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dwight

heym sr 21 .243 twist rate?

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Guest sean1967

I think you'll find its a 1:9 twist.

 

You might find you struggle to get it to shoot 100grn well if its a 1:10.

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I think you'll find its a 1:9 twist.

 

You might find you struggle to get it to shoot 100grn well if its a 1:10.

 

Harry

 

Do you have a link to this?The reason I ask is that when I looked at them a few years back the importer at the time informed me they were 1:10

 

Why don`t you think that twist rate wouldn`t stabilize well with 100 grainers ?

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Guest sean1967

Tom, Dick. Fred.?????????

 

An ex-colleauge of mine actually owns one. With 3 barrels 1 of which is the .243. :D

 

1:10 twist has always been marginal for 100gr .243's since the day they were first launched in the `50's.

 

Remington found that out to their cost with the Rem 6mm.

 

Some of the barrel makers even go as far as recommending 1:8 for a dedicated 100gr shooting barrel.

 

As for the science. The physics of ballistics There has been shed loads of articles and research papers written about the direct and indirect correlation between twist rates and bullet head stability. Some of them I've read, some of them I have understood, some of them, I have either not read or not understood.

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Three of the biggest manufacturers (Remmy,Sako,Tikka) and a good few others give their standard twist rate for a 243 at 1:10

 

Still the biggest factory stalking round sold in the UK is the 100 grain so you`d think that they stabilize well enough in the majority of these rifles :D

 

I`m glad you cleared up the Heym twist rate question though.Makes you wonder why some one selling a product wouldn`t take the time to find out the basics of what they`re offering :D

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Guest sean1967
Three of the biggest manufacturers (Remmy,Sako,Tikka) and a good few others give their standard twist rate for a 243 at 1:10

 

Still the biggest factory stalking round sold in the UK is the 100 grain so you`d think that they stabilize well enough in the majority of these rifles :D

 

I`m glad you cleared up the Heym twist rate question though.Makes you wonder why some one selling a product wouldn`t take the time to find out the basics of what they`re offering ;)

 

What you say is correct. That is why those who own those particular brands usually find that they get slightly improved accuracy when they drop down into the 80-90grn bracket.

 

The factors influencing sales volumes are complex and another tale all together. You work for a retailer, I'm sure you're well aware of what makes people buy and what doesn't.

 

It takes all sorts to make a world and the same applies to retail. Some retailers if they don't know will say so others will work on the principle of BBB's. I guess you can't expect them to know every last little detail about every one of their products including all of its variations. Doesn't the sr21 accept something like 15-17 different calibres in its standard form?

 

Did you by any chance ask them what twist rate was for 6x62 Freres? :D

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Guest sean1967
My .243 has a 1:9 1/8 rate of twist, not sure if this helps you!

 

Whats the make Sprags?

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Did you by any chance ask them what twist rate was for 6x62 Freres? :D

 

It seems bizarre that such an obscure calibre should be offered in a factory configuration does it not.Blazer also offer it in their listings :D

 

 

After looking on the ammo guide it apparently gives ballistics similar to the 6mm-06 and is based on a 9.3x62 case ;)

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Can anyone, in simple terms, explain the relationship between twist rate and bullet weight?

 

What works well in theory with a slow twist or a fast twist?

 

I believe my steyr in .243 is a 1:10 twist, nothing on the website or manual but I been infornmed that is the case by a good source.

 

Jerry

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Guest sean1967

I think it was P.O. Ackley who said "Theres nothing new when it comes to ballistics", and he should know.

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Can anyone, in simple terms, explain the relationship between twist rate and bullet weight?

 

What works well in theory with a slow twist or a fast twist?

 

I believe my steyr in .243 is a 1:10 twist, nothing on the website or manual but I been infornmed that is the case by a good source.

 

Jerry

 

 

Jerry

 

A couple of links that will explain it far better than I could :D

 

http://www.gunnersden.com/index.htm.rifle-...wist-rates.html

 

And

 

http://www.chuckhawks.com/rifle_barrel.htm

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The reason i posted this question was because my friend shoot deer with his heym 243 using 100gn fed powershock.we recently did a bit 100yd target shooting and it shoots spot on to 100..

