Archive for May 2010

IZH MP655 BB and pellet pistol – Part 3

by B.B. Pelletier

Before we start, I have a some announcements.

Pyramyd Air’s 3rd annual airgun garage sale is on June 5 from 10 am to 3 pm. There will be discontinued, blemished and used guns, scopes and other accessories — plus dented tins of pellets. John Goff from Crosman will be flipping burgers and Pyramyd Air’s technicians will be on hand to help with any questions you might have. Come early for the best selection!

The 18th annual Daisy Get Together will be held on Sunday, August 22, at the Kalamazoo County Fairgrounds Expo Center in Kalamazoo, Michigan, from 9 am to 3 pm. Admission is $2.00…and well worth the entry fee! If you have any interest in buying, selling, trading or seeing vintage BB guns, cap guns and toy guns, this is THE place to go. Besides those great old Daisy guns, there will be plenty of other brands, many so rare that you probably won’t see a second example anywhere else. Contact Bill Duimstra (616-738-2425 or ) or Wes Powers (517-423-4148) for a brochure.

Last but not least, I’d like to thank our military men and women, both current and past, who have given so much to guarantee our freedoms.

Part 1

Part 2


The IZH MP-655K BB and pellet repeater.

The MP655K CO2 pistol is unique in that it shoots both BBs and pellets. In part 2, we looked at velocity with BBs. Today, we’ll look at velocity with pellets.

Update: The following crossed-out paragraph should not have appeared in this blog report. As stated in part 1 of the report on this pistol, the 655K does not have blowback, although the slide moves freely. We’re sorry for the confusion on this! I don’t think I stressed this enough in the first 2 reports, but this pistol has blowback. Not only do you get 90 consistent shots, but the slide moves for every one of them. The mass of the synthetic slide is low, so the felt recoil is lighter than you might expect. But it’s there. Normally, a blowback gun will get far fewer shots because some of the gas is used for moving the slide. Somehow, IZH has found a way around that. They’ve given us our cake and allowed us to eat it too.

Hobbys
Mac tested the RWS Hobby pellets with a fresh CO2 cartridge. Weighing only 7 grains, we expected to get good velocity from Hobbys. And, we often get good target accuracy at close range.

Shooting single-action, Hobbys averaged 292 fps, with a range from 269 to 328 fps. The average velocity produced a muzzle energy of 1.33 ft-lbs.

On double-action, Hobbys averaged 325 fps, with a range from 304 to 348 fps. The average muzzle velocity produced 1.64 ft-lbs. It’s pretty obvious that the MP-655K is a little more powerful double-action than single.

Premiers
The other pellet Mac tested is the Crosman Premier (7.9 grains) on double-action. The average velocity was 230 fps, with a range from 208 to 240 fps. That gives a muzzle energy of 0.93 ft-lbs.

On single-action, the pellet averaged 206 fps, with a range from 192 to 218 fps. That gives a muzzle energy of 0.74 ft-lbs.

How many shots?
We already answered this question when we tested BBs. You’re gonna get the same performance on pellets as you did on BBs. In other words, a useful string for plinkers of 90 shots. No reason to over-complicate this. A projectile is projectile — the gun doesn’t care what’s going down the bore.

The 655K, which is the Russian MR 445 Varjag, is a novel sidearm. We’ve already seen many innovations, such as how the BB magazine works. In our next and final report, we’ll look at accuracy with both BBs and pellets.

IZH MP-656K or TT33 BB pistol – Part 1

by B.B. Pelletier


The IZH Baikal MP656K, which is the BB gun version of the Tula Tokarev…commonly called the TT33 Tokarev.

I always like to give you guys something to talk about over the weekend. Today’s pistol should generate a lot of conversation. Not only is it a BB pistol made on the TT33 Tokarev styling, this one is made out of a real Tokarev.

Back during the Vietnam War, I owned two of these. Each was a Norinco Chi Com variant of the Russian Tokarev. I learned then what a novel little pistol this is. It fires a .30 cal (7.62mm) bottlenecked cartridge that closely resembles the .30 cal. broomhandle Mauser round. I fount it possible to make reloads from highly reworked 5.56mm brass. But the brass swelled, and I don’t recommend it to anybody. Ammunition was impossible to come by in the 1970s, but it’s pretty common today.

