User Panel
User Panel
User Panel
|
Posted: 8/6/2018 10:07:51 AM EDT
Last year, I was lucky enough to acquire a Ross MKI in .303 British. Early Ross rifles are known for having very tight bores and this one gauges at .302" at its narrowest, .304" at its widest point. It headspaces correctly and the action is in good shape. It's mechanically sound.
Initially I'd like to test it with cast bullets in a low-velocity loading. If it performs well, I'd eventually like to fire it with standard velocity, jacketed .303 Brit loads. What size bullet would you be willing to use in a bore this size? Thanks. 
|
|
|
|
Posted: 8/6/2018 10:23:31 AM EDT
[#1]
Interesting. I'm no help on your question, but I believe that rifle was compared to the '03 Springfield or the '17 Enfield within the last year on "Guns & Ammo" TV in that segment where Craig Boddington and the older NRA guy shoot old firearms from the same era.
I'd never even heard of this rifle until that show, and some reading into its history was enlightening. Have fun with that project. |
|
|
|
Posted: 8/6/2018 11:14:29 AM EDT
[#2]
I would hesitate shooting .308 out of that tight a barrel. Nice rifle.
|
|
|
|
Posted: 8/6/2018 12:24:08 PM EDT
[#3]
How did you measure the barrel?
The groove diameter is the dimension you need, not the bore diameter on top of the lands. |
|
|
|
Posted: 8/6/2018 12:24:46 PM EDT
[#4]
I would shoot nothing except properly sized bullets in that rifle.
SAAMI Specs for 303 British - Bullet diameter: 0.3095" to 0.3125" Barrel bore diameter: 0.303" Barrel groove diameter: 0.314" I believe bullets for 303 British are usually sized to the nominal spec value of 0.311" diameter. In that regard, 0.308" diameter bullets are too small. They will shoot but I this you might see reduced accuracy, blow by, leading or copper fouling,... stuff like that. Personally, I wouldn't do it. I'd get bullets of the proper size. |
|
|
|
Posted: 8/6/2018 1:36:57 PM EDT
[#5]
Quote HistoryQuoted:
I would shoot nothing except properly sized bullets in that rifle. SAAMI Specs for 303 British - Bullet diameter: 0.3095" to 0.3125" Barrel bore diameter: 0.303" Barrel groove diameter: 0.314" I believe bullets for 303 British are usually sized to the nominal spec value of 0.311" diameter. In that regard, 0.308" diameter bullets are too small. They will shoot but I this you might see reduced accuracy, blow by, leading or copper fouling,... stuff like that. Personally, I wouldn't do it. I'd get bullets of the proper size. |
|
|
|
Posted: 8/6/2018 1:56:28 PM EDT
[#6]
Last post has it.
+/- 0.001 from spec of 0.303 inch. Your fine it’s as good a tolerance as can be expected in the olden days for gov work. It’s a very minor thing. You still have room for engraving/ metal displacement in the groove. I am assuming we are talking about copper jacketed rounds. If lead you need the depth of the grooves and cast/size 0.002” bigger. |
|
|
|
Posted: 8/6/2018 2:50:15 PM EDT
[#7]
Quote HistoryQuoted:
Seems this rifle is fine for .303 bullets. Start low, work up. |
|
|
|
Posted: 8/6/2018 2:50:53 PM EDT
[#8]
Quote HistoryQuoted:
Last post has it. +/- 0.001 from spec of 0.303 inch. Your fine it’s as good a tolerance as can be expected in the olden days for gov work. It’s a very minor thing. You still have room for engraving/ metal displacement in the groove. I am assuming we are talking about copper jacketed rounds. If lead you need the depth of the grooves and cast/size 0.002” bigger. |
|
|
|
Posted: 8/6/2018 3:04:27 PM EDT
[#9]
Quote HistoryQuoted: How do you arrive at that conclusion based on the SAAMI specs? You are saying 0.302" diameter is okay. How? Why? What is the basis for that? I have a shit load of milsurps. The older they are the more they wander from the drawing. One of my favorites, the US Krag is notorious for not being on spec, especially for the grooves. They worked and survived their service lives and then some. The Swiss k31s are not even .300 bore all the time. They are tighter and shoot extremely well. If you work up your load you’ll be fine. Match rifle makers often order tight bores from barrel suppliers. ETA the Finnish rifles were rebarrelled to a tighter bore but would still shoot Russian larger ammo if they had to. How may .308 bored M28, M39s have been chugging away with .311 ammo? Lots. |
|
|
|
Posted: 8/6/2018 3:06:41 PM EDT
[#10]
Quote HistoryQuoted:
How did you measure the barrel? The groove diameter is the dimension you need, not the bore diameter on top of the lands. Yes, that's a very good point. I think I have mistakenly assumed the measurement was taken from the grooves rather than the lands. 
|
|
|
|
Posted: 8/6/2018 3:27:54 PM EDT
[#11]
I cannot believe that diameter is correct. It is a well used military rifle and passed inspection when it was made. It was shot a lot with 303 ball ammo.
