Lead strips in 375 Win T/C

[ohland]

Dad is working up some slow 375249 (249gr) 375 Win loads for someone that can't take much punishment.

Sounds like a mild 22 Hornet. I was surprised that we were going, and I didn't grab my ProChrono. No ideal what the velocity is, my guess 1200 or so. PB (oops!), pretty much straight WW.

105704

See the lead strips? He's using a .377 H&I die.

[petroid]

Was the lead in the bore or the throat? I see this sometimes in the throat where boolits will shave as they chamber and leave flakes of lead right at the chamber/throat junction.

[ohland]

He was saying that the leading was towards the throat. Here is a bigger strip.

105718

Snap. Either thicker brass (NOT!), a .375 H&I, or get a reamer for the throat. I thought of a tapered boolit, but if this is shaving the edge, then the taper won't fix it.

[Larry Gibson]

What lube?

What powder/charge?

Is a GC used?

Larry Gibson

[Gemsbok405]

Problem with the 375 Win (I have one in Ruger #3) is that the bullet front band, in most cases, is still in the chamber transition area, and not in the freebore / parallel throat.

The 375 Win case (2.020")was made 'short' to work with the original WW 250 gr JSP bullet. This bullet fills the throat well and alignment is not a problem.

With a cast bullet loaded with thinner brass, or a tighter freebore, the bullet may be out of alignment with the throat and the initial jump to parallel throat can result in side of bullet scraping off some lead as enters this area.

If seat bullets further out, and light crimp with LEE FCD, can solve this problem...

I do find after several shots in my #3, that the powder crud build up (at front of chamber) helps to align bullets a lot better...

[ohland]

Problem with the 375 Win (I have one in Ruger #3) is that the bullet front band, in most cases, is still in the chamber transition area, and not in the freebore / parallel throat.
The 375 Win case (2.020")was made 'short' to work with the original WW 250 gr JSP bullet. This bullet fills the throat well and alignment is not a problem. solve this problem...

Hmm, then a longer OAL should help align things. I hope.

Er, chamber transition area... I _assume_ that is tapered? Rain on my parade, 38-55 brass was beckoning to me for a little bit.

[ohland]

105921

If I wanted to see more stripping, I'd go to a gentleman's club. Looking at this, it isn't being scraped off by the chamber, instead it is lengthwise down the rifling. This barrel only had a few copper colored boolits down it (less than 50) so it might not be smoothed out.

Used the JBM Stability calculator http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi (under IE, Firefox threw an error) I came up with 5.6 or so, this makes me confused about this:

105922

100 yards, little wind, front sling stud removed from forend. There was some sight changing and different POA, but I never saw three boolits acting like they wanted to get it on. Load right now is @9 grains of Unique. Looking in from the breech, I swear the rifling is maybe .1" from the case diameter. Not much freebore there. One version of reality is the T/C Contender has a 1:12 twist.

Trying to get my dad to use the 50 yard target. The loads were dropping about a foot from the "L" when we started.

[Gemsbok405]

Your chamber throat sounds a bit like ".38-55" style, not at all like the correct SAAMI spec for a 375 win. Perhaps you have a 1:12 barrel in .38-55 as well...said .377 sized CB would not seal and likely be cause of leading!

[fryboy]

ummm 375-249 ? typo ???? 248 is the plain based 250-ish grain and 449 is the 265-ish grained gas check version ... mine does tolerable with .376 and better with .377 ( carbine,rifle and pistol ) the pistol seems to collect lube at the case mouth junction ( build up ) 8 grains of unique works fair in it with the old lee mold ( not so much the new lee mold ) my accuracy with the lyman 248 was umm way less than stellar ( thankfully no leading to speak of however ) my first thought is to try them either unsized or larger , and set just where they barely touch the rifling or engrave a smidgen ,second thought is to quench the boolits if they are larger than the throat/bore
i have a 375-296 it cast a wee bit smaller than i prefer , if i dont push them they tend to lead a wee bit , i'm guessing that the "push pressure" oburtrates the base enough ( sure i'd like to think it's my special lube but i know better lolz ) you may also want to pull a loaded boolit and make sure that they're not getting sized smaller than desired
in my pistol ( 14" hunter model ) i can push the 375-248 to 1800 FPS with ease and no leading ,accuracy however wasnt there for me
rocky raab used to have a page devoted to this caliber , he stated he got a lil better accuracy with red dot than unique ( albeit with a 240 grainer )

non-relevant question - north of the cheddar curtain .... still stateside if my understanding is correct ?