This BB pistol is so remarkable, that I’m going to expand the introduction to two reports so I can show you details of the gun. Today will be a general intro.


Just like the firearm, all the controls work on the BB pistol.

Tremendous realism
There are no compromises in this gun. It’s made from a genuine Russian Tokarev pistol. That means it’s all steel, and the black plastic grip panels have CCCP next to the Soviet star. The pistol I’m examining has a frame date of 1950.

In the past, guns made from firearms have been problematic and often removed from the market. As soon as these are in stock, buy one. Do not hesitate!

Single-action only
The Tokarev firearm is a single-action pistol, and the BB pistol is also single-action. To fire the gun, you must cock the hammer each time you shoot. That may slow down you down because you can’t fire the gun by simply pulling the trigger. So, this is more of a collector’s gun than an action shooter’s gun.


The MP-656K uncocked.


The MP-656K half-cocked.


The MP-656K cocked.


Field-stripped, if you want.

Field-stripped
Just like the firearm, the TT33 field strips quite easily. In my second report, I’ll have more to say about the internal parts since some of them are novel and require an explanation.

Realism, realism, realism!
Several years ago, we had some Kalashnikov BB guns called Junker models 1, 2 and 3. Not only did they resemble an AK47, they were made from the same parts. The Junkers were taken off the shelves quickly and are now quite scarce in the United States. While we don’t believe the same thing will happen with this pistol, true collectors should order one right away. Like a Makarov, this is real deal!

Benjamin Marauder, .25 caliber – Part 2

by B.B. Pelletier

Part 1

The last time I looked at the Marauder was when I was out of the hospital for 4 days in April. Today, thanks to the help of Mac, I’ll look at velocity. Mac tested several pellets you’re likely to use in the rifle. Because pellets have been coming up with odd weights lately, Mac weighed them to see what they really weigh. He tested Sam Yang, H&N Baracudas, Benjamin domes and Eun Jins.

The H&N Baracudas ranged from 29.8 grains to 30.3 grains. That’s a very tight spread, but not as heavy as advertised (which is 31.02). The average weight for Baracudas was 30.0 grains. We’ve weighed the Benjamin domes before, but Mac did it again. This group ranged from 27.3 to 27.9 grains. An EXTREMELY tight spread. The average was 27.6 grains. Beeman Crow Magnums ranged from 26.2 to 26.4 grains. Again, an extremely tight spread. The average was 26.3 grains. Eun Jins ranged from 35.1 to 36.0 grains. Also, not bad for such a heavyweight pellet. The average was 35.4 grains. Sam Yang was the heaviest pellet of all, ranging from 42.1 to 42.4 grains. That was also the tightest spread. The average weight was 42.3 grains. The longest pellet Mac tested in the Marauder magazine was the Sam Yang, which measured 0.456 inches long. That indicates you can use very beefy pellets in this gun, if you want.

Velocities
Sam Yang: Velocity ranged from a low of 663 to a high of 676. Average was 671 fps. That equates to an average muzzle energy of 30 ft-lbs.

Eun Jin Domes: Velocity ranged from a low of 712 fps to a high of 732 fps. Average was 724 fps. Which equates to an average muzzle energy of 41.21 ft-lbs.

Benjamin domes: Ranged from a low of 791 fps to a high of 802 fps. The average was 797 fps. The average muzzle energy was 38.94 ft-lbs.

H&N Baracudas: Ranged from a low of 774 fps to a high of 782 fps. The average for this pellet was 779 fps. Average muzzle energy was 40.43 ft-lbs.

The Beeman Crow Magnums: Ranged from a low of 814 fps to a high of 825 fps. The average was 819 fps. Average muzzle energy was 39.18 ft-lbs.

While Mac was testing the gun, all strings were fired starting at 3000 psi. In other words, he topped off the gun between each string. In doing so, he noted that the initial shots were lower in velocity, meaning that this particular rifle needs a fill of somewhat less than 3000 for optimal performance.

