I'm sure this has been covered but can someone tell me what the mag box length is on the Kimber Montana .223's?


X-VERMINATOR

if no one chimes in, i will measure mine tonight for you.

it looks like the mag box can be lengthened like we do with the M700 .223s, but the bolt stop and ejector may also need modded, and that may be a problem. i don't know.

Thank you! Hopefully the folks at Kimber were smart enough to allow the 1-9" barrel to be fed properly....


X-VERMINATOR

well, not really.

with the 75 grain Amax seated to kiss the lands, i wind up with 2.43" COAL.

mag box is 2.40"

and the 2.43" unfired cartridge will not eject properly.

so the fix would be to lengthen the mag box (easy), shorten the ejector (easy), and modify the bolt stop so the bolt will travel another .1" or so to the rear. the bolt stop mod is the only question mark here. it may be as easy as filing .1" from the stop, but i haven't really looked at this yet.

plan B is to just seat the Amax bullets to fit the mag box and carry on. if accuracy is there, i may just do that.

plan C is to order a Lilja 1-8" barrel and a .223 AI reamer cut to work with mag box length loads.

it all boils down to if the bolt stop can be modded. i won't guess, as i haven't taken mine out and really looked at it yet. the bolt stop from a .308 Montana may already be modified for the extra travel.

That figures...I could live with the 2.4" magbox. It would handle VLD's best suited for the 9" twist. However as you stated the throat will need to be cut properly. Not being able to reach the lands usually means bad news for VLD's.

Thanks for the help..very much appreciated. It would be interesting to have some of the other Montana/.223 owners chime in to see if all Montana throats are cut the same..........Anybody?

X-VERMINATOR

xverminator,

All of the Kimber chambers are to SSAMI specs. It is a one piece reamer which means the chamber and throat are cut at the same time.

Headache

So your saying every factory chambered .223 (Rem., Win., Kimber, Ruger, Cooper, etc.) has the same throat length because they are chambered to SAAMI specs................I think not!


X-VERMINATOR

I think the man said that all "Kimber" rifles are cut that way.

Usually you can't reach the lands because the COAL latitude of the magazine won't allow as often with VLD bullets a lot of the extra length is ahead of the ogave,
The solution isn't a throat cut but modifying the magazine to allow for a longer COAL. You would need a shorter than SAAMI spec throat otherwise.

I think you misunderstood what I was asking. I surely could have worded it better.....See below.



X-VERMINATOR

FVA, I understand perfectly what the issues with VLD's and short mags are. With past builds I have done both, lengthen the mag and/or cut the lead to accomodate. Again, appearently I worded things wrong.

Let me try to clarify by starting over with a question..................................... Can someone tell me what the lead length is on a .223 remington "Sammy" spec reamer?



X-VERMINATOR

xverminator,

The lead (free bore) length for the 223 Remington is .025+.015" (this can vary due to tolerence stack-up) with a lead (free bore) diameter of .224+.002" then you reach the basic angle of 3 degrees 10 minutes and 36 second.

The greates contributor to bullet jump is the diameter of the lead (free bore) in conjunction with the forcing cone angle (ball seat). As the lead diameter increases the shallow angle moves outward with it creating a much longer bullet jump.

Most, if not all production firearms are made to SAAMI specification for liability reasons.

Headache

That was my point exactly.....throat length varies! Both between rifle makers and even within the same factory. That unless Kimber chambers every rifle with the same reamer. I would agree with you that lead length on most "Sammy" spec reamers runs very close to .025". However, Kimber advertises there chambers as "match" and to me that typically means a longer lead of around .065"....Much closer to a "Sammy" 5.56 chamber.

The only thing I was wondering in reguards to the Kimbers was wether or not the throat length is consistant from production run to production run.......I'm sure there are more than a few samples owned by folks here. It was a simple request for a few individuals who own Lil' Skies to chime in about C.O.A.L in their rifles..........that's all.


X-VERMINATOR

The chambering reamer creates the complete chamber all in one. The chambers created by that reamer will produce consistent chambers for the life of the reamer. When the reamer is replaced you may see a slight difference, but it will be very little as the reamer manufacturers hold the dimensions very tight.

A match grade chamber is held very close to the minimum chamber dimensions of that specific caliber, so you should not see a lead of .065" for the 223 Rem. The tolerence on chamber diameters are Min +.002 so there is very little to play with in that area. The headspace is the primary area to control. Most of the rimless cases have a headspace tolerence of min +.010". Most manufacurers hold min +.007/.008". Match chambers have min +.004". Kimbers meet this spec.

Headache