backwoods83
Well-Known Member
- Joined
- Jan 8, 2011
- Messages
- 3,491
Forester dies or Redding comp dies, rcbs hand primer is fine, try for .004" below flush.
High extreme spread
- Thread starter D Scott
- Start date
Help Support Long Range Hunting Forum
woods
Well-Known Member
IME seating depth does have an effect on ES and SD. My question would be, how much did you vary your seating depth between loads?
For example, in my 6.5 rem mag (26" Douglas barrel tight necked) I did a seating depth test with 130 gr SSII's starting at .015" off and varied by .015" to .090" and it gave the following results
.015" off - ES 31, SD 11.67
.030" off - ES 31, SD 11.70
.045" off - ES 23, SD 9.80
.060" off - ES 8, SD 4.00
.075" off - ES 27, SD 11.40
.090" off - ES 52, SD 31.70
So seating depth can make a huge difference in ES & SD. Most just don't like to seat that far off the lands, hence my question as to how much you varied between seating depth loads
D Scott
Well-Known Member
I have seated from5 thous off to 25 thous off, no real changes in accuracy, at least short range, didnt go as far off as you suggest, but will give it a try
thanks
thanks
barnesuser28
Well-Known Member
Have you been keeping up with throat erosion? My 284 win has .010" of erosion in just over 400 rounds.
D Scott
Well-Known Member
yes, I've been noticing how my actual chamber measurement has increased a few thous, I have about 1400 down the tube now, which leads me to another question, as the throat erodes and the bullet is seated farther out , to match the lands, will this cause a sig change in pressure as there is more volume in the case ? any thoughts ?
thanks Scott
thanks Scott
I also bought 200 Lapua cases in 260 Rem about a year ago and had similar issues, two different lots. Resizing difficulty, erratic accuracy, etc. I bought some Norma brass an all was fine. I have had great results with Lapua brass in my other rifles but ended up trashing the Lapua 260 brass and haven't used it again.
A couple of questions. With 1400 rounds through the rifle, did the ES issues develop recently? If results were originally OK, did you change any components, or use a new lot of powder, bullets, or brass?
Generally, you shouldn't see much, if any change with only a few thousandths of wear, particularly with standard shaped bullets. It doesn't seem like this should be your issue, but barrels can wear out prematurely. 1400 rounds isn't a lot for a 260, bit I had a 308 go bad at 2000 rounds which was not typical.
The Magnetospeed can change accuracy, POI, or both. Some rifles are unaffected at all. It depends on your specific barrel's harmonics when the MS is attached to the barrel. It is critical that the barrel straps are secure and the unit does not move at all when fired. Using a piece of rubber, or the additional rubber pad on top of the barrel,
under the strap secures it well. I don't measure groups, or zero when using the MS. Even with this inconvenience, I still think it's a superb unit for accurately measuring velocity and ES.IMO
MagnumManiac
Well-Known Member
I don't chase the lands, I found it prudent to increase the powder charge to keep the velocity consistent because changing the seating depth changes the expansion ratio which changes the barrel harmonics more than I like, I was forever chasing my tail getting my groups back to spec after altering the seating depth to match the same amount off the lands.
When I changed the powder charge alone, accuracy would come back almost immediately, some minor tweaking has still been necessary, but nothing like when I was chasing the lands, too many variables that accumulated with each change.
Cheers.
gun)
Trickymissfit
Well-Known Member
I use the K&M, and the priming device on my Forster press about 95% of the time. Also have the Lee and the RCBS. Have used the Sinclair a little bit, and it's also a very good tool. The Sinclair and problems with my hands didn't mix, otherwise I would still own one. The Forster is extremely consistent, as it seats the primer .0045" +/-.0005" everytime. The K&M and the Sinclair have a very nice feel to them.
gary
woods
Well-Known Member
You should read Bergers recommendations for finding seating depth. They recommend .040" between loads
http://www.longrangehunting.com/for...accuracy-berger-vld-bullets-your-rifle-40204/
Seating between .005" off and .025" off will not even get you much variation at all
D Scott
Well-Known Member
thanks for all the great feedback, I will give those ideas a try, also great article from Berger , I wish we saw more articles like that,
thanks Scott
thanks Scott
FAL Shot
Well-Known Member
I have found that seating depth is no big deal in CZ rifles. It is also no big deal in my brother-in-laws Ruger M77 rifles. CZ rifles have the chamber hammer forged at the same time the barrel is made, by the same mandrel. As long as the chamber is accurately aligned with the barrel, and case necks are straight and concentric, the bullet does not start out crooked and get axially misaligned in the barrel. There is hardly any diference in accuracy whether the bullet is almost on the lands or .250" off the lands, provided it is a bullet the rifle likes.
