What barrel length are you running? My experience with the heavy 22s has been that barrel length (more friction?) contributes something to the blowup equation.
F-Open: 300 WM?
- Thread starter davidjoe
- Start date
My new barrels were twin blanks 1.50” for about 4” from the receiver face, then a taper to 1” at 32”, finished, from the face.
But I made a very painful decision at initial chambering to go ahead and slice 3 inches off the end of one of them, for 29” from the receiver face. Cutting off tapered 5-R virgin steel is like heating the living room by igniting small piles of Varget, just plain agonizing.
Neither one have had a problem with blowups, but I didn’t know exactly where I’d see reduced heat, nationals was coming abd I was hedging to try to end up with at least one assured string shooter. The shorter barrel of the two just might shoot better, too early to know.
By comparison, the 8 original 8 twist barrels are roughly 34.5 from the face and taper to 1.15” instead of 1.0”.
The 300 Win Mag with those long barrels can push them to or just over 2,000 FPS at 1,000, and the target of Tim’s above, when he tested one back in time was fairly close to that, and I would never give a tester anything that showed pressure signs. I also don’t intentionally over stress primer pockets.
But as I found with time, string fire shooting isn’t compatible with that velocity at that twist and length. While a failing, old, and inexpensive scale could have been an issue even back then, unrealized yet, I also feel that barrel heat could damage jackets even with perfectly uniform charge weights.
One thing I am convinced of is that these are very accurate bullets.
Question from the field after day one in Louisiana. 300WM/250’s.
We are running mid 90’s F after the first relay. When the barrel started cool, it shot a 198-10X.
Scores dropped steeply despite cooling efforts as it heated up for match 2 and 3.
Is there any metallurgical reason not to use something like a can of compressed CO2 or even ice bags, to try to start a match say 50 degrees colder than where it wants to start?
I have shot a hunting rifle that was likely sub freezing and it didn’t hurt anything, but I’m not keen on something unforeseen like egregious fire cracking from unusual expansion, either.
If the string is going to add, say 75 degrees to the temp, am I thinking correctly that this will be true regardless of where it starts?
I’m going to that bastion of accuracy resources soon, Walmart Supercenter 1.7 miles away.
We are running mid 90’s F after the first relay. When the barrel started cool, it shot a 198-10X.
Scores dropped steeply despite cooling efforts as it heated up for match 2 and 3.
Is there any metallurgical reason not to use something like a can of compressed CO2 or even ice bags, to try to start a match say 50 degrees colder than where it wants to start?
I have shot a hunting rifle that was likely sub freezing and it didn’t hurt anything, but I’m not keen on something unforeseen like egregious fire cracking from unusual expansion, either.
If the string is going to add, say 75 degrees to the temp, am I thinking correctly that this will be true regardless of where it starts?
I’m going to that bastion of accuracy resources soon, Walmart Supercenter 1.7 miles away.
46and2
Silver $$ Contributor
You will have condensation in the bore from compressed gas.
This moisture will have an effect on pressures but unsure what effect the interaction with powder fouling.
Metallurgically, I know you shouldn't quench red hot CM or CS. I frequently quench 316L SS but I'm unsure about 416R SS.
Yes, I got a large ice chest instead. I actually didn’t find CO2. My plan is to start the barrel as cold as ice bags from the hotel machine can get it. Cold, but dry. I don’t plan to necessarily cool it down quickly, as there is time between matches, but rather slowly cool it below ambient to the maximum extent possible.
The loads aren’t high pressure, but the gun doesn’t shoot as small starting warm. I have seen that as a couple of matches now. I did also try mopping barrel between two and three like BR does, but that didn’t help me.
Sandstorm
Gold $$ Contributor
I used to keep my ammo in a cooler as well in trying to mitigate the ambient temp's in Arizona with
well over 105 some days before we get done.
It will help some with the first 10 rounds but after that your back to almost cookin again. Folks used to run Ice water with a small pump through the barrel as well........Im not comfortable doing that however.
but cooling the Ammo does help be it ever so brief.
well over 105 some days before we get done.