I would slug it myself. If it is correct, which I highly doubt, I would use carcano bullets. |
|
|
|
Posted: 8/6/2018 3:38:21 PM EDT
[#12]
Explain gages at .303"? Are you saying a .303" drill rod will enter the muzzle or breech, but nothing bigger. Or are you saying a chamber cast measures .303" on the bore? Huge difference.
.303 Enfield rifles are supposed to use .311" to .312" bullets. .308" will work, but may not be as accurate and will allow gas to pass between the bullet jacket and the bore. This can increase copper fouling and create other issues. The groove depth determines bullet selection, not the rifling lands. |
|
|
|
Posted: 8/6/2018 7:10:53 PM EDT
[#13]
If it's good to go with .311" bullets, I have some 139gr lead spitzers with gas-check. What sort of powder would people consider for a low-velocity load with these bullets in .303 Brit?
Thanks. Quote HistoryQuoted:
Explain gages at .303"? Are you saying a .303" drill rod will enter the muzzle or breech, but nothing bigger. Or are you saying a chamber cast measures .303" on the bore? Huge difference. Quote HistoryQuoted:
Explain gages at .303"? Are you saying a .303" drill rod will enter the muzzle or breech, but nothing bigger. Or are you saying a chamber cast measures .303" on the bore? Huge difference. Quoted:
Interesting. I'm no help on your question, but I believe that rifle was compared to the '03 Springfield or the '17 Enfield within the last year on "Guns & Ammo" TV in that segment where Craig Boddington and the older NRA guy shoot old firearms from the same era. I'd never even heard of this rifle until that show, and some reading into its history was enlightening. Have fun with that project. |
|
|
|
Posted: 8/7/2018 10:22:59 AM EDT
[#14]
Dumb question. Does it have an odd number of lands and grooves?
If so it’s easy enough to measure the bore with plug gages. Not so much the groove. Even driving a slug through and trying to measure an odd number grooved slug is slightly complicated. |
|
|
|
Posted: 8/7/2018 4:19:24 PM EDT
[#15]
Lets start here, and when we lead slug a barrel, it's the grooves measurement we are looking for.
So in regards to 303 British, a tight bore will have the grooves at .311", while a loose bore on some rifles are upwards of .318" isntead. So again, until you know the groove size of the bore via lead slugging to determine such, your really don't have a clue what size bullet you need isntead. If the bore .311", and your using a .312" jacket bullet, then will high pressure signs well before you get to max data. If the bore is .318", and your loading with a .312 bullet, then the bullet may stabilize, but is going to shoot more like a shotgun with patterning, then tight groups with the amount of blow by past the bullet not sealing off to the bore instead. As for cast bullets, size at least .001" larger than the bore size, and sizing .002" larger than bore somethings will shoot a tighter groups if you have min bullet engagement to the lands instead. |
|
|
|
Posted: 8/7/2018 6:07:01 PM EDT
[#16]
Quote HistoryQuoted:
Lets start here, and when we lead slug a barrel, it's the grooves measurement we are looking for. http://www.firearmsid.com/Galleries/illustrations/rifling/rifling_6R.gif So in regards to 303 British, a tight bore will have the grooves at .311", while a loose bore on some rifles are upwards of .318" isntead. So again, until you know the groove size of the bore via lead slugging to determine such, your really don't have a clue what size bullet you need isntead. If the bore .311", and your using a .312" jacket bullet, then will high pressure signs well before you get to max data. If the bore is .318", and your loading with a .312 bullet, then the bullet may stabilize, but is going to shoot more like a shotgun with patterning, then tight groups with the amount of blow by past the bullet not sealing off to the bore instead. As for cast bullets, size at least .001" larger than the bore size, and sizing .002" larger than bore somethings will shoot a tighter groups if you have min bullet engagement to the lands instead. Quote HistoryQuoted:
Lets start here, and when we lead slug a barrel, it's the grooves measurement we are looking for. http://www.firearmsid.com/Galleries/illustrations/rifling/rifling_6R.gif So in regards to 303 British, a tight bore will have the grooves at .311", while a loose bore on some rifles are upwards of .318" isntead. So again, until you know the groove size of the bore via lead slugging to determine such, your really don't have a clue what size bullet you need isntead. If the bore .311", and your using a .312" jacket bullet, then will high pressure signs well before you get to max data. If the bore is .318", and your loading with a .312 bullet, then the bullet may stabilize, but is going to shoot more like a shotgun with patterning, then tight groups with the amount of blow by past the bullet not sealing off to the bore instead. As for cast bullets, size at least .001" larger than the bore size, and sizing .002" larger than bore somethings will shoot a tighter groups if you have min bullet engagement to the lands instead. I slugged it today and it's measuring around .315" in the grooves, so an average bore with some wear. Foolishly I confused the measurement of the lands for the grooves, hence the misleading thread title and OP. Quoted:
Dumb question. Does it have an odd number of lands and grooves? If so it’s easy enough to measure the bore with plug gages. Not so much the groove. Even driving a slug through and trying to measure an odd number grooved slug is slightly complicated. |
|
|
|
Posted: 8/8/2018 2:23:54 PM EDT
[#17]
.304" at the lands, .315" at the grooves, should shoot OK with .312" jacketed bullets, but if you are casting for this barrel, then standard 303 British mold which will produce a .313" bullet, power coat the bullet to solve leading and help build up the OD of the bullet, and then size the bullet at .316" for this rig. If with PC coating your still not at .316", then pretty easy to use a cast bullet to polish out the mold to get it throw a slightly larger OD bullet isntead.
https://leeprecision.com/mold-dc-c312-185-1r.html As for gas checks, you can store buy them, or just punch your own. Hence with powder coating, that will solve any leading problem in the barrel so you don't need a gas check, but may need the gas checks to get the bullet to print well isntead. Regarding load, unique at max load of 14.5gr (start point of 10.8gr/1300fps as you work up the load) should have be around 1600fps with the above lee bullet PC and sized .316" /.001" larger than the bore of the rig. And again, you can push a PC bullet well past 2K without needing a gas check even in a rifle, but the glitch with a rifle bullet designed for a GC, tends to not shoot well if the bullet does not get a gas check. I bring this up, since if you know someone with a mill, not hard to shave the top of the mold to remove the gas check section from the mold, or just ream the GC in the mold to enlarge it instead. Here is reaming, https://americanhandgunner.com/modifying-lee-molds/ While this is a lee 310gr GC design mold that the top of the mold was flywheel cut to remove the gas section of the mold so it throws a 270gr bullet isntead. 
|
|
|
|
Posted: 8/9/2018 5:41:27 PM EDT
[#18]
Quote HistoryQuoted:
.304" at the lands, .315" at the grooves, should shoot OK with .312" jacketed bullets, but if you are casting for this barrel, then standard 303 British mold which will produce a .313" bullet, power coat the bullet to solve leading and help build up the OD of the bullet, and then size the bullet at .316" for this rig. If with PC coating your still not at .316", then pretty easy to use a cast bullet to polish out the mold to get it throw a slightly larger OD bullet isntead. https://leeprecision.com/mold-dc-c312-185-1r.html As for gas checks, you can store buy them, or just punch your own. Hence with powder coating, that will solve any leading problem in the barrel so you don't need a gas check, but may need the gas checks to get the bullet to print well isntead. Regarding load, unique at max load of 14.5gr (start point of 10.8gr/1300fps as you work up the load) should have be around 1600fps with the above lee bullet PC and sized .316" /.001" larger than the bore of the rig. And again, you can push a PC bullet well past 2K without needing a gas check even in a rifle, but the glitch with a rifle bullet designed for a GC, tends to not shoot well if the bullet does not get a gas check. I bring this up, since if you know someone with a mill, not hard to shave the top of the mold to remove the gas check section from the mold, or just ream the GC in the mold to enlarge it instead. Here is reaming, https://americanhandgunner.com/modifying-lee-molds/ While this is a lee 310gr GC design mold that the top of the mold was flywheel cut to remove the gas section of the mold so it throws a 270gr bullet isntead. https://i.imgur.com/waszAfl.jpg https://i.imgur.com/3gkV21K.jpg |
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