In rifles where the chamber is drilled after the barrel is button rifled or cut rifled, chamber/bore misalignment is common and almost a certainty in cheaply made rifles. The $400 rifles with injection molded plastic stocks and bolts that feel like a mop handle in a mop bucket when they are worked are probably going to be sensitive to seating depth, since a good custom barrel costs as much as many want to pay for a new rifle these days,
In two of my CZ 527 rifles, when you load just about any bullet to book specs, the bullet will be almost touching the lands. On both of my brother-in-laws M77 rifles, when you load to book spec lengths, you will be far from the lands, .140" in the case of his .30-06. In my CZ 550 7x57 with a light bullet, as far as .250" from the lands. They all shoot factory loads about equally well, and shoot well developed handloads very well. In the M77 .22-250, you can't load at the lands and get the cartridge in the magazine. It shoots 1/2 MOA with several bullets with the bullets far from the lands.
In a good barrel that is properly made, seating depth isn't going to be an issue with most bullets. Almost every modern semi-auto military rifle I ran across is made to where if you can get the cartridge in the magazine, you do not have to worry about the bullet being shoved in the lands. You are .075" off the lands in my FAL if you load to magazine length. The BIG difference is in type of bullets you shoot in it, and the powder shoving the bullet.
A long soft bullet with very little bearing surface such as a Berger VLD will be the worst type of bullet for needing exact seating depth. Once they start a wobble in the bore, it never goes away.
Tangent ogives are better than secant ogives for getting a consistent distance from the lands, and you can't much go by C.O.A.L. with a secant ogive. Many seating dies will put a circular dent in the nose of a Hornady A-Max, and it will vary with seating pressure giving one more variable to consider. Same goes for the Berger VLD. You will need an overall length gauge and measure from where the bullet contacts the rifling lands and measure every bullet and use a micrometer seating die if you like soft secant ogive bullets. I solved my problem by using a Redding seating die that has a larger contact area that does not "bite the bullet" on the nose so hard when a bullet is seated.
The chances of getting a misaligned chamber in a hammer forged barrel is astronomical unless the barrels are made in bulk and then chambered when an order comes in. A big company like CZ isn't going to use such practices, and they have the latest ISO certifications with a recently retooled factory that pretty much guarantees such things do not occur, and one rifle of the same type will shoot almost the same as another of the same type with the same load. The same is true of the new Winchester Model 70 rifles as they are made in a highly automated factory mostly by CNC machines, the same as the FN machine guns are made. In such highly automated, modern and high volume factories as CZ and FN, they set the low price point where you can have an affordable rifle and still have it precise and accurate. A person who owns CZ, Kimber and Cooper rifles tells me the CZ rifles are the most consistently accurate in spite of being the lowest cost, but the Kimber and Cooper rifles are very accurate as well and are "fancier". My gunsmith has a CZ rifle that puts bullets through the same hole at 100 yards, consistently. He works on all brands, and praises CZ highly, as well as the new Winchester Model 70. Buying a costly custom rifle to get match grade accuracy is now totally unnecessary when you buy recent production from these two companies.
Like I said, I see issues where the CZ rifle likes one bullet better than the other, because bullets are not the same, but it is not fussy about seating depth when a proper bullet/powder combination is found. Putting out a ridiculous plastic stocked centerfire rifle for $400 is something that CZ has not stooped to yet, unlike many American manufacturers. My gunsmith bemoans the fact that most people will not pay that extra $200 to get a properly stocked rifle, and American manufacturers have noticed that most costomers (not misspelled, as many customers are really costomers) shop by looks and the price tag.
There are also those who shop by the price tag and expect a high priced custom rifle to shoot better than a PROPERLY made production rifle. The custom gun market owes a lot to those people. A Nosler custom rifle is guaranteed 1/2 MOA with Nosler custom ammo ONLY. My CZ rifles, ALL of them, are that accurate out of the box with properly developed handloads, and with 5-shot groups, not the cheating 3-shot group specification many manufacturers use. They know their barrels will warp out as they heat up, not being made to current military type stress relief methods as CZ obviously uses, and probably Winchester M70 made in the FN factory as well. I just shoot my CZ rifles when working up loads these days, and do not worry about cooldown in the 5-shot group. I also use temp stable Extreme powders exclusively now. To not do so does NOT take advantage of the features that Hodgdon and CZ is giving you by making their products temp stable.
A CZ 550 bolt rifle is a true SHTF rifle, and Russian Special Forces think so as well, having used them for decades.
I expect my bullets to be "seating depth insensitive" as well. Such a situation exists, so why not take advantage of it and have one less thing to worry about???
