30-30 is tumbling

Please note the picture of entry holes from Hornady Lever 160 grain ammo. I’m shooting a 1963 Marlin 336 lever. Any suggestion on hand loading heavier or lighter or?

 

It would help to know the specifics of the load that was doing that. Also the twist rate of the barrel.

 

Factory ammo. 160 grFTX 2400 FPS at muzzle. 1:10 twist. 18” barrel

 

Sorry. 20” barrel

 

Hmm, it looks like your gun doesn’t like those at all.



The FTX .30-30 bullet is a polymer-nosed boat tail, I wonder if it is too long for the twist. (It shouldn’t be though.) I’ve loaded the green-tipped “Zombie” FTX bullets using Leverevolution and they haven’t had any issues in my 1970’s era 1894 Win.

Any tumbling with 150 or 170 gr or mono-metal bullets in your 336?

Stay safe.

 

The bullet is obviously not stable out of your rifle... and your rifle isn't out of the ordinary.

Question: Is it a MicroGroove barrel? (it will say on the barrel.)

 

It has been my experience that the marlins do not like the 160 grain FTX bullets. Not sure why could be that it is a boat tail design and the rubber point it has. I would use a traditional bullet design, as it probably offers more surface to engage the lands and grooves allowing the 150's and 170's grainers to stabilize.

 

It has been my experience in my 1967 336 Texan and an early 70s Glenfield 336, both with microgroove barrels, that Hornady 160s at 2400 fps are quite accurate. I have loaded a lot of these bullets over Leverevolution and have had excellent results.

The twist rate 1:10, unless you have a non-standard replacement barrel, so stabilizing those 160s is not a problem from that perspective.

There's either something wrong with the barrel, or the bullets. If there's nothing obviously wrong with the bullets (oddly different weights, visual deformity), it's the barrel. Have you checked velocity worth a chronograph?

Is the rifle new to you? Is this the first time trying the 160 FTX? Are you sure the barrel is lead free? Is the crown in perfect shape? Is the throat shot out? Can you see the rifling in the barrel? Can you see anything in the barrel that ought not be there?

 

I agree, turnAround doesn't like the FTX ammo. Downloading the FTX bullet helps but very little.

 

I've read every since they released those that many 30-30s shoot them like a dream and others shoot them miserably. My late 80s model 336 shoots them OK. Borescope pictures of the ones that don't shoot that bullet well would be interesting to see.

 

Last time I seen a rifle do that part of the rifling in the barrel was gone

 

If that is factory full power ammunition try a lighter bullet and retest. I'm not going to overanalyze one target with keyholes. If you get good results with the lighter bullet problem solved, still looks that bad borescope it.

 

That's pretty bad. I've seen this in undersized bullets and bulets that wouldn't stabalize.

 

Have you fired other bullets that don't tumble?

 

that’s kind of my thought... either a worn MG barrel, or a fouled barrel. I could just be the gun, too. My brothers 336 absolutely hated 150’s, but did well with 170’s... so you never know. Granted, it didn’t keyhole... that’s why I’m thinking the rifling isn’t, for some reason, stabilizing the bullet.

 

There is no way a jacketed .308 160grs bullet fired at 2400 FPS from a 1:10 twist .30 cal barrel keyholes unless the bullet is NOT .308, the barrel is NOT .308, or the rifling is gone.

Still need to hear from OP on a number of questions.

 

When Marlin introduced micro grooving in their rifles in the 1950's they changed the groove 3 times. So depending how many grooves your rifle has could determine why some rifles like the FTX 160 grain bullets and others do not. The following is from an article on the Marlin micro grooves.

• .22 centerfire -- 16 grooves, .015" wide, .001" deep
• .30 caliber -- 16 grooves, .030" wide and .002" deep (this would be changed in 1958 to 22 grooves .024" wide, and .002" deep; and then again in 1968 to 12 grooves, .040" wide, .0028" deep)
• .32 caliber -- 16 grooves, .035" wide, and .0015" deep
• .35 caliber -- 16 grooves, .040" wide, and .002" deep (this would be changed in 1968 to 12 grooves, .055" wide, .0028" deep)

Here is the link to the article incase anyone is interested.

https://leverguns.com/articles/fryxell/microgrove-barrels.htm

 

Whether the OP’s barrel “likes” the 160 FTX or not is not the issue here.

Again, a .308 160 grs jacketed bullet will not keyhole from a .30 cal barrel unless the bullet is not .308, the barrel is not .308, or the rifling is seriously impaired.

There is nothing about micro groove barrels that would explain or cause a.308 160 grs bullet to keyhole. There is something wrong with the bullets or the barrel.

 

That's what I mean... the shallowness of the MG rifling. Someone at one time could have done something to the bore... it wouldn't take much.

 

It would take quite a bit to corrode or wear away the rifling.

Still wondering if the rifle is new to the OP. The bore wants slugging. If these are the first rounds through the rifle, it wants checking for things like whether someone rebored it to say, 35/30-30.

 

I was thinking something like lapping compound/bullets, or trying to remove excessive fouling with a stainless bore brush... something Bubba.

 

Whats that bullets OAL vs bearing surface? Then compared to the average 150/170grn FP thats normally used? If it,s way off it may not stabilize in a worm MG compared to new MG or standard rifling like a typical 6 or 8 groove.

 

Yeah, it would have to be something severe like that.