Gunsmithing m700 / dbm feeding issue

[beretta_man11]

I've got a feeding issue in my 700sa in 243win.
The stock is a greybull precision (made by B&C), seekins dbm, magpul 700 5rd mag.

When everything is bolted together, the round's rim sits too low and the bolt won't catch it, but the tip of the bullet looks to be very high. Is the remedy to mill off some of the rear aluminuim pillar, or could it be a mag issue? (also, the rear portion of the dbm sits proud in the stock by roughly 1/8" or so)

 

[Iamero]

If the bolt is barely missing the round, then the easy attempt at a solution is to open up the feed lips on your magazine so that the rear of the round sits a little higher in the mag (they can be bent back down into place if this doesn't solve your issue). Open them up just enough to where the lips still hold the rounds in the magazine, but let them sit a little higher up in your action.

If this doesn't work then yea, you'll want to get the bottom metal to sit a little farther up in your stock.

 

[JMGlasgow]

Try a different magazine like an AICS 10 round. In my experience and others I shoot with, the Magpul mags don't feed well. If it still does the same thing, then the rear of the bottom metal probably needs to be brought up.

 

[308pirate]

Not a mag issue. Magpuls feed flawlessly in my rifle (Howa/KRG chassis)

 

[sobrbiker883]

Is the B&C properly inletted for the Seekins DBM?

 

[beretta_man11]

Is the B&C properly inletted for the Seekins DBM?

I don't believe so. It fits well into the stock, but I think the rear pillar may need to be milled down a fuzz to get the mag seated a little deeper.

 

[jducos]

Find out what the proper height of the rear pillar needs to be for a seeking dbm. Compare that measurement with yours. That will tell you if your inlet depth is correct and you can go from there

 

[LongRifles Inc.]

Step one. Remove bolt
Two: Insert your magazine with a round loaded.
3: Look down the arse end of your receiver. If you cannot see the edge of the primer pocket invading the receiver bore then you need more case overlap. This is why it runs like poo.

Couple ways to resolve this. You could molest the feed lips and it might help you some. The range to work in here is quite small. The edges of the lips need to be just under the tangent point(s) of the case body, otherwise they get grabby. You'll feel it immediately when running the bolt. You want flats on the case, not the edges.

Another way is to go black smith and sink the DBM into the stock more. Not the easiest thing to do at home and they have a habit of looking like total crap because now everything is sunk in the stock.

Yet another is to remove the release lever and modify it. If your a ninja with a TIG welder you can add a zip of material and shape it on a belt sander. -I've done this. Another way is to turn a pin from mild steel and press fit it into the release lever hole. Then relocate the hole lower so that it raises the lever further into the magazine well. I have done this as well. You can't go very far with this as the louver feature on the back of the mag hangs up where the clearance slot is on the back of the mag well at some point. That and the mag box lid hits the bottom of the DBM also. There is a narrow range where this does work however. Done it more than once for folks.

The key here is getting the case to present properly to the bolt face. The primer pocket/receiver bore should form an upside down figure "8" when its correct. You do get a narrow margin of error. Too low and your back to square one. Too high and feed lips start dragging on the bolt body. That'll really feel like crap if the bolt is fluted.

Hope this helps.

C.

 

[Dai Bando]

Step one. Remove bolt
Two: Insert your magazine with a round loaded.
3: Look down the arse end of your receiver. If you cannot see the edge of the primer pocket invading the receiver bore then you need more case overlap. This is why it runs like poo.

Couple ways to resolve this. You could molest the feed lips and it might help you some. The range to work in here is quite small. The edges of the lips need to be just under the tangent point(s) of the case body, otherwise they get grabby. You'll feel it immediately when running the bolt. You want flats on the case, not the edges.

Another way is to go black smith and sink the DBM into the stock more. Not the easiest thing to do at home and they have a habit of looking like total crap because now everything is sunk in the stock.

Yet another is to remove the release lever and modify it. If your a ninja with a TIG welder you can add a zip of material and shape it on a belt sander. -I've done this. Another way is to turn a pin from mild steel and press fit it into the release lever hole. Then relocate the hole lower so that it raises the lever further into the magazine well. I have done this as well. You can't go very far with this as the louver feature on the back of the mag hangs up where the clearance slot is on the back of the mag well at some point. That and the mag box lid hits the bottom of the DBM also. There is a narrow range where this does work however. Done it more than once for folks.

The key here is getting the case to present properly to the bolt face. The primer pocket/receiver bore should form an upside down figure "8" when its correct. You do get a narrow margin of error. Too low and your back to square one. Too high and feed lips start dragging on the bolt body. That'll really feel like crap if the bolt is fluted.

Hope this helps.

C.

Good info here. Thanks Chad.

 

[beretta_man11]

Thanks Chad.

 

[eklarsen]

Is "runs like poo" a technical term?