In rifles where the chamber is drilled after the barrel is button rifled or cut rifled, chamber/bore misalignment is common and almost a certainty in cheaply made rifles. The $400 rifles with injection molded plastic stocks and bolts that feel like a mop handle in a mop bucket when they are worked are probably going to be sensitive to seating depth, since a good custom barrel costs as much as many want to pay for a new rifle these days,
In two of my CZ 527 rifles, when you load just about any bullet to book specs, the bullet will be almost touching the lands. On both of my brother-in-laws M77 rifles, when you load to book spec lengths, you will be far from the lands, .140" in the case of his .30-06. In my CZ 550 7x57 with a light bullet, as far as .250" from the lands. They all shoot factory loads about equally well, and shoot well developed handloads very well. In the M77 .22-250, you can't load at the lands and get the cartridge in the magazine. It shoots 1/2 MOA with several bullets with the bullets far from the lands.
In a good barrel that is properly made, seating depth isn't going to be an issue with most bullets. Almost every modern semi-auto military rifle I ran across is made to where if you can get the cartridge in the magazine, you do not have to worry about the bullet being shoved in the lands. You are .075" off the lands in my FAL if you load to magazine length. The BIG difference is in type of bullets you shoot in it, and the powder shoving the bullet.
A long soft bullet with very little bearing surface such as a Berger VLD will be the worst type of bullet for needing exact seating depth. Once they start a wobble in the bore, it never goes away.
Tangent ogives are better than secant ogives for getting a consistent distance from the lands, and you can't much go by C.O.A.L. with a secant ogive. Many seating dies will put a circular dent in the nose of a Hornady A-Max, and it will vary with seating pressure giving one more variable to consider. Same goes for the Berger VLD. You will need an overall length gauge and measure from where the bullet contacts the rifling lands and measure every bullet and use a micrometer seating die if you like soft secant ogive bullets. I solved my problem by using a Redding seating die that has a larger contact area that does not "bite the bullet" on the nose so hard when a bullet is seated.
The chances of getting a misaligned chamber in a hammer forged barrel is astronomical unless the barrels are made in bulk and then chambered when an order comes in. A big company like CZ isn't going to use such practices, and they have the latest ISO certifications with a recently retooled factory that pretty much guarantees such things do not occur, and one rifle of the same type will shoot almost the same as another of the same type with the same load. The same is true of the new Winchester Model 70 rifles as they are made in a highly automated factory mostly by CNC machines, the same as the FN machine guns are made. In such highly automated, modern and high volume factories as CZ and FN, they set the low price point where you can have an affordable rifle and still have it precise and accurate. A person who owns CZ, Kimber and Cooper rifles tells me the CZ rifles are the most consistently accurate in spite of being the lowest cost, but the Kimber and Cooper rifles are very accurate as well and are "fancier". My gunsmith has a CZ rifle that puts bullets through the same hole at 100 yards, consistently. He works on all brands, and praises CZ highly, as well as the new Winchester Model 70. Buying a costly custom rifle to get match grade accuracy is now totally unnecessary when you buy recent production from these two companies.
Like I said, I see issues where the CZ rifle likes one bullet better than the other, because bullets are not the same, but it is not fussy about seating depth when a proper bullet/powder combination is found. Putting out a ridiculous plastic stocked centerfire rifle for $400 is something that CZ has not stooped to yet, unlike many American manufacturers. My gunsmith bemoans the fact that most people will not pay that extra $200 to get a properly stocked rifle, and American manufacturers have noticed that most costomers (not misspelled, as many customers are really costomers) shop by looks and the price tag.
There are also those who shop by the price tag and expect a high priced custom rifle to shoot better than a PROPERLY made production rifle. The custom gun market owes a lot to those people. A Nosler custom rifle is guaranteed 1/2 MOA with Nosler custom ammo ONLY. My CZ rifles, ALL of them, are that accurate out of the box with properly developed handloads, and with 5-shot groups, not the cheating 3-shot group specification many manufacturers use. They know their barrels will warp out as they heat up, not being made to current military type stress relief methods as CZ obviously uses, and probably Winchester M70 made in the FN factory as well. I just shoot my CZ rifles when working up loads these days, and do not worry about cooldown in the 5-shot group. I also use temp stable Extreme powders exclusively now. To not do so does NOT take advantage of the features that Hodgdon and CZ is giving you by making their products temp stable.
A CZ 550 bolt rifle is a true SHTF rifle, and Russian Special Forces think so as well, having used them for decades.
I expect my bullets to be "seating depth insensitive" as well. Such a situation exists, so why not take advantage of it and have one less thing to worry about???
