Cast 308win too much jamb?

[oley55]

First time putzing with cast boolits for a bottle neck cartridge and am on the lower edge of the learning curve.

Mold is a Lee LH 312-160 GC mold that LEE recently had on closeout for $15 so I bought it just to play with and learn. So I don't need to be jumping through any elaborate hoops to make it work. It's only near purpose in life will be paper punching at 100/200 yards.

The rifle is a Savage 110 in 308 WIN with a Criterion 1:10, 24" SS barrel. Pound cast of throat/barrel MICed at: throat- .31045", lands- .3082".

PC'd and sized boolits with an NOE B310 sizer bushing MIC at .3106" on the GC. The drive band above the GC is .3101" (.0004" GC spring back??)

COAL to just touching the lands is 2.595". At this length the GC is below the neck and crimp/lube groove is inside the neck. Seated to 2.665" even with the first groove and the GC mostly/nearly even with the bottom of the neck is giving me a jamb of .070".

The bolt closes with out anymore than normal resistance. Is a jamb of .070" too much?

Test loads will be with either Unique or IMR4227 (only powders on hand that I can find data for). Any recommendations for one of these over the other?

The first pic shows the seated lengths side by side with bullet lying beside where GC would be just barely inside the neck. The second pic shows the pound cast slug and the jamb loaded bullet. The red dot is just to help identify the location of the jambed land groove.

[ShooterAZ]

It looks only slightly engraved to me, my opinion is that you should be fine.

[RickinTN]

Try both powders as they are both winners. Mid range charges for both. The bullet is a little long for your rifles' throat but probably will work. Give it a try and see what happens.
Rick

[Mk42gunner]

Well you are PC so you don't have to worry about lube contaminating the powder, so I would try both ways.

Did you anneal the gas checks? That can help with springback when sizing.

Robert

[oley55]

If the above seems ok, what if I went a wee bit longer so I can be sure hot gases don't get around the gas check in the neck? The pic is seating at the second ring/lube groove with a 2.717" COAL making it a .122" jamb. The land engraving doesn't seem to be much more. Bolt cycling was still easy and COAL did not change upon extraction.

Guess I was/am concerned an overly jambed boolit would overly elevate chamber pressure. The dummy part of my brain says jambing lead boolits is less of a concern than jambing jacketed boolits, but my dummy thoughts can always use a little confirmation.

No, I did not anneal the checks, but I wouldn't think .0004" spring back of the checks could be an issue other than a chance for the check to scrap out a little residue. Do folks normally anneal gas checks?

[Larry Gibson]

Your putting a 31 caliber bullet design into a 30 caliber bore. Thus the nose before the PC id probably .302 - .303 +/- instead of the .300 diameter +/- the nose needs to be to slip into the bore with a tight slip fit without "jamming". In that weight range the Lee C309-160-1R, the RCBS 308-165-SIL or the NOE 310-165-FN would have been better choices for future consideration. Your bullet "jamming" as such would be okay on the shooting range but not for general field use.

If you have to extract a loaded cartridge the bullet may very well stick [especially when the throat is fouled after numerous shots] in the throat with the case extracted spilling the powder in the action. That's not good. You got what you got though so might as well give it a try on the range.

[oley55]

Larry,

unfortunately I have recycled those I didn't PC, but I do have a few pure lead bullets I had cast for slugging and such. The nose in the area where I would be bumping the lands measures .3025". I'd say that falls nicely between your predicted .302-.303". Surprising in that my COWW alloy as cast were .311 while these pure lead are only .308" which seems odd, but that a whole different topic.

I think I'll go with my first light jambs and see how it goes. I for one (at the range or in the field) do not relish the idea of cleaning dumped powder out of my action.

edit: if or when I decide to invest in a better mold I like the profile of the NOE 309-172-FN. https://noebulletmolds.com/site/shop/308-311/309-172-fn-aq4/309-172-fn-aq4-2-cavity-gc-elco/

[charlie b]

First, I do not hunt, only paper targets. I have a Savage rifle with stock barrel (12BVSS) and 1/10 twist. My bullets are PC and gas checked. They are fit to jam into the lands quite a bit, ie, it takes a bit of force to get them to chamber. I have had to remove a couple without firing. One left the bullet in the bore, the other did not. I am careful to raise the muzzle up when opening the action so the powder does not spill into the action.

My two favorite bullets are the XCB (NOE 310-165) and the 210gn Eagan (Acc 31-210E). The XCB is seated well into the case, much like your photos. They still shoot very well. The 210gn are bore riders and are nose sized to fit (.302"). Their bases are still just below the case neck. Bodies are sized with .309 die (the GC springs back to .310).

I usually load 1800-2000fps (4198 or 3031). When I have done things right I get close to MOA out to 300yd.

