I purchased a Mossberg atr 100 in .308 about 6 months ago, and i have some information about the rifle. The atr 100 cost about $325 at my local gun shop. My first impression was fairly good, the stock came in walnut and the finish was satin but no chips or marks on the wood. I ordered a .308 with a wood stock because bedding compound sticks to wood better then plastic. The trigger was very rough out of the box and the pull felt like it was in the 8 pound range. Bolt operation was smooth except for the fact that sometimes the magazine follower would stick up and forward causing the bolt to get stuck about half way forward during closure, with no round in the magazine. This was fixed with a light sanding on the front outside portion of the plastic magazine follower. The end of the barrel was crowned and i had a feeling that accuracy should be decent. Overall i was pleased with my purchase.

At the 100 yard range i bore sighted the rifle and began to put holes in the paper. My groups were not that hot, They averaged 2-3 inches with 168 gr federal match, and even more with Winchester white box and Remington green box. My groups began to move in horizontal stings of 4-5 inches, this was due to the scope mounts getting loose. Something was wrong so i went online and proceeded to do the following things;
1- filed, sanded, then polished the trigger sear to bolt sear connection. I reduced the pull to about 5 pounds with a light coat of grease on the sear.
2- dremeled the bottom of the scope mounts and the top of the receiver. I then epoxied the two together and used Lock-tite on the screws. Horizontal spread dissapated!
3- purchased a better scope. 10X40mm Super Sniper, carried by SWFA.com. Very nice glass etched reticle.
4- puchased 30mm scope mounts by leupold, and blue lock-tited the threads.
5- polished the bore and barrel with wenol metal polish from Germany.
6- loaded some match ammo. 168 gr sierra matchkings, 44.4 grains of varget powder, and federal match primers, in match cases and softseated the rounds in the chamber. This rifle likes softseating.
7- Roughed up the inside of the wood stock with my dremel and bedded the receiver with brownells bedding compound.
8- free-floated the barrel with about a ¼ inch of space between the wood and the bottom of the barrel, just to be safe.
After I did these upgrades, I went to the range to punch some more paper. I was delighted with my results, under 1 moa , or 1 inch at 100 yards, with match ammo. Factory federal match was consistently 1 inch vertical and ½ inch horizontal, Probably due to the fact that they scoop their powder loads and not weigh it. Hornady TAP match was averaging about ¾ of an inch, Winchester and Remington match were at about 1 inch.
I even tried some Russian made “brown bear” ammo and this stuff was terrible, the group opened up to over 6 inches. My 175 gr. Sierra match-kings loaded with 43 grains of Varget powder shot the best at ½ inch vertical and ½ horizontal. One 3 shot group was even touching. It seems that the 1 to 10” barrel twist likes the heavier 175 gr. bullet.
The only thing that is holding this rifle back is the trigger, no matter how smooth I polish that sear I can watch the crosshairs move as I pull the trigger. If there was some way to lighten the springs this rifle could shoot better then me. All in all this is a great rifle, if you do the above mods.

Welcome to the forum mradventure. Rules are simple, be nice and join in. Please don't double post.

Got a friend whom just bought one in 270 last fall. Their selling at Wally world today for $249.99. I don't know what scope he put on his, he got it at the last gunshow for sixty bucks, but it shoots good and the gun seems to be a bargian at todays dollar.

I went thru the same trigger antics, actually cut back the sear edge. I didn't do anything to the springs, but did polish everything inside after taking it apart. We ended up with around a 3.5 trigger or perhaps just a shade lighter.

The best group we got was just over two inches edge of hole to edge of hole, but he was using some old handloads probably 20 years old. This rifle has the composite stock so we didn't do any bedding on it.

He doesn't hunt much anymore and this is minute of deer for him so it'll probably stay the way it is. He's putting together some new handloads with it, but I think about all he shoots is the 139 grain loads.

Must be Mossberg quit making adjustable triggers? I've found changing the trigger sear angle works wonders for triggers. If the trigger spring is 5lbs you'll not get it below that. Remove the trigger spring and check it for length if it is longer than the space it is in, very carefully remove a coil or two to decrease the springs preload. Some are quite thick and stiff, with this a good old fashioned ball point pen spring resized to the right lenght gives a better trigger. Aftermarket triggers are also a good deal.

Loading for a .308, try sierra 150gn spitzers and IMR4064, when I was in the benchrest fun arena a friend Fred Heimler from Cedar Springs shot them in matches and came home with baubles most every week. I know the match bullets are great, but any .308 shooter owes it to theirselves to try the 150 sierras and 4064. I've tried it in many .308s of every action style and get top groups from this combo.

Hello all
Sorry about posting twice i dont know how this website works yet.
About slanting the trigger, do you think that it would slam fire? What are your thoughts? I am trying to take the trigger assembly apart, because i found 2 springs inside that look really thick and have a hard compression to them. The whole trigger assembly has a kind of compression pin that doesn't look removable. So I might damage the assembly if I attempt to take it apart. I was thinking of replacing the springs but i don't want to run into any safety issues. Any thoughts?