Shroud straightened
Mac noticed that the barrel shroud seemed to be pulling to one side when he examined it. Since accuracy testing was next, he decided to straighten it. He loosened the Allen screws that hold the shroud to its bracket, and immediately the shroud centered itself. Perhaps, when it was assembled, it got bumped during assembly. This is something you’ll want to look at when you get your own rifle.


Does your Marauder shroud touch the bracket, as shown above?


If the shroud on your Marauder is touching the bracket on one side, loosen the two Allen screws shown above to center the shroud.


Loosening the Allen screws will send your shroud straight toward the center of the bracket.

That’s it for velocity and power. Next, we’ll look at accuracy.

More on manufacturing tolerances

by B.B. Pelletier

Today’s guest blog is so fantastic, I jumped at the chance to use it. Brian has been making precision aircraft and missile parts for over 30 years, so he knows quite a bit about the subject of manufacturing tolerances. Take it away, Brian.

by Brian Saada, aka Brian in Idaho

If you’re a regular reader of the Pyramyd Air blog, then you probably read BB’s article of May 21, Pellet Variation What Do You Do?

The simple answer to that question is — not much! Or, as BB noted, you can weigh, sort and package your pellets with some semblance of order as to actual weights. Still, some of us may want to know more about these types of manufacturing variation(s) and what causes them. Is there no perfection to be had out there? In production manufacturing, there’s no perfection — only allowable tolerance or deviation from the norm.

Manufacturing tolerance
So, what is this tolerance thing anyway? Simply stated, a tolerance is an allowable range of dimension or weight or other measurable feature of a part or product. If the part or product falls within the “tolerance,” then it’s assumed to be fit for the application or use for which it was designed. As an example, if the head diameter of a .177 lead pellet can be functional or useable in a range of sizes (tolerance) from .175 through .178 diameters, then the manufacturing tolerance allows for pellets inside the tins we buy at Pyramyd Air to be .175 or .176 or .177…and also .178 in diameter. In plain, old-fashioned drawing or blueprint terms, we would see this written as .175 / .178 diameter for the nominal size .177 pellet. In practical terms, we feel these variations in our single-shot guns each time we push a pellet into the breech or barrel.

Nominal size
Wait a minute…what’s this nominal size stuff? A .177 diameter pellet or pellet gun barrel diameter is .177. Right? Not exactly. A nominal size simply means the size that can be normally expected or used in relation to some industry standard or design standard. As many of us know, the infamous steel BB that is called .177 is not .177 at all. It is typically .173 diameter but its tolerance allows it to be as small as .171 and as large as .177 (almost never at .177 diameter, per Daisy data). The nominal size of .177 is used in labeling and packaging for pellets, BBs and guns. It is not the actual or as-measured size of much of anything!

Weight and size relationship
As we know, a lead pellet is more or less a tube, depending on the style of the pellet. I say tube because, it has an outside diameter and an inside diameter too. Sure, it may not be totally hollow, but at least on the skirt surfaces we can see the inner and outer diameters. So, if a pellet diameter can vary (tolerance) does that affect the weight too? Potentially, it does. Both the inside and outside diameter can vary, and not always at the same time! Whew, more variation and larger tolerances? No, more often than not, it would be the changes in the forming die that squeezes the pellet into shape from lead wire that affects or controls the weight (along with the inside and outside diameters). Larger outside diameters or growth in the head size = greater weight. Given the density of lead, it doesn’t take much change in diameter to affect the weight of the pellet. Remember, we’re talking tenths of grams or less, and a significant change to the pellet diameter is a lot of additional surface area (weight) for an object as tiny as a lead pellet!

OK, enough on the math lesson and tolerance talk. What BB did not mention in his article about pellet weight variation was the somewhat-related topic of pellet sizing. Years ago, pellet sizing was a fairly common practice among serious airgunners. A pellet sizer was simply a hand-held steel die that forced the pellet into a specific diameter. Since then, these pellet sizers have lost their popularity except for certain die-hards (pun intended) who demand ultimate control over their pellets (wait, isn’t that us?). Now, unless the sizer sheared off some material when used, it did not affect weight. Then, as now, the only way to deal with weight variation was through sorting. Back then, we also sized the pellets after sorting out the weights. A lot of work for (arguably) little gain.

