muzzle fit test?

[dualsport]

We've all heard and read about how your boolit must not slip right into the muzzle of your gun or bad stuff happens. I'm curious what others have found using boolits that were not quite fat enough to pass the muzzle test. I have a mold that throws a 311299 at .300/.310. Testing with three different guns to begin this week. I recall Veral Smith having something to say about this. I'll re-read that chapter.

[454PB]

There is something seriously wrong if a boolit will fit in the muzzle. If you fired that boolit, it would be inaccurate and deposit leading in the bore.

You don't measure cast boolits by a muzzle fit test, you do it by slugging the bore.

[runfiverun]

you want the nose to engrave the rifling.
this helps center the round,build up powder pressure,and helps control nose slumping.

[45 2.1]

With whats been posted, this should be a interesting thread. If the boolits nose goes in the muzzle past the ogive radius, it will be a mediocre shooter. The boolit should be as big as the throat with the nose matching the throat taper into the bore.

[454PB]

Many years ago my BIL asked me to see if I could make his Remington 721 in 30/06 shoot. He had owned it for years and used it successfully to bag dozens of deer. One year, he couldn't hit anything with it and he knew I love to tinker with guns and loads, so he asked me to check it out. I loaded up some of my favorite recipes and took it to the range. The best it would do was 12" groups at 100 yards, so I brought it home for cleaning and a closer inspection. The muzzle looked really big, so I dropped a .308 jacketed bullet in base first and it went in 3/4 of it's length.

I had the local gunsmith remove an inch of the barrel, and it was a good shooter again, 1 1/2" groups were the norm. The only thing we could figure is he had apparently fired it with some kind of obstruction in the muzzle.

[44man]

Sounds logical! But maybe he cleaned from the muzzle with no muzzle protector and wallowed the muzzle out.
Revolvers get ruined big time like that.
I watched my neighbor scrubbing like crazy on his new SRH while he walked around his garage. I gritted my teeth and told him about it but it had no affect. He had some cheap cleaning kit.

[Maven]

There was an article by Robert Sears in E.H. Harrsion's "Cast Bullets" (NRA), which advocated testing a CB at the muzzle as a quick and dirty predictor of accuracy. Like most rules/predictions, there are exceptions. To wit, how well a CB fits the throat, whether the body fits the bore (sizing diameter), and/or its bearing length will overcome a less-than-ideal muzzle fit. E.g., I use Lyman's #314299 in both my M 39 Finn (7.62 x 54R) @ .312" and M 1909 Arg. Mau. (7.65 x 53mm) @ .313", but get excellent accuracy even though -299's nose is unmarked by the rifling. This is even more remarkable since the Mauser's bore is less than pristine. Moreover, the Lee ~175gr. CB for the 8mm Mau. drops into the muzzle of my 8mm Mau. of its own weight, yet shoots about as accurately as an LBT CB that doesn't (and is fitted to that gun). In sum, CB -> muzzle fit or engraving as a determinant of accuracy works most of the time, but there ARE exceptions to Sears' test.

[dualsport]

Small range test today. I shot a very nice issue 03a3 I got here. The load; NOE 311299 ww +1% tin air cooled, gator checks and home made lube. As cast they are .300/.311. I sized 'em in a .312 die, 10 gently and 10 bumping the nose up to .301. The .300s will not pass the muzzle test, the .301s will not enter the muzzle. Shot them all over 17.5 gr. of A 2400. No difference! Both 10 shot groups were just under 2 1/2" at 100 yds. off a bench. I call that great, I think I have a winner. I know a fatter nose is the usual best way to go but it seems sometimes it's not the end-all deal. I'll try some hotter loads using 4350 and see what happens.

[btroj]

I don't know if it is as much a way to tell what will work as it is a way to help tell what won't.

Just because it won't enter the muzzle doesn't mean it it will shoot but a nose that is loose in the muzzle is a sign of poor fit.

I frequently run this test more for peace of mind than anything.

[.22-10-45]

Hello, everyone..this should be an interesting post! I have found more often than not, concerning firearms and loading for same, that blanket statements rarely are true 100% of time. In stating that a bullet nose must engrave at muzzle or will not shoot..It depends on the bullet design..for a bore rider type sure..but what if a fellow has a lovern style..or the old Sharps-Bailey? I have several .38 & .40 rifle moulds with nose dia.'s that don't even come close to fitting bore..but still manage to group well in 1" at 100yds.

[sw282]

l remember from shooting factory varmint class at my gun club the benchrest guys telling about bore cleaning and bullet runout. Even tho l was shooting an old M70 243 Varmint push feed it really made a difference in the accuracy of those 60 gr Sierra HPs. Always clean from breach to muzzle and use a bore guide. Seat bullet so it just touches the lands. These 2 little tricks shrunk my groups by 20%.
l have never shot cast boolits in a rifle but these hints should help those too..
The "never" may change shortly because l have this little break open H&R Topper in 30-30 l have been thinking of casting for. lt has one flaw that effects all rifles in the accuracy dept. --A sorry trigger. Nothing messes up a good group more than a heavy/gritty trigger. l learned that working around Kenny Jarrett's shop for a couple years back in the day

[badgeredd]

We (Hornet and I) often use the muzzle test on firearms at gun shows. I am in total agrrement with btroj when he said:

"I don't know if it is as much a way to tell what will work as it is a way to help tell what won't."

If one comes across a rifle with a sloppy fit at the muzzle it often points to the fact that the last 2" of so of the barrel has been worn out likely with poor cleaning methods. That tells me that if I wish to shoot a gun "as is" it may well be a big problem, and it does give me a notion as to what I might run into. It does not definitively tell me it will shoot or not.

Edd

[Cadillo]

Careless cleaning resulting in cleaning rod wear to muzzle. This is very common in rifles that have been cleaned with jointed rods. Whenever I look at an M1 Garand I'm thinking of trading into I carry not only a throat erosion gauge, but also an M2 cartridge to see how much of the bullet the rifle's muzzle will swallow. In my experience muzzle wear is even more detrimental ro accuracy than throat erosion. Your experience with that rifle seems to bear this out.


Many years ago my BIL asked me to see if I could make his Remington 721 in 30/06 shoot. He had owned it for years and used it successfully to bag dozens of deer. One year, he couldn't hit anything with it and he knew I love to tinker with guns and loads, so he asked me to check it out. I loaded up some of my favorite recipes and took it to the range. The best it would do was 12" groups at 100 yards, so I brought it home for cleaning and a closer inspection. The muzzle looked really big, so I dropped a .308 jacketed bullet in base first and it went in 3/4 of it's length.

I had the local gunsmith remove an inch of the barrel, and it was a good shooter again, 1 1/2" groups were the norm. The only thing we could figure is he had apparently fired it with some kind of obstruction in the muzzle.

[454PB]

There's a couple of reasons that I doubt cleaning from the muzzle caused this problem.

First, my BIL cleaned this rifle once a year, right before hunting season. Second, he always cleaned from the breach. Third, the flaring at the muzzle was so big, I don't think you could purposely enlarge it that much. You could place a .308" bullet in the muzzle and wiggle it 1/8". And finally, the rifle had shot well up until the muzzle damage was discovered, no gradual degradation as you would see from bad cleaning practices.