It will help some with the first 10 rounds but after that your back to almost cookin again. Folks used to run Ice water with a small pump through the barrel as well........Im not comfortable doing that however.
but cooling the Ammo does help be it ever so brief.
I have wondered about putting sponge in the gap between the forend and barrel, then spraying the barrel from the top, as I do with alcohol, which runs down and soaks the sponge.
I’m shooting A-Tips 250’s and 230’s versus Berger 245’s today at 200 yards.
I think this is the best magnum group I have shot at 200.
I’m shooting four guns but the one that shot this group is an angled butt stock with a pinch bag and the barreled action is liquid rubbered to the channel full length of the barrel.
It’s not photogenic but it shoots and I’ll clean that up. Unlike glue, it can be taken out quite readily.
The A-Tip bullets are HBN coated and the Berger are not. This is not fair to the Berger bullets because going back and forth means they are dealing with barrels that begin with coating.
I think this is the best magnum group I have shot at 200.
I’m shooting four guns but the one that shot this group is an angled butt stock with a pinch bag and the barreled action is liquid rubbered to the channel full length of the barrel.
It’s not photogenic but it shoots and I’ll clean that up. Unlike glue, it can be taken out quite readily.
The A-Tip bullets are HBN coated and the Berger are not. This is not fair to the Berger bullets because going back and forth means they are dealing with barrels that begin with coating.
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Infrequent Shooter
Gold $$ Contributor
agree, excellent shooting.
JoeDuke
Gold $$ Contributor
These was a somewhat local shooter who had built a pump rig to pump kerosene thru his barrel to cool it between matches. Then I believe he just patched it dry to go back to the line but could be a bit mistaken in this. It was a long time ago. Best I remember, his kerosene container was also inside a cooler so he could put ice around it. might be worth a try as it does alleviate the moisture in the barrel problem. But it does just substitute kerosine though and that has to be addressed before shooting.
Joe, I’m about there myself, - liquid cooling from the inside. I’m thinking about cutting the top off of a helium tank and welding three little support legs to it to make an old school Shilen style water dipping tank. Then running patches down the barrel.
My string fire stocks are synthetic or aluminum so there’s no concern about damaging the forend, and I think every barrel I have ever ordered is stainless steel.
I watch a lot of forging programs. Temperature of course softens metal which is bad enough, but I think our hot barrels’ interior surface is also pulled and stretched by the bullet, moreso, much in the same way that hot tires and hot asphalt try stick to each other. We don’t want them to “hook up” at all, unlike in racing.
Ideally the more compliant bullet would obturate, seal the barrel but otherwise just slide right down it without imparting much additional damage to either surface. They don’t slide down whatsoever, as anyone with a rod and stuck bullet knows.
Heat from friction didn’t help us get to the target faster or more accurately (we could always sub in faster powders as needed) and might blow up a bullet, but in any case wears out the barrel. This is partly why I really like HBN.
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JoeDuke
Gold $$ Contributor
The system I remember was all mounted in a little rolling cart arrangement. There was the tank, battery, and pump all mounted in it. There were a couple of hoses. One had fixture that inserted thru the action to seal in the chamber much like a cleaning rod guide. The other hose fit the muzzle and returned fluid back to the tank. It also incorporated a gun holding arrangement muzzle down on the cart. A completely self contained setup.
I recall a guy with a cold water flushing system, which he used cool his unlimited BR rifle. This was in 1972. I've seen the concept recycled a half dozen times since. Personally, I think it's not a bad idea. WH
There’s two parts love of the 250 A-Tip in this potential color scheme, Will, and one part humor, as I have learned not to shoot them through too hot a barrel!
I have coated the inside. It’s tall enough that when the rifle displaces water, it will rise to the desired level without spilling out, and without the barrel hitting the bottom either.