So, yes, jamming them a bit is OK as long as you are aware that removing a loaded cartridge from the chamber is not a simple task.

[LenH]

I have been fooling around with a NOE 310-167-FN-AK3, it is a lot better than a NOE 310 -199 SP bullet that one was too heavy and my rifle is a Remington 700 in .308 with a 1-12 twist.
That 199 gr bullet was too long and it would jamb the bullet into the lands and had at least 4 or 5 leave the bullet in the barrel and dump powder all over the place.

Since the 199 sisn't shoot so well I got the 167 and things have picked up. My best group was with 17.5 gr of 2400. I started testing with RL-7 but am still testing that powder.
I would have to look it up but most of the loads with Unique were cat sneeze loads. They were fairly accurate and I could shoot those all day long.

I haven't tried 4227, can't find it and quit looking.

[Larry Gibson]

Larry,

unfortunately I have recycled those I didn't PC, but I do have a few pure lead bullets I had cast for slugging and such. The nose in the area where I would be bumping the lands measures .3025". I'd say that falls nicely between your predicted .302-.303". Surprising in that my COWW alloy as cast were .311 while these pure lead are only .308" which seems odd, but that a whole different topic.

I think I'll go with my first light jambs and see how it goes. I for one (at the range or in the field) do not relish the idea of cleaning dumped powder out of my action.

edit: if or when I decide to invest in a better mold I like the profile of the NOE 309-172-FN. https://noebulletmolds.com/site/shop/308-311/309-172-fn-aq4/309-172-fn-aq4-2-cavity-gc-elco/

You might try an alloy of COWW + 2% tin, then mix that with lead at 50/50. Water Quench the bullets right out of the mould. That will harden the bullets so they can be used at 1800 - 2000 fps. w/o any problems associated with too soft an alloy at those velocities. You will get a smaller diameter nose that may slip fit into the bore. I would GC and use a lube in lieu of PC. If you PC it will increase the diameter of the nose. Only way to find out is to try it both ways.

[oley55]

Larry,

for grins a couple weeks ago I tried heat treating some 2% and 50/50 at 450 for an hour then dropped into ice water. Via pencil I went from 11-12 bhn to 13 bhn. I had flat filed four sides before heat treating so I can continue to check them for up to a month.

Without further testing I wonder if quenching 50/50 is worth the effort, or I didn't do something right.

As for lube vs PC, this Lee mold only seems to be suitable for tumble lubing.

[Forrest r]

Using the same bullet (lee 160gr tl design) that has been pc'd and shot in a 308w. 10-shot group @ 100yds
https://i.imgur.com/PWiZFog.jpg

I load those bullets long enough so they "jamb" into the lands the same as you are doing. Doesn't matter if they're pc'd or as cast. I simply change to a longer oal for the as cast bullets. I do the same thing with the XCB (NOE 310-165) bullet. The lee or the xcb are not bore riding bullets so I load both of them long enough to extend into the rifling leaving marks on the bullet like what the op posted.

I never had any issues ejecting a live round with these bullets that have need jambed into the lands. Perhaps I use a little more neck tension on the bullets then others use? I use rcbs dies with the standard jacketed bullet (.308") reloading expander when full length sizing and then use a lee universal expander to open the case mouth up to accept a (.310") cast bullet.

That lee bullet is actually a pretty impressive design that holds it's own at lower velocities accuracy wise. They can be pushed pretty hard and still hold +/- 2" groups @ 100yds/10-shot groups. My plinking/blammo ammo load with this lee bullet holds 2" @ 100yds doing 2600fps+.

[Larry Gibson]

Larry,

for grins a couple weeks ago I tried heat treating some 2% and 50/50 at 450 for an hour then dropped into ice water. Via pencil I went from 11-12 bhn to 13 bhn. I had flat filed four sides before heat treating so I can continue to check them for up to a month.

Without further testing I wonder if quenching 50/50 is worth the effort, or I didn't do something right.

As for lube vs PC, this Lee mold only seems to be suitable for tumble lubing.

Well it does take some time for the alloy to reach max hardness. My COWW +2% and 50/50'd usually hits 15 BHN +/- after 10 - 14 days. That is the equal of Lyman #2 BHN and thus is sufficient for most all cast bullet shooting. The objective was to get a smaller diameter bullet, especially on the nose. With that alloy the higher lead content will give a bit more shrinkage. The nose should be in the .300 to .301 +/- range and should not then "jamb" as much into the leade/rifling. What is the bullet nose diameter with that alloy after at least 48 hours since cast?

[waksupi]

The problem with too much engagement,is if you eject the cartridge, the bullet is likely to stay in the bore. Better to have a good throat fit.