Cartridges with a smaller Groove diameter than you thought

[Billo]

Sometimes you come across a cartridge you thought you knew only to discover it actually has a smaller groove diameter

The 35 Whelen is actually a 357 not a 358

[straightshooter]

Remington standardised the 35 Whelen wildcat with a 0.358 bullet diameter.
The assertion that it is 0.357 might come as news to Remington (or what's left of it).
In practice the precise dimensions that barrel makers end up with is usually determined by the quality standards they adhere to.
A 358 projectile in a 357 groove diameter is hardly a problem but a 357 bullet in a 358 groove diameter especially if it has a very short bearing surface could have accuracy issues.

[Billo]

Remington standardised the 35 Whelen wildcat with a 0.358 bullet diameter.
The assertion that it is 0.357 might come as news to Remington (or what's left of it).
In practice the precise dimensions that barrel makers end up with is usually determined by the quality standards they adhere to.
A 358 projectile in a 357 groove diameter is hardly a problem but a 357 bullet in a 358 groove diameter especially if it has a very short bearing surface could have accuracy issues.

I'm not sure what you mean straightshooter by Remington standardizing a Cartridge design with a Bullet ?

The only standards are SAAMI where the cartridge dimension along with the barrel bore and groove specs are listed, Yes you could ask gunsmith to build a Whelen with a large 358 groove diameter. A mate just built a 358 Winchester and he chose to go the other path and use a 0.357 Groove so he could utililize the cheap pistol pills.

35 Whelen, 350 Remington Magnum and the 35 Remington are all listed as having a 0.357 Barrel groove diameter, the only 2 cartridges to run the larger 0.358 groove diameter is the 358 WInchester and 356 Win

[Oldbloke]

I think it works like this.
Someone designs and test a wild cat.
A Gun manufacturer decides there is a dollar in it.
Tweeks the design. (Sometimes)
Starts producing firearms and ammo.
Applies to SAAMI to make it a Standard.

I may well be çorected tho.

[Billo]

Yeap thats how see it too Oldbloke, funny thing even the 35 Nosler has a 0.357 groove diameter ( a cartridge I was unaware of ).

[No1Mk3]

Cartridges don't have a groove diameter, barrels do. The 35 Whelen, as designed by James Howe of Griffen & Howe fame, was made with a .358 bullet. When Remington legitemized the wildcat information supplied to SAAMI specified the bullet diameter at .359 +0.000 -0.003. The groove diameter was listed as .357 and bore at .349.

[Billo]

Cartridges don't have a groove diameter, barrels do. The 35 Whelen, as designed by James Howe of Griffen & Howe fame, was made with a .358 bullet. When Remington legitemized the wildcat information supplied to SAAMI specified the bullet diameter at .359 +0.000 -0.003. The groove diameter was listed as .357 and bore at .349.

Yeah maybe I could worded the title a little better but you knew what I meant and yes it a 0.357 groove diameter, the only reason I posted as some Mono copper bullet I was using were undersized for my 358 bore, blow by was affecting velocity, hopefully a new design will rectify this issue

[Larry]

For me the surprise has been in the larger 44 45 cal range. which depending on cartridge can be significantly smaller.

[Billo]

For me the surprise has been in the larger 44 45 cal range. which depending on cartridge can be significantly smaller.

Hey Larry which 44 & 45s are you refering too

[Wyliecoyote]

This is one area that often gets maligned, blamed or praised for ultimate accuracy potential. It is more critical with cast and monolithic but not so with cup and lead core projectiles. The old Swedish Mausers are renowned for their accuracy but most wouldn't be aware their groove size is not 0.264" but more like 0.265" or 0.266". Given that, it is a rarity to see a bad shooting Swede so it is fairly safe to say that the moderate pressure they operate at is enough to obturate the cup and lead core projectile to seal the bore and maintain accuracy.

[ruger 375]

This is one area that often gets maligned, blamed or praised for ultimate accuracy potential. It is more critical with cast and monolithic but not so with cup and lead core projectiles. The old Swedish Mausers are renowned for their accuracy but most wouldn't be aware their groove size is not 0.264" but more like 0.265" or 0.266". Given that, it is a rarity to see a bad shooting Swede so it is fairly safe to say that the moderate pressure they operate at is enough to obturate the cup and lead core projectile to seal the bore and maintain accuracy.

very interested in your take on this. Are you saying the degree of sealing in the boor is a primary factor as to the 6.5 shooting ability?

in relation to the subject....for the un informed lets go larger than bore re 404 j

[Billo]

This is one area that often gets maligned, blamed or praised for ultimate accuracy potential. It is more critical with cast and monolithic but not so with cup and lead core projectiles. The old Swedish Mausers are renowned for their accuracy but most wouldn't be aware their groove size is not 0.264" but more like 0.265" or 0.266". Given that, it is a rarity to see a bad shooting Swede so it is fairly safe to say that the moderate pressure they operate at is enough to obturate the cup and lead core projectile to seal the bore and maintain accuracy.

very interested in your take on this. Are you saying the degree of sealing in the boor is a primary factor as to the 6.5 shooting ability?

in relation to the subject....for the un informed lets go larger than bore re 404 j

The fast twist and long bearing surface of the heavy for calibre projectiles, accuracy has never been an issue

I tried to run a light weight 0.265 mono copper pill in a 6.5PRC recently and found out pretty quickly this was a no go zone as far as pressure and speed was concerned

[ruger 375]

What was the issue with pressure and speed mate if i may ask....I'm assuming the node timing depending on many things like length of barrel and projectiles and powder used etc may be an issue here not some random idea.......i could do the pressure and node timing if you are interested

[Wyliecoyote]

The degree of sealing to groove size has everything to do with accuracy where the old Swedes are an anomaly to this for whatever reason. Generally a miss match of that amount is the worst for accuracy.
With cast bullets it is generally accepted that bullets a thou or two over groove size are needed to get the best potential accuracy where the majority of custom rimfire barrels are lapped to have some level of choke or gradual taper toward the muzzle.

