MGM problems?

[Dirtysteve]

Last spring I bought a 264 win mag barrel from MGM.
I have tried many different loads with IMR 4350 and 130 to 140 gr accubonds, partitions and some hornady's.
I cannot get it to shoot under 2 inches.
Also when loading at the top of the load chart 57 grs behind a 140 gr bullet I am showing signs of pressure and have several cases that after shooting I can't get (full length sized die and trimmed) resized to fit back into the barrel with out having to slam it shut.

Any ideas?
Should I send it back?
 
 

[kynardsj]

Have had MGM build me two barrels in the last few years. Both were great with no problems. I would contact them and discuss the problem. Good luck on your outcome.

[DEACONLLB]

A MGM rep told me that all their chambers are match grade therefore in reloading you may be having problems because the chamber is too tight That is the problem that I had with one of their 7x57 barrels my reloads were just not working because of case length and overall length not being correct when I used the reloading info for that round had to snap it shut to get it to close. They may wont you to return it and have the chamber polished a bit. I have one of their 357 mag barrels and have had no problems with factory ammo but have not shot any reloads in it yet.
Deaconllb

[Rol Page]

I have an MGM 24" 260 Remington barrel, purchased last summer.   Nosler 130 Accubond at a published 2,760FPS per Nosler manual will group 1.5 /- inches @ 100yds while the Sierra 120 Prohunter @ 2,800FPS per Sierra manual will group 1.0 /-" @ 100yds.  This is in my Encore.  The scope is a Leupold 2.5x8 VariX III.  Occasionally I will get better groups, approaching 1/2" or 2 touching and a flier.
 
I am suspecting my trifocals, scope parallax, and or my handloads are the limiting factors in my case.  During barrel break-in I found that Remington and Federal Fusion were grouping terrible.  Have not tried factory loads lately.  Good Luck and please share your findings, they may help others like me. 

[Grumulkin]

I have an MGM barrel that's excellent but others apparently haven't been so fortunate:


https://www.matchgrademachine.com/forum/viewtopic.php?t=1835


By the way, I wouldn't be happy with a barrel as expensive as an MGM barrel that would only do 1 to 1.5 inches at 100 yards.  Mine, fortunately, will do about 1.5 inches at 200 yards.

[sweetwyominghome]

If you were able to easily open the frame and extract the fired casing, chances are your cases are now too long after sizing and need to be trimmed. Also, 4350 is a bit on the fast side for this cartridge. Give some slower propellants like Re-22 and Re-25 a whirl.
 
As to pressure signs, keep in mind this is a custom barrel and held to min specs. For those which had book loads available, my MGM barrels would top out in velocity with LESS than the max loads published in various manuals.   

[Bugflipper]

I had the same problem when they first took over the company with a 7tcu. A fully sized cartridge would have to be forced pretty hard. Then as you are saying it had to be slammed shut. I contacted them and they said most likely the die was not sizing it as tight as the chamber was. They said that was the first one they had cut with that particular reamer and it could be in need of replacing (was used before they bought the company). My oal and case length were good. They offered to fix it for free with a new reamer and pay shipping both ways. Once I figured out what the problem was I just chucked a patch in a low speed cordless drill and put some jewelers rouge on it. Just a quick pass through then tried a shell. Went through that 3 or 4 times until it fit properly. I might have had 15-20 mgm barrels and that was the only one that was that way. Not really a problem at all though. That was the best shooting contender barrel I ever owned.

[Dirtysteve]

After several more loads with no luck I contacted MGM and it's going back for an accuracy test and to have the chamber looked at. I believe it needs to be polished as it appears to be rough.
Hopefully all will work out.
Thanks for all the help

[OK hunter]

Good luck.  I trust the folks there to do the right thing.

[Muddyboots]

They stand behind their products so I feel confident it will be right when you get it back. I have a .500 S7W 26" heavy for my Encore that shoots ridiculous for a big bore.  Even at .50 cal, the one hole group is pretty awesome. I use it in IN shotgun zones. Never going back to slugs!!
Muddy

[Bugflipper]

Sorry to steer off topic a bit.


Muddyboots, what is the recoil on that 500 like? Been thinking about getting a heavy, slow chambering for close range hunting.


DirtySteve, if you don't mind give us an update on the outcome when you get it back, thanks.

[smokehouserex]

 
 
  Hey Dirtysteve:
  I don't know about your bbl. but it does sound like you have a minimum chamber. 57 gr. of 4350 is pretty hot for a 140gr. bullet in my rifle. I loaded 120 gr.speer in mine with 57-58 gr. of 4350 and it did OK, I never tried to shoot 3 shots without waiting between shots but it would cloverleaf them. I would take more than 1 gun to the range with me. Some may disagree with this practice but I was interested in what it did with a cool bbl. This cartridge is way overbore and it eats bbls. at best so I babied it and it satisfied me until it got the sore throat, I set the bbl. back and rechambered but it did no good, still about 1 1/2-2 in. groups. The bbl is a Douglas air guage.
  I did have the same problem with hard to chamber rounds, had to pull bullets and work on the brass, it grows rapidly, thick necks and length. This cartridge loads needs to be worked up carefully and slowly, like CW said the other day, just because the manual recommends a load it may be too hot for your rifle. Go slowly, my rifle never shot anything but 120's to my satisfaction.
  One more thing, if you don't have at least a 26" bbl. then with light bullets, you really only have a hot 270win.Might be something to consider.      I know that I have.
  I hope this may be of some help to you.
  HM

[Dirtysteve]

Sorry it's taken so long to get back with this info.
MGM was good to work with. They did and accuracy test and checked the chamber. Everything looked good.
They supplied me with 2 targets and load data for each that was right around an inch.
They only charged me shipping because they were longer than expected.
Here is the targets they sent me

Well I was still unhappy. $400 for a barrel that doesn't even shoot as good as my factory barrels is very dissapointing.
I decided to take there load data and start working on some more loads to see what I could come up with.
After several frustrating attempts I was ready to cut my losses and sale.
I sat down last night and loaded up one more batch of different loads to give it one more try.
Today was my lucky day.
140 gr Partition
62 grs Retumbo
CCI 250
COAL 3.260
Produced the reuslts I have been looking for
This was the best one of the buch

This has been my first custom barrel and the most frusrtating barrel I have ever had to find a load for.
I am very happy with it now but I think in the future I will just stick to factory barrels.
 
 

[sirsloop]

I have a .204 18" full bull MGM barrel.  I neck size only and have zero issues with shutting or extracting.  It also groups sub MOA, and I think it's still more accurate than me.