.308 Chamber

M

morrisammo

Guest
Hello this is my first post to the Benchrest forums.

I have a question that I cannot seem to get the info anyplace.

Let me set this up.
I have shot many types of shooting sports.
3 Gun is the game of choice at this time.

I have a DPMS LR-308, and if you have not heard they have feeding problems.
when the gun shoots and I do my part I can get a good group.
.561 at 200, I don't know how that holds up in your world? But for me that is a good group.

I cannot get a answer on how this barrel is chambered?

308 Win
7.62mm NATO
7.62mm NATO Nat'l. Match
7.62mm/39 (SAAMI)

Does anyone have the exact dimensions for these reamers?
I sure can't find them on the net.

I have worked on my hand loads to get this gun to run, with some success.
The one that runs in the gun dependably is to finish re-size the whole loaded round.
But then the accuracy suffers, and the squeezing of the bullet during this process cannot be good.

A friend of mine is renting a pull through reamer and I'll going to give it a spin in my chamber. and hope for the best.

Does anyone have any ideas?

Thanks

Jim
 
Any semi platform is only as good as it's magazine system,hence the reason plastic isn't used to manufacture links for full rattle battle weapons.

Pulling a reamer into your DPMS 308 chamber is not a wise option,as doing so will increase head space.

The trigger groups in DPMS LR308's require work/replacement to acquire an acceptable trigger.

Spend a couple hundred dollars more & purchase an ArmaLite AR-10.
ArmaLite GenI M14 mags & GenII mags work reliably.
 
not the mags,,,

Dans40X said:
Any semi platform is only as good as it's magazine system,hence the reason plastic isn't used to manufacture links for full rattle battle weapons.

Pulling a reamer into your DPMS 308 chamber is not a wise option,as doing so will increase head space.

The trigger groups in DPMS LR308's require work/replacement to acquire an acceptable trigger.

Spend a couple hundred dollars more & purchase an ArmaLite AR-10.
ArmaLite GenI M14 mags & GenII mags work reliably.
Click to expand...

It's not the Mags,,,
it is the chamber,, I have been loading for 25+ years. I do all of the right things with the brass, even neck trim them. they fall in and out of the chamber gauge.
but they do not always chamber in the gun, and then they get stuck!! in a big way.

I have to pry the bolt carrier back to get the round out,

with the reamer,, I plan on just lightly touching it, as not to change the head space. I will be interested to see how much metal gets cut out of the chamber. At this point I can't hurt it,, the gun runs %50,, if this dosnt work.
I will re-barrel the gun.

Thanks for the input,,, getting any input is hard.

Jim
 
have you considered sending back to the maker ???

i, to, am an ar10 real gun shooter, as in armalite.

mine shoot fine.

have you asked dpms what the chamber is....???

if you put a reamer in the chamber, the maker owes you nothing.

mike in co
 
morrisammo said:
I have worked on my hand loads to get this gun to run, with some success.
The one that runs in the gun dependably is to finish re-size the whole loaded round.
But then the accuracy suffers, and the squeezing of the bullet during this process cannot be good.



Does anyone have any ideas?

Thanks

Jim
Click to expand...

Hi Jim,.

I've got an idea. I think your ammo is too fat near the base to seat completely in your chamber. Does factory ammo work OK?

You say that you can "finish size" and the gun runs but the accurracy suffers. Are you using a FL die to do this "finish sizing"? If so the loss of accurracy is not a surprise. If you are squeezing the bullet to a smaller diameter with this sizing operation the effect on accurracy is worse than an oversize bore.

Various die mfgs. can supply body dies which are a full length die with enough clearance in the neck area to not size the case except on the body and shoulder but not at all on the neck. Also, small base and small base body dies are available for 308 and 223 specifically for semi-auto rifle applications. They squeeze the body of the case above the web to less than SAAMI spec to aid feeding.

I use Redding body and small base body dies to massage my loaded Palma ammo if it doesn't gauge right in my chambers.