Recently there was an instance of a batch of 7mm match bullets that were mearsuring close to a half thou undersize and consequently shot like junk in one particular rifle that was a known performer. Another batch that was known to shoot well were measured and found to be two tenths above 0.284". So seven tenths made the difference between winner and also ran. Now we're talking a quarter MOA rifle suddenly having outliers going to beyond half MOA where in FClass or Fly this is not acceptable.
As to the point Billo made. Two things, the first being monos being under or over nominal groove size are a no go zone. One shoots like crap, the other spikes pressure and is the reason all manufacturers cite warnings when working up loads. The second is more complex and can be best summed up by my many years working with 6 mils for long range. Krieger and some others like Broughton make 6mm barrels in either a 0.236" or 0.237" bore with a 0.243" groove size. Someone comes up to me at a match as was done just recently and says what speed should i be getting out my 6BR because the chono is saying 2830 fps and others are saying they're getting over 2900? He says he is using IBI barrel and i know so and so is using a 237 Krieger. That one thou in bore size is all it takes to change the pressure curve where in one instance a barrel i had fitted was able to get beyond 3000 fps with a 107 SMK and a lot of Re15, something only 6mm Dashers can achieve.
Dan Lilja made barrels of undersized bore dimensions and he knew that in doing so his barrels were capable of getting more potential speed than a SAAMI spec barrel. The problem was that while they shone twice as bright they lived half as long because the throats had less material to burn out and so died a quicker death. A cut and shut could get them going again but most just tossed them. Most barrel manufacturers rule of thumb is a two thou land height but it is widely known that some alteration from that can be beneficial.

[ruger 375]

To be honest there are so many inaccuracies in that novel......i don't mean to be rude but thoughts ideals and actual ballistic fact are very different.....the throat story. Is rubbish.....the .t though under or over shooting like s**t.....is rubbish as we can barely even measure that....twist makes more difference and it doesn't come into effect in pressure testing......anyways agree to disagree

[Billo]

What was the issue with pressure and speed mate if i may ask....I'm assuming the node timing depending on many things like length of barrel and projectiles and powder used etc may be an issue here not some random idea.......i could do the pressure and node timing if you are interested

Let just say I had too much pressure for what should have been a moderate start load (stiff bolt lift). Speed was average, the experiment ended

[ruger 375]

Send me the load if you like and I'll run some numbers. You may as well find out if you wasted the time brass powder and pills

[Wyliecoyote]

Please point out the innacuracies going on your experience.

[ruger 375]

Wylie, we can't even measure what you are saying with any degree of accuracy....the old swedes theory anomaly line is rubbish as all rifles work under the same principles no matter what condition temp calibre etc. back in the states we made projectiles with so much variance our pressure equipment couldn't even measure these small amounts you speak of.....I'm guessing temp or powder or something else was an issue.....not a batch as a catch would of been 400,000 rounds and half the potential buyers would of been pissed off. s**t happens mate, and to be honest half of the information on every forum is someone's opinion..... But as you know everyone just like an arse has one. The lilja barrels are great barrels dan had tighter specs not bagged or more wear etc....that is a whole other subject..... Please stick to facts and not guess points of topic as there are many new people here and reading through comments there is a ton of opinions but not backed up buy facts or numbers. The newer members make make a decision on their reloading based on false statements

[Wyliecoyote]

Not sure where you're going with that but if it couldn't be measured to what i stated, i question the quality of the bullets you refer to. Swedes are an anomaly because they shoot better than most older military rifles. But they are only very average compared to the run of the mill commercial rifles sold now which still says a lot for their ability.

Bergara is the new kid on the block but is able to hone barrels to a tenth or better before rifling their barrels. Neimi made bullet dies to tenths of a thou tolerance for hundreds of custom and commercial bullet manufacturers in the past. These days bullet dies are made and measured to even tighter tolerances using EDM. Match benrest bullets are measured to a couple of tenths at the pressure ring by all serious benchrest competitors when looking through batch lots. Even air rifle pellets are sold to a half thou nominal size from some suppliers. Pilots for chamber reamers are sold in one ten thou increments to smiths all over the world. Deltronic pins for bore measurement are sold in one ten thou increments. So it can be done and is done daily and easily.

https://youtu.be/CUm_YXzJJOU


There are bore micrometers of which i have one that can accurately measure to a couple of tenths.
Yes Lilja barrels are a quality barrel but i no longer fit them beyond 22lr, PRS rarely use them because they simply don't see a full season of competition. The same can be said for Fclass and fullbore.

https://precisionrifleblog.com/2024/04/ ... -pros-use/

Everything i have stated is fact and experience and can be corroborated by countless others who have gone beyond the keyboard in search of accuracy.

[ruger 375]

sorry you lost me in the first sentence swedes shoot better in the first line and bullets.....and an anomoly......seriously....... if we cant measure it or differences that is fact....i didnt read the rest as its obviously just some random thoughts coming into your head to look impressive or something....im not sure, but i can pressure test everything you say and show you are incorrect, happy to do do or just say hey mate i dis agree...