These are clips for the Remington 8 and 81 self loading rifles. I have had help in identifying them from Bob Taylor and Peter Mackinven, thanks to both of you. The markings on the clips refer to the calibre .25, .30. .32 and .35 Remington cartridges introduced for the Model 8 in 1906. The rifle design was improved to produce the model 81 in about 1936, when .300 Savage was added to the range, and discontinued around 1951. The clip for .35 Rem/.300 Savage has a wider stop than the one for the 25-30-32 calibres. This is because the latter clip is shorter end to end (the cartridges are of smaller head diameter), thus the 35 clip has to have a wider stop to prevent it from entering too far into the receiver, which is identical for all calibers. This variation is true for all the variants of these clips.
The brass clips are standard production up to about 1940; the slots in the ends are so the sides can be nipped slightly inwards to provide extra grip to the cartridges. The flat steel clip is late Remington production, probably post-1940 and a similar one was made for the larger calibres and will be marked for 300 and 35 calibre but I don