I will put rubber “U” shaped trim on the rim, and then it should be good to go. The idea is to start the string with an ice water temperature barrel inside and out.
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The 300WM is a pussy cat. The recoil is not that bad. I can put 60 down range and not even have a bruise on my shoulder. I am 50 years old and close to crippled compared to my youth. Been shooting the 300WM for hunting and long range work and reloading for it since 1995. I got my son a light weight 300WM when he said he wanted to go Elk hunting.
Is it the best choice by todays standards for long range competition? No! Can it still be very competitive you bet your Douluth Trading Company underware it can be! The trick is choosing a chamber reamer that is designed for precision shooting combined with really good reloading habits! You do not want a SAAMI chamber reamer. In the past when I was running a 300WM for long range target shooting I went SAAMI minimum then throated for the bullet I wanted to run. There are better options today as I understand it.
In the right hands the 300WM set a lot of records in the past. Just like with the right bullet it is a devasting hunting cartridge. Since I have not competed with a 300WM since 2007 I am not up to scratch on modern trends but I still hunt with one.
Handling recoil is more mental than physical combined with good diet and a little bit of exercise. Technique plays a role too their are tiny littlle women that shoot big bore hand guns and hadle it better than most men. It was not that long ago when most men where 5'5" to 5'8" and 145lbs. and these guys went to war with a 30-06. A lot of us shot NRA High Power with a 30-06 in all postions.
Look at what guys do today with long barreled 308Win in F-TR! Between the long barrels, faster twist rates, modern bullet designs and powder! It ain't your Dad's or Grandfathers 7,62 NATO or 308Win!
Read the article on the Mk248 Mod 1 or Mk248.1 as a starting point. Keep in mind this is not ammo loaded by someone competing and was not designed to be either just a military cartridge to reach out and kill humans at long ranges with far less weight than a 338LM weapons platform!
Your allowed a 10kg rifle. That much mass mitagates a lot of recoil. Some of that weight should be ballast so you can always shed a few ounces should your scale differ from the scale in use at the match.
So while I do not think 300WM is the ideal cartridge I would not let it deter me. When you burn out the barrel if you do not like it easy to go a different direction and just build yourself a hunting rig and reuse the brass, bullets and dies for hunting. Let's face it competing with a magnum or cartridge with magnum like performance is going to burn through barrels at the level of competition and volume fire and fast strings!
Is it the best choice by todays standards for long range competition? No! Can it still be very competitive you bet your Douluth Trading Company underware it can be! The trick is choosing a chamber reamer that is designed for precision shooting combined with really good reloading habits! You do not want a SAAMI chamber reamer. In the past when I was running a 300WM for long range target shooting I went SAAMI minimum then throated for the bullet I wanted to run. There are better options today as I understand it.
In the right hands the 300WM set a lot of records in the past. Just like with the right bullet it is a devasting hunting cartridge. Since I have not competed with a 300WM since 2007 I am not up to scratch on modern trends but I still hunt with one.
Handling recoil is more mental than physical combined with good diet and a little bit of exercise. Technique plays a role too their are tiny littlle women that shoot big bore hand guns and hadle it better than most men. It was not that long ago when most men where 5'5" to 5'8" and 145lbs. and these guys went to war with a 30-06. A lot of us shot NRA High Power with a 30-06 in all postions.
Look at what guys do today with long barreled 308Win in F-TR! Between the long barrels, faster twist rates, modern bullet designs and powder! It ain't your Dad's or Grandfathers 7,62 NATO or 308Win!
Read the article on the Mk248 Mod 1 or Mk248.1 as a starting point. Keep in mind this is not ammo loaded by someone competing and was not designed to be either just a military cartridge to reach out and kill humans at long ranges with far less weight than a 338LM weapons platform!
Your allowed a 10kg rifle. That much mass mitagates a lot of recoil. Some of that weight should be ballast so you can always shed a few ounces should your scale differ from the scale in use at the match.