He said to me that when out deer shooting deer to 100-150 is no bother but any further out than that is more often a complete miss.

Last thurs we were both out shotting deer and we spotted one around 200-220 out and he asked my for my rifle(6.5x55) to take the shot as he has taken shots at this range before with the heym and had total misses.He took the shot and was bang on for a heart lung.

So what im thinking is that the 243 100gn is losing stability beyond the 100-150yd range...I could be wrong.It might just be him.

If a bullet is unstable at what range would it be noticable..

 

Dwight.

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Guest Sprags
Whats the make Sprags?

 

 

 

 

It's a Remington 700 Sean.

 

 

Regards,Sprags!!

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Dwight

 

It could be that or that the bullet is simply running out of steam at that range if its spot on at 100yds :D

 

If you look at Federal ballistic charts the 243 100g bullet drops around 6" to the 250 mark

 

It`s probably best to put up some targets at various ranges to work out the drops.

 

If the bullet is unstable at longer ranges you`ll see the keyholing

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Dwight

 

It could be that or that the bullet is simply running out of steam at that range if its spot on at 100yds :D

 

If you look at Federal ballistic charts the 243 100g bullet drops around 6" to the 250 mark

 

It`s probably best to put up some targets at various ranges to work out the drops.

 

If the bullet is unstable at longer ranges you`ll see the keywholing

Thanks mate..

We`ll give it a go

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Dwight

 

The bullet will not be 'running out of steam ' at that range, at a guess its ballistics should be good to drop a deer out to at least 400yds

 

It is most likely that your friend is not aware of the amount of drop his round takes on at that distance and therefore not aiming high enough OR is unaware of the amount of effect wind is having as the distances increase and again not making enough allowances

 

the best thig to do is to get some range time somewhere and learn how the rifle bullet combo works on targets before he engages any more live targets at those ranges

 

Ian

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Duey

 

You are correct in hindsight I should have not said running out of steam but should have said dropping more than the shooter was aware at that range as you pointed out

 

 

Apologies for the confusion :D

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The reason i posted this question was because my friend shoot deer with his heym 243 using 100gn fed powershock.we recently did a bit 100yd target shooting and it shoots spot on to 100..

He said to me that when out deer shooting deer to 100-150 is no bother but any further out than that is more often a complete miss.

Last thurs we were both out shotting deer and we spotted one around 200-220 out and he asked my for my rifle(6.5x55) to take the shot as he has taken shots at this range before with the heym and had total misses.He took the shot and was bang on for a heart lung.

So what im thinking is that the 243 100gn is losing stability beyond the 100-150yd range...I could be wrong.It might just be him.

If a bullet is unstable at what range would it be noticable..

 

Dwight.

 

First of all, if you have the barrel handy, you can measure the twist yourself, rather than wait for answers as to what might be the twist. If you have a cleaning rod and fresh brush, run that thru the bore until you just about get to the muzzle. Make a mark at top dead centre on the cleaning rod just where it comes out from the back of the action or rear of your bore guide. Pull the cleaning rod back towards you, making sure it doesn't slip(it needs to freely swivel in the twist) until that mark is again top dead centre. Measure along your cleaning rod from that mark to the back of the action or bore guide, wherever you made your initial. That is your twist rate.

 

Second. If a bullet is stable at 100-150yds, it's not going to lose stability in the next 100-150 yds. There's probably some other reason.

 

a 10 twist is the absolute minimum I would use for many of the 100gr projectiles in 6mm/243, and who knows how close to 10 some are using in factory pipes unless you measure it yourself..Better to use faster than 10 if going to the heavy end of the spectrum of 6mm bullets. The reason Remington and the like would use 10 twist is because they are more prone to consider 85-90 ish grain bullets as the heaviest, aren't making rifles for the UK market. I've seen enough difference in group diameters versus twist rates that anyone asking to rebarrel the 6mm for deer would get a recommendation of faster than 10 twist.