Summing it up
Manufacturing tolerances allow for mass production. Otherwise, we would handcraft each pellet to within .0001 grams of weight to each other, and we would probably manufacture two or three tins of pellets per day at a cost of, say, $150 per tin. Oops, can’t do that, now can we? Still, BB’s advice about weight-sorting your pellets is the most practical and useful piece of advice on this subject.

Enough for now, I’m off to send some of my pellets to the local testing lab to check on the standard deviation of the chemical and physical elements as relates to the density and weight of the lead alloy. Right! Typical airgunner!

IZH MP655 BB and pellet pistol – Part 2

by B.B. Pelletier

I’m still in the hospital, but my best friend, Mac, has come to my house and is doing some testing at my request. I’m now able to evaluate current airguns again based on his tests. So, let’s do part 2 of the IZH Baikal MP655K.

Part 1


The IZH MP655 is an interesting and uncommon CO2 gun.

I told you in part 1 that this is a different air pistol. And, indeed, it is. It shoots both BBs and pellets. Therefore, I’ll concentrate on BBs only in this report, as there are many different things you haven’t seen before that I’d like to cover.


The MP 655K shoots both BBs and pellets. The BB clip is the one on the left — with the magnet in the center.

BBs load in what we would call the slide in an accumulator on top of the gun. You simply pour them in, keeping the muzzle down. The BB circular clip is installed at the rear of this slide chamber and can be distinguished from the pellet clip by its magnet and an internal step in each hole that precisely orients the BB.


Each slot in the BB clip has a ridge or step to properly align the BBs.


The round object is a pressure plate that pushes the BBs into the BB clip.


The BB mechanism is quite intricate. The arrow points to the BB indexer.

This gun holds up to 100 BBs; and in all testing, it didn’t misfire one time. That means that every time the trigger was pulled, a BB came out the muzzle. That, by itself, is noteworthy.

When you’re done filling the BB accumulator, push the slide backward and don’t overlook the final detent or hump for the slide to click into place. When the slide is moved, a slick gray pressure plate puts pressure on the BBs that are aligned with the circular clip. This plate is what ensures reliable feeding. In part 1, I mentioned that gravity is what the pistol uses. While gravity does play a part, this pressure plate is by far more important and a significant feature that other guns do not have. Also in part 1, I mentioned that the cleaning rod was used to install the clips. But Mac didn’t find that necessary during his tests.

Mac tested the gun with Daisy BBs. All shots that follow were fired double-action. Shot #1 went 372 fps. Shot #2 was 361, #3 was 345 and so on until shot #10 was 290 fps. An interval of 10 seconds between shots was allowed to let the gun normalize to the ambient temperature. On a hot day, you can expect higher numbers than those that I’m going to report. The next 10 shots varied between 294 fps and 316 fps, with an average of about 306 fps. Shots 20-30 ranged from 286 to 305 fps, with an average of 297 fps.

You’re probably thinking that the gun is low-powered and running out of gas. Watch this. Shots 30 through 40 ranged between 300 fps and 334 fps, with an average of about 320 fps. So, the gun is simply seeking where it wants to be. In all, Mac fired 90 shots, ending when the velocity was 253 fps. From shots 50+, the average velocity was below 300 fps.

At one point, Mac got so excited that he cut lose and fired the gun 20 times as fast as he could pull the trigger. Perfect functioning with no failures to feed!

Single-action
The pistol performs more powerfully in the single-action mode. On one test, the average was 315 fps with a low of 306 and a high of 326. However, after pausing for several minutes, a second string without a new cartridge began at 370 fps. By the end, it had dropped down to 308. So, cooling plays a big part in how this pistol operates. The CO2 valve is isolated from your hand by the gun’s large grip. Therefore, the gun will regulate itself and may even perform different than expected on warm days. My gauge wasn’t able to measure the double-action trigger-pull weight, but the single-action pull was a crisp 5 lbs. Even part of the single-action trigger-pull involves advancing the clip. So, that makes the pull heavier than necessary. The actual single-action trigger-pull is more like 3.5 lbs. after the clip has been advanced.

