pm

Hi Barry Just a quick note in reply on the 2208 vs 2206H velocity issue.The ADI listings give the nod to 2208 with an 80gn pill and this is taken in a 24 inch barrel. Given that most of us use at least a 28 inch tube the 2208 should gain even more advantage which seems to be the case with my rifles.Things do vary a bit between barrels though with the conversion barrel giving 2910 fps with 25gn of 08 and another MAB 29inch in an adaptor giving 3055 fps with the same load.The longer tube gives 3155 with 25.4gn of 08 but this load is a bit too hot.I too have experienced the pierced primer problem even using rem 71/2 or br4 primers. It has a lot to do with the clearance of the pin ,Omark pins run around the 68 thou mark and this works ok if there is minimal clearance but if the hole is too large(I had one that was 80 thou)it is a constant problem.I also had one sent from MAB with a smaller hole and ground the pin down and it works a treat-62.5 thou is the size.As for the vertical group difference I may not have hit on the best load for 06H yet but other shooters around here have found the same-it seems as though the opposite is true as far as this goes for these powders in the 308. Regards Malcolm

Bart
Posts: 64
Joined: Wed Mar 14, 2007 4:31 pm
Location: Waikerie, South Australia

#9 Postby Bart » Sat Mar 17, 2007 10:05 pm

Thanks heaps for the feedback guys. The info on the powders and loads is great also. The more the better as it will give me a good start on this project. A query to the F-class guys, is this calibre used much for this shooting.

Guest

#10 Postby Guest » Sun Mar 18, 2007 8:00 am

Bart,
It's a great little calibre for F Class Standard. Overall probably won't be as good as a well tuned 308 in windy conditions at long ranges, but non-the-less they are very competitive.
Barry

Malcolm Hill
Posts: 251
Joined: Fri Aug 25, 2006 9:40 pm
Location: Mid North S.A.

5.56 conversion

#11 Postby Malcolm Hill » Sun Mar 18, 2007 6:46 pm

Hi Bart Just got home from the S.A. D.R.A. teams event at Lower Light range where our no. 6 D.R.A. team cleaned up the F class section. Four of our team used 223's the other one a 308. It was shot over 300,500 and 800 mts under fairly tricky conditions with wind shifts and changes of direction five to six degrees during some rounds as is normal this time of year on this range.Shot on fullbore targets we were 56 points up for the off rifle aggregate against the other teams which I think all used 308,s with one team also having 2 F Open rifles in their squad. It has been a while since I have seen a 308 win against a 223 in F std over our way so have no doubts about them being competive.
Regards Malcolm.

bruce talty
Posts: 76
Joined: Fri Sep 23, 2005 2:37 pm
Location: Brisbane

Re: MAB - 5.56 Conv Kit 1:8" twist

#12 Postby bruce talty » Mon Mar 19, 2007 8:09 pm

Bart wrote:Has anyone had any experience with these conversion kits? I have an old Omark target rifle with a Black Mountain barrel fitted and is a little on the sloppy side after having over 9,000 rounds pumped through it and I am keen to try out 5.56 shooting. Is it worth going with one of these conversion kits or is there a better alternative?
G'Day Bart i don't think MAB make the Omark .223 Conversion Kit anymore, i was at the Victorian Queens last week and heard someone say you can't get the kit anymore, but don't kow how true this is i could ask at QRA if they have any or you could ring MAB that would be the best. The .223 is a good little cartridge to shoot but when it comes to reloading it is not as forgiving as the .308W to load.Bruce

bruce talty
Posts: 76
Joined: Fri Sep 23, 2005 2:37 pm
Location: Brisbane

.223 Remington

#13 Postby bruce talty » Fri Sep 21, 2007 7:34 pm

Ken L wrote:They are a reasonably economical aproach to lower recoil shooting but I would sugest going for a 1:7.5 twist for the 80 grain SMK HPBT's and develop a load using 2206H instead of 2208 as is the custom.

Ken L
Don't agree with you i had a mate of mine shoot 90 grain JLK VLD's last weekend in a old 1X8" and they shot tighter than 80 grain SMK in a 22BR.He shot the first shoot with the 80 grain SMK and the 90 grainer in his second shoot had a much tighter group under the same wind conditions, my .223 Rem had a 1X8 MADDCO and shot very well out to 1000 yds on a good day and i used nothing but AR2208 tried 2 tins of 2206H and couldn't get the velocity with it, i got 3000F/S with 2208 chamber had a long throat which is what you want if you are going to shoot 80 grainers only. Bruce


Return to “Full-bore/Target Rifle”

Who is online

Users browsing this forum: No registered users and 5 guests