 

JR

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My own take on the sako/tikka 1 in 10 twist is this.People tend to use them for deer, almost certainly when using 100 grain bullets.dont take this the wrong way chaps, especially the deer shooters here, but most deer shooters we get in the shop are perfectly happy with the bds 4" group at 100 yards...they think thats adequate for deer, so the sako/tikka twist works for them.Give the same thing to a target shooter, and he will walk away.My sako 75 when it was a .243 wouldnt shoot anything over 87 grains accuratley. I personally believe remington have the best twist rate of 9 and 1/8" it seems to shoot everything from 58 grain v-max, to a 100 grain deer bullet. Incidentally though, i believe the sako/tikka,s perform well with factory 100 grainers, especially sako,s own brand.They could be using a very slow powder, which is apparently one of the tricks to get better accuracy from a 100 grain bullet.

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First of all, if you have the barrel handy, you can measure the twist yourself, rather than wait for answers as to what might be the twist. If you have a cleaning rod and fresh brush, run that thru the bore until you just about get to the muzzle. Make a mark at top dead centre on the cleaning rod just where it comes out from the back of the action or rear of your bore guide. Pull the cleaning rod back towards you, making sure it doesn't slip(it needs to freely swivel in the twist) until that mark is again top dead centre. Measure along your cleaning rod from that mark to the back of the action or bore guide, wherever you made your initial. That is your twist rate.

 

Second. If a bullet is stable at 100-150yds, it's not going to lose stability in the next 100-150 yds. There's probably some other reason.

 

a 10 twist is the absolute minimum I would use for many of the 100gr projectiles in 6mm/243, and who knows how close to 10 some are using in factory pipes unless you measure it yourself..Better to use faster than 10 if going to the heavy end of the spectrum of 6mm bullets. The reason Remington and the like would use 10 twist is because they are more prone to consider 85-90 ish grain bullets as the heaviest, aren't making rifles for the UK market. I've seen enough difference in group diameters versus twist rates that anyone asking to rebarrel the 6mm for deer would get a recommendation of faster than 10 twist.

 

JR

Thanks JR..

Thats just too easy...lol

Why didnt i think of that method :lol:

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Baldie

 

Well done, I wasn't sure about mentioning the 4" group of the BDS myself when i first posted but it has to be taken into consideration

 

If at a 100yds the group is between 2-4" the group at 200yds will therefore be between 4-8" combine this with all the other factors calculated into margin of errors then a miss at 200yds can be common

 

If the grouping achieved at 100yds is not at or below 1" then I would suggest a slightly lighter bullet that groups better as it is shot placement rather than bullet weight or caliber that is the crittical factor in a clean humane cull of any animal

 

Ian

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Baldie

 

Well done, I wasn't sure about mentioning the 4" group of the BDS myself when i first posted but it has to be taken into consideration

 

If at a 100yds the group is between 2-4" the group at 200yds will therefore be between 4-8" combine this with all the other factors calculated into margin of errors then a miss at 200yds can be common

 

If the grouping achieved at 100yds is not at or below 1" then I would suggest a slightly lighter bullet that groups better as it is shot placement rather than bullet weight or caliber that is the crittical factor in a clean humane cull of any animal

 

Ian

 

Sometimes forget that some peoples version of 'acceptable groups' is often not quite what I'd accept as accurate. Took me years to convince the good ol' boys back home that the fact you hit a 1 gallon milk jug at 25 yds was probably not the best test, and 'sighting in' was explained as 'well you take your first shot on the deer and see where you miss, then you adjust and keep shooting until you hit it, or run out of ammo.'..Bless 'em..

 

JR

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Guest sean1967
a 10 twist is the absolute minimum I would use for many of the 100gr projectiles in 6mm/243, and who knows how close to 10 some are using in factory pipes unless you measure it yourself..Better to use faster than 10 if going to the heavy end of the spectrum of 6mm bullets. The reason Remington and the like would use 10 twist is because they are more prone to consider 85-90 ish grain bullets as the heaviest, aren't making rifles for the UK market. I've seen enough difference in group diameters versus twist rates that anyone asking to rebarrel the 6mm for deer would get a recommendation of faster than 10 twist.

JR

 

Exactly!

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