Before you change your rifle change your loading setup to work with your specific chamber.

Greg
 
308 chambering

Jim: I know this is a basic question, but I'm going to ask it anyway. Are you using brass that was fired in another chamber? if so, all bets are off, as to if it will chamber in your rifle, especially if it is ex-military. If new factory ammo (as mentioned above) will not chamber, then you have a rifle problem, and if you alter anything, your warranty is null and void. If, on the other hand, factory ammo chambers, then you have an ammunition problem, and the first place I would look is the brass, it's probably oversize in the case head area. As also mentioned above, did you really mean 7.62x39? The correct military designation for the 308 is 7.62x51mm.
 
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all good stuff

Typo cut and paste on the 39,,,,,

I still would like to know the exact dimensions of the different reamers.

I sent the upper back to DPMS once already. It does the same thing,, I did not ask what reamer they are using, I didn't think of that at the time.. I hear you on the warrantee,,, but at this point I don't care about that.
I just want a gun that runs.

Most Factory ammo works in the gun.

So I know it is my loads,, but if they fit easily in a chamber gage. They should feed I and out of the chamber?
At least I would think so. (I have proved myself wrong on that one)

For my precision loads I have some Hornady Match brass. Shooting 155 Nosler Competition bullets. 44.5 of Varget.

For the loads on hosier 3 gun stages I use mixed brass.. and some Rem PSP's

The brass could be a problem. With full finish sizing,,, all of the loads work.

I have Lee dies and Dillon dies. and have been trying many settings. to get the hand loads to work.

I have had more luck with the Lee dies, setting the die touching the shell holder, so that I get as much of the case re-sized as possible. All I did to finish size was pull the capping pin on the Lee die,, the necks went from .4?? to .429,, all of those rounds fire %100,, dependable!! But like I said the accuracy suffered.

It very well could be the base, that is expanded.

One thing I need to do is mark a hand load that will not fit in the gun, with majicmarker all over and chamber it,, and see where it rubs..

if it is the base,,, what do I do next to fix it??

spend more money on dies,, run a reamer in it, or re-barrel it,, and cut my losses?

Jim
 
I just found this....

308 Win (Std. neck .345)
308 Win (.343 neck, short throat)
308 Win Match (short throat 2.825 O.A. neck .342)
308 Palma (155 Gr. Sierra 2.810 O.A. neck .342)
308 Win BR (.336 neck)


But what one does DPMS use??????
 
Jim,

I don't know what DPMS uses for a reamer but they do. Ask them. Get a Redding SB body or SB FL die. Your case gauge obviously is not working with your chamber. Quit depending on it to give you meaningful info. Use your rifle chamber as your gauge, it is exactly the same as itself. If your sized brass doesn't slip in and out of you chamber without drag then your ammo won't either.

BTW, I think .5xx" at 200 yds. is very good.


Greg
 
Greg Culpepper said:
Jim,

I don't know what DPMS uses for a reamer but they do. Ask them. Get a Redding SB body or SB FL die. Your case gauge obviously is not working with your chamber. Quit depending on it to give you meaningful info. Use your rifle chamber as your gauge, it is exactly the same as itself. If your sized brass doesn't slip in and out of you chamber without drag then your ammo won't either.

BTW, I think .5xx" at 200 yds. is very good.


Greg
Click to expand...

I just got off of the Phone with DPMS,, they didn't know exactly what type .308 chamber they cut in the gun. but told me that Pacific tool sells them the reamers.
I e-mailed them asking the same question.
I also just told the DPMS guy, that Yes I'm voiding the warrantee. and don't care about that, (those of us that start gunsmithing can't stop ourselves anyway)
He also told me about the base.. I will have to look into those small base dies.

Thank you this info is a big BIG help!
 
You're simply not resizing enough. The small-base dies will cure your problem.

As an aside, do you need to shoot those 155's? Wouldn't something lighter with less recoil be a competitive advantage, other things being equal?

Greg J.
 
