Gunsmithing Defiance LA dbm pillar length

[Tbaxl]

I recently purchased a defiance long action dbm for hunting because of the recessed mag release. However, I am going to pillar bed my stock now and when I asked surgeon about the correct pillar length they told me they did not know. So if any one here has installed pillars for a defiance long action dbm, what lengths did you cut your pillars too? thanks.

 

[pabrousseau]

pillars would need to be the proper length for whatever stock you are using with the receiver and bottom metal at the proper depth in the stock.

 

[Tbaxl]

pillars would need to be the proper length for whatever stock you are using with the receiver and bottom metal at the proper depth in the stock.

Ok, well I’m making the stock out of black walnut myself. So I’m kinda flying by the seat of my pants here. Typically yes, I would base it off the stock, however I basically have the ability to set everything at whatever depth I want (within reason). So my question is if defiance spec’d a particular pillar length because I can find one anywhere.

 

[pabrousseau]

there are better qualified on here than me for this I am sure. you could assemble the receiver and bottom metal with magazine box with your receiver screws making sure action functions properly and measure pillar length . or finish stock inletting for your receiver and bottom metal and then measure pillar length just as you would if you were pillar glass bedding an existing rifle. I hope this helps. what cartridge will you chamber for?

 

[spife7980]

@Defiance Machine

So my question is if defiance spec’d a particular pillar length because I can find one anywhere.

 

[Tbaxl]

@Defiance Machine

I called them already and was told they do not have a recommended pillar length

 

[Tbaxl]

there are better qualified on here than me for this I am sure. you could assemble the receiver and bottom metal with magazine box with your receiver screws making sure action functions properly and measure pillar length . or finish stock inletting for your receiver and bottom metal and then measure pillar length just as you would if you were pillar glass bedding an existing rifle. I hope this helps. what cartridge will you chamber for?

It’s for a 280 AI. And I have the stock inserted for the action already, I’m going to install pillars that over length and trim them down with a mill as I inlet for the bottom metal. I just don’t what length to finish at.

 

[pabrousseau]

if your receiver is placed properly pillar length will be correct when the bottom metal seats at desired depth to suit you and the action functions as intended. this will be trial and error.

 

[Defiance Machine]

Email our sales team, [email protected], as they'll have a couple questions to ask you first.

 

[LRI]

The "proper" length for ANY DBM installation is where the magazine of choice presents the cartridge so that the primer pocket (large rifle) lies tangent to the lower portion of the receiver bore. -This is relevant to staggered stack, center feed, or center stack, center feed.

Staggered stack, staggered feeds like the AW's don't play by quite the same rules.

On most DBM's this puts the pillar length at around 1.075 for the rear and .725 up front. That's a ballpark number relevant to most DBM's made today. Not everyone makes stuff the same way. The whole system has to be gamed out. If you pile the bedding compound on and "float" the receiver over showline and don't compress the pillar, then the whole thing is a wash and the pillar has to be shortened.

Some tips:

Link to LRI DBM with general install notes


It's never a bad idea to trim and mock the assembly up out of the stock. If it feeds "on the bench" it should feed once its all clam'd together. Pay attention to the rear portion of the magazine mortise in the receiver. The little peninsula like feature between the Mickey Mouse ears is notorious for hanging up on the back of the magazine (preventing complete engagement).

The fix in that situation is to whittle the receiver so there's enough clearance.

Hope this helps.

C.

 

[Tbaxl]

The "proper" length for ANY DBM installation is where the magazine of choice presents the cartridge so that the primer pocket (large rifle) lies tangent to the lower portion of the receiver bore. -This is relevant to staggered stack, center feed, or center stack, center feed.

Staggered stack, staggered feeds like the AW's don't play by quite the same rules.

On most DBM's this puts the pillar length at around 1.075 for the rear and .725 up front. That's a ballpark number relevant to most DBM's made today. Not everyone makes stuff the same way. The whole system has to be gamed out. If you pile the bedding compound on and "float" the receiver over showline and don't compress the pillar, then the whole thing is a wash and the pillar has to be shortened.

Some tips:

Link to LRI DBM with general install notes


It's never a bad idea to trim and mock the assembly up out of the stock. If it feeds "on the bench" it should feed once its all clam'd together. Pay attention to the rear portion of the magazine mortise in the receiver. The little peninsula like feature between the Mickey Mouse ears is notorious for hanging up on the back of the magazine (preventing complete engagement).

The fix in that situation is to whittle the receiver so there's enough clearance.

Hope this helps.