Removing the CO2 cartridge
The owner’s manual states that you can’t remove the CO2 cartridge unless all the gas has been exhausted. However, Mac discovered that the CO2 cartridge screw has extremely fine threads, and you won’t have to dry-fire your gun until empty. When the gas is lower and you want to change cartridges, slowly unscrew the access plug to exhaust the gas very slowly.

Next time, we’ll take a look at velocity with pellets.

Projectile weight

by B.B. Pelletier

Update on Tom/B.B.: Tom’s condition continues to improve, and some milestones the doctors have set have been reached and even surpassed. Since Saturday, he’s been all smiles and has perked up quite a bit because his best friend, Mac, has arrived for a week’s stay. He’ll be testing guns and providing velocity and accuracy data, which B.B. will use to write blogs over the next few weeks. Since Mac is a heck of a great shot, we should be seeing some really good targets and groups.

Today’s blog is based on the various comments to the previous blogs about Pellet variation and Mass production.

AlanL has previously commented that light pellets might be more efficient and was wondering about things like drag. He specifically mentioned using aluminum for pellets. I thought I would take today and do a short report on some projectile weight changes that have been made and had major impacts over the years.


Daisy’s BBs didn’t always look like this, they weren’t always this size and they weren’t always made of steel.

The first caliber BB gun was actually shotgun shot-size BB. That’s supposed to be a round lead ball 0.180 inches in diameter. Early BB guns shot this because the shot was readily available, and owners didn’t have to make any special provisions to get it. Every hardware store carried shotgun shot.

When the 20th century dawned, the Daisy company decided to lighten their lead shot, so they down-sized it to 0.175 inches. This reduced the amount of lead that went into each projectile. It doesn’t sound like a lot, but the savings are great when you’re selling millions and billions of shot. The benefits were that the new shot flew faster in given guns. Of course, being smaller, it didn’t work in the older guns; so different size shot tubes for Daisy’s private-branded Air Rifle Shot had to be fabricated for new guns.

Fast-forwarding to the 1920s, Daisy began to get returns of their BB guns with shot stuck in the tubes. When they looked at the problem, most of these were coming from the Minneapolis area. They went there and discovered that kids were going to the scrap piles behind the American Ball Company and picking out round steel balls that would fit in their BB guns. They gauged the shot by dropping it down the muzzle to see if it stuck in the shot tube. This new type of shot worked well, but it wasn’t suited for the shot tube, which was designed for lead. Daisy saw another savings opportunity, though, and they contracted with American Ball to produce Bullseye Air Rifle Shot. We’re now into the 1930s, and Daisy guns are shooting what we see today — traditional steel BBs. They went even faster than the older lead shot, but they didn’t shoot quite as true. The shot size was now nominally 0.173 inches. Daisy was able to reduce the power of the springs in their guns, making them easier to cock and producing an overall better product.

World War II
WWII caused shortages of materials that halted production of BB guns for the duration. When the war was over, critical supplies — such as steel plate — were still in shortage and hard to come by. So, the BB gun industry took several years to ramp up into production. Since steel was such a critical item, Daisy experimented with aluminum shot. This is where today’s story plays out, AlanL. Aluminum shot was very, very fast and had absolutely no accuracy whatsoever. Daisy had discovered the threshold beyond which you cannot lighten the projectile. So, they went back to steel, and we’ve been there ever since.

Airsoft
For more proof that lightweight projectiles are less accurate, you only need to look at the world of airsoft. An airsoft BB of 0.12 grams is often selected for smaller, less expensive airsoft guns because it flies very fast. But, when put in a potentially more accurate gun, they cannot be controlled and usually fly erratically. Airsoft snipers have learned this and understand the importance of balancing the weight of the ammo with the gun.

Pellet weights
You’ll notice that there are some optimum pellet weights. If you look at what’s available for sale, you’ll find that many of the pellets are clustered within a central weight range. When you go too heavy, they become clumsy and inaccurate. When you go too light, they become erratic and inaccurate. For long-range shooting, you want a heavier projectile and a more powerful powerplant that’s suited to that projectile weight.