[ohland]

My bad, when I measured the boolit length, I noticed it is a plain base (PB) NOT a GC. My error!

[ohland]

ummm 375-249 ? typo ???? 248 is the plain based 250-ish grain... mine does tolerable with .376 and better with .377... my first thought is to try them either unsized or larger , and set just where they barely touch the rifling or engrave a smidgen ,second thought is to quench the boolits if they are larger than the throat/bore
i have a 375-296 it cast a wee bit smaller than i prefer , if i dont push them they tend to lead a wee bit , i'm guessing that the "push pressure" obdurates the base enough ... you may also want to pull a loaded boolit and make sure that they're not getting sized smaller than desired in my pistol ( 14" hunter model ) i can push the 375-248 to 1800 FPS with ease and no leading ,accuracy however wasnt there for me rocky raab used to have a page devoted to this caliber , he stated he got a lil better accuracy with red dot than unique ( albeit with a 240 grainer ) non-relevant question - north of the cheddar curtain .... still stateside if my understanding is correct ?

375248, Plain Base, sized to .377 (measured sized boolit). Dad went and sized all of them at once, so trying a .378 will be a bit. Red Dot may perform better (doesn't hurt that a pound of new manufacture is sitting on the shelf).

As to the Cheddar Curtain, it is a defensive line just north of the kleptocracy of Illinois. We try to keep control of our beloved smoked string cheese, good beer, and verdant cranberry fields away from the flatlanders. In reality, that is where most of the US funds for border security go. Sorry, 'tis true - Texas, New Mexico, Arizona, and Kalifornia, but strategic priorities must come first. At least that is what it seems to be. Though I see no ECPs, sally ports, barricades, inspection areas, or other control measures...

[ohland]

Your chamber throat sounds a bit like ".38-55" style, not at all like the correct SAAMI spec for a 375 win. Perhaps you have a 1:12 barrel in .38-55 as well...said .377 sized CB would not seal and likely be cause of leading!

.378 might be better? Also, who would have a decent reamer to make this .375 a bit more cast boolit friendly? Not going to wonder on a 38-55 reamer, since the .375 uses a wider .399-.400 neck. But I would be happier with a throat with a better leade, not such an immediate transition...

[fryboy]

mmm cranberries and cheese ,as for beer ...eh, it's all bad :kidding: actually it was something i googled once back when i first heard it i just rarely read of it ( one is more apt to hear the term chiraq than cheddar curtain - at least where i'm at )

i caught the size but am most curious to the size after seating and crimping and then being pulled , sometimes they can be swaged smaller by seating , as stated i have several 375 barrels , no two seem to prefer the same thing ( or to borrow a phrase "it is what it is " ) a good example is i have one boolit that tends to do best in a 14" contender barrel with next to starting loads yet the 15" encore barrel does better when they're pushed near max with a slower powder , the three longer rifle barrels seem to prefer a different casting ( i've tried many fast slow and all sorts of inbetween loads )
i'm also curious to the size of your throat ,most my tc's seem to run much tighter than ye old 38-55's and what not , tho there could be a few generous ones out there
the best advice i can give on the throat if you wish it altered would be mike bellm
http://www.bellmtcs.com/store/index.php?cid=468

[ohland]

106692
http://www.gmdr.com/lever/375w240_dat.htm

Greg did an extensive workup of a number of Cowboy Action type loads.

375 Winchester 240gr RNFP
PR: WLR CM: Win TempF: 56 OAL: 2.450"

PT PW Vel SD GS
Unique 5.0 818 15.1 3.3
6.0 929 6.8 0.77
7.0 1015 12.2 3.7
8.0 1103 12.4 12.0
9.0 1169 10.0 12.0

[runfiverun]

I'm getting that this is in a contender.
if so their throats are generally comparable to the marlins.
I had to go to 379 in my marlin and seat long to get the boolit across that stupid throat gap.
once I done those two things I could push the rifle fast or slow without too much trouble other than height of impact on the target.

[JSH]

I picked up my .375 barrel on a whim. It was one of the first barrels I cast for. It shoots exceptionally well with a PB and a gc bullet. My powder of choice is sr4759 and 5744, I have used unique as well.
The pattern rather than group makes me wonder on two things. Bench technique and crown. Yes I will agree the leading going on is bad but I have seen worse shoot better.
50 rounds of jacketed is still enough to leave a mess of gilding metal and carbon fouling. If it will strip a jacketed bullet it will darn sure mess up a cat bullet.
I would clean with a good copper solvent and some jb bore paste.
My tc likes a .377 cb but have also used .378.
Jeff