C.

I appreciate the reply, the info about wanting the primer tangent with the lower portion of the receiver bore helps a lot. And yea, I cut a few pieces of wood and drilled holes and have using those for mock up and adjusting the lengths as need be. Also you’ll have a bolt coming your way in a few weeks for this rifle as well.

 

[Tbaxl]

I actually called your office today and after speaking with someone I assume was from the sales team I was told

Email our sales team, [email protected], as they'll have a couple questions to ask you first.

that you did not recommend a specific pillar length. However LRI’s reply cleared things up for me and I already have corrected.

 

[Terry Cross]

Every maker of a DBM will have an exact pillar length specified.
Most makers of DBMs include pillars already cut to length because of this.
All brands are not the same spec for pillar length.
Ball parking it is not a good idea.

Whether you use any pillars or not, the Z-axis distance between DBM hardware and the bottom of the receiver has to hit the dimension the maker specifies.

I believe half of the threads in this forum that ask for help with magazine feeding issues or binding is because the DBMs are not installed correctly in relation to the receiver.

Talk to the right person at Defiance and you should get your numbers.

./

 

[Tbaxl]

Every maker of a DBM will have an exact pillar length specified.
Most makers of DBMs include pillars already cut to length because of this.
All brands are not the same spec for pillar length.
Ball parking it is not a good idea.

Whether you use any pillars or not, the Z-axis distance between DBM hardware and the bottom of the receiver has to hit the dimension the maker specifies.

I believe half of the threads in this forum that ask for help with magazine feeding issues or binding is because the DBMs are not installed correctly in relation to the receiver.

Talk to the right person at Defiance and you should get your numbers.

./

That’s the issue, I’ve emailed back and forth and talked twice on the phone with defiance. Each time I have been told they did not ship pillars with the dbm and that they did not have a recommended length. However I use @LongRifles Inc. advice on having the primer tangent to receiver bore and in testing it has fed perfectly. So I hope to get it right with enough trial and error.

 

[LRI]

Every maker of a DBM will have an exact pillar length specified.
Most makers of DBMs include pillars already cut to length because of this.
All brands are not the same spec for pillar length.
Ball parking it is not a good idea.

Whether you use any pillars or not, the Z-axis distance between DBM hardware and the bottom of the receiver has to hit the dimension the maker specifies.

I believe half of the threads in this forum that ask for help with magazine feeding issues or binding is because the DBMs are not installed correctly in relation to the receiver.

Talk to the right person at Defiance and you should get your numbers.

./

If the DBM/barreled action were the only components involved in this assembly then I would agree 100%. They aren't however.

Magazines...

We have a half dozen or so different manufacturer's involved in this game and no two are alike. Then compound the problem with no one actually posting a print to set a standard to reference from. So, it's reverse engineered. Then its reverse engineered again when someone comes along and makes a floor metal for it. Pandora's box...

- With the introduction of our DBM, I've just recently begun to appreciate just how much work this really is if you want it right.

The "rules" set forth by the folks making the hardware only get you so far. It's the package system that ultimately drives the boat and its been my experience that case presentation to the bolt nose is where this gets solved.

C.

 

[Terry Cross]

We provide a print with pillar length and other info in addition to the actual pillars already cut to length. Even the included stock bolts are already to length. If the bottom metal is installed to spec and A.I. magazines are used, the user should not have problems. Pretty simple "rule".

Yes, it is possible for a user to receive a genuine A.I. brand magazine that may be damaged or out of spec but there has to be an datum or benchmark to design the hardware to so I use the original A.I.

Any magazine manufacturer that is not Accuracy International is simply trying to build a copy of an Accuracy International magazine.

Accordingly I use Accuracy International magazines and data to determine the pillar length of bottom metal This seems to be working for me so far as I am selling a butt load of DBM hardware with excellent results from users.

If other brands of magazines wonder away from original OEM dimensions during their attempt to reverse engineer the product then the responsibility for proper function definitely falls back to the builder and owner. If tweaks are then made to accommodate a certain magazine, that DBM hardware becomes married to that non OEM compliant magazine and probably will cease functioning correctly with original A.I. mags.

I totally agree that it is all about the presentation of the cartridge into the path of the bolt cycle. I also totally agree that it is a shit show when you start mixing in multiple magazine manufacturers with different specs trying to chase the A.I. product.

If someone is using hardware without documentation and/or magazines that are clones of the A.I., then most certainly you would have to exit the proven path with your final goal of placing the seated magazine in the correct position for proper function.



./