Pellet head size

5.53 in .22 works for me

Lets think on this ...

Pellets can't take as much "squeezing down" as bullets undergo during shooting. Pressures in the guns are just so much less that it robs a lot of energy trying to extrude the pellet into the rifling. So that's one problem with pellets that are too large. By the same token, pressures being so much less in an AG you can hardly afford to shoot a pellet that does not seal the bore (never mind how badly they will shoot).

Now with that problem in mind consider that a spring rifle generates a lot of heat in the chamber at the moment of firing while a PCP generates a lot of cooling in the chamber at that time. I have never seen a comparison of the pressures generated by my suspicion is that spring rifles generate higher pressures than PCPs at the moment when the pellet is being forced into the bore by the expanding gasses. I have no evidence for this, it is my suspicion.

A thin skirt will likely more readily form a good seal for the gasses pushing the pellet down the bore. A thicker skirt may well need to be forced into the bore with a tool before the shot (in the case of springers) or require more cocking effort in the case of magazine fed rifles. The same would also be true of softer vs harder alloys.

So it is complicated, and worse than that I am no authority, I'm just some clown pretending I have a clue.

My experience tells me that I have the best luck shooting larger diameter pellets made of softer lead with thinner skirts. It also suggests to me that the assumptions I have made above are true. I usually start by finding a pellet weight that shoots well in my rifle and then dial in head size. First figure out the weight the gun likes to shoot (and with PCPs that's going to vary more than with springers). Then figure out which head size works best in your rifle. I usually start with the largest and buy 4 tins in that pellet which shot best in the first part of testing. As soon as I find a pellet that meets what I expect from the rifle, I buy a minimum of 4 tins in that head size.

Good luck.

Whenever in doubt always go the bigger size because you can always size them down but not the opposite way around.

There is always variety of head sizes within a given tin of pellets. If you have a tin of pellets that shoot really well, measure the head size.

You can then sort out the head sizes from every tin going forward. Buy a pelletgage.

https://pelletgage.com/

I find that pellet head size makes a huge difference in my rifles. My Weihrauch 97/77 spring rifles show a strong preference for 5.53 mm while my AA 410 and Daystate RW prefer 5.52. You just have to shoot a variety of pellets and groups to figure out which one your rifle likes best. There is no short cut.

My observations have been that so long as the head is large enough to engage the rifling, it has as much opportunity to group well as any other.

I have found no barrels that needed a specific head size down to the hundredths of a mm. That’s not to say there aren’t barrels with, say, an oversized bore that need pellets on the upper end of the size spectrum, just that a specific size like 5.53mm will not be needed.

Once the head is big enough to “ride the rails” of the rifling, it’s big enough. Then the rest is up to whether the pellets are consistent and the barrel happens to like them.

Being so large that the head is sized down by the groove diameter is as bad for accuracy as a pellet that is too small in my experience.

If were talking about Magnum springers go with the larger head. My chronograph data shooting my RWS 34 and Sig ASP20 have shown better power with the larger heads. Accuracy also seems a little better or the same. Looser fitting pellets start moving down the bore before the piston has reached the end of it's compression stroke. EXAMPLE. I tried some JSB 14.35gr domes in my .22cal M34 and they are just way to loose ! Fired three shots over the chrony for an average of 660 fps. The same rifle shoots 14.5 gr Superdomes at 740 fps. The accuracy with these is fair to good. The skirts are large but the heads are kind of loose on the Superdome. The 14.66gr H&N FTT with the 5.54mm has good accuracy and power at 725 fps. So far, the most accurate and highest velocity I've gotten with my M34 was with the 14.5gr Sig Venom lead pellet. Not sure of the head diameter but they fit like the H&N FTT. These average 747 fps. 

My Sig results are nearly similar. The JSB 14.35 gr get about 822 fps while with snugger fitting H&N 14.7gr pellets get me up to 840+ fps. The JSB's are not that accurate in the Sig. Kind of strange but the H&N's are not that accurate either. Can't figure out why ?? Yet, the 14.5 gr Sig Venom's are very accurate. Go figure ?? They also average in the 840's for velocity. Bottom line....stick with tighter pellets in your magnum springer.

I also have a RWS 34 in .177cal. The 8.44gr JSB's with the 4.52mm head average 912 fps. The 4.53mm head version shoot 925 fps and the accuracy is the same as the 4.52mm head.

My FX Crown .22 with factory barrel like JSB 18.1 sized to 5.52. I also have a 5.50 sizer, they did not have a 5.51 when I ordered them. If I only do one I believe I‘ve noticed more grouping consistency with sizing than with weighing across all variety of pellets I have experimented with. 

I wonder since lead is soft are there materials for 3D printers that could accurately make sizing dyes that would last and to the 1/100th of a mm.

Oledawg,

Question, If a guy wanted to make a pellet sizer, do you just drill a hole followed by the correct sized Reemer?

CAD 3D Metal printer needed. If you drill a hole followed by a reamer won't it be a tad too large? Unless you go a hair smaller I guess. Only trial and error will tell you the truth. Start small then work your way up. Or just go and drill a buffet of holes of varying sizes all at once then ream chase them all. Run pellets through all of them as your test bed. Shoot and know which one works best for that particular gun. I would think cast iron or stainless steel would be better than brass or aluminum for longevity sake.

Pellet sizer from TBT. I use the 4.52mm sizer.

http://www.airrifletuning.com/products/tbt-pellet-sizers/

They might not have any in stock.

I made a sizer and dies for use with the .22cal. Dies were made on a lathe using a #4 tapered pencil reamer. The pellets drop into die about half way before getting pushed through the die to the finished size. Made them out of brass and cold rolled steel.

FYI pellet skirts are deliberately 7 - 10 thousandths over the nominal caliber so as to minimize blow-by. Therefore running pellets completely through a sizer is generally not desirable. 

I'm all about JSB pellets. However, I can almost assure you that no matter what head size you order, there will be little rhyme or reason to the pellets in the tins.

I have noticed pellets sized all the way head and skirt has a difference in springers more than PCPs and have experienced better accuracy in some but not all guns. HW springers liked sized pellets the most. Specifically 0.1785 using the old Beeman Pell sizer and tried all sizes and all calibers and this one stood out the most.

FYI pellet skirts are deliberately 7 - 10 thousandths over the nominal caliber so as to minimize blow-by. Therefore running pellets completely through a sizer is generally not desirable.

Click to expand...

I realize that. But some - like the Superdome - have even larger skirts than many of the others. Sizing the skirt slightly is beneficial because of microscopic flaws in the skirt edge. Not only that, sizing gets rid of slightly oval shaped skirt that you may not notice with the naked eye.