Pellet variation: What do you do?

by B.B. Pelletier

Update on Tom/B.B.: Tom is doing well. He keeps telling me he feels fantastic. His voice is getting stronger and stronger, as demonstrated by the 8-10 times a day he calls me with things he wants me to do, dictating new scripts for the Airgun Academy videos, blogs, blog answers, his Shotgun News column, etc. It’s obvious that he’s suffering from airgun withdrawal and needs to immerse himself in things.

Announcement: Just a reminder that Pyramyd Air is having an airgun garage sale on June 5. They’ve extended the hours, so now it’s being held from 10 am to 3 pm. They keeping adding more stuff to the sale pile, so they wanted to give everyone more time to look around.


Pyramyd Air is raffling off this Benjamin Trail NP XL in .22 caliber. Tickets are available at the 3rd Annual Garage Sale.

Speaking of the garage sale, don’t forget that Pyramyd Air is raffling off a gun that Crosman is donating, a Benjamin Trail NP XL rifle in .22 caliber. Raffle tickets are $1 each or 6 for $5, with proceeds going to Warrensville Heights Economic Development.

Now, on to today’s blog.

In the past few days, we’ve done some interesting experiments with pellet weight variation, and some eyes have been opened for sure. You’re now discovering what I knew when I competed in field target in the 1990s. Pellet weights vary and there’s nothing you can do about it.

For general use, it doesn’t really matter. If you’re shooting at pop cans or even bottle caps, a variation of five-tenths of a grain won’t matter that much. But, if you’re trying to shoot competitively, like field target at different ranges, then pellet variation is your enemy.

Before every match, I used to weight-sort my pellets. I shot a Daystate Harrier, and I shot it with Crosman 10.5-grain Premiers and later with Beeman Kodiaks, which weighed 10.65 grains. But, when I would weight-sort the pellets out of the box or tin, I would get many piles of pellets that weighed a tenth of a grain different. The Premiers, for example, most commonly weighed 10.4 grains. I might get as many as 40% of a box of Premiers at that weight. So, that becomes the group of pellets I would compete with. Those would be transferred into a tin, where they were oiled before loading into the gun.

When I competed, the Kodiaks also varied in weight, though not as much as the Premiers. The largest number of pellets at any one weight usually was 10.6 grains. I found that by sorting pellets by weight, my groups shrank significantly, and I could count on 2 or 3 extra points every match. That’s what matters, and that’s why we sort our pellets by weight.

If we hadn’t done the experiments, many of you would have never believed that pellets vary as widely as they do. Some of you are still discovering that even premium pellets can vary by a huge margin. Also, we note that over time, manufacturers’ tolerances tend to change and the average pellet weight may not agree with what’s on the tin. So, the prudent competitor trusts no one and verifies the pellet weight himself.

Manufacturing: How accurate?
During the M1 Carbine production program, one firm was heat-treating receivers on the basis of their color outside the furnace. It seemed as though the production personnel were able to very closely estimate the temperature of the metal based on the color. To speed things up, the plant dropped their thermocouple measuring test and allowed their employees to estimate receiver temperature by color. When the government finally caught the problem, they discovered that people guessing the temperature were actually off by 75 degrees. A tolerance variation that was enough to reject tens of thousands of receivers. So, don’t think that manufacturing is ever that precise. The tests we’ve done have demonstrated that it’s not.

Zero defects
Years ago, there were programs called “zero defects.” That means something does not depart from the specifications in any way. No manufacturing process can guarantee zero defects. It’s simply impossible. The only way you can have a true zero defects program is to inspect 100% of the products and sort for acceptance on that basis. When you weigh pellets, that’s what you’re doing.

10-meter shooting
Don’t worry about weighing pellets if you’re a 10-meter shooter. The distance is always the same, plus it’s so close to the muzzle that weight variation has little or no influence on accuracy.

To weigh or not to weigh
If you’re shooting just for fun, forget sorting pellets by weight. It isn’t necessary. But when you want the absolute most accuracy you can get from a particular gun and pellet and when the range stretches out past 25-30 yards, then definitely sort your pellets by weight.

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