MP 512M Barrel ID

[fnash]

Just received my MP 512M and noticed that the barrel ID is large in that the pellets  just fall in and sometimes go below the opening edge.  If the skirt of the pellet swells out and seals it is ok, but do they swell out that much?  I also took a pellet and pushed it through the barrel with a cleaning rod and notice that there were loose spots along the way. Tight, loose, tight, loose so to speak.. I was using RWS pellets and they are fairly large on the skirt.. Maybe a pellet with a large skirt would shoot better in this rifle.. but which pellet has the largest skirt?  Any help on this?  It shoot pretty good but it is harsh.. It only shoot in the 500's but is still hard to keep the scope in place. I will have to get a mount with a stop screw. There are two indents on the rail for that  purpose.  It is pretty powerful for it's weight, 7 pounds. Seems like a toy compared to my heavier rifles but sure has a punch... FN

[Gene_SC]

Frank, did you try another brand of pellet. Maybe you got a bad lot of pellets. Generally the RWS Superdomes fit snug in all my air rifles. The pellet really should not fall past the breach hole. And the pellet should have some uniform resistance from one end of barrel to the other. Only exception would be a barrel that was choked.

Gene

[fnash]

I will try the Superdomes right now. I don't know which one i used. I will try each of them. Back later...Fn

[fnash]

Tried all my RWS pellets, the Beeman Ram Jet and Gamo Hunter. The all go through about the same. The pellet will fall a little better than a sixteenth beyond the breach hole. When I push it with a cleaning rod it is snug at first when pushing from the breach end. Will be almost free ( can feel a slight drag) until it gets to the muzzle where if feels like it is choked down some.. I have not tried this with my other guns as they do not have the loose pellet fit.... FN

[howie1a]

Hi I got a mp 512m too mine was a little harsh till I did a tune it is an easy rifle to take apart it didn't need a compresser to take it down just cleaning the power plant and polishing the trigger sear helps a lot I've kep mine with iron sights and I had to put a spacer in the barrel pivot it was loose and was not able to get tight enough I used a pellet can top it was a good fit that helped a lot I only have the daisy wadcutters I don't mind wadcutters but daisy pellets are not made very good lots of bent skirts but at 10yds with iron sights i am able to keep 5 pellets in a 3/4" bull not tight some touching but it's not easy seeing the bull good at that distance, my eyes are not \as good as when I was younger. I just turned 70 last week and I still scuba dive. I built a new wood stock for the 512 it added some stability to the rifle about 1 lb. more in weight but I think it's the solid feel that you get with wood over plastic.It's a nice fun gun to shoot and a keeper. I hope you like yours as much as  I like my mp512m it just feels right.

[fnash]

Hi Howie. You did not mention if the barrel ID was a bit larger than most other rifles. The pellets in mine fit a bit loose near the end of the breach, but pushed just a little they tighten and then the muzzle feels a bit choked... Which is alright too..  I have not taken mine apart but looks like by removing the pin the trigger and all come right out. My trigger seems to be fine, just that the trigger blade itself is not rounded and the square edges seems sharp after shooting awhile.  Am I right on that in that the trigger comes out along with the end piece??  I would like to have a look see of the cylinder and what is inside, maybe hone it a bit... and tar the spring... can you advise on that some,,, thanks....FN

[Big_Bill]

Hello Frank,

If you intend on going into your springer air rifle, I would strongly recommend using a spring compressor, it may not seem necessary at this time, but the eyes you save may be your own. Even though you may not feel the need for one, a loose spring can be very painful and dangerous !

I don't want our family members hurt !

Bill

[fnash]

Thanks for the warning Bill, and it is wise to use a compressor... I do have one and use it on any rifle I work on.. I would not take that chance.. Besides if you don't get hurt, things will fly all over the place and will never be found, won't even know what the heck the part was....... Thanks Again.... FN

[howie1a]

I have a spring compresser but when takeing it apart I found the spring pressure was not very hard, the instructions that came with the rifle didn't say antthin about needing a compresser, also when puching a pellet throught the barrel it had some choke at the end as it should. the sear can be removed by slipping the pin that holds out enought to get the sear out without takeing the hole trigger asse. appart. you will need a rag to put oner the trigger unit then takeing the power plant appare if you look at the assembley you will see thet after removing the pin at the end of the popwer plant the trigger unit needs to be turned to releace the sprin not much and the spring is not under a lot of pressure a rag will help keeping your hand from hurting when appling pressure. you can use a spring compresser if you want to but I don't thing in this rifle it is needed.

[fnash]

Hi Howie, being as you said it was so easy I took my  512 apart today to tune it. I think I found out why it was so harsh. The piston just fell out as the seal was undersize to the piston. It has been slamming. I could not figure why a low power rifle would almost knock the scope off the rifle.  The seal measured .975" and the piston measures .978". I could see an imprint of the bottom of the cylinder in the seal. Now I have to find a seal. Wanted to send Jim Maccari an email today to see if he can help me but seems his web site is shut down today, maybe for the weekend.... The seal looks just like a synthetic B3 seal but the mushroom it fits over is smaller.  Has  to fit a .648" top with a .50" groove. And another thing I think a B3 spring would work also. Just a little longer to give it some needed extra push...  FN

[howie1a]

Hi do ypu think you could put something in side the seal befor putting it back in the gun to make it tighter maybe a washer, ect.? something to stretch it out.

[fnash]

Good idea,, I will give that a try.. just finished making a shim as you did out of a pellet tin for the barrel pivot.. Maybe I can heat it in some hot water to make it easier to stretch... Will try to cook something up... Thanks Howie..... FN

[fnash]

Contacted  eaacorp@eaacorp.com     about  the seal, no response yet. They have a parts list with prices, shows breakdown of rifle which would be very helpful.. FN

[dank]

If you can find some heat shrink it might do the trick otherwise I've used Teflon plumbers tape and wraped the end of the piston before installing the seal. We are talking about 3/100ths right?

P.S. My 512 is coming today!

[fnash]

Yes 3/100th..  I have ordered new seal but not arrived as yet. It does shoot in the 500's as is, so am thinking a seal that fits should make a difference..  If yours seem to slam and jolt you may have the same problem. Mine would push the scope off the dovetail.. As stated above.... Sure hope you don't have the problem... I have polished everything while waiting for the seal.  Unlike a Chinese spring the ends are not flattened, so had to do that and polish. Also no guide on the rear of the spring ...   They do have a nice long guide on the front, steel... It is simple to take apart. You have to turn the trigger assembly slightly counter clockwise after removing the rear pin as it has  a notch where a small pin holds everything in place..  When putting back together you have to wiggle the trigger up and down to allow the pin to go in, otherwise it binds up and if you force it you will break or bend the trigger...  FN