155

SGJennings said:
You're simply not resizing enough. The small-base dies will cure your problem.

As an aside, do you need to shoot those 155's? Wouldn't something lighter with less recoil be a competitive advantage, other things being equal?

Greg J.
Click to expand...

150's are the small ones..:D

for 200 to 500 the 155's fly well. I was able to do head shots on a Larue at 500.. as well,, that makes me happy!

Once I get this to run I'm working up a 175SMK load for the gun. for the longer stuff..

I have a JP tank break on the gun and a carbon fiber hand guard.. Lupy--1.5-5 M/RT scope.. . not bad on the recoil at all.. in my mind I thought it would be a big deal in reality,, not a problem.

I'm ordering the Redding SM """Designed for use with semi-automatic firearms for improved feeding. Shell holder sold separately. """""

I so hope you are correct,,, I'll know in a week when I get the die,,

Thanks for putting up with a 3 Gunner running a rattle trap!

Jim
 
f d shuster said:
. . .The correct military designation for the 308 is 7.62x51mm.
Click to expand...

fd

I'm gonna nit-pick here so don't get upset.

The correct designation is 7.62 MM NATO. There is no "x51" in it.

And, it's not really correct to say that it's the military designation for the 308. The 7.62 MM NATO is one cartridge and the 308 Winchester is another. The specs are not the same.

Nit picking, to be sure. But I collect US Military and like to keep things correct.:)

ray
 
Cheechako said:
fd

I'm gonna nit-pick here so don't get upset.

The correct designation is 7.62 MM NATO. There is no "x51" in it.

And, it's not really correct to say that it's the military designation for the 308. The 7.62 MM NATO is one cartridge and the 308 Winchester is another. The specs are not the same.

Nit picking, to be sure. But I collect US Military and like to keep things correct.:)

ray
Click to expand...

It is all good...

I actually cut and pasted those from a web page from a CO that sells reamers.

These type of re-loading questions are not the run of the mill. (so I have found) and I'm very happy to get your feedback. and experience.

Jim
 
Cartridge designation(s)

Ray: Not nit picking and not upset either, but, page 220 (and others) of Lyman's reloading manual #49, across the top of the page: 308 Winchester (7.62 x 51mm) (7.62 NATO). I was trying to come up with a description as close to the 7.62 x 39 that was used, obviousely in error, and "51mm" fits the bill. Yes, I agree, my last sentence was incorrect, should have stopped when I was ahead--- hate it when I do that. Frank
 
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When you said "3-gun", I thought you'd be interested in shooting the minimum recoiling load that would make major power factor.

See this thread for a round that makes MPF, works in a standard AR and recoils a heck of a lot less than a 308.
Keep in mind that mine is in a bolt gun, not an AR. My load might blow an AR to smithereens.
 
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Jim

Before spending any $$ or running reamers in and out of your chamber, I'd suggest you call Dave Kiff and talk to him about what the chamber might be. He is a very easy-to-talk-to guy and may be able to help solve your problem. It's worth a try, at least.

fd

It's perfectly OK for Lyman to list the 3 different cartridge names. They're not the only ones that do that. They have to cater to their customers and sure don't want anyone to get confused when it comes to loading data.

The 308/7.62 MM NATO/ 7.62x51 is but one example of names that change and become acceptable with common usage. After a while, the origin is lost to history. Even dictionaries are revised every few years.

All is good.:)

Ray
 
I have 3 of DPMS's 308 uppers now and they all shoot good with a little work done to the bore.
i also shoot 3-gun but in Open class.
I use std 308 FL dies.
All I can tell you on the chamber is that the throat is approx +.200" freebore compared to mag OAL.
I read through all the posts and I didn't notice what the exact problem was???
Is the bolt not closing? A feeding problem would be with the mags but you said it's the chamber?
DPMS had a problem with their 10rd mags not having the correct bent feed lips.
It is alway possible that the reamer broke down and caused an undersize body condition or a corner broke down or something.
How about an description of the problem?

Nick
 
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