So while I do not think 300WM is the ideal cartridge I would not let it deter me. When you burn out the barrel if you do not like it easy to go a different direction and just build yourself a hunting rig and reuse the brass, bullets and dies for hunting. Let's face it competing with a magnum or cartridge with magnum like performance is going to burn through barrels at the level of competition and volume fire and fast strings!
My draw to the Win Mag in F-Class had to do with brass unavailability in the RSAUM. It was a withering commercial round about 4 years ago, but it was fantastic in Fclass. I had seen brass limitations with the 300 WSM as well, and I frankly didn’t want to reward Norma for cancelling perfectly fine 7 RSAUM brass, (soft headed if being picky) by ordering many thousands of WSM cases at $2.50 a piece, at least, fighting over another small supply.
Additionally, the RSAUM was shooting inside 300 WSM loads. I knew there was a WSM 7 option, but the truth is several of us had already blown up EOL 195’s, and I had no headroom with the smaller Saum, so faster 195’s were not a prudent option. Brass paucity issues remained as well, with it. 30 cal barrel life was claimed to be better.
About the time saum brass supplies were truly insufferable, the 250 A-Tip was out. A lot of guys don’t realize that this bullet wiped out the feasibility of .338 diameter 300 grain bullets in bullseye competition. I used the Lapua Mag with 300 grain bullets, and it already drifted more than 195’s shot in anything. But 250 A-Tips’ BC smoked every possible combo in the Lapua Mag including the 300 A-Tips, in the wind, so badly that mine are all dormant. This remains true of current bullet options (solids, maybe, aside).
To me, the 250 A-Tip required exploitation, and the cartridge, like the powder, would be the variable. As you say, we have enough weight at our disposal to tame 30 cal recoil. The questions for me were do I want to pay somewhat more for bullets, powder and maybe barrels. Am I confident that the bullet shoots small.
The 250’s will shoot as small at 200 yards as 180 hybrids will, and A-Tips are about unbeatable on comparators. When I saw this, it answered the other questions about cost. We already spend so much to travel around doing this, what matters to us is points on the card. 215’s score great, provided you aim at the right spot, but to have the same leeway, they need to go something like 3,450 FPS.
All scores will eventually be wind call limited with all shooters once they iron out all physical and mechanical issues. You can improve wind skills, you can move closer to the target, or you can block the wind.
Shooting higher BC is functionally no different than moving closer to the target, blocking the wind is hard to get away with, and I will posit that just as there is some mathematical expression, some amount of weight on the barbell, and some time on the mile run, there IS a level of wind reading talent that we just aren’t getting past, at least any faster than the other guy has progressed.
The Win Mag had a following in match use in the 70’s and maybe a while beyond, and this seemed reinforced when I debated options, from the number of old 40-X’s chambered for it, but not many if any larger than it, that I was seeing for sale and collecting.
Hornady had already released the 300 PRC. This was a tough call, because the Hornady 250 A-Tip seemed a natural fit. But on closer examination it is a shorter column, and when we use the slowest powders to minimize peak pressure spiking with the heaviest bullets, a stretched column is more conducive to progressively building up pressure slowly.
Also, circling back to the beginning, I think if a brass maker exists, it’s going to make 300 Win Mag, and because it’s a crowded market, the price will be fair, from now to the end of guns.
I don’t think a bigger cartridge would help, like the Norma Mag. I already work hard to mitigate barrel heat. And by “heat” I mean just regular Fclass temperatures. I actually need to shoot below saum temperatures to be reasonably sure that a bullet won’t blow up. I coat the bullets and often spray the barrel. I think that is more an A-Tip need than a Win Mag cartridge issue. The mod 2 runs a lot more H-1000 than I do with my heavier bullets. I’m at or just under 2,750 FPS.
It’s hard to say what is ideal. The 308 in very good hands usually splits F-Open at the middle of page one, sometimes much higher up than that. I’m beginning to see a better LR potential for me, than my other calibers delivered, definitely when it’s